#Topic Canvas #Alias Canvas_Reference #Class SkCanvas Canvas provides an interface for drawing, and how the drawing is clipped and transformed. Canvas contains a stack of Matrix and Clip values. Canvas and Paint together provide the state to draw into Surface or Device. Each Canvas draw call transforms the geometry of the object by the concatenation of all Matrix values in the stack. The transformed geometry is clipped by the intersection of all of Clip values in the stack. The Canvas draw calls use Paint to supply drawing state such as Color, Typeface, text size, stroke width, Shader and so on. To draw to a pixel-based destination, create Raster_Surface or GPU_Surface. Request Canvas from Surface to obtain the interface to draw. Canvas generated by Raster_Surface draws to memory visible to the CPU. Canvas generated by GPU_Surface uses Vulkan or OpenGL to draw to the GPU. To draw to a document, obtain Canvas from SVG_Canvas, Document_PDF, or Picture_Recorder. Document based Canvas and other Canvas Subclasses reference Device describing the destination. Canvas can be constructed to draw to Bitmap without first creating Raster_Surface. This approach may be deprecated in the future. #Topic Overview #Subtopic Subtopics #Table #Legend # topics # description ## #Legend ## #ToDo generate a TOC here ## #Table ## #Subtopic ## #Subtopic Constants #Table #Legend # constants # description ## #Legend ## # Lattice::Flags # Controls Lattice transparency. ## # PointMode # Sets drawPoints options. ## # SaveLayerFlags # Sets SaveLayerRec options. ## # SrcRectConstraint # Sets drawImageRect options. ## #Table ## #Subtopic ## #Subtopic Structs #Table #Legend # struct # description ## #Legend ## # Lattice # Divides Bitmap, Image into a rectangular grid. ## # SaveLayerRec # Contains state to create Layer. ## #Table ## #Subtopic ## #Subtopic Constructors Create the desired type of Surface to obtain its Canvas when possible. Constructors are useful when no Surface is required, and some helpers implicitly create Raster_Surface. #Table #Legend # # description ## #Legend ## # SkCanvas() # No Surface, no dimensions. ## # SkCanvas(int width, int height, const SkSurfaceProps* props = nullptr) # No Surface, set dimensions, Surface_Properties. ## # SkCanvas(SkBaseDevice* device) # Existing Device. (SkBaseDevice is private.) ## # SkCanvas(const SkBitmap& bitmap) # Uses existing Bitmap. ## # SkCanvas(const SkBitmap& bitmap, const SkSurfaceProps& props) # Uses existing Bitmap and Surface_Properties. ## # MakeRasterDirect # Creates from SkImageInfo and Pixel_Storage. ## # MakeRasterDirectN32 # Creates from image data and Pixel_Storage. ## #Table ## #Subtopic ## #Subtopic Member_Functions #Table #Legend # function # description ## #Legend ## # accessTopLayerPixels # Returns writable pixel access if available. ## # accessTopRasterHandle # Returns context that tracks Clip and Matrix. ## # clear() # Fills Clip with Color. ## # clipPath # Combines Clip with Path. ## # clipRRect # Combines Clip with Round_Rect. ## # clipRect # Combines Clip with Rect. ## # clipRegion # Combines Clip with Region. ## # concat() # Multiplies Matrix by Matrix. ## # discard() # Makes Canvas contents undefined. ## # drawAnnotation # Associates a Rect with a key-value pair.## # drawArc # Draws Arc using Clip, Matrix, and Paint.## # drawAtlas # Draws sprites using Clip, Matrix, and Paint.## # drawBitmap # Draws Bitmap at (x, y) position. ## # drawBitmapLattice # Draws proportionally stretched Bitmap. ## # drawBitmapNine # Draws Nine_Patch Bitmap. ## # drawBitmapRect # Draws Bitmap, source Rect to destination Rect. ## # drawCircle # Draws Circle using Clip, Matrix, and Paint. ## # drawColor # Fills Clip with Color and Blend_Mode. ## # drawDRRect # Draws double Round_Rect stroked or filled. ## # drawDrawable # Draws Drawable, encapsulated drawing commands. ## # drawIRect # Draws IRect using Clip, Matrix, and Paint. ## # drawImage # Draws Image at (x, y) position. ## # drawImageLattice # Draws proportionally stretched Image. ## # drawImageNine # Draws Nine_Patch Image. ## # drawImageRect # Draws Image, source Rect to destination Rect. ## # drawLine # Draws line segment between two points.## # drawOval # Draws Oval using Clip, Matrix, and Paint. ## # drawPaint # Fills Clip with Paint. ## # drawPatch # Draws Coons_Patch. ## # drawPath # Draws Path using Clip, Matrix, and Paint. ## # drawPicture # Draws Picture using Clip and Matrix. ## # drawPoint # Draws point at (x, y) position. ## # drawPoints # Draws array as points, lines, polygon. ## # drawPosText # Draws text at array of (x, y) positions. ## # drawPosTextH # Draws text at x positions with common baseline. ## # drawRRect # Draws Round_Rect using Clip, Matrix, and Paint. ## # drawRect # Draws Rect using Clip, Matrix, and Paint. ## # drawRegion # Draws Region using Clip, Matrix, and Paint. ## # drawRoundRect # Draws Round_Rect using Clip, Matrix, and Paint. ## # drawText # Draws text at (x, y), using font advance. ## # drawTextBlob # Draws text with arrays of positions and Paint. ## # drawTextOnPath # Draws text following Path contour. ## # drawTextOnPathHV # Draws text following Path with offsets. ## # drawTextRSXform # Draws text with array of RSXform. ## # drawString # Draws null terminated string at (x, y) using font advance. ## # drawVertices # Draws Vertices, a triangle mesh. ## # flush() # Triggers execution of all pending draw operations. ## # getBaseLayerSize # Gets size of base Layer in global coordinates. ## # getDeviceClipBounds # Returns IRect bounds of Clip. ## # getDrawFilter # Legacy; to be deprecated. ## # getGrContext # Returns GPU_Context of the GPU_Surface. ## # getLocalClipBounds # Returns Clip bounds in source coordinates. ## # getMetaData # Associates additional data with the canvas. ## # getProps # Copies Surface_Properties if available. ## # getSaveCount # Returns depth of stack containing Clip and Matrix. ## # getTotalMatrix # Returns Matrix. ## # imageInfo # Returns Image_Info for Canvas. ## # isClipEmpty # Returns if Clip is empty. ## # isClipRect # Returns if Clip is Rect and not empty. ## # MakeRasterDirect # Creates Canvas from SkImageInfo and pixel data. ## # MakeRasterDirectN32 # Creates Canvas from image specifications and pixel data. ## # makeSurface # Creates Surface matching SkImageInfo and SkSurfaceProps. ## # peekPixels # Returns if Canvas has direct access to its pixels. ## # quickReject # Returns if Rect is outside Clip. ## # readPixels # Copies and converts rectangle of pixels from Canvas. ## # resetMatrix # Resets Matrix to identity. ## # restore() # Restores changes to Clip and Matrix, pops save stack. ## # restoreToCount # Restores changes to Clip and Matrix to given depth. ## # rotate() # Rotates Matrix. ## # save() # Saves Clip and Matrix on stack. ## # saveLayer # Saves Clip and Matrix on stack; creates Layer. ## # saveLayerAlpha # Saves Clip and Matrix on stack; creates Layer; sets opacity. ## # saveLayerPreserveLCDTextRequests # Saves Clip and Matrix on stack; creates Layer for LCD text. ## # scale() # Scales Matrix. ## # setAllowSimplifyClip # Experimental. ## # setDrawFilter # Legacy; to be deprecated. ## # setMatrix # Sets Matrix. ## # skew() # Skews Matrix. # # translate() # Translates Matrix. ## # writePixels # Copies and converts rectangle of pixels to Canvas. ## #Table ## #Subtopic ## #Topic Overview ## # ------------------------------------------------------------------------------ #Method static std::unique_ptr MakeRasterDirect(const SkImageInfo& info, void* pixels, size_t rowBytes, const SkSurfaceProps* props = nullptr) Allocates raster Canvas that will draw directly into pixels. Canvas is returned if all parameters are valid. Valid parameters include: info dimensions are zero or positive; info contains Image_Color_Type and Image_Alpha_Type supported by Raster_Surface; pixels is not nullptr; rowBytes is zero or large enough to contain info width pixels of Image_Color_Type. Pass zero for rowBytes to compute rowBytes from info width and size of pixel. If rowBytes is greater than zero, it must be equal to or greater than info width times bytes required for Image_Color_Type. Pixel buffer size should be info height times computed rowBytes. Pixels are not initialized. To access pixels after drawing, call flush() or peekPixels. #Param info width, height, Image_Color_Type, Image_Alpha_Type, Color_Space, of Raster_Surface; width, or height, or both, may be zero ## #Param pixels pointer to destination pixels buffer ## #Param rowBytes interval from one Surface row to the next, or zero ## #Param props LCD striping orientation and setting for device independent fonts; may be nullptr ## #Return Canvas if all parameters are valid; otherwise, nullptr ## #Example #Description Allocates a three by three bitmap, clears it to white, and draws a black pixel in the center. ## void draw(SkCanvas* ) { SkImageInfo info = SkImageInfo::MakeN32Premul(3, 3); // device aligned, 32 bpp, Premultiplied const size_t minRowBytes = info.minRowBytes(); // bytes used by one bitmap row const size_t size = info.computeMinByteSize(); // bytes used by all rows SkAutoTMalloc storage(size); // allocate storage for pixels SkPMColor* pixels = storage.get(); // get pointer to allocated storage // create a SkCanvas backed by a raster device, and delete it when the // function goes out of scope. std::unique_ptr canvas = SkCanvas::MakeRasterDirect(info, pixels, minRowBytes); canvas->clear(SK_ColorWHITE); // white is Unpremultiplied, in ARGB order canvas->flush(); // ensure that pixels are cleared SkPMColor pmWhite = pixels[0]; // the Premultiplied format may vary SkPaint paint; // by default, draws black canvas->drawPoint(1, 1, paint); // draw in the center canvas->flush(); // ensure that point was drawn for (int y = 0; y < info.height(); ++y) { for (int x = 0; x < info.width(); ++x) { SkDebugf("%c", *pixels++ == pmWhite ? '-' : 'x'); } SkDebugf("\n"); } } #StdOut --- -x- --- ## ## #SeeAlso MakeRasterDirectN32 SkSurface::MakeRasterDirect ## # ------------------------------------------------------------------------------ #Method static std::unique_ptr MakeRasterDirectN32(int width, int height, SkPMColor* pixels, size_t rowBytes) Allocates raster Canvas specified by inline image specification. Subsequent Canvas calls draw into pixels. Image_Color_Type is set to kN32_SkColorType. Image_Alpha_Type is set to kPremul_SkAlphaType. To access pixels after drawing, call flush() or peekPixels. Canvas is returned if all parameters are valid. Valid parameters include: width and height are zero or positive; pixels is not nullptr; rowBytes is zero or large enough to contain width pixels of kN32_SkColorType. Pass zero for rowBytes to compute rowBytes from width and size of pixel. If rowBytes is greater than zero, it must be equal to or greater than width times bytes required for Image_Color_Type. Pixel buffer size should be height times rowBytes. #Param width pixel column count on Raster_Surface created; must be zero or greater ## #Param height pixel row count on Raster_Surface created; must be zero or greater ## #Param pixels pointer to destination pixels buffer; buffer size should be height times rowBytes ## #Param rowBytes interval from one Surface row to the next, or zero ## #Return Canvas if all parameters are valid; otherwise, nullptr ## #Example #Description Allocates a three by three bitmap, clears it to white, and draws a black pixel in the center. ## void draw(SkCanvas* ) { const int width = 3; const int height = 3; SkPMColor pixels[height][width]; // allocate a 3x3 Premultiplied bitmap on the stack // create a SkCanvas backed by a raster device, and delete it when the // function goes out of scope. std::unique_ptr canvas = SkCanvas::MakeRasterDirectN32( width, height, pixels[0], // top-left of the bitmap sizeof(pixels[0])); // byte width of the each row // write a premultiplied value for white into all pixels in the bitmap canvas->clear(SK_ColorWHITE); SkPMColor pmWhite = pixels[0][0]; // the Premultiplied format may vary SkPaint paint; // by default, draws black canvas->drawPoint(1, 1, paint); // draw in the center canvas->flush(); // ensure that pixels is ready to be read for (int y = 0; y < height; ++y) { for (int x = 0; x < width; ++x) { SkDebugf("%c", pixels[y][x] == pmWhite ? '-' : 'x'); } SkDebugf("\n"); } } #StdOut --- -x- --- ## ## #SeeAlso MakeRasterDirect SkSurface::MakeRasterDirect SkImageInfo::MakeN32Premul ## # ------------------------------------------------------------------------------ #Method SkCanvas() Creates an empty Canvas with no backing device or pixels, with a width and height of zero. #Return empty Canvas ## #Example #Description Passes a placeholder to a function that requires one. ## #Function // Returns true if either the canvas rotates the text by 90 degrees, or the paint does. static void check_for_up_and_down_text(const SkCanvas* canvas, const SkPaint& paint) { bool paintHasVertical = paint.isVerticalText(); const SkMatrix& matrix = canvas->getTotalMatrix(); bool matrixIsVertical = matrix.preservesRightAngles() && !matrix.isScaleTranslate(); SkDebugf("paint draws text %s\n", paintHasVertical != matrixIsVertical ? "top to bottom" : "left to right"); } static void check_for_up_and_down_text(const SkPaint& paint) { SkCanvas canvas; // placeholder only, does not have an associated device check_for_up_and_down_text(&canvas, paint); } ## void draw(SkCanvas* canvas) { SkPaint paint; check_for_up_and_down_text(paint); // paint draws text left to right paint.setVerticalText(true); check_for_up_and_down_text(paint); // paint draws text top to bottom paint.setVerticalText(false); canvas->rotate(90); check_for_up_and_down_text(canvas, paint); // paint draws text top to bottom } #StdOut paint draws text left to right paint draws text top to bottom paint draws text top to bottom ## ## #SeeAlso MakeRasterDirect SkRasterHandleAllocator::MakeCanvas SkSurface::getCanvas SkCreateColorSpaceXformCanvas ## # ------------------------------------------------------------------------------ #Method SkCanvas(int width, int height, const SkSurfaceProps* props = nullptr) Creates Canvas of the specified dimensions without a Surface. Used by Subclasses with custom implementations for draw methods. If props equals nullptr, Surface_Properties are created with Surface_Properties_Legacy_Font_Host settings, which choose the pixel striping direction and order. Since a platform may dynamically change its direction when the device is rotated, and since a platform may have multiple monitors with different characteristics, it is best not to rely on this legacy behavior. #Param width zero or greater ## #Param height zero or greater ## #Param props LCD striping orientation and setting for device independent fonts; may be nullptr ## #Return Canvas placeholder with dimensions ## #Example SkCanvas canvas(10, 20); // 10 units wide, 20 units high canvas.clipRect(SkRect::MakeXYWH(30, 40, 5, 10)); // clip is outside canvas' device SkDebugf("canvas %s empty\n", canvas.getDeviceClipBounds().isEmpty() ? "is" : "is not"); #StdOut canvas is empty ## ## #SeeAlso MakeRasterDirect SkSurfaceProps SkPixelGeometry SkCreateColorSpaceXformCanvas ## # ------------------------------------------------------------------------------ #Method explicit SkCanvas(SkBaseDevice* device) Construct a canvas that draws into device. Used by child classes of SkCanvas. #ToDo Since SkBaseDevice is private, shouldn't this be private also? ## #Param device specifies a device for the canvas to draw into ## #Return Canvas that can be used to draw into device ## #Example #Error "Unsure how to create a meaningful example." SkPDFCanvas::SkPDFCanvas(const sk_sp& dev) : SkCanvas(dev.get()) {} ## #ToDo either remove doc or figure out a way to fiddle it ## #SeeAlso MakeRasterDirect SkRasterHandleAllocator::MakeCanvas SkSurface::getCanvas SkCreateColorSpaceXformCanvas ## # ------------------------------------------------------------------------------ #Method explicit SkCanvas(const SkBitmap& bitmap) Construct a canvas that draws into bitmap. Sets SkSurfaceProps::kLegacyFontHost_InitType in constructed Surface. Bitmap is copied so that subsequently editing bitmap will not affect constructed Canvas. May be deprecated in the future. #ToDo Should be deprecated? ## #Param bitmap width, height, Image_Color_Type, Image_Alpha_Type, and pixel storage of Raster_Surface ## #Return Canvas that can be used to draw into bitmap ## #Example #Description The actual output depends on the installed fonts. ## SkBitmap bitmap; // create a bitmap 5 wide and 11 high bitmap.allocPixels(SkImageInfo::MakeN32Premul(5, 11)); SkCanvas canvas(bitmap); canvas.clear(SK_ColorWHITE); // white is Unpremultiplied, in ARGB order SkPixmap pixmap; // provides guaranteed access to the drawn pixels if (!canvas.peekPixels(&pixmap)) { SkDebugf("peekPixels should never fail.\n"); } const SkPMColor* pixels = pixmap.addr32(); // points to top-left of bitmap SkPMColor pmWhite = pixels[0]; // the Premultiplied format may vary SkPaint paint; // by default, draws black, 12 point text canvas.drawString("!", 1, 10, paint); // 1 char at baseline (1, 10) for (int y = 0; y < bitmap.height(); ++y) { for (int x = 0; x < bitmap.width(); ++x) { SkDebugf("%c", *pixels++ == pmWhite ? '-' : 'x'); } SkDebugf("\n"); } #StdOut ----- ---x- ---x- ---x- ---x- ---x- ---x- ----- ---x- ---x- ----- #StdOut ## ## #SeeAlso MakeRasterDirect SkRasterHandleAllocator::MakeCanvas SkSurface::getCanvas SkCreateColorSpaceXformCanvas ## #EnumClass ColorBehavior #Private Android framework only. ## #Code enum class ColorBehavior { kLegacy, }; ## #Const kLegacy 0 Is a placeholder to allow specialized constructor; has no meaning. ## ## #Method SkCanvas(const SkBitmap& bitmap, ColorBehavior behavior) #Private Android framework only. ## #Param bitmap specifies a bitmap for the canvas to draw into ## #Param behavior specializes this constructor; value is unused ## #Return Canvas that can be used to draw into bitmap ## #NoExample ## ## # ------------------------------------------------------------------------------ #Method SkCanvas(const SkBitmap& bitmap, const SkSurfaceProps& props) Construct a canvas that draws into bitmap. Use props to match the device characteristics, like LCD striping. bitmap is copied so that subsequently editing bitmap will not affect constructed Canvas. #Param bitmap width, height, Image_Color_Type, Image_Alpha_Type, and pixel storage of Raster_Surface ## #Param props order and orientation of RGB striping; and whether to use device independent fonts ## #Return Canvas that can be used to draw into bitmap ## #Example #Description The actual output depends on the installed fonts. ## SkBitmap bitmap; // create a bitmap 5 wide and 11 high bitmap.allocPixels(SkImageInfo::MakeN32Premul(5, 11)); SkCanvas canvas(bitmap, SkSurfaceProps(0, kUnknown_SkPixelGeometry)); canvas.clear(SK_ColorWHITE); // white is Unpremultiplied, in ARGB order SkPixmap pixmap; // provides guaranteed access to the drawn pixels if (!canvas.peekPixels(&pixmap)) { SkDebugf("peekPixels should never fail.\n"); } const SkPMColor* pixels = pixmap.addr32(); // points to top-left of bitmap SkPMColor pmWhite = pixels[0]; // the Premultiplied format may vary SkPaint paint; // by default, draws black, 12 point text canvas.drawString("!", 1, 10, paint); // 1 char at baseline (1, 10) for (int y = 0; y < bitmap.height(); ++y) { for (int x = 0; x < bitmap.width(); ++x) { SkDebugf("%c", *pixels++ == pmWhite ? '-' : 'x'); } SkDebugf("\n"); } #StdOut ----- ---x- ---x- ---x- ---x- ---x- ---x- ----- ---x- ---x- ----- #StdOut ## ## #SeeAlso MakeRasterDirect SkRasterHandleAllocator::MakeCanvas SkSurface::getCanvas SkCreateColorSpaceXformCanvas ## # ------------------------------------------------------------------------------ #Method virtual ~SkCanvas() Draw saved Layers, if any. Free up resources used by Canvas. #Example #Description Canvas Layer draws into bitmap. saveLayerAlpha sets up an additional drawing surface that blends with the bitmap. When Layer goes out of scope, Layer Destructor is called. The saved Layer is restored, drawing transparent letters. ## void draw(SkCanvas* canvas) { SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(200, 200)); { SkCanvas offscreen(bitmap); SkPaint paint; paint.setTextSize(100); offscreen.drawString("ABC", 20, 160, paint); SkRect layerBounds = SkRect::MakeXYWH(32, 32, 192, 192); offscreen.saveLayerAlpha(&layerBounds, 128); offscreen.clear(SK_ColorWHITE); offscreen.drawString("DEF", 20, 160, paint); } canvas->drawBitmap(bitmap, 0, 0, nullptr); } ## #SeeAlso State_Stack ## # ------------------------------------------------------------------------------ #Method SkMetaData& getMetaData() Returns storage to associate additional data with the canvas. The storage is freed when Canvas is deleted. #Return storage that can be read from and written to ## #Example const char* kHelloMetaData = "HelloMetaData"; SkCanvas canvas; SkMetaData& metaData = canvas.getMetaData(); SkDebugf("before: %s\n", metaData.findString(kHelloMetaData)); metaData.setString(kHelloMetaData, "Hello!"); SkDebugf("during: %s\n", metaData.findString(kHelloMetaData)); metaData.removeString(kHelloMetaData); SkDebugf("after: %s\n", metaData.findString(kHelloMetaData)); #StdOut before: (null) during: Hello! after: (null) #StdOut ## ## #SeeAlso SkMetaData ## # ------------------------------------------------------------------------------ #Method SkImageInfo imageInfo() const Returns Image_Info for Canvas. If Canvas is not associated with Raster_Surface or GPU_Surface, returned Image_Color_Type is set to kUnknown_SkColorType. #Return dimensions and Image_Color_Type of Canvas ## #Example SkCanvas emptyCanvas; SkImageInfo canvasInfo = emptyCanvas.imageInfo(); SkImageInfo emptyInfo; SkDebugf("emptyInfo %c= canvasInfo\n", emptyInfo == canvasInfo ? '=' : '!'); #StdOut emptyInfo == canvasInfo ## ## #SeeAlso SkImageInfo MakeRasterDirect makeSurface ## # ------------------------------------------------------------------------------ #Method bool getProps(SkSurfaceProps* props) const If Canvas is associated with Raster_Surface or GPU_Surface, copies Surface_Properties and returns true. Otherwise, return false and leave props unchanged. #Param props storage for writable SkSurfaceProps ## #Return true if Surface_Properties was copied ## #ToDo This seems old style. Deprecate? ## #Example SkBitmap bitmap; SkCanvas canvas(bitmap, SkSurfaceProps(0, kRGB_V_SkPixelGeometry)); SkSurfaceProps surfaceProps(0, kUnknown_SkPixelGeometry); SkDebugf("isRGB:%d\n", SkPixelGeometryIsRGB(surfaceProps.pixelGeometry())); if (!canvas.getProps(&surfaceProps)) { SkDebugf("getProps failed unexpectedly.\n"); } SkDebugf("isRGB:%d\n", SkPixelGeometryIsRGB(surfaceProps.pixelGeometry())); #StdOut isRGB:0 isRGB:1 #StdOut ## ## #SeeAlso SkSurfaceProps makeSurface ## # ------------------------------------------------------------------------------ #Method void flush() Triggers the immediate execution of all pending draw operations. If Canvas is associated with GPU_Surface, resolves all pending GPU operations. If Canvas is associated with Raster_Surface, has no effect; raster draw operations are never deferred. #ToDo In an overview section on managing the GPU, include: - flush should never change what is drawn - call to kick off gpu work - calling too much impacts performance - some calls (peekPixels, prepareForExternalIO) call it internally - canvas call is local, GrContext::flush is global - diffentiate between flush, flushAndSignalSemaphores - normally never needs to be called - call it when sharing gpu resources, feeling memory pressure, swapping out app, and before abandoning context - also call to say "I'm finished drawing here", e.g., when drawing to a GPU-backed offscreen surface (created with SkSurface::MakeRenderTarget) for posterity: this doesn't show a difference: fiddle.skia.org/c/@flushfail ## #Example #Error "haven't thought of a useful example to put here" ## #SeeAlso peekPixels SkSurface::flush() GrContext::flush() SkSurface::prepareForExternalIO GrContext::abandonContext() ## # ------------------------------------------------------------------------------ #Method virtual SkISize getBaseLayerSize() const Gets the size of the base or root Layer in global canvas coordinates. The origin of the base Layer is always (0,0). The area available for drawing may be smaller (due to clipping or saveLayer). #Return integral width and height of base Layer ## #Example SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(20, 30)); SkCanvas canvas(bitmap, SkSurfaceProps(0, kUnknown_SkPixelGeometry)); canvas.clipRect(SkRect::MakeWH(10, 40)); SkIRect clipDeviceBounds = canvas.getDeviceClipBounds(); if (clipDeviceBounds.isEmpty()) { SkDebugf("Empty clip bounds is unexpected!\n"); } SkDebugf("clip=%d,%d\n", clipDeviceBounds.width(), clipDeviceBounds.height()); SkISize baseLayerSize = canvas.getBaseLayerSize(); SkDebugf("size=%d,%d\n", baseLayerSize.width(), baseLayerSize.height()); #StdOut clip=10,30 size=20,30 ## ## #ToDo is this the same as the width and height of surface? ## #SeeAlso getDeviceClipBounds ## # ------------------------------------------------------------------------------ #Method sk_sp makeSurface(const SkImageInfo& info, const SkSurfaceProps* props = nullptr) Creates Surface matching info and props, and associates it with Canvas. Returns nullptr if no match found. If props is nullptr, matches Surface_Properties in Canvas. If props is nullptr and Canvas does not have Surface_Properties, creates Surface with default Surface_Properties. #Param info width, height, Image_Color_Type, Image_Alpha_Type, and Color_Space ## #Param props Surface_Properties to match; may be nullptr to match Canvas ## #Return Surface matching info and props, or nullptr if no match is available ## #Example sk_sp surface = SkSurface::MakeRasterN32Premul(5, 6); SkCanvas* smallCanvas = surface->getCanvas(); SkImageInfo imageInfo = SkImageInfo::MakeN32Premul(3, 4); sk_sp compatible = smallCanvas->makeSurface(imageInfo); SkDebugf("compatible %c= nullptr\n", compatible == nullptr ? '=' : '!'); SkDebugf("size = %d, %d\n", compatible->width(), compatible->height()); #StdOut compatible != nullptr size = 3, 4 ## ## #SeeAlso SkSurface SkSurface::makeSurface SkImageInfo SkSurfaceProps ## # ------------------------------------------------------------------------------ #Method virtual GrContext* getGrContext() Returns GPU_Context of the GPU_Surface associated with Canvas. #Return GPU_Context, if available; nullptr otherwise ## #Example void draw(SkCanvas* canvas) { if (canvas->getGrContext()) { canvas->clear(SK_ColorRED); } else { canvas->clear(SK_ColorBLUE); } } ## #ToDo fiddle should show both CPU and GPU out ## #SeeAlso GrContext ## # ------------------------------------------------------------------------------ #Method void* accessTopLayerPixels(SkImageInfo* info, size_t* rowBytes, SkIPoint* origin = nullptr) Returns the pixel base address, Image_Info, rowBytes, and origin if the pixels can be read directly. The returned address is only valid while Canvas is in scope and unchanged. Any Canvas call or Surface call may invalidate the returned address and other returned values. If pixels are inaccessible, info, rowBytes, and origin are unchanged. #Param info storage for writable pixels' Image_Info; may be nullptr ## #Param rowBytes storage for writable pixels' row bytes; may be nullptr ## #Param origin storage for Canvas top Layer origin, its top-left corner; may be nullptr ## #Return address of pixels, or nullptr if inaccessible ## #Example void draw(SkCanvas* canvas) { if (canvas->accessTopLayerPixels(nullptr, nullptr)) { canvas->clear(SK_ColorRED); } else { canvas->clear(SK_ColorBLUE); } } ## #Example #Description Draws "ABC" on the device. Then draws "DEF" in Layer, and reads Layer to add a large dotted "DEF". Finally blends Layer with the device. The Layer and blended result appear on the CPU and GPU but the large dotted "DEF" appear only on the CPU. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setTextSize(100); canvas->drawString("ABC", 20, 160, paint); SkRect layerBounds = SkRect::MakeXYWH(32, 32, 192, 192); canvas->saveLayerAlpha(&layerBounds, 128); canvas->clear(SK_ColorWHITE); canvas->drawString("DEF", 20, 160, paint); SkImageInfo imageInfo; size_t rowBytes; SkIPoint origin; uint32_t* access = (uint32_t*) canvas->accessTopLayerPixels(&imageInfo, &rowBytes, &origin); if (access) { int h = imageInfo.height(); int v = imageInfo.width(); int rowWords = rowBytes / sizeof(uint32_t); for (int y = 0; y < h; ++y) { int newY = (y - h / 2) * 2 + h / 2; if (newY < 0 || newY >= h) { continue; } for (int x = 0; x < v; ++x) { int newX = (x - v / 2) * 2 + v / 2; if (newX < 0 || newX >= v) { continue; } if (access[y * rowWords + x] == SK_ColorBLACK) { access[newY * rowWords + newX] = SK_ColorGRAY; } } } } canvas->restore(); } ## #ToDo there are no callers of this that I can find. Deprecate? ## #ToDo fiddle should show both CPU and GPU out ## #SeeAlso SkImageInfo SkPixmap ## # ------------------------------------------------------------------------------ #Method SkRasterHandleAllocator::Handle accessTopRasterHandle() const Returns custom context that tracks the Matrix and Clip. Use Raster_Handle_Allocator to blend Skia drawing with custom drawing, typically performed by the host platform user interface. The custom context returned is generated by SkRasterHandleAllocator::MakeCanvas, which creates a custom canvas with raster storage for the drawing destination. #Return context of custom allocation ## #Example #Description #ToDo ## ## #Function static void DeleteCallback(void*, void* context) { delete (char*) context; } class CustomAllocator : public SkRasterHandleAllocator { public: bool allocHandle(const SkImageInfo& info, Rec* rec) override { char* context = new char[4]{'s', 'k', 'i', 'a'}; rec->fReleaseProc = DeleteCallback; rec->fReleaseCtx = context; rec->fHandle = context; rec->fPixels = context; rec->fRowBytes = 4; return true; } void updateHandle(Handle handle, const SkMatrix& ctm, const SkIRect& clip_bounds) override { // apply canvas matrix and clip to custom environment } }; ## void draw(SkCanvas* canvas) { const SkImageInfo info = SkImageInfo::MakeN32Premul(1, 1); std::unique_ptr c2 = SkRasterHandleAllocator::MakeCanvas(std::unique_ptr( new CustomAllocator()), info); char* context = (char*) c2->accessTopRasterHandle(); SkDebugf("context = %.4s\n", context); } #StdOut context = skia ## #ToDo skstd::make_unique could not be used because def is private -- note to fix in c++14? ## ## #SeeAlso SkRasterHandleAllocator ## # ------------------------------------------------------------------------------ #Method bool peekPixels(SkPixmap* pixmap) Returns true if Canvas has direct access to its pixels. Pixels are readable when Device is raster. Pixels are not readable when Canvas is returned from GPU_Surface, returned by SkDocument::beginPage, returned by SkPictureRecorder::beginRecording, or Canvas is the base of a utility class like SkDumpCanvas. pixmap is valid only while Canvas is in scope and unchanged. Any Canvas or Surface call may invalidate the pixmap values. #Param pixmap storage for pixel state if pixels are readable; otherwise, ignored ## #Return true if Canvas has direct access to pixels ## #Example SkPixmap pixmap; if (canvas->peekPixels(&pixmap)) { SkDebugf("width=%d height=%d\n", pixmap.bounds().width(), pixmap.bounds().height()); } #StdOut width=256 height=256 ## ## #SeeAlso readPixels SkBitmap::peekPixels SkImage::peekPixels SkSurface::peekPixels ## # ------------------------------------------------------------------------------ #Method bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX, int srcY) Copies Rect of pixels from Canvas into dstPixels. Matrix and Clip are ignored. Source Rect corners are (srcX, srcY) and (imageInfo().width(), imageInfo().height()). Destination Rect corners are (0, 0) and (dstInfo.width(), dstInfo.height()). Copies each readable pixel intersecting both rectangles, without scaling, converting to dstInfo.colorType() and dstInfo.alphaType() if required. Pixels are readable when Device is raster, or backed by a GPU. Pixels are not readable when SkCanvas is returned by SkDocument::beginPage, returned by SkPictureRecorder::beginRecording, or Canvas is the base of a utility class like SkDumpCanvas. The destination pixel storage must be allocated by the caller. Pixel values are converted only if Image_Color_Type and Image_Alpha_Type do not match. Only pixels within both source and destination rectangles are copied. dstPixels contents outside Rect intersection are unchanged. Pass negative values for srcX or srcY to offset pixels across or down destination. Does not copy, and returns false if: #List # Source and destination rectangles do not intersect. ## # Canvas pixels could not be converted to dstInfo.colorType() or dstInfo.alphaType(). ## # Canvas pixels are not readable; for instance, Canvas is document-based. ## # dstRowBytes is too small to contain one row of pixels. ## ## #Param dstInfo width, height, Image_Color_Type, and Image_Alpha_Type of dstPixels ## #Param dstPixels storage for pixels; dstInfo.height() times dstRowBytes, or larger ## #Param dstRowBytes size of one destination row; dstInfo.width() times pixel size, or larger ## #Param srcX offset into readable pixels in x; may be negative ## #Param srcY offset into readable pixels in y; may be negative ## #Return true if pixels were copied ## #Example #Width 64 #Height 64 #Description A black circle drawn on a blue background provides an image to copy. readPixels copies one quarter of the canvas into each of the four corners. The copied quarter circles overdraw the original circle. ## canvas->clear(SK_ColorBLUE); SkPaint paint; canvas->drawCircle(32, 32, 28, paint); SkImageInfo info = SkImageInfo::Make(64, 64, kBGRA_8888_SkColorType, kPremul_SkAlphaType); sk_sp data(SkData::MakeUninitialized(info.minRowBytes() * info.height())); sk_bzero(data->writable_data(), info.minRowBytes() * info.height()); for (int x : { 32, -32 } ) { for (int y : { 32, -32 } ) { canvas->readPixels(info, data->writable_data(), info.minRowBytes(), x, y); } } sk_sp image = SkImage::MakeRasterData(info, data, info.minRowBytes()); canvas->drawImage(image, 0, 0); ## #Example #Description Canvas returned by Raster_Surface has Premultiplied pixel values. clear() takes Unpremultiplied input with Color_Alpha equal 0x80 and Color_RGB equal 0x55, 0xAA, 0xFF. Color_RGB is multiplied by Color_Alpha to generate Premultiplied value 0x802B5580. readPixels converts pixel back to Unpremultiplied value 0x8056A9FF, introducing error. ## canvas->clear(0x8055aaff); for (SkAlphaType alphaType : { kPremul_SkAlphaType, kUnpremul_SkAlphaType } ) { uint32_t pixel = 0; SkImageInfo info = SkImageInfo::Make(1, 1, kBGRA_8888_SkColorType, alphaType); if (canvas->readPixels(info, &pixel, 4, 0, 0)) { SkDebugf("pixel = %08x\n", pixel); } } #StdOut pixel = 802b5580 pixel = 8056a9ff ## ## #SeeAlso peekPixels writePixels drawBitmap drawImage SkBitmap::readPixels SkPixmap::readPixels SkImage::readPixels SkSurface::readPixels ## # ------------------------------------------------------------------------------ #Method bool readPixels(const SkPixmap& pixmap, int srcX, int srcY) Copies Rect of pixels from Canvas into pixmap. Matrix and Clip are ignored. Source Rect corners are (srcX, srcY) and (imageInfo().width(), imageInfo().height()). Destination Rect corners are (0, 0) and (pixmap.width(), pixmap.height()). Copies each readable pixel intersecting both rectangles, without scaling, converting to pixmap.colorType() and pixmap.alphaType() if required. Pixels are readable when Device is raster, or backed by a GPU. Pixels are not readable when SkCanvas is returned by SkDocument::beginPage, returned by SkPictureRecorder::beginRecording, or Canvas is the base of a utility class like SkDumpCanvas. Caller must allocate pixel storage in pixmap if needed. Pixel values are converted only if Image_Color_Type and Image_Alpha_Type do not match. Only pixels within both source and destination Rects are copied. pixmap pixels contents outside Rect intersection are unchanged. Pass negative values for srcX or srcY to offset pixels across or down pixmap. Does not copy, and returns false if: #List # Source and destination rectangles do not intersect. ## # Canvas pixels could not be converted to pixmap.colorType() or pixmap.alphaType(). ## # Canvas pixels are not readable; for instance, Canvas is document-based. ## # Pixmap pixels could not be allocated. ## # pixmap.rowBytes() is too small to contain one row of pixels. ## ## #Param pixmap storage for pixels copied from Canvas ## #Param srcX offset into readable pixels in x; may be negative ## #Param srcY offset into readable pixels in y; may be negative ## #Return true if pixels were copied ## #Example #Description clear() takes Unpremultiplied input with Color_Alpha equal 0x80 and Color_RGB equal 0x55, 0xAA, 0xFF. Color_RGB is multiplied by Color_Alpha to generate Premultiplied value 0x802B5580. ## void draw(SkCanvas* canvas) { canvas->clear(0x8055aaff); uint32_t pixels[1] = { 0 }; SkPixmap pixmap(SkImageInfo::MakeN32Premul(1, 1), pixels, 4); canvas->readPixels(pixmap, 0, 0); SkDebugf("pixel = %08x\n", pixels[0]); } #StdOut pixel = 802b5580 ## ## #SeeAlso peekPixels writePixels drawBitmap drawImage SkBitmap::readPixels SkPixmap::readPixels SkImage::readPixels SkSurface::readPixels ## # ------------------------------------------------------------------------------ #Method bool readPixels(const SkBitmap& bitmap, int srcX, int srcY) Copies Rect of pixels from Canvas into bitmap. Matrix and Clip are ignored. Source Rect corners are (srcX, srcY) and (imageInfo().width(), imageInfo().height()). Destination Rect corners are (0, 0) and (bitmap.width(), bitmap.height()). Copies each readable pixel intersecting both rectangles, without scaling, converting to bitmap.colorType() and bitmap.alphaType() if required. Pixels are readable when Device is raster, or backed by a GPU. Pixels are not readable when SkCanvas is returned by SkDocument::beginPage, returned by SkPictureRecorder::beginRecording, or Canvas is the base of a utility class like SkDumpCanvas. Caller must allocate pixel storage in bitmap if needed. Bitmap values are converted only if Image_Color_Type and Image_Alpha_Type do not match. Only pixels within both source and destination rectangles are copied. Bitmap pixels outside Rect intersection are unchanged. Pass negative values for srcX or srcY to offset pixels across or down bitmap. Does not copy, and returns false if: #List # Source and destination rectangles do not intersect. ## # Canvas pixels could not be converted to bitmap.colorType() or bitmap.alphaType(). ## # Canvas pixels are not readable; for instance, Canvas is document-based. ## # bitmap pixels could not be allocated. ## # bitmap.rowBytes() is too small to contain one row of pixels. ## ## #Param bitmap storage for pixels copied from Canvas ## #Param srcX offset into readable pixels in x; may be negative ## #Param srcY offset into readable pixels in y; may be negative ## #Return true if pixels were copied ## #Example #Description clear() takes Unpremultiplied input with Color_Alpha equal 0x80 and Color_RGB equal 0x55, 0xAA, 0xFF. Color_RGB is multiplied by Color_Alpha to generate Premultiplied value 0x802B5580. ## void draw(SkCanvas* canvas) { canvas->clear(0x8055aaff); SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(1, 1)); canvas->readPixels(bitmap, 0, 0); SkDebugf("pixel = %08x\n", bitmap.getAddr32(0, 0)[0]); } #StdOut pixel = 802b5580 ## ## #SeeAlso peekPixels writePixels drawBitmap drawImage SkBitmap::readPixels SkPixmap::readPixels SkImage::readPixels SkSurface::readPixels ## # ------------------------------------------------------------------------------ #Method bool writePixels(const SkImageInfo& info, const void* pixels, size_t rowBytes, int x, int y) Copies Rect from pixels to Canvas. Matrix and Clip are ignored. Source Rect corners are (0, 0) and (info.width(), info.height()). Destination Rect corners are (x, y) and (imageInfo().width(), imageInfo().height()). Copies each readable pixel intersecting both rectangles, without scaling, converting to imageInfo().colorType() and imageInfo().alphaType() if required. Pixels are writable when Device is raster, or backed by a GPU. Pixels are not writable when SkCanvas is returned by SkDocument::beginPage, returned by SkPictureRecorder::beginRecording, or Canvas is the base of a utility class like SkDumpCanvas. Pixel values are converted only if Image_Color_Type and Image_Alpha_Type do not match. Only pixels within both source and destination rectangles are copied. Canvas pixels outside Rect intersection are unchanged. Pass negative values for x or y to offset pixels to the left or above Canvas pixels. Does not copy, and returns false if: #List # Source and destination rectangles do not intersect. ## # pixels could not be converted to Canvas imageInfo().colorType() or imageInfo().alphaType(). ## # Canvas pixels are not writable; for instance, Canvas is document-based. ## # rowBytes is too small to contain one row of pixels. ## ## #Param info width, height, Image_Color_Type, and Image_Alpha_Type of pixels ## #Param pixels pixels to copy, of size info.height() times rowBytes, or larger ## #Param rowBytes size of one row of pixels; info.width() times pixel size, or larger ## #Param x offset into Canvas writable pixels in x; may be negative ## #Param y offset into Canvas writable pixels in y; may be negative ## #Return true if pixels were written to Canvas ## #Example SkImageInfo imageInfo = SkImageInfo::MakeN32(256, 1, kPremul_SkAlphaType); for (int y = 0; y < 256; ++y) { uint32_t pixels[256]; for (int x = 0; x < 256; ++x) { pixels[x] = SkColorSetARGB(x, x + y, x, x - y); } canvas->writePixels(imageInfo, &pixels, sizeof(pixels), 0, y); } ## #SeeAlso readPixels drawBitmap drawImage SkBitmap::writePixels ## # ------------------------------------------------------------------------------ #Method bool writePixels(const SkBitmap& bitmap, int x, int y) Copies Rect from pixels to Canvas. Matrix and Clip are ignored. Source Rect corners are (0, 0) and (bitmap.width(), bitmap.height()). Destination Rect corners are (x, y) and (imageInfo().width(), imageInfo().height()). Copies each readable pixel intersecting both rectangles, without scaling, converting to imageInfo().colorType() and imageInfo().alphaType() if required. Pixels are writable when Device is raster, or backed by a GPU. Pixels are not writable when SkCanvas is returned by SkDocument::beginPage, returned by SkPictureRecorder::beginRecording, or Canvas is the base of a utility class like SkDumpCanvas. Pixel values are converted only if Image_Color_Type and Image_Alpha_Type do not match. Only pixels within both source and destination rectangles are copied. Canvas pixels outside Rect intersection are unchanged. Pass negative values for x or y to offset pixels to the left or above Canvas pixels. Does not copy, and returns false if: #List # Source and destination rectangles do not intersect. ## # bitmap does not have allocated pixels. ## # bitmap pixels could not be converted to Canvas imageInfo().colorType() or imageInfo().alphaType(). ## # Canvas pixels are not writable; for instance, Canvas is document based. ## # bitmap pixels are inaccessible; for instance, bitmap wraps a texture. ## ## #Param bitmap contains pixels copied to Canvas ## #Param x offset into Canvas writable pixels in x; may be negative ## #Param y offset into Canvas writable pixels in y; may be negative ## #Return true if pixels were written to Canvas ## #Example void draw(SkCanvas* canvas) { SkImageInfo imageInfo = SkImageInfo::MakeN32Premul(2, 2); SkBitmap bitmap; bitmap.setInfo(imageInfo); uint32_t pixels[4]; bitmap.setPixels(pixels); for (int y = 0; y < 256; y += 2) { for (int x = 0; x < 256; x += 2) { pixels[0] = SkColorSetRGB(x, y, x | y); pixels[1] = SkColorSetRGB(x ^ y, y, x); pixels[2] = SkColorSetRGB(x, x & y, y); pixels[3] = SkColorSetRGB(~x, ~y, x); canvas->writePixels(bitmap, x, y); } } } ## #SeeAlso readPixels drawBitmap drawImage SkBitmap::writePixels ## # ------------------------------------------------------------------------------ #Topic State_Stack Canvas maintains a stack of state that allows hierarchical drawing, commonly used to implement windows and views. The initial state has an identity matrix and and an infinite clip. Even with a wide-open clip, drawing is constrained by the bounds of the Canvas Surface or Device. Canvas savable state consists of Clip, Matrix, and Draw_Filter. Clip describes the area that may be drawn to. Matrix transforms the geometry. Draw_Filter (deprecated on most platforms) modifies the paint before drawing. save(), saveLayer, saveLayerPreserveLCDTextRequests, and saveLayerAlpha save state and return the depth of the stack. restore(), restoreToCount, and ~SkCanvas() revert state to its value when saved. Each state on the stack intersects Clip with the previous Clip, and concatenates Matrix with the previous Matrix. The intersected Clip makes the drawing area the same or smaller; the concatenated Matrix may move the origin and potentially scale or rotate the coordinate space. Canvas does not require balancing the state stack but it is a good idea to do so. Calling save() without restore() will eventually cause Skia to fail; mismatched save() and restore() create hard to find bugs. It is not possible to use state to draw outside of the clip defined by the previous state. #Example #Description Draw to ever smaller clips; then restore drawing to full canvas. Note that the second clipRect is not permitted to enlarge Clip. ## #Height 160 void draw(SkCanvas* canvas) { SkPaint paint; canvas->save(); // records stack depth to restore canvas->clipRect(SkRect::MakeWH(100, 100)); // constrains drawing to clip canvas->clear(SK_ColorRED); // draws to limit of clip canvas->save(); // records stack depth to restore canvas->clipRect(SkRect::MakeWH(50, 150)); // Rect below 100 is ignored canvas->clear(SK_ColorBLUE); // draws to smaller clip canvas->restore(); // enlarges clip canvas->drawLine(20, 20, 150, 150, paint); // line below 100 is not drawn canvas->restore(); // enlarges clip canvas->drawLine(150, 20, 50, 120, paint); // line below 100 is drawn } ## Each Clip uses the current Matrix for its coordinates. #Example #Description While clipRect is given the same rectangle twice, Matrix makes the second clipRect draw at half the size of the first. ## #Height 128 void draw(SkCanvas* canvas) { canvas->clipRect(SkRect::MakeWH(100, 100)); canvas->clear(SK_ColorRED); canvas->scale(.5, .5); canvas->clipRect(SkRect::MakeWH(100, 100)); canvas->clear(SK_ColorBLUE); } ## #SeeAlso save() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha restore() restoreToCount #Method int save() Saves Matrix, Clip, and Draw_Filter (Draw_Filter deprecated on most platforms). Calling restore() discards changes to Matrix, Clip, and Draw_Filter, restoring the Matrix, Clip, and Draw_Filter to their state when save() was called. Matrix may be changed by translate(), scale(), rotate(), skew(), concat(), setMatrix, and resetMatrix. Clip may be changed by clipRect, clipRRect, clipPath, clipRegion. Saved Canvas state is put on a stack; multiple calls to save() should be balance by an equal number of calls to restore(). Call restoreToCount with result to restore this and subsequent saves. #Return depth of saved stack ## #Example #Description The black square is translated 50 pixels down and to the right. Restoring Canvas state removes translate() from Canvas stack; the red square is not translated, and is drawn at the origin. ## #Height 100 void draw(SkCanvas* canvas) { SkPaint paint; SkRect rect = { 0, 0, 25, 25 }; canvas->drawRect(rect, paint); canvas->save(); canvas->translate(50, 50); canvas->drawRect(rect, paint); canvas->restore(); paint.setColor(SK_ColorRED); canvas->drawRect(rect, paint); } ## #SeeAlso saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha restore() restoreToCount ## # ------------------------------------------------------------------------------ #Method void restore() Removes changes to Matrix, Clip, and Draw_Filter since Canvas state was last saved. The state is removed from the stack. Does nothing if the stack is empty. #Example void draw(SkCanvas* canvas) { SkCanvas simple; SkDebugf("depth = %d\n", simple.getSaveCount()); simple.restore(); SkDebugf("depth = %d\n", simple.getSaveCount()); } ## #SeeAlso save() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha restoreToCount ## # ------------------------------------------------------------------------------ #Method int getSaveCount() const Returns the number of saved states, each containing: Matrix, Clip, and Draw_Filter. Equals the number of save() calls less the number of restore() calls plus one. The save count of a new canvas is one. #Return depth of save state stack ## #Example void draw(SkCanvas* canvas) { SkCanvas simple; SkDebugf("depth = %d\n", simple.getSaveCount()); simple.save(); SkDebugf("depth = %d\n", simple.getSaveCount()); simple.restore(); SkDebugf("depth = %d\n", simple.getSaveCount()); } #StdOut depth = 1 depth = 2 depth = 1 ## ## #SeeAlso save() restore() restoreToCount ## # ------------------------------------------------------------------------------ #Method void restoreToCount(int saveCount) Restores state to Matrix, Clip, and Draw_Filter values when save(), saveLayer, saveLayerPreserveLCDTextRequests, or saveLayerAlpha returned saveCount. Does nothing if saveCount is greater than state stack count. Restores state to initial values if saveCount is less than or equal to one. #Param saveCount depth of state stack to restore ## #Example void draw(SkCanvas* canvas) { SkDebugf("depth = %d\n", canvas->getSaveCount()); canvas->save(); canvas->save(); SkDebugf("depth = %d\n", canvas->getSaveCount()); canvas->restoreToCount(0); SkDebugf("depth = %d\n", canvas->getSaveCount()); } #StdOut depth = 1 depth = 3 depth = 1 ## ## #SeeAlso restore() getSaveCount save() ## #Topic State_Stack ## # ------------------------------------------------------------------------------ #Topic Layer #Substitute layer #Alias Layers Layer allocates a temporary Bitmap to draw into. When the drawing is complete, the Bitmap is drawn into the Canvas. Layer is saved in a stack along with other saved state. When state with a Layer is restored, the Bitmap is drawn into the previous Layer. Layer may be initialized with the contents of the previous Layer. When Layer is restored, its Bitmap can be modified by Paint passed to Layer to apply Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode. #Method int saveLayer(const SkRect* bounds, const SkPaint* paint) Saves Matrix, Clip, and Draw_Filter (Draw_Filter deprecated on most platforms), and allocates a Bitmap for subsequent drawing. Calling restore() discards changes to Matrix, Clip, and Draw_Filter, and draws the Bitmap. Matrix may be changed by translate(), scale(), rotate(), skew(), concat(), setMatrix, and resetMatrix. Clip may be changed by clipRect, clipRRect, clipPath, clipRegion. Rect bounds suggests but does not define the Bitmap size. To clip drawing to a specific rectangle, use clipRect. Optional Paint paint applies Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode when restore() is called. Call restoreToCount with returned value to restore this and subsequent saves. #Param bounds hint to limit the size of the Layer; may be nullptr ## #Param paint graphics state for Layer; may be nullptr ## #Return depth of saved stack ## #Example #Description Rectangles are blurred by Image_Filter when restore() draws Layer to main Canvas. ## #Height 128 void draw(SkCanvas* canvas) { SkPaint paint, blur; blur.setImageFilter(SkBlurImageFilter::Make(3, 3, nullptr)); canvas->saveLayer(nullptr, &blur); SkRect rect = { 25, 25, 50, 50}; canvas->drawRect(rect, paint); canvas->translate(50, 50); paint.setColor(SK_ColorRED); canvas->drawRect(rect, paint); canvas->restore(); } ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha SaveLayerRec ## #Method int saveLayer(const SkRect& bounds, const SkPaint* paint) Saves Matrix, Clip, and Draw_Filter (Draw_Filter deprecated on most platforms), and allocates a Bitmap for subsequent drawing. Calling restore() discards changes to Matrix, Clip, and Draw_Filter, and draws the Bitmap. Matrix may be changed by translate(), scale(), rotate(), skew(), concat(), setMatrix, and resetMatrix. Clip may be changed by clipRect, clipRRect, clipPath, clipRegion. Rect bounds suggests but does not define the Layer size. To clip drawing to a specific rectangle, use clipRect. Optional Paint paint applies Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode when restore() is called. Call restoreToCount with returned value to restore this and subsequent saves. #Param bounds hint to limit the size of Layer; may be nullptr ## #Param paint graphics state for Layer; may be nullptr ## #Return depth of saved stack ## #Example #Description Rectangles are blurred by Image_Filter when restore() draws Layer to main Canvas. The red rectangle is clipped; it does not fully fit on Layer. Image_Filter blurs past edge of Layer so red rectangle is blurred on all sides. ## #Height 128 void draw(SkCanvas* canvas) { SkPaint paint, blur; blur.setImageFilter(SkBlurImageFilter::Make(3, 3, nullptr)); canvas->saveLayer(SkRect::MakeWH(90, 90), &blur); SkRect rect = { 25, 25, 50, 50}; canvas->drawRect(rect, paint); canvas->translate(50, 50); paint.setColor(SK_ColorRED); canvas->drawRect(rect, paint); canvas->restore(); } ## #SeeAlso save() restore() saveLayerPreserveLCDTextRequests saveLayerAlpha SaveLayerRec ## #Method int saveLayerPreserveLCDTextRequests(const SkRect* bounds, const SkPaint* paint) Saves Matrix, Clip, and Draw_Filter (Draw_Filter deprecated on most platforms), and allocates a Bitmap for subsequent drawing. LCD_Text is preserved when the Layer is drawn to the prior Layer. Calling restore() discards changes to Matrix, Clip, and Draw_Filter, and draws Layer. Matrix may be changed by translate(), scale(), rotate(), skew(), concat(), setMatrix, and resetMatrix. Clip may be changed by clipRect, clipRRect, clipPath, clipRegion. Rect bounds suggests but does not define the Layer size. To clip drawing to a specific rectangle, use clipRect. Optional Paint paint applies Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode when restore() is called. Call restoreToCount with returned value to restore this and subsequent saves. Draw text on an opaque background so that LCD_Text blends correctly with the prior Layer. LCD_Text drawn on a background with transparency may result in incorrect blending. #Param bounds hint to limit the size of Layer; may be nullptr ## #Param paint graphics state for Layer; may be nullptr ## #Return depth of saved stack ## #Example SkPaint paint; paint.setAntiAlias(true); paint.setLCDRenderText(true); paint.setTextSize(20); for (auto preserve : { false, true } ) { preserve ? canvas->saveLayerPreserveLCDTextRequests(nullptr, nullptr) : canvas->saveLayer(nullptr, nullptr); SkPaint p; p.setColor(SK_ColorWHITE); // Comment out the next line to draw on a non-opaque background. canvas->drawRect(SkRect::MakeLTRB(25, 40, 200, 70), p); canvas->drawString("Hamburgefons", 30, 60, paint); p.setColor(0xFFCCCCCC); canvas->drawRect(SkRect::MakeLTRB(25, 70, 200, 100), p); canvas->drawString("Hamburgefons", 30, 90, paint); canvas->restore(); canvas->translate(0, 80); } ## #SeeAlso save() restore() saveLayer saveLayerAlpha SaveLayerRec ## #Method int saveLayerAlpha(const SkRect* bounds, U8CPU alpha) Saves Matrix, Clip, and Draw_Filter (Draw_Filter deprecated on most platforms), and allocates Bitmap for subsequent drawing. Calling restore() discards changes to Matrix, Clip, and Draw_Filter, and blends Layer with alpha opacity onto prior Layer. Matrix may be changed by translate(), scale(), rotate(), skew(), concat(), setMatrix, and resetMatrix. Clip may be changed by clipRect, clipRRect, clipPath, clipRegion. Rect bounds suggests but does not define Layer size. To clip drawing to a specific rectangle, use clipRect. alpha of zero is fully transparent, 255 is fully opaque. Call restoreToCount with returned value to restore this and subsequent saves. #Param bounds hint to limit the size of Layer; may be nullptr ## #Param alpha opacity of Layer ## #Return depth of saved stack ## #Example SkPaint paint; paint.setColor(SK_ColorRED); canvas->drawCircle(50, 50, 50, paint); canvas->saveLayerAlpha(nullptr, 128); paint.setColor(SK_ColorBLUE); canvas->drawCircle(100, 50, 50, paint); paint.setColor(SK_ColorGREEN); paint.setAlpha(128); canvas->drawCircle(75, 90, 50, paint); canvas->restore(); ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests SaveLayerRec ## #Enum #Code enum { kIsOpaque_SaveLayerFlag = 1 << 0, kPreserveLCDText_SaveLayerFlag = 1 << 1, kInitWithPrevious_SaveLayerFlag = 1 << 2, kDontClipToLayer_Legacy_SaveLayerFlag = kDontClipToLayer_PrivateSaveLayerFlag, }; ## SaveLayerFlags provides options that may be used in any combination in SaveLayerRec, defining how Layer allocated by saveLayer operates. #Const kIsOpaque_SaveLayerFlag 1 Creates Layer without transparency. Flag is ignored if Layer Paint contains Image_Filter or Color_Filter. ## #Const kPreserveLCDText_SaveLayerFlag 2 Creates Layer for LCD text. Flag is ignored if Layer Paint contains Image_Filter or Color_Filter. ## #Const kInitWithPrevious_SaveLayerFlag 4 Initializes Layer with the contents of the previous Layer. ## #Const kDontClipToLayer_Legacy_SaveLayerFlag 0x80000000 #Private to be deprecated: bug.skia.org/2440 ## Only present on Android. Skips setting a clip to the Layer bounds. ## #Example #Height 160 #Description Canvas Layer captures red and blue circles scaled up by four. scalePaint blends Layer back with transparency. ## void draw(SkCanvas* canvas) { SkPaint redPaint, bluePaint, scalePaint; redPaint.setColor(SK_ColorRED); canvas->drawCircle(21, 21, 8, redPaint); bluePaint.setColor(SK_ColorBLUE); canvas->drawCircle(31, 21, 8, bluePaint); SkMatrix matrix; matrix.setScale(4, 4); scalePaint.setAlpha(0x40); scalePaint.setImageFilter( SkImageFilter::MakeMatrixFilter(matrix, kNone_SkFilterQuality, nullptr)); SkCanvas::SaveLayerRec saveLayerRec(nullptr, &scalePaint, SkCanvas::kInitWithPrevious_SaveLayerFlag); canvas->saveLayer(saveLayerRec); canvas->restore(); } ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha SaveLayerRec #Enum ## #Typedef uint32_t SaveLayerFlags ## #Struct SaveLayerRec #Code struct SaveLayerRec { SaveLayerRec*(... const SkRect* fBounds; const SkPaint* fPaint; const SkImageFilter* fBackdrop; SaveLayerFlags fSaveLayerFlags; }; ## SaveLayerRec contains the state used to create the Layer. #Member const SkRect* fBounds fBounds is used as a hint to limit the size of Layer; may be nullptr. fBounds suggests but does not define Layer size. To clip drawing to a specific rectangle, use clipRect. ## #Member const SkPaint* fPaint fPaint modifies how Layer overlays the prior Layer; may be nullptr. Color_Alpha, Blend_Mode, Color_Filter, Draw_Looper, Image_Filter, and Mask_Filter affect Layer draw. ## #Member const SkImageFilter* fBackdrop fBackdrop applies Image_Filter to the prior Layer when copying to the Layer; may be nullptr. Use kInitWithPrevious_SaveLayerFlag to copy the prior Layer without an Image_Filter. ## #Member const SkImage* fClipMask restore() clips Layer by the Color_Alpha channel of fClipMask when Layer is copied to Device. fClipMask may be nullptr. . ## #Member const SkMatrix* fClipMatrix fClipMatrix transforms fClipMask before it clips Layer. If fClipMask describes a translucent gradient, it may be scaled and rotated without introducing artifacts. fClipMatrix may be nullptr. ## #Member SaveLayerFlags fSaveLayerFlags fSaveLayerFlags are used to create Layer without transparency, create Layer for LCD text, and to create Layer with the contents of the previous Layer. ## #Example #Height 160 #Description Canvas Layer captures a red Anti-aliased circle and a blue Aliased circle scaled up by four. After drawing another red circle without scaling on top, the Layer is transferred to the main canvas. ## void draw(SkCanvas* canvas) { SkPaint redPaint, bluePaint; redPaint.setAntiAlias(true); redPaint.setColor(SK_ColorRED); canvas->drawCircle(21, 21, 8, redPaint); bluePaint.setColor(SK_ColorBLUE); canvas->drawCircle(31, 21, 8, bluePaint); SkMatrix matrix; matrix.setScale(4, 4); auto scaler = SkImageFilter::MakeMatrixFilter(matrix, kNone_SkFilterQuality, nullptr); SkCanvas::SaveLayerRec saveLayerRec(nullptr, nullptr, scaler.get(), 0); canvas->saveLayer(saveLayerRec); canvas->drawCircle(125, 85, 8, redPaint); canvas->restore(); } ## #Method SaveLayerRec() Sets fBounds, fPaint, and fBackdrop to nullptr. Clears fSaveLayerFlags. #Return empty SaveLayerRec ## #Example SkCanvas::SaveLayerRec rec1; rec1.fSaveLayerFlags = SkCanvas::kIsOpaque_SaveLayerFlag; SkCanvas::SaveLayerRec rec2(nullptr, nullptr, SkCanvas::kIsOpaque_SaveLayerFlag); SkDebugf("rec1 %c= rec2\n", rec1.fBounds == rec2.fBounds && rec1.fPaint == rec2.fPaint && rec1.fBackdrop == rec2.fBackdrop && rec1.fSaveLayerFlags == rec2.fSaveLayerFlags ? '=' : '!'); #StdOut rec1 == rec2 ## ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha ## #Method SaveLayerRec(const SkRect* bounds, const SkPaint* paint, SaveLayerFlags saveLayerFlags = 0) Sets fBounds, fPaint, and fSaveLayerFlags; sets fBackdrop to nullptr. #Param bounds Layer dimensions; may be nullptr ## #Param paint applied to Layer when overlaying prior Layer; may be nullptr ## #Param saveLayerFlags SaveLayerRec options to modify Layer ## #Return SaveLayerRec with empty backdrop ## #Example SkCanvas::SaveLayerRec rec1; SkCanvas::SaveLayerRec rec2(nullptr, nullptr); SkDebugf("rec1 %c= rec2\n", rec1.fBounds == rec2.fBounds && rec1.fPaint == rec2.fPaint && rec1.fBackdrop == rec2.fBackdrop && rec1.fSaveLayerFlags == rec2.fSaveLayerFlags ? '=' : '!'); #StdOut rec1 == rec2 ## ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha ## #Method SaveLayerRec(const SkRect* bounds, const SkPaint* paint, const SkImageFilter* backdrop, SaveLayerFlags saveLayerFlags) Sets fBounds, fPaint, fBackdrop, and fSaveLayerFlags. #Param bounds Layer dimensions; may be nullptr ## #Param paint applied to Layer when overlaying prior Layer; may be nullptr ## #Param backdrop prior Layer copied with Image_Filter; may be nullptr ## #Param saveLayerFlags SaveLayerRec options to modify Layer ## #Return SaveLayerRec fully specified ## #Example SkCanvas::SaveLayerRec rec1; SkCanvas::SaveLayerRec rec2(nullptr, nullptr, nullptr, 0); SkDebugf("rec1 %c= rec2\n", rec1.fBounds == rec2.fBounds && rec1.fPaint == rec2.fPaint && rec1.fBackdrop == rec2.fBackdrop && rec1.fSaveLayerFlags == rec2.fSaveLayerFlags ? '=' : '!'); #StdOut rec1 == rec2 ## ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha ## #Method SaveLayerRec(const SkRect* bounds, const SkPaint* paint, const SkImageFilter* backdrop, const SkImage* clipMask, const SkMatrix* clipMatrix, SaveLayerFlags saveLayerFlags) #Experimental Not ready for general use. ## Sets fBounds, fPaint, fBackdrop, fClipMask, fClipMatrix, and fSaveLayerFlags. clipMatrix uses Color_Alpha channel of image, transformed by clipMatrix, to clip Layer when drawn to Canvas. Implementation is not complete; has no effect if Device is GPU-backed. #Param bounds Layer dimensions; may be nullptr ## #Param paint graphics state applied to Layer when overlaying prior Layer; may be nullptr ## #Param backdrop prior Layer copied with Image_Filter; may be nullptr ## #Param clipMask clip applied to Layer; may be nullptr ## #Param clipMatrix matrix applied to clipMask; may be nullptr to use identity matrix ## #Param saveLayerFlags SaveLayerRec options to modify Layer ## #Return SaveLayerRec fully specified ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha ## #Struct ## #Method int saveLayer(const SaveLayerRec& layerRec) Saves Matrix, Clip, and Draw_Filter (Draw_Filter deprecated on most platforms), and allocates Bitmap for subsequent drawing. Calling restore() discards changes to Matrix, Clip, and Draw_Filter, and blends Bitmap with Color_Alpha opacity onto the prior Layer. Matrix may be changed by translate(), scale(), rotate(), skew(), concat(), setMatrix, and resetMatrix. Clip may be changed by clipRect, clipRRect, clipPath, clipRegion. SaveLayerRec contains the state used to create the Layer. Call restoreToCount with returned value to restore this and subsequent saves. #Param layerRec Layer state ## #Return depth of save state stack ## #Example #Description The example draws an image, and saves it into a Layer with kInitWithPrevious_SaveLayerFlag. Next it punches a hole in Layer and restore with SkBlendMode::kPlus. Where Layer was cleared, the original image will draw unchanged. Outside of the circle the mandrill is brightened. ## #Image 3 // sk_sp image = GetResourceAsImage("images/mandrill_256.png"); canvas->drawImage(image, 0, 0, nullptr); SkCanvas::SaveLayerRec rec; SkPaint paint; paint.setBlendMode(SkBlendMode::kPlus); rec.fSaveLayerFlags = SkCanvas::kInitWithPrevious_SaveLayerFlag; rec.fPaint = &paint; canvas->saveLayer(rec); paint.setBlendMode(SkBlendMode::kClear); canvas->drawCircle(128, 128, 96, paint); canvas->restore(); ## #ToDo above example needs to replace GetResourceAsImage with way to select image in fiddle ## #SeeAlso save() restore() saveLayer saveLayerPreserveLCDTextRequests saveLayerAlpha ## #Topic Layer ## # ------------------------------------------------------------------------------ #Topic Matrix #Method void translate(SkScalar dx, SkScalar dy) Translate Matrix by dx along the x-axis and dy along the y-axis. Mathematically, replace Matrix with a translation matrix Premultiplied with Matrix. This has the effect of moving the drawing by (dx, dy) before transforming the result with Matrix. #Param dx distance to translate in x ## #Param dy distance to translate in y ## #Example #Height 128 #Description scale() followed by translate() produces different results from translate() followed by scale(). The blue stroke follows translate of (50, 50); a black fill follows scale of (2, 1/2.f). After restoring the clip, which resets Matrix, a red frame follows the same scale of (2, 1/2.f); a gray fill follows translate of (50, 50). ## void draw(SkCanvas* canvas) { SkPaint filledPaint; SkPaint outlinePaint; outlinePaint.setStyle(SkPaint::kStroke_Style); outlinePaint.setColor(SK_ColorBLUE); canvas->save(); canvas->translate(50, 50); canvas->drawCircle(28, 28, 15, outlinePaint); // blue center: (50+28, 50+28) canvas->scale(2, 1/2.f); canvas->drawCircle(28, 28, 15, filledPaint); // black center: (50+(28*2), 50+(28/2)) canvas->restore(); filledPaint.setColor(SK_ColorGRAY); outlinePaint.setColor(SK_ColorRED); canvas->scale(2, 1/2.f); canvas->drawCircle(28, 28, 15, outlinePaint); // red center: (28*2, 28/2) canvas->translate(50, 50); canvas->drawCircle(28, 28, 15, filledPaint); // gray center: ((50+28)*2, (50+28)/2) } ## #SeeAlso concat() scale() skew() rotate() setMatrix ## # ------------------------------------------------------------------------------ #Method void scale(SkScalar sx, SkScalar sy) Scale Matrix by sx on the x-axis and sy on the y-axis. Mathematically, replace Matrix with a scale matrix Premultiplied with Matrix. This has the effect of scaling the drawing by (sx, sy) before transforming the result with Matrix. #Param sx amount to scale in x ## #Param sy amount to scale in y ## #Example #Height 160 void draw(SkCanvas* canvas) { SkPaint paint; SkRect rect = { 10, 20, 60, 120 }; canvas->translate(20, 20); canvas->drawRect(rect, paint); canvas->scale(2, .5f); paint.setColor(SK_ColorGRAY); canvas->drawRect(rect, paint); } ## #SeeAlso concat() translate() skew() rotate() setMatrix ## # ------------------------------------------------------------------------------ #Method void rotate(SkScalar degrees) Rotate Matrix by degrees. Positive degrees rotates clockwise. Mathematically, replace Matrix with a rotation matrix Premultiplied with Matrix. This has the effect of rotating the drawing by degrees before transforming the result with Matrix. #Param degrees amount to rotate, in degrees ## #Example #Description Draw clock hands at time 5:10. The hour hand and minute hand point up and are rotated clockwise. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setStyle(SkPaint::kStroke_Style); canvas->translate(128, 128); canvas->drawCircle(0, 0, 60, paint); canvas->save(); canvas->rotate(10 * 360 / 60); // 10 minutes of 60 scaled to 360 degrees canvas->drawLine(0, 0, 0, -50, paint); canvas->restore(); canvas->rotate((5 + 10.f/60) * 360 / 12); // 5 and 10/60 hours of 12 scaled to 360 degrees canvas->drawLine(0, 0, 0, -30, paint); } ## #SeeAlso concat() translate() skew() scale() setMatrix ## # ------------------------------------------------------------------------------ #Method void rotate(SkScalar degrees, SkScalar px, SkScalar py) Rotate Matrix by degrees about a point at (px, py). Positive degrees rotates clockwise. Mathematically, construct a rotation matrix. Premultiply the rotation matrix by a translation matrix, then replace Matrix with the resulting matrix Premultiplied with Matrix. This has the effect of rotating the drawing about a given point before transforming the result with Matrix. #Param degrees amount to rotate, in degrees ## #Param px x-coordinate of the point to rotate about ## #Param py y-coordinate of the point to rotate about ## #Example #Height 192 void draw(SkCanvas* canvas) { SkPaint paint; paint.setTextSize(96); canvas->drawString("A1", 130, 100, paint); canvas->rotate(180, 130, 100); canvas->drawString("A1", 130, 100, paint); } ## #SeeAlso concat() translate() skew() scale() setMatrix ## # ------------------------------------------------------------------------------ #Method void skew(SkScalar sx, SkScalar sy) Skew Matrix by sx on the x-axis and sy on the y-axis. A positive value of sx skews the drawing right as y increases; a positive value of sy skews the drawing down as x increases. Mathematically, replace Matrix with a skew matrix Premultiplied with Matrix. This has the effect of skewing the drawing by (sx, sy) before transforming the result with Matrix. #Param sx amount to skew in x ## #Param sy amount to skew in y ## #Example #Description Black text mimics an oblique text style by using a negative skew in x that shifts the geometry to the right as the y values decrease. Red text uses a positive skew in y to shift the geometry down as the x values increase. Blue text combines x and y skew to rotate and scale. ## SkPaint paint; paint.setTextSize(128); canvas->translate(30, 130); canvas->save(); canvas->skew(-.5, 0); canvas->drawString("A1", 0, 0, paint); canvas->restore(); canvas->save(); canvas->skew(0, .5); paint.setColor(SK_ColorRED); canvas->drawString("A1", 0, 0, paint); canvas->restore(); canvas->skew(-.5, .5); paint.setColor(SK_ColorBLUE); canvas->drawString("A1", 0, 0, paint); ## #SeeAlso concat() translate() rotate() scale() setMatrix ## # ------------------------------------------------------------------------------ #Method void concat(const SkMatrix& matrix) Replace Matrix with matrix Premultiplied with existing Matrix. This has the effect of transforming the drawn geometry by matrix, before transforming the result with existing Matrix. #Param matrix matrix to Premultiply with existing Matrix ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setTextSize(80); paint.setTextScaleX(.3); SkMatrix matrix; SkRect rect[2] = {{ 10, 20, 90, 110 }, { 40, 130, 140, 180 }}; matrix.setRectToRect(rect[0], rect[1], SkMatrix::kFill_ScaleToFit); canvas->drawRect(rect[0], paint); canvas->drawRect(rect[1], paint); paint.setColor(SK_ColorWHITE); canvas->drawString("Here", rect[0].fLeft + 10, rect[0].fBottom - 10, paint); canvas->concat(matrix); canvas->drawString("There", rect[0].fLeft + 10, rect[0].fBottom - 10, paint); } ## #SeeAlso translate() rotate() scale() skew() setMatrix ## # ------------------------------------------------------------------------------ #Method void setMatrix(const SkMatrix& matrix) Replace Matrix with matrix. Unlike concat(), any prior matrix state is overwritten. #Param matrix matrix to copy, replacing existing Matrix ## #Example #Height 128 void draw(SkCanvas* canvas) { SkPaint paint; canvas->scale(4, 6); canvas->drawString("truth", 2, 10, paint); SkMatrix matrix; matrix.setScale(2.8f, 6); canvas->setMatrix(matrix); canvas->drawString("consequences", 2, 20, paint); } ## #SeeAlso resetMatrix concat() translate() rotate() scale() skew() ## # ------------------------------------------------------------------------------ #Method void resetMatrix() Sets Matrix to the identity matrix. Any prior matrix state is overwritten. #Example #Height 128 void draw(SkCanvas* canvas) { SkPaint paint; canvas->scale(4, 6); canvas->drawString("truth", 2, 10, paint); canvas->resetMatrix(); canvas->scale(2.8f, 6); canvas->drawString("consequences", 2, 20, paint); } ## #SeeAlso setMatrix concat() translate() rotate() scale() skew() ## # ------------------------------------------------------------------------------ #Method const SkMatrix& getTotalMatrix() const Returns Matrix. This does not account for translation by Device or Surface. #Return Matrix in Canvas ## #Example SkDebugf("isIdentity %s\n", canvas->getTotalMatrix().isIdentity() ? "true" : "false"); #StdOut isIdentity true ## ## #SeeAlso setMatrix resetMatrix concat() ## #Topic Matrix ## # ------------------------------------------------------------------------------ #Topic Clip Clip is built from a stack of clipping paths. Each Path in the stack can be constructed from one or more Path_Contour elements. The Path_Contour may be composed of any number of Path_Verb segments. Each Path_Contour forms a closed area; Path_Fill_Type defines the area enclosed by Path_Contour. Clip stack of Path elements successfully restrict the Path area. Each Path is transformed by Matrix, then intersected with or subtracted from the prior Clip to form the replacement Clip. Use SkClipOp::kDifference to subtract Path from Clip; use SkClipOp::kIntersect to intersect Path with Clip. A clipping Path may be Anti-aliased; if Path, after transformation, is composed of horizontal and vertical lines, clearing Anti-alias allows whole pixels to either be inside or outside the clip. The fastest drawing has a Aliased, rectangular clip. If clipping Path has Anti-alias set, clip may partially clip a pixel, requiring that drawing blend partially with the destination along the edge. A rotated rectangular Anti-aliased clip looks smoother but draws slower. Clip can combine with Rect and Round_Rect primitives; like Path, these are transformed by Matrix before they are combined with Clip. Clip can combine with Region. Region is assumed to be in Device coordinates and is unaffected by Matrix. #Example #Height 90 #Description Draw a red circle with an Aliased clip and an Anti-aliased clip. Use an image filter to zoom into the pixels drawn. The edge of the Aliased clip fully draws pixels in the red circle. The edge of the Anti-aliased clip partially draws pixels in the red circle. ## SkPaint redPaint, scalePaint; redPaint.setAntiAlias(true); redPaint.setColor(SK_ColorRED); canvas->save(); for (bool antialias : { false, true } ) { canvas->save(); canvas->clipRect(SkRect::MakeWH(19.5f, 11.5f), antialias); canvas->drawCircle(17, 11, 8, redPaint); canvas->restore(); canvas->translate(16, 0); } canvas->restore(); SkMatrix matrix; matrix.setScale(6, 6); scalePaint.setImageFilter( SkImageFilter::MakeMatrixFilter(matrix, kNone_SkFilterQuality, nullptr)); SkCanvas::SaveLayerRec saveLayerRec( nullptr, &scalePaint, SkCanvas::kInitWithPrevious_SaveLayerFlag); canvas->saveLayer(saveLayerRec); canvas->restore(); ## #Method void clipRect(const SkRect& rect, SkClipOp op, bool doAntiAlias) Replace Clip with the intersection or difference of Clip and rect, with an Aliased or Anti-aliased clip edge. rect is transformed by Matrix before it is combined with Clip. #Param rect Rect to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Param doAntiAlias true if Clip is to be Anti-aliased ## #Example #Height 128 void draw(SkCanvas* canvas) { canvas->rotate(10); SkPaint paint; paint.setAntiAlias(true); for (auto alias: { false, true } ) { canvas->save(); canvas->clipRect(SkRect::MakeWH(90, 80), SkClipOp::kIntersect, alias); canvas->drawCircle(100, 60, 60, paint); canvas->restore(); canvas->translate(80, 0); } } ## #SeeAlso clipRRect clipPath clipRegion ## #Method void clipRect(const SkRect& rect, SkClipOp op) Replace Clip with the intersection or difference of Clip and rect. Resulting Clip is Aliased; pixels are fully contained by the clip. rect is transformed by Matrix before it is combined with Clip. #Param rect Rect to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Example #Height 192 #Width 280 void draw(SkCanvas* canvas) { SkPaint paint; for (SkClipOp op: { SkClipOp::kIntersect, SkClipOp::kDifference } ) { canvas->save(); canvas->clipRect(SkRect::MakeWH(90, 120), op, false); canvas->drawCircle(100, 100, 60, paint); canvas->restore(); canvas->translate(80, 0); } } ## #SeeAlso clipRRect clipPath clipRegion ## #Method void clipRect(const SkRect& rect, bool doAntiAlias = false) Replace Clip with the intersection of Clip and rect. Resulting Clip is Aliased; pixels are fully contained by the clip. rect is transformed by Matrix before it is combined with Clip. #Param rect Rect to combine with Clip ## #Param doAntiAlias true if Clip is to be Anti-aliased ## #Example #Height 133 #Description A circle drawn in pieces looks uniform when drawn Aliased. The same circle pieces blend with pixels more than once when Anti-aliased, visible as a thin pair of lines through the right circle. ## void draw(SkCanvas* canvas) { canvas->clear(SK_ColorWHITE); SkPaint paint; paint.setAntiAlias(true); paint.setColor(0x8055aaff); SkRect clipRect = { 0, 0, 87.4f, 87.4f }; for (auto alias: { false, true } ) { canvas->save(); canvas->clipRect(clipRect, SkClipOp::kIntersect, alias); canvas->drawCircle(67, 67, 60, paint); canvas->restore(); canvas->save(); canvas->clipRect(clipRect, SkClipOp::kDifference, alias); canvas->drawCircle(67, 67, 60, paint); canvas->restore(); canvas->translate(120, 0); } } ## #SeeAlso clipRRect clipPath clipRegion ## #Method void androidFramework_setDeviceClipRestriction(const SkIRect& rect) Sets the maximum clip rectangle, which can be set by clipRect, clipRRect and clipPath and intersect the current clip with the specified rect. The maximum clip affects only future clipping operations; it is not retroactive. The clip restriction is not recorded in pictures. Pass an empty rect to disable maximum clip. #Private This is private API to be used only by Android framework. ## #Param rect maximum allowed clip in device coordinates #Param ## ## #Method void clipRRect(const SkRRect& rrect, SkClipOp op, bool doAntiAlias) Replace Clip with the intersection or difference of Clip and rrect, with an Aliased or Anti-aliased clip edge. rrect is transformed by Matrix before it is combined with Clip. #Param rrect Round_Rect to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Param doAntiAlias true if Clip is to be Anti-aliased ## #Example #Height 128 void draw(SkCanvas* canvas) { canvas->clear(SK_ColorWHITE); SkPaint paint; paint.setAntiAlias(true); paint.setColor(0x8055aaff); SkRRect oval; oval.setOval({10, 20, 90, 100}); canvas->clipRRect(oval, SkClipOp::kIntersect, true); canvas->drawCircle(70, 100, 60, paint); } ## #SeeAlso clipRect clipPath clipRegion ## #Method void clipRRect(const SkRRect& rrect, SkClipOp op) Replace Clip with the intersection or difference of Clip and rrect. Resulting Clip is Aliased; pixels are fully contained by the clip. rrect is transformed by Matrix before it is combined with Clip. #Param rrect Round_Rect to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Example #Height 128 void draw(SkCanvas* canvas) { SkPaint paint; paint.setColor(0x8055aaff); auto oval = SkRRect::MakeOval({10, 20, 90, 100}); canvas->clipRRect(oval, SkClipOp::kIntersect); canvas->drawCircle(70, 100, 60, paint); } ## #SeeAlso clipRect clipPath clipRegion ## #Method void clipRRect(const SkRRect& rrect, bool doAntiAlias = false) Replace Clip with the intersection of Clip and rrect, with an Aliased or Anti-aliased clip edge. rrect is transformed by Matrix before it is combined with Clip. #Param rrect Round_Rect to combine with Clip ## #Param doAntiAlias true if Clip is to be Anti-aliased ## #Example #Height 128 void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); auto oval = SkRRect::MakeRectXY({10, 20, 90, 100}, 9, 13); canvas->clipRRect(oval, true); canvas->drawCircle(70, 100, 60, paint); } ## #SeeAlso clipRect clipPath clipRegion ## #Method void clipPath(const SkPath& path, SkClipOp op, bool doAntiAlias) Replace Clip with the intersection or difference of Clip and path, with an Aliased or Anti-aliased clip edge. Path_Fill_Type determines if path describes the area inside or outside its contours; and if Path_Contour overlaps itself or another Path_Contour, whether the overlaps form part of the area. path is transformed by Matrix before it is combined with Clip. #Param path Path to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Param doAntiAlias true if Clip is to be Anti-aliased ## #Example #Description Top figure uses SkPath::kInverseWinding_FillType and SkClipOp::kDifference; area outside clip is subtracted from circle. Bottom figure uses SkPath::kWinding_FillType and SkClipOp::kIntersect; area inside clip is intersected with circle. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkPath path; path.addRect({20, 30, 100, 110}); path.setFillType(SkPath::kInverseWinding_FillType); canvas->save(); canvas->clipPath(path, SkClipOp::kDifference, false); canvas->drawCircle(70, 100, 60, paint); canvas->restore(); canvas->translate(100, 100); path.setFillType(SkPath::kWinding_FillType); canvas->clipPath(path, SkClipOp::kIntersect, false); canvas->drawCircle(70, 100, 60, paint); } ## #SeeAlso clipRect clipRRect clipRegion ## #Method void clipPath(const SkPath& path, SkClipOp op) Replace Clip with the intersection or difference of Clip and path. Resulting Clip is Aliased; pixels are fully contained by the clip. Path_Fill_Type determines if path describes the area inside or outside its contours; and if Path_Contour overlaps itself or another Path_Contour, whether the overlaps form part of the area. path is transformed by Matrix before it is combined with Clip. #Param path Path to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Example #Description Overlapping Rects form a clip. When clip Path_Fill_Type is set to SkPath::kWinding_FillType, the overlap is included. Set to SkPath::kEvenOdd_FillType, the overlap is excluded and forms a hole. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkPath path; path.addRect({20, 15, 100, 95}); path.addRect({50, 65, 130, 135}); path.setFillType(SkPath::kWinding_FillType); canvas->save(); canvas->clipPath(path, SkClipOp::kIntersect); canvas->drawCircle(70, 85, 60, paint); canvas->restore(); canvas->translate(100, 100); path.setFillType(SkPath::kEvenOdd_FillType); canvas->clipPath(path, SkClipOp::kIntersect); canvas->drawCircle(70, 85, 60, paint); } ## #SeeAlso clipRect clipRRect clipRegion ## #Method void clipPath(const SkPath& path, bool doAntiAlias = false) Replace Clip with the intersection of Clip and path. Resulting Clip is Aliased; pixels are fully contained by the clip. Path_Fill_Type determines if path describes the area inside or outside its contours; and if Path_Contour overlaps itself or another Path_Contour, whether the overlaps form part of the area. path is transformed by Matrix before it is combined with Clip. #Param path Path to combine with Clip ## #Param doAntiAlias true if Clip is to be Anti-aliased ## #Example #Height 212 #Description Clip loops over itself covering its center twice. When clip Path_Fill_Type is set to SkPath::kWinding_FillType, the overlap is included. Set to SkPath::kEvenOdd_FillType, the overlap is excluded and forms a hole. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkPath path; SkPoint poly[] = {{20, 20}, { 80, 20}, { 80, 80}, {40, 80}, {40, 40}, {100, 40}, {100, 100}, {20, 100}}; path.addPoly(poly, SK_ARRAY_COUNT(poly), true); path.setFillType(SkPath::kWinding_FillType); canvas->save(); canvas->clipPath(path, SkClipOp::kIntersect); canvas->drawCircle(50, 50, 45, paint); canvas->restore(); canvas->translate(100, 100); path.setFillType(SkPath::kEvenOdd_FillType); canvas->clipPath(path, SkClipOp::kIntersect); canvas->drawCircle(50, 50, 45, paint); } ## #SeeAlso clipRect clipRRect clipRegion ## # ------------------------------------------------------------------------------ #Method void setAllowSimplifyClip(bool allow) #Experimental Only used for testing. ## Set to simplify clip stack using PathOps. ## # ------------------------------------------------------------------------------ #Method void clipRegion(const SkRegion& deviceRgn, SkClipOp op = SkClipOp::kIntersect) Replace Clip with the intersection or difference of Clip and Region deviceRgn. Resulting Clip is Aliased; pixels are fully contained by the clip. deviceRgn is unaffected by Matrix. #Param deviceRgn Region to combine with Clip ## #Param op Clip_Op to apply to Clip ## #Example #Description region is unaffected by canvas rotation; iRect is affected by canvas rotation. Both clips are Aliased; this is not noticeable on Region clip because it aligns to pixel boundaries. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkIRect iRect = {30, 40, 120, 130 }; SkRegion region(iRect); canvas->rotate(10); canvas->save(); canvas->clipRegion(region, SkClipOp::kIntersect); canvas->drawCircle(50, 50, 45, paint); canvas->restore(); canvas->translate(100, 100); canvas->clipRect(SkRect::Make(iRect), SkClipOp::kIntersect); canvas->drawCircle(50, 50, 45, paint); } ## #SeeAlso clipRect clipRRect clipPath ## #Method bool quickReject(const SkRect& rect) const Return true if Rect rect, transformed by Matrix, can be quickly determined to be outside of Clip. May return false even though rect is outside of Clip. Use to check if an area to be drawn is clipped out, to skip subsequent draw calls. #Param rect Rect to compare with Clip ## #Return true if rect, transformed by Matrix, does not intersect Clip ## #Example void draw(SkCanvas* canvas) { SkRect testRect = {30, 30, 120, 129 }; SkRect clipRect = {30, 130, 120, 230 }; canvas->save(); canvas->clipRect(clipRect); SkDebugf("quickReject %s\n", canvas->quickReject(testRect) ? "true" : "false"); canvas->restore(); canvas->rotate(10); canvas->clipRect(clipRect); SkDebugf("quickReject %s\n", canvas->quickReject(testRect) ? "true" : "false"); } #StdOut quickReject true quickReject false ## ## #SeeAlso getLocalClipBounds getTotalMatrix SkBitmap::drawsNothing ## #Method bool quickReject(const SkPath& path) const Return true if path, transformed by Matrix, can be quickly determined to be outside of Clip. May return false even though path is outside of Clip. Use to check if an area to be drawn is clipped out, to skip subsequent draw calls. #Param path Path to compare with Clip ## #Return true if path, transformed by Matrix, does not intersect Clip ## #Example void draw(SkCanvas* canvas) { SkPoint testPoints[] = {{30, 30}, {120, 30}, {120, 129} }; SkPoint clipPoints[] = {{30, 130}, {120, 130}, {120, 230} }; SkPath testPath, clipPath; testPath.addPoly(testPoints, SK_ARRAY_COUNT(testPoints), true); clipPath.addPoly(clipPoints, SK_ARRAY_COUNT(clipPoints), true); canvas->save(); canvas->clipPath(clipPath); SkDebugf("quickReject %s\n", canvas->quickReject(testPath) ? "true" : "false"); canvas->restore(); canvas->rotate(10); canvas->clipPath(clipPath); SkDebugf("quickReject %s\n", canvas->quickReject(testPath) ? "true" : "false"); #StdOut quickReject true quickReject false ## } ## #SeeAlso getLocalClipBounds getTotalMatrix SkBitmap::drawsNothing ## #Method SkRect getLocalClipBounds() const Return bounds of Clip, transformed by inverse of Matrix. If Clip is empty, return SkRect::MakeEmpty, where all Rect sides equal zero. Rect returned is outset by one to account for partial pixel coverage if Clip is Anti-aliased. #Return bounds of Clip in local coordinates ## #Example #Description Initial bounds is device bounds outset by 1 on all sides. Clipped bounds is clipPath bounds outset by 1 on all sides. Scaling the canvas by two in x and y scales the local bounds by 1/2 in x and y. ## SkCanvas local(256, 256); canvas = &local; SkRect bounds = canvas->getLocalClipBounds(); SkDebugf("left:%g top:%g right:%g bottom:%g\n", bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom); SkPoint clipPoints[] = {{30, 130}, {120, 130}, {120, 230} }; SkPath clipPath; clipPath.addPoly(clipPoints, SK_ARRAY_COUNT(clipPoints), true); canvas->clipPath(clipPath); bounds = canvas->getLocalClipBounds(); SkDebugf("left:%g top:%g right:%g bottom:%g\n", bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom); canvas->scale(2, 2); bounds = canvas->getLocalClipBounds(); SkDebugf("left:%g top:%g right:%g bottom:%g\n", bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom); #StdOut left:-1 top:-1 right:257 bottom:257 left:29 top:129 right:121 bottom:231 left:14.5 top:64.5 right:60.5 bottom:115.5 ## ## # local canvas in example works around bug in fiddle ## #Bug 6524 ## #SeeAlso getDeviceClipBounds getBaseLayerSize quickReject ## #Method bool getLocalClipBounds(SkRect* bounds) const Return bounds of Clip, transformed by inverse of Matrix. If Clip is empty, return false, and set bounds to SkRect::MakeEmpty, where all Rect sides equal zero. bounds is outset by one to account for partial pixel coverage if Clip is Anti-aliased. #Param bounds Rect of Clip in local coordinates ## #Return true if Clip bounds is not empty ## #Example void draw(SkCanvas* canvas) { SkCanvas local(256, 256); canvas = &local; SkRect bounds; SkDebugf("local bounds empty = %s\n", canvas->getLocalClipBounds(&bounds) ? "false" : "true"); SkPath path; canvas->clipPath(path); SkDebugf("local bounds empty = %s\n", canvas->getLocalClipBounds(&bounds) ? "false" : "true"); } #StdOut local bounds empty = false local bounds empty = true ## ## # local canvas in example works around bug in fiddle ## #Bug 6524 ## #SeeAlso getDeviceClipBounds getBaseLayerSize quickReject ## #Method SkIRect getDeviceClipBounds() const Return IRect bounds of Clip, unaffected by Matrix. If Clip is empty, return SkRect::MakeEmpty, where all Rect sides equal zero. Unlike getLocalClipBounds, returned IRect is not outset. #Return bounds of Clip in Device coordinates ## #Example void draw(SkCanvas* canvas) { #Description Initial bounds is device bounds, not outset. Clipped bounds is clipPath bounds, not outset. Scaling the canvas by 1/2 in x and y scales the device bounds by 1/2 in x and y. ## SkCanvas device(256, 256); canvas = &device; SkIRect bounds = canvas->getDeviceClipBounds(); SkDebugf("left:%d top:%d right:%d bottom:%d\n", bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom); SkPoint clipPoints[] = {{30, 130}, {120, 130}, {120, 230} }; SkPath clipPath; clipPath.addPoly(clipPoints, SK_ARRAY_COUNT(clipPoints), true); canvas->save(); canvas->clipPath(clipPath); bounds = canvas->getDeviceClipBounds(); SkDebugf("left:%d top:%d right:%d bottom:%d\n", bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom); canvas->restore(); canvas->scale(1.f/2, 1.f/2); canvas->clipPath(clipPath); bounds = canvas->getDeviceClipBounds(); SkDebugf("left:%d top:%d right:%d bottom:%d\n", bounds.fLeft, bounds.fTop, bounds.fRight, bounds.fBottom); #StdOut left:0 top:0 right:256 bottom:256 left:30 top:130 right:120 bottom:230 left:15 top:65 right:60 bottom:115 ## } ## #ToDo some confusion on why with an identity Matrix local and device are different ## #SeeAlso getLocalClipBounds getBaseLayerSize quickReject # device canvas in example works around bug in fiddle ## #Bug 6524 ## ## #Method bool getDeviceClipBounds(SkIRect* bounds) const Return IRect bounds of Clip, unaffected by Matrix. If Clip is empty, return false, and set bounds to SkRect::MakeEmpty, where all Rect sides equal zero. Unlike getLocalClipBounds, bounds is not outset. #Param bounds Rect of Clip in device coordinates ## #Return true if Clip bounds is not empty ## #Example void draw(SkCanvas* canvas) { SkIRect bounds; SkDebugf("device bounds empty = %s\n", canvas->getDeviceClipBounds(&bounds) ? "false" : "true"); SkPath path; canvas->clipPath(path); SkDebugf("device bounds empty = %s\n", canvas->getDeviceClipBounds(&bounds) ? "false" : "true"); } #StdOut device bounds empty = false device bounds empty = true ## ## #SeeAlso getLocalClipBounds getBaseLayerSize quickReject ## #Topic Clip ## # ------------------------------------------------------------------------------ #Method void drawColor(SkColor color, SkBlendMode mode = SkBlendMode::kSrcOver) Fill Clip with Color color. mode determines how Color_ARGB is combined with destination. #Param color Unpremultiplied Color_ARGB ## #Param mode SkBlendMode used to combine source color and destination ## #Example canvas->drawColor(SK_ColorRED); canvas->clipRect(SkRect::MakeWH(150, 150)); canvas->drawColor(SkColorSetARGB(0x80, 0x00, 0xFF, 0x00), SkBlendMode::kPlus); canvas->clipRect(SkRect::MakeWH(75, 75)); canvas->drawColor(SkColorSetARGB(0x80, 0x00, 0x00, 0xFF), SkBlendMode::kPlus); ## #SeeAlso clear SkBitmap::erase drawPaint ## # ------------------------------------------------------------------------------ #Method void clear(SkColor color) Fill Clip with Color color using SkBlendMode::kSrc. This has the effect of replacing all pixels contained by Clip with color. #Param color Unpremultiplied Color_ARGB ## #Example void draw(SkCanvas* canvas) { canvas->save(); canvas->clipRect(SkRect::MakeWH(256, 128)); canvas->clear(SkColorSetARGB(0x80, 0xFF, 0x00, 0x00)); canvas->restore(); canvas->save(); canvas->clipRect(SkRect::MakeWH(150, 192)); canvas->clear(SkColorSetARGB(0x80, 0x00, 0xFF, 0x00)); canvas->restore(); canvas->clipRect(SkRect::MakeWH(75, 256)); canvas->clear(SkColorSetARGB(0x80, 0x00, 0x00, 0xFF)); } ## #SeeAlso drawColor SkBitmap::erase drawPaint ## # ------------------------------------------------------------------------------ #Method void discard() Make Canvas contents undefined. Subsequent calls that read Canvas pixels, such as drawing with SkBlendMode, return undefined results. discard() does not change Clip or Matrix. discard() may do nothing, depending on the implementation of Surface or Device that created Canvas. discard() allows optimized performance on subsequent draws by removing cached data associated with Surface or Device. It is not necessary to call discard() once done with Canvas; any cached data is deleted when owning Surface or Device is deleted. #ToDo example? not sure how to make this meaningful w/o more implementation detail ## #SeeAlso flush() SkSurface::prepareForExternalIO GrContext::abandonContext #NoExample ## ## # ------------------------------------------------------------------------------ #Method void drawPaint(const SkPaint& paint) Fill Clip with Paint paint. Paint components Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Blend_Mode affect drawing; Path_Effect in paint is ignored. # can Path_Effect in paint ever alter drawPaint? #Param paint graphics state used to fill Canvas ## #Example void draw(SkCanvas* canvas) { SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE }; SkScalar pos[] = { 0, SK_Scalar1/2, SK_Scalar1 }; SkPaint paint; paint.setShader(SkGradientShader::MakeSweep(256, 256, colors, pos, SK_ARRAY_COUNT(colors))); canvas->drawPaint(paint); } ## #SeeAlso clear drawColor SkBitmap::erase ## # ------------------------------------------------------------------------------ #Enum PointMode #Code enum PointMode { kPoints_PointMode, kLines_PointMode, kPolygon_PointMode, }; ## Selects if an array of points are drawn as discrete points, as lines, or as an open polygon. #Const kPoints_PointMode 0 Draw each point separately. ## #Const kLines_PointMode 1 Draw each pair of points as a line segment. ## #Const kPolygon_PointMode 2 Draw the array of points as a open polygon. ## #Example #Description The upper left corner shows three squares when drawn as points. The upper right corner shows one line; when drawn as lines, two points are required per line. The lower right corner shows two lines; when draw as polygon, no miter is drawn at the corner. The lower left corner shows two lines with a miter when path contains polygon. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(10); SkPoint points[] = {{64, 32}, {96, 96}, {32, 96}}; canvas->drawPoints(SkCanvas::kPoints_PointMode, 3, points, paint); canvas->translate(128, 0); canvas->drawPoints(SkCanvas::kLines_PointMode, 3, points, paint); canvas->translate(0, 128); canvas->drawPoints(SkCanvas::kPolygon_PointMode, 3, points, paint); SkPath path; path.addPoly(points, 3, false); canvas->translate(-128, 0); canvas->drawPath(path, paint); } ## #SeeAlso drawLine drawPoint drawPath ## # ------------------------------------------------------------------------------ #Method void drawPoints(PointMode mode, size_t count, const SkPoint pts[], const SkPaint& paint) Draw pts using Clip, Matrix and Paint paint. count is the number of points; if count is less than one, has no effect. mode may be one of: kPoints_PointMode, kLines_PointMode, or kPolygon_PointMode. If mode is kPoints_PointMode, the shape of point drawn depends on paint Paint_Stroke_Cap. If paint is set to SkPaint::kRound_Cap, each point draws a circle of diameter Paint_Stroke_Width. If paint is set to SkPaint::kSquare_Cap or SkPaint::kButt_Cap, each point draws a square of width and height Paint_Stroke_Width. If mode is kLines_PointMode, each pair of points draws a line segment. One line is drawn for every two points; each point is used once. If count is odd, the final point is ignored. If mode is kPolygon_PointMode, each adjacent pair of points draws a line segment. count minus one lines are drawn; the first and last point are used once. Each line segment respects paint Paint_Stroke_Cap and Paint_Stroke_Width. Paint_Style is ignored, as if were set to SkPaint::kStroke_Style. Always draws each element one at a time; is not affected by Paint_Stroke_Join, and unlike drawPath, does not create a mask from all points and lines before drawing. #Param mode whether pts draws points or lines ## #Param count number of points in the array ## #Param pts array of points to draw ## #Param paint stroke, blend, color, and so on, used to draw ## #Example #Height 200 #Description #List # The first column draws points. ## # The second column draws points as lines. ## # The third column draws points as a polygon. ## # The fourth column draws points as a polygonal path. ## # The first row uses a round cap and round join. ## # The second row uses a square cap and a miter join. ## # The third row uses a butt cap and a bevel join. ## ## The transparent color makes multiple line draws visible; the path is drawn all at once. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(10); paint.setColor(0x80349a45); const SkPoint points[] = {{32, 16}, {48, 48}, {16, 32}}; const SkPaint::Join join[] = { SkPaint::kRound_Join, SkPaint::kMiter_Join, SkPaint::kBevel_Join }; int joinIndex = 0; SkPath path; path.addPoly(points, 3, false); for (const auto cap : { SkPaint::kRound_Cap, SkPaint::kSquare_Cap, SkPaint::kButt_Cap } ) { paint.setStrokeCap(cap); paint.setStrokeJoin(join[joinIndex++]); for (const auto mode : { SkCanvas::kPoints_PointMode, SkCanvas::kLines_PointMode, SkCanvas::kPolygon_PointMode } ) { canvas->drawPoints(mode, 3, points, paint); canvas->translate(64, 0); } canvas->drawPath(path, paint); canvas->translate(-192, 64); } } ## #SeeAlso drawLine drawPoint drawPath ## # ------------------------------------------------------------------------------ #Method void drawPoint(SkScalar x, SkScalar y, const SkPaint& paint) Draw point at (x, y) using Clip, Matrix and Paint paint. The shape of point drawn depends on paint Paint_Stroke_Cap. If paint is set to SkPaint::kRound_Cap, draw a circle of diameter Paint_Stroke_Width. If paint is set to SkPaint::kSquare_Cap or SkPaint::kButt_Cap, draw a square of width and height Paint_Stroke_Width. Paint_Style is ignored, as if were set to SkPaint::kStroke_Style. #Param x left edge of circle or square ## #Param y top edge of circle or square ## #Param paint stroke, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); paint.setColor(0x80349a45); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(100); paint.setStrokeCap(SkPaint::kRound_Cap); canvas->scale(1, 1.2f); canvas->drawPoint(64, 96, paint); canvas->scale(.6f, .8f); paint.setColor(SK_ColorWHITE); canvas->drawPoint(106, 120, paint); } ## #SeeAlso drawPoints drawCircle drawRect drawLine drawPath ## #Method void drawPoint(SkPoint p, const SkPaint& paint) Draw point p using Clip, Matrix and Paint paint. The shape of point drawn depends on paint Paint_Stroke_Cap. If paint is set to SkPaint::kRound_Cap, draw a circle of diameter Paint_Stroke_Width. If paint is set to SkPaint::kSquare_Cap or SkPaint::kButt_Cap, draw a square of width and height Paint_Stroke_Width. Paint_Style is ignored, as if were set to SkPaint::kStroke_Style. #Param p top-left edge of circle or square ## #Param paint stroke, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); paint.setColor(0x80349a45); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(100); paint.setStrokeCap(SkPaint::kSquare_Cap); canvas->scale(1, 1.2f); canvas->drawPoint({64, 96}, paint); canvas->scale(.6f, .8f); paint.setColor(SK_ColorWHITE); canvas->drawPoint(106, 120, paint); } ## #SeeAlso drawPoints drawCircle drawRect drawLine drawPath ## # ------------------------------------------------------------------------------ #Method void drawLine(SkScalar x0, SkScalar y0, SkScalar x1, SkScalar y1, const SkPaint& paint) Draws line segment from (x0, y0) to (x1, y1) using Clip, Matrix, and Paint paint. In paint: Paint_Stroke_Width describes the line thickness; Paint_Stroke_Cap draws the end rounded or square; Paint_Style is ignored, as if were set to SkPaint::kStroke_Style. #Param x0 start of line segment on x-axis ## #Param y0 start of line segment on y-axis ## #Param x1 end of line segment on x-axis ## #Param y1 end of line segment on y-axis ## #Param paint stroke, blend, color, and so on, used to draw ## #Example SkPaint paint; paint.setAntiAlias(true); paint.setColor(0xFF9a67be); paint.setStrokeWidth(20); canvas->skew(1, 0); canvas->drawLine(32, 96, 32, 160, paint); canvas->skew(-2, 0); canvas->drawLine(288, 96, 288, 160, paint); ## #SeeAlso drawPoint drawCircle drawRect drawPath ## #Method void drawLine(SkPoint p0, SkPoint p1, const SkPaint& paint) Draws line segment from p0 to p1 using Clip, Matrix, and Paint paint. In paint: Paint_Stroke_Width describes the line thickness; Paint_Stroke_Cap draws the end rounded or square; Paint_Style is ignored, as if were set to SkPaint::kStroke_Style. #Param p0 start of line segment ## #Param p1 end of line segment ## #Param paint stroke, blend, color, and so on, used to draw ## #Example SkPaint paint; paint.setAntiAlias(true); paint.setColor(0xFF9a67be); paint.setStrokeWidth(20); canvas->skew(1, 0); canvas->drawLine({32, 96}, {32, 160}, paint); canvas->skew(-2, 0); canvas->drawLine({288, 96}, {288, 160}, paint); ## #SeeAlso drawPoint drawCircle drawRect drawPath ## # ------------------------------------------------------------------------------ #Method void drawRect(const SkRect& rect, const SkPaint& paint) Draw Rect rect using Clip, Matrix, and Paint paint. In paint: Paint_Style determines if rectangle is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness, and Paint_Stroke_Join draws the corners rounded or square. #Param rect rectangle to draw ## #Param paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPoint rectPts[] = { {64, 48}, {192, 160} }; SkPaint paint; paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(20); paint.setStrokeJoin(SkPaint::kRound_Join); SkMatrix rotator; rotator.setRotate(30, 128, 128); for (auto color : { SK_ColorRED, SK_ColorBLUE, SK_ColorYELLOW, SK_ColorMAGENTA } ) { paint.setColor(color); SkRect rect; rect.set(rectPts[0], rectPts[1]); canvas->drawRect(rect, paint); rotator.mapPoints(rectPts, 2); } } ## #SeeAlso drawIRect drawRRect drawRoundRect drawRegion drawPath drawLine ## # ------------------------------------------------------------------------------ #Method void drawIRect(const SkIRect& rect, const SkPaint& paint) Draw IRect rect using Clip, Matrix, and Paint paint. In paint: Paint_Style determines if rectangle is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness, and Paint_Stroke_Join draws the corners rounded or square. #Param rect rectangle to draw ## #Param paint stroke or fill, blend, color, and so on, used to draw ## #Example SkIRect rect = { 64, 48, 192, 160 }; SkPaint paint; paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(20); paint.setStrokeJoin(SkPaint::kRound_Join); for (auto color : { SK_ColorRED, SK_ColorBLUE, SK_ColorYELLOW, SK_ColorMAGENTA } ) { paint.setColor(color); canvas->drawIRect(rect, paint); canvas->rotate(30, 128, 128); } ## #SeeAlso drawRect drawRRect drawRoundRect drawRegion drawPath drawLine ## # ------------------------------------------------------------------------------ #Method void drawRegion(const SkRegion& region, const SkPaint& paint) Draw Region region using Clip, Matrix, and Paint paint. In paint: Paint_Style determines if rectangle is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness, and Paint_Stroke_Join draws the corners rounded or square. #Param region region to draw ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkRegion region; region.op( 10, 10, 50, 50, SkRegion::kUnion_Op); region.op( 10, 50, 90, 90, SkRegion::kUnion_Op); SkPaint paint; paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(20); paint.setStrokeJoin(SkPaint::kRound_Join); canvas->drawRegion(region, paint); } ## #SeeAlso drawRect drawIRect drawPath ## # ------------------------------------------------------------------------------ #Method void drawOval(const SkRect& oval, const SkPaint& paint) Draw Oval oval using Clip, Matrix, and Paint. In paint: Paint_Style determines if Oval is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness. #Param oval Rect bounds of Oval ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { canvas->clear(0xFF3f5f9f); SkColor kColor1 = SkColorSetARGB(0xff, 0xff, 0x7f, 0); SkColor g1Colors[] = { kColor1, SkColorSetA(kColor1, 0x20) }; SkPoint g1Points[] = { { 0, 0 }, { 0, 100 } }; SkScalar pos[] = { 0.2f, 1.0f }; SkRect bounds = SkRect::MakeWH(80, 70); SkPaint paint; paint.setAntiAlias(true); paint.setShader(SkGradientShader::MakeLinear(g1Points, g1Colors, pos, SK_ARRAY_COUNT(g1Colors), SkShader::kClamp_TileMode)); canvas->drawOval(bounds , paint); } ## #SeeAlso drawCircle drawPoint drawPath drawRRect drawRoundRect ## # ------------------------------------------------------------------------------ #Method void drawRRect(const SkRRect& rrect, const SkPaint& paint) Draw Round_Rect rrect using Clip, Matrix, and Paint paint. In paint: Paint_Style determines if rrect is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness. rrect may represent a rectangle, circle, oval, uniformly rounded rectangle, or may have any combination of positive non-square radii for the four corners. #Param rrect Round_Rect with up to eight corner radii to draw ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkRect outer = {30, 40, 210, 220}; SkRect radii = {30, 50, 70, 90 }; SkRRect rRect; rRect.setNinePatch(outer, radii.fLeft, radii.fTop, radii.fRight, radii.fBottom); canvas->drawRRect(rRect, paint); paint.setColor(SK_ColorWHITE); canvas->drawLine(outer.fLeft + radii.fLeft, outer.fTop, outer.fLeft + radii.fLeft, outer.fBottom, paint); canvas->drawLine(outer.fRight - radii.fRight, outer.fTop, outer.fRight - radii.fRight, outer.fBottom, paint); canvas->drawLine(outer.fLeft, outer.fTop + radii.fTop, outer.fRight, outer.fTop + radii.fTop, paint); canvas->drawLine(outer.fLeft, outer.fBottom - radii.fBottom, outer.fRight, outer.fBottom - radii.fBottom, paint); } ## #SeeAlso drawRect drawRoundRect drawDRRect drawCircle drawOval drawPath ## # ------------------------------------------------------------------------------ #Method void drawDRRect(const SkRRect& outer, const SkRRect& inner, const SkPaint& paint) Draw Round_Rect outer and inner using Clip, Matrix, and Paint paint. outer must contain inner or the drawing is undefined. In paint: Paint_Style determines if Round_Rect is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness. If stroked and Round_Rect corner has zero length radii, Paint_Stroke_Join can draw corners rounded or square. GPU-backed platforms optimize drawing when both outer and inner are concave and outer contains inner. These platforms may not be able to draw Path built with identical data as fast. #Param outer Round_Rect outer bounds to draw ## #Param inner Round_Rect inner bounds to draw ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkRRect outer = SkRRect::MakeRect({20, 40, 210, 200}); SkRRect inner = SkRRect::MakeOval({60, 70, 170, 160}); SkPaint paint; canvas->drawDRRect(outer, inner, paint); } ## #Example #Description Outer Rect has no corner radii, but stroke join is rounded. Inner Round_Rect has corner radii; outset stroke increases radii of corners. Stroke join does not affect inner Round_Rect since it has no sharp corners. ## void draw(SkCanvas* canvas) { SkRRect outer = SkRRect::MakeRect({20, 40, 210, 200}); SkRRect inner = SkRRect::MakeRectXY({60, 70, 170, 160}, 10, 10); SkPaint paint; paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(20); paint.setStrokeJoin(SkPaint::kRound_Join); canvas->drawDRRect(outer, inner, paint); paint.setStrokeWidth(1); paint.setColor(SK_ColorWHITE); canvas->drawDRRect(outer, inner, paint); } ## #SeeAlso drawRect drawRoundRect drawRRect drawCircle drawOval drawPath ## # ------------------------------------------------------------------------------ #Method void drawCircle(SkScalar cx, SkScalar cy, SkScalar radius, const SkPaint& paint) Draw Circle at (cx, cy) with radius using Clip, Matrix, and Paint paint. If radius is zero or less, nothing is drawn. In paint: Paint_Style determines if Circle is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness. #Param cx Circle center on the x-axis ## #Param cy Circle center on the y-axis ## #Param radius half the diameter of Circle ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); canvas->drawCircle(128, 128, 90, paint); paint.setColor(SK_ColorWHITE); canvas->drawCircle(86, 86, 20, paint); canvas->drawCircle(160, 76, 20, paint); canvas->drawCircle(140, 150, 35, paint); } ## #SeeAlso drawOval drawRRect drawRoundRect drawPath drawArc drawPoint drawLine ## #Method void drawCircle(SkPoint center, SkScalar radius, const SkPaint& paint) Draw Circle at center with radius using Clip, Matrix, and Paint paint. If radius is zero or less, nothing is drawn. In paint: Paint_Style determines if Circle is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness. #Param center Circle center ## #Param radius half the diameter of Circle ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); canvas->drawCircle(128, 128, 90, paint); paint.setColor(SK_ColorWHITE); canvas->drawCircle({86, 86}, 20, paint); canvas->drawCircle({160, 76}, 20, paint); canvas->drawCircle({140, 150}, 35, paint); } ## #SeeAlso drawOval drawRRect drawRoundRect drawPath drawArc drawPoint drawLine ## # ------------------------------------------------------------------------------ #Method void drawArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle, bool useCenter, const SkPaint& paint) Draw Arc using Clip, Matrix, and Paint paint. Arc is part of Oval bounded by oval, sweeping from startAngle to startAngle plus sweepAngle. startAngle and sweepAngle are in degrees. startAngle of zero places start point at the right middle edge of oval. A positive sweepAngle places Arc end point clockwise from start point; a negative sweepAngle places Arc end point counterclockwise from start point. sweepAngle may exceed 360 degrees, a full circle. If useCenter is true, draw a wedge that includes lines from oval center to Arc end points. If useCenter is false, draw Arc between end points. If Rect oval is empty or sweepAngle is zero, nothing is drawn. #Param oval Rect bounds of Oval containing Arc to draw ## #Param startAngle angle in degrees where Arc begins ## #Param sweepAngle sweep angle in degrees; positive is clockwise ## #Param useCenter if true, include the center of the oval ## #Param paint Paint stroke or fill, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkRect oval = { 4, 4, 60, 60}; for (auto useCenter : { false, true } ) { for (auto style : { SkPaint::kFill_Style, SkPaint::kStroke_Style } ) { paint.setStyle(style); for (auto degrees : { 45, 90, 180, 360} ) { canvas->drawArc(oval, 0, degrees , useCenter, paint); canvas->translate(64, 0); } canvas->translate(-256, 64); } } } ## #Example #Height 64 void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); paint.setStrokeWidth(4); SkRect oval = { 4, 4, 60, 60}; float intervals[] = { 5, 5 }; paint.setPathEffect(SkDashPathEffect::Make(intervals, 2, 2.5f)); for (auto degrees : { 270, 360, 540, 720 } ) { canvas->drawArc(oval, 0, degrees, false, paint); canvas->translate(64, 0); } } ## #SeeAlso SkPath::arcTo drawCircle drawOval drawPath ## # ------------------------------------------------------------------------------ #Method void drawRoundRect(const SkRect& rect, SkScalar rx, SkScalar ry, const SkPaint& paint) Draw Round_Rect bounded by Rect rect, with corner radii (rx, ry) using Clip, Matrix, and Paint paint. In paint: Paint_Style determines if Round_Rect is stroked or filled; if stroked, Paint_Stroke_Width describes the line thickness. If rx or ry are less than zero, they are treated as if they are zero. If rx plus ry exceeds rect width or rect height, radii are scaled down to fit. If rx and ry are zero, Round_Rect is drawn as Rect and if stroked is affected by Paint_Stroke_Join. #Param rect Rect bounds of Round_Rect to draw ## #Param rx axis length in x of oval describing rounded corners ## #Param ry axis length in y of oval describing rounded corners ## #Param paint stroke, blend, color, and so on, used to draw ## #Example #Description Top row has a zero radius a generates a rectangle. Second row radii sum to less than sides. Third row radii sum equals sides. Fourth row radii sum exceeds sides; radii are scaled to fit. ## void draw(SkCanvas* canvas) { SkVector radii[] = { {0, 20}, {10, 10}, {10, 20}, {10, 40} }; SkPaint paint; paint.setStrokeWidth(15); paint.setStrokeJoin(SkPaint::kRound_Join); paint.setAntiAlias(true); for (auto style : { SkPaint::kStroke_Style, SkPaint::kFill_Style } ) { paint.setStyle(style ); for (size_t i = 0; i < SK_ARRAY_COUNT(radii); ++i) { canvas->drawRoundRect({10, 10, 60, 40}, radii[i].fX, radii[i].fY, paint); canvas->translate(0, 60); } canvas->translate(80, -240); } } ## #SeeAlso DrawRRect drawRect drawDRRect drawPath drawCircle drawOval drawPoint ## # ------------------------------------------------------------------------------ #Method void drawPath(const SkPath& path, const SkPaint& paint) Draw Path path using Clip, Matrix, and Paint paint. Path contains an array of Path_Contour, each of which may be open or closed. In paint: Paint_Style determines if Round_Rect is stroked or filled: if filled, Path_Fill_Type determines whether Path_Contour describes inside or outside of fill; if stroked, Paint_Stroke_Width describes the line thickness, Paint_Stroke_Cap describes line ends, and Paint_Stroke_Join describes how corners are drawn. #Param path Path to draw ## #Param paint stroke, blend, color, and so on, used to draw ## #Example #Description Top rows draw stroked path with combinations of joins and caps. The open contour is affected by caps; the closed contour is affected by joins. Bottom row draws fill the same for open and closed contour. First bottom column shows winding fills overlap. Second bottom column shows even odd fills exclude overlap. Third bottom column shows inverse winding fills area outside both contours. ## void draw(SkCanvas* canvas) { SkPath path; path.moveTo(20, 20); path.quadTo(60, 20, 60, 60); path.close(); path.moveTo(60, 20); path.quadTo(60, 60, 20, 60); SkPaint paint; paint.setStrokeWidth(10); paint.setAntiAlias(true); paint.setStyle(SkPaint::kStroke_Style); for (auto join: { SkPaint::kBevel_Join, SkPaint::kRound_Join, SkPaint::kMiter_Join } ) { paint.setStrokeJoin(join); for (auto cap: { SkPaint::kButt_Cap, SkPaint::kSquare_Cap, SkPaint::kRound_Cap } ) { paint.setStrokeCap(cap); canvas->drawPath(path, paint); canvas->translate(80, 0); } canvas->translate(-240, 60); } paint.setStyle(SkPaint::kFill_Style); for (auto fill : { SkPath::kWinding_FillType, SkPath::kEvenOdd_FillType, SkPath::kInverseWinding_FillType } ) { path.setFillType(fill); canvas->save(); canvas->clipRect({0, 10, 80, 70}); canvas->drawPath(path, paint); canvas->restore(); canvas->translate(80, 0); } } ## #SeeAlso SkPath drawLine drawArc drawRect drawPoints ## # ------------------------------------------------------------------------------ #Topic Draw_Image drawImage, drawImageRect, and drawImageNine can be called with a bare pointer or a smart pointer as a convenience. The pairs of calls are otherwise identical. #Method void drawImage(const SkImage* image, SkScalar left, SkScalar top, const SkPaint* paint = nullptr) Draw Image image, with its top-left corner at (left, top), using Clip, Matrix, and optional Paint paint. If paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. #Param image uncompressed rectangular map of pixels ## #Param left left side of image ## #Param top top side of image ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 64 #Image 4 void draw(SkCanvas* canvas) { // sk_sp image; SkImage* imagePtr = image.get(); canvas->drawImage(imagePtr, 0, 0); SkPaint paint; canvas->drawImage(imagePtr, 80, 0, &paint); paint.setAlpha(0x80); canvas->drawImage(imagePtr, 160, 0, &paint); } ## #SeeAlso drawBitmap drawImageLattice drawImageNine drawImageRect SkPaint::setImageFilter ## # ------------------------------------------------------------------------------ #Method void drawImage(const sk_sp& image, SkScalar left, SkScalar top, const SkPaint* paint = nullptr) Draw Image image, with its top-left corner at (left, top), using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. #Param image uncompressed rectangular map of pixels ## #Param left left side of image ## #Param top pop side of image ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 64 #Image 4 void draw(SkCanvas* canvas) { // sk_sp image; canvas->drawImage(image, 0, 0); SkPaint paint; canvas->drawImage(image, 80, 0, &paint); paint.setAlpha(0x80); canvas->drawImage(image, 160, 0, &paint); } ## #SeeAlso drawBitmap drawImageLattice drawImageNine drawImageRect SkPaint::setImageFilter ## # ------------------------------------------------------------------------------ #Enum SrcRectConstraint #Code enum SrcRectConstraint { kStrict_SrcRectConstraint, kFast_SrcRectConstraint, }; ## SrcRectConstraint controls the behavior at the edge of source Rect, provided to drawImageRect, trading off speed for precision. Image_Filter in Paint may sample multiple pixels in the image. Source Rect restricts the bounds of pixels that may be read. Image_Filter may slow down if it cannot read outside the bounds, when sampling near the edge of source Rect. SrcRectConstraint specifies whether an Image_Filter is allowed to read pixels outside source Rect. #Const kStrict_SrcRectConstraint Requires Image_Filter to respect source Rect, sampling only inside of its bounds, possibly with a performance penalty. ## #Const kFast_SrcRectConstraint Permits Image_Filter to sample outside of source Rect by half the width of Image_Filter, permitting it to run faster but with error at the image edges. ## #Example #Height 64 #Description redBorder contains a black and white checkerboard bordered by red. redBorder is drawn scaled by 16 on the left. The middle and right bitmaps are filtered checkerboards. Drawing the checkerboard with kStrict_SrcRectConstraint shows only a blur of black and white. Drawing the checkerboard with kFast_SrcRectConstraint allows red to bleed in the corners. ## void draw(SkCanvas* canvas) { SkBitmap redBorder; redBorder.allocPixels(SkImageInfo::MakeN32Premul(4, 4)); SkCanvas checkRed(redBorder); checkRed.clear(SK_ColorRED); uint32_t checkers[][2] = { { SK_ColorBLACK, SK_ColorWHITE }, { SK_ColorWHITE, SK_ColorBLACK } }; checkRed.writePixels( SkImageInfo::MakeN32Premul(2, 2), (void*) checkers, sizeof(checkers[0]), 1, 1); canvas->scale(16, 16); canvas->drawBitmap(redBorder, 0, 0, nullptr); canvas->resetMatrix(); sk_sp image = SkImage::MakeFromBitmap(redBorder); SkPaint lowPaint; lowPaint.setFilterQuality(kLow_SkFilterQuality); for (auto constraint : { SkCanvas::kStrict_SrcRectConstraint, SkCanvas::kFast_SrcRectConstraint } ) { canvas->translate(80, 0); canvas->drawImageRect(image.get(), SkRect::MakeLTRB(1, 1, 3, 3), SkRect::MakeLTRB(16, 16, 48, 48), &lowPaint, constraint); } } ## #SeeAlso drawImageRect drawImage SkPaint::setImageFilter ## # ------------------------------------------------------------------------------ #Method void drawImageRect(const SkImage* image, const SkRect& src, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw Rect src of Image image, scaled and translated to fill Rect dst. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within src; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param image Image containing pixels, dimensions, and format ## #Param src source Rect of image to draw from ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within src or draw faster ## #Example #Height 64 #Description The left bitmap draws with Paint default kNone_SkFilterQuality, and stays within its bounds; there is no bleeding with kFast_SrcRectConstraint. the middle and right bitmaps draw with kLow_SkFilterQuality; with kStrict_SrcRectConstraint, the filter remains within the checkerboard, and with kFast_SrcRectConstraint red bleeds on the edges. ## void draw(SkCanvas* canvas) { uint32_t pixels[][4] = { { 0xFFFF0000, 0xFFFF0000, 0xFFFF0000, 0xFFFF0000 }, { 0xFFFF0000, 0xFF000000, 0xFFFFFFFF, 0xFFFF0000 }, { 0xFFFF0000, 0xFFFFFFFF, 0xFF000000, 0xFFFF0000 }, { 0xFFFF0000, 0xFFFF0000, 0xFFFF0000, 0xFFFF0000 } }; SkBitmap redBorder; redBorder.installPixels(SkImageInfo::MakeN32Premul(4, 4), (void*) pixels, sizeof(pixels[0])); sk_sp image = SkImage::MakeFromBitmap(redBorder); SkPaint lowPaint; for (auto constraint : { SkCanvas::kFast_SrcRectConstraint, SkCanvas::kStrict_SrcRectConstraint, SkCanvas::kFast_SrcRectConstraint } ) { canvas->drawImageRect(image.get(), SkRect::MakeLTRB(1, 1, 3, 3), SkRect::MakeLTRB(16, 16, 48, 48), &lowPaint, constraint); lowPaint.setFilterQuality(kLow_SkFilterQuality); canvas->translate(80, 0); } } ## #SeeAlso SrcRectConstraint drawImage drawImageLattice drawImageNine ## # ------------------------------------------------------------------------------ #Method void drawImageRect(const SkImage* image, const SkIRect& isrc, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw IRect isrc of Image image, scaled and translated to fill Rect dst. Note that isrc is on integer pixel boundaries; dst may include fractional boundaries. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within isrc; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param image Image containing pixels, dimensions, and format ## #Param isrc source IRect of image to draw from ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within isrc or draw faster ## #Example #Image 4 void draw(SkCanvas* canvas) { // sk_sp image; for (auto i : { 1, 2, 4, 8 } ) { canvas->drawImageRect(image.get(), SkIRect::MakeLTRB(0, 0, 100, 100), SkRect::MakeXYWH(i * 20, i * 20, i * 20, i * 20), nullptr); } } ## #SeeAlso SrcRectConstraint drawImage drawImageLattice drawImageNine ## # ------------------------------------------------------------------------------ #Method void drawImageRect(const SkImage* image, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw Image image, scaled and translated to fill Rect dst, using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within image; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param image Image containing pixels, dimensions, and format ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within image or draw faster ## #Example #Image 4 void draw(SkCanvas* canvas) { // sk_sp image; for (auto i : { 20, 40, 80, 160 } ) { canvas->drawImageRect(image.get(), SkRect::MakeXYWH(i, i, i, i), nullptr); } } ## #SeeAlso SrcRectConstraint drawImage drawImageLattice drawImageNine ## # ------------------------------------------------------------------------------ #Method void drawImageRect(const sk_sp& image, const SkRect& src, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw Rect src of Image image, scaled and translated to fill Rect dst. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within src; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param image Image containing pixels, dimensions, and format ## #Param src source Rect of image to draw from ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within src or draw faster ## #Example #Height 64 #Description Canvas scales and translates; transformation from src to dst also scales. The two matrices are concatenated to create the final transformation. ## void draw(SkCanvas* canvas) { uint32_t pixels[][2] = { { SK_ColorBLACK, SK_ColorWHITE }, { SK_ColorWHITE, SK_ColorBLACK } }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeN32Premul(2, 2), (void*) pixels, sizeof(pixels[0])); sk_sp image = SkImage::MakeFromBitmap(bitmap); SkPaint paint; canvas->scale(4, 4); for (auto alpha : { 50, 100, 150, 255 } ) { paint.setAlpha(alpha); canvas->drawImageRect(image, SkRect::MakeWH(2, 2), SkRect::MakeWH(8, 8), &paint); canvas->translate(8, 0); } } ## #SeeAlso SrcRectConstraint drawImage drawImageLattice drawImageNine ## # ------------------------------------------------------------------------------ #Method void drawImageRect(const sk_sp& image, const SkIRect& isrc, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw IRect isrc of Image image, scaled and translated to fill Rect dst. isrc is on integer pixel boundaries; dst may include fractional boundaries. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within image; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param image Image containing pixels, dimensions, and format ## #Param isrc source IRect of image to draw from ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within image or draw faster ## #Example #Height 64 void draw(SkCanvas* canvas) { uint32_t pixels[][2] = { { 0x00000000, 0x55555555}, { 0xAAAAAAAA, 0xFFFFFFFF} }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeN32Premul(2, 2), (void*) pixels, sizeof(pixels[0])); sk_sp image = SkImage::MakeFromBitmap(bitmap); SkPaint paint; canvas->scale(4, 4); for (auto color : { SK_ColorRED, SK_ColorBLUE, SK_ColorGREEN } ) { paint.setColorFilter(SkColorFilter::MakeModeFilter(color, SkBlendMode::kPlus)); canvas->drawImageRect(image, SkIRect::MakeWH(2, 2), SkRect::MakeWH(8, 8), &paint); canvas->translate(8, 0); } } ## #SeeAlso SrcRectConstraint drawImage drawImageLattice drawImageNine ## # ------------------------------------------------------------------------------ #Method void drawImageRect(const sk_sp& image, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw Image image, scaled and translated to fill Rect dst, using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within image; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param image Image containing pixels, dimensions, and format ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within image or draw faster ## #Example #Height 64 void draw(SkCanvas* canvas) { uint32_t pixels[][2] = { { 0x00000000, 0x55550000}, { 0xAAAA0000, 0xFFFF0000} }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeN32Premul(2, 2), (void*) pixels, sizeof(pixels[0])); sk_sp image = SkImage::MakeFromBitmap(bitmap); SkPaint paint; canvas->scale(4, 4); for (auto color : { SK_ColorRED, SK_ColorBLUE, SK_ColorGREEN } ) { paint.setColorFilter(SkColorFilter::MakeModeFilter(color, SkBlendMode::kPlus)); canvas->drawImageRect(image, SkRect::MakeWH(8, 8), &paint); canvas->translate(8, 0); } } ## #SeeAlso SrcRectConstraint drawImage drawImageLattice drawImageNine ## # ------------------------------------------------------------------------------ #Method void drawImageNine(const SkImage* image, const SkIRect& center, const SkRect& dst, const SkPaint* paint = nullptr) Draw Image image stretched proportionally to fit into Rect dst. IRect center divides the image into nine sections: four sides, four corners, and the center. Corners are unmodified or scaled down proportionately if their sides are larger than dst; center and four sides are scaled to fit remaining space, if any. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. #Param image Image containing pixels, dimensions, and format ## #Param center IRect edge of image corners and sides ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 128 #Description The leftmost image is smaller than center; only corners are drawn, all scaled to fit. The second image equals the size of center; only corners are drawn without scaling. The remaining images are larger than center. All corners draw without scaling. The sides and center are scaled if needed to take up the remaining space. ## void draw(SkCanvas* canvas) { SkIRect center = { 20, 10, 50, 40 }; SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(60, 60)); SkCanvas bitCanvas(bitmap); SkPaint paint; SkColor gray = 0xFF000000; int left = 0; for (auto right: { center.fLeft, center.fRight, bitmap.width() } ) { int top = 0; for (auto bottom: { center.fTop, center.fBottom, bitmap.height() } ) { paint.setColor(gray); bitCanvas.drawIRect(SkIRect::MakeLTRB(left, top, right, bottom), paint); gray += 0x001f1f1f; top = bottom; } left = right; } sk_sp image = SkImage::MakeFromBitmap(bitmap); SkImage* imagePtr = image.get(); for (auto dest: { 20, 30, 40, 60, 90 } ) { canvas->drawImageNine(imagePtr, center, SkRect::MakeWH(dest, dest), nullptr); canvas->translate(dest + 4, 0); } } ## #SeeAlso drawImage drawBitmapNine drawImageLattice drawImageRect ## # ------------------------------------------------------------------------------ #Method void drawImageNine(const sk_sp& image, const SkIRect& center, const SkRect& dst, const SkPaint* paint = nullptr) Draw Image image stretched proportionally to fit into Rect dst. IRect center divides the image into nine sections: four sides, four corners, and the center. Corners are not scaled, or scaled down proportionately if their sides are larger than dst; center and four sides are scaled to fit remaining space, if any. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If image is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from image bounds. If generated mask extends beyond image bounds, replicate image edge colors, just as Shader made from SkImage::makeShader with SkShader::kClamp_TileMode set replicates the image edge color when it samples outside of its bounds. #Param image Image containing pixels, dimensions, and format ## #Param center IRect edge of image corners and sides ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 128 #Description The two leftmost images has four corners and sides to the left and right of center. The leftmost image scales the width of corners proportionately to fit. The third and fourth image corners are not scaled; the sides and center are scaled to fill the remaining space. The rightmost image has four corners scaled vertically to fit, and uses sides above and below center to fill the remaining space. ## void draw(SkCanvas* canvas) { SkIRect center = { 20, 10, 50, 40 }; SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(60, 60)); SkCanvas bitCanvas(bitmap); SkPaint paint; SkColor gray = 0xFF000000; int left = 0; for (auto right: { center.fLeft, center.fRight, bitmap.width() } ) { int top = 0; for (auto bottom: { center.fTop, center.fBottom, bitmap.height() } ) { paint.setColor(gray); bitCanvas.drawIRect(SkIRect::MakeLTRB(left, top, right, bottom), paint); gray += 0x001f1f1f; top = bottom; } left = right; } sk_sp image = SkImage::MakeFromBitmap(bitmap); for (auto dest: { 20, 30, 40, 60, 90 } ) { canvas->drawImageNine(image, center, SkRect::MakeWH(dest, 110 - dest), nullptr); canvas->translate(dest + 4, 0); } } ## #SeeAlso drawImage drawBitmapNine drawImageLattice drawImageRect ## # ------------------------------------------------------------------------------ #Method void drawBitmap(const SkBitmap& bitmap, SkScalar left, SkScalar top, const SkPaint* paint = nullptr) Draw Bitmap bitmap, with its top-left corner at (left, top), using Clip, Matrix, and optional Paint paint. If Paint paint is not nullptr, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. #Param bitmap Bitmap containing pixels, dimensions, and format ## #Param left left side of bitmap ## #Param top top side of bitmap ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 64 void draw(SkCanvas* canvas) { uint8_t pixels[][8] = { { 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00}, { 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00}, { 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00}, { 0xFF, 0xFF, 0x00, 0xFF, 0xFF, 0x00, 0xFF, 0xFF}, { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, { 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00}, { 0x00, 0xFF, 0x00, 0xFF, 0xFF, 0x00, 0xFF, 0x00}, { 0xFF, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0xFF} }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeA8(8, 8), (void*) pixels, sizeof(pixels[0])); SkPaint paint; canvas->scale(4, 4); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xFF007F00} ) { paint.setColor(color); canvas->drawBitmap(bitmap, 0, 0, &paint); canvas->translate(12, 0); } } ## #SeeAlso drawImage drawBitmapLattice drawBitmapNine drawBitmapRect SkBitmap::readPixels SkBitmap::writePixels ## # ------------------------------------------------------------------------------ #Method void drawBitmapRect(const SkBitmap& bitmap, const SkRect& src, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw Rect src of Bitmap bitmap, scaled and translated to fill Rect dst. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within src; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param bitmap Bitmap containing pixels, dimensions, and format ## #Param src source Rect of image to draw from ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within src or draw faster ## #Example #Height 64 void draw(SkCanvas* canvas) { uint8_t pixels[][8] = { { 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00}, { 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00}, { 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00}, { 0xFF, 0xFF, 0x00, 0xFF, 0xFF, 0x00, 0xFF, 0xFF}, { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, { 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00}, { 0x00, 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00}, { 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00} }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeA8(8, 8), (void*) pixels, sizeof(pixels[0])); SkPaint paint; paint.setMaskFilter(SkBlurMaskFilter::Make(kSolid_SkBlurStyle, 6)); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xFF007F00} ) { paint.setColor(color); canvas->drawBitmapRect(bitmap, SkRect::MakeWH(8, 8), SkRect::MakeWH(32, 32), &paint); canvas->translate(48, 0); } } ## #SeeAlso drawImageRect drawBitmap drawBitmapLattice drawBitmapNine ## # ------------------------------------------------------------------------------ #Method void drawBitmapRect(const SkBitmap& bitmap, const SkIRect& isrc, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw IRect isrc of Bitmap bitmap, scaled and translated to fill Rect dst. isrc is on integer pixel boundaries; dst may include fractional boundaries. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within isrc; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param bitmap Bitmap containing pixels, dimensions, and format ## #Param isrc source IRect of image to draw from ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint sample strictly within isrc, or draw faster ## #Example #Height 64 void draw(SkCanvas* canvas) { uint8_t pixels[][8] = { { 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00}, { 0x00, 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00}, { 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0x00, 0xFF}, { 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0x00, 0xFF}, { 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00, 0xFF}, { 0xFF, 0x00, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0xFF}, { 0x00, 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00}, { 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00} }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeA8(8, 8), (void*) pixels, sizeof(pixels[0])); SkPaint paint; paint.setFilterQuality(kHigh_SkFilterQuality); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xFF007F00, 0xFF7f007f} ) { paint.setColor(color); canvas->drawBitmapRect(bitmap, SkIRect::MakeWH(8, 8), SkRect::MakeWH(32, 32), &paint); canvas->translate(48.25f, 0); } } ## #SeeAlso drawImageRect drawBitmap drawBitmapLattice drawBitmapNine ## # ------------------------------------------------------------------------------ #Method void drawBitmapRect(const SkBitmap& bitmap, const SkRect& dst, const SkPaint* paint, SrcRectConstraint constraint = kStrict_SrcRectConstraint) Draw Bitmap bitmap, scaled and translated to fill Rect dst. bitmap bounds is on integer pixel boundaries; dst may include fractional boundaries. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. constraint set to kStrict_SrcRectConstraint limits Paint Filter_Quality to sample within bitmap; set to kFast_SrcRectConstraint allows sampling outside to improve performance. #Param bitmap Bitmap containing pixels, dimensions, and format ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Param constraint filter strictly within bitmap or draw faster ## #Example #Height 64 void draw(SkCanvas* canvas) { uint32_t pixels[][2] = { { 0x00000000, 0x55550000}, { 0xAAAA0000, 0xFFFF0000} }; SkBitmap bitmap; bitmap.installPixels(SkImageInfo::MakeN32Premul(2, 2), (void*) pixels, sizeof(pixels[0])); SkPaint paint; canvas->scale(4, 4); for (auto color : { SK_ColorRED, SK_ColorBLUE, SK_ColorGREEN } ) { paint.setColorFilter(SkColorFilter::MakeModeFilter(color, SkBlendMode::kPlus)); canvas->drawBitmapRect(bitmap, SkRect::MakeWH(8, 8), &paint); canvas->translate(8, 0); } } ## #SeeAlso drawImageRect drawBitmap drawBitmapLattice drawBitmapNine ## # ------------------------------------------------------------------------------ #Method void drawBitmapNine(const SkBitmap& bitmap, const SkIRect& center, const SkRect& dst, const SkPaint* paint = nullptr) Draw Bitmap bitmap stretched proportionally to fit into Rect dst. IRect center divides the bitmap into nine sections: four sides, four corners, and the center. Corners are not scaled, or scaled down proportionately if their sides are larger than dst; center and four sides are scaled to fit remaining space, if any. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. #Param bitmap Bitmap containing pixels, dimensions, and format ## #Param center IRect edge of image corners and sides ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 128 #Description The two leftmost bitmap draws has four corners and sides to the left and right of center. The leftmost bitmap draw scales the width of corners proportionately to fit. The third and fourth draw corners are not scaled; the sides and center are scaled to fill the remaining space. The rightmost bitmap draw has four corners scaled vertically to fit, and uses sides above and below center to fill the remaining space. ## void draw(SkCanvas* canvas) { SkIRect center = { 20, 10, 50, 40 }; SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(60, 60)); SkCanvas bitCanvas(bitmap); SkPaint paint; SkColor gray = 0xFF000000; int left = 0; for (auto right: { center.fLeft, center.fRight, bitmap.width() } ) { int top = 0; for (auto bottom: { center.fTop, center.fBottom, bitmap.height() } ) { paint.setColor(gray); bitCanvas.drawIRect(SkIRect::MakeLTRB(left, top, right, bottom), paint); gray += 0x001f1f1f; top = bottom; } left = right; } for (auto dest: { 20, 30, 40, 60, 90 } ) { canvas->drawBitmapNine(bitmap, center, SkRect::MakeWH(dest, 110 - dest), nullptr); canvas->translate(dest + 4, 0); } } ## #SeeAlso drawImageNine drawBitmap drawBitmapLattice drawBitmapRect ## # ------------------------------------------------------------------------------ #Struct Lattice #Code struct Lattice { enum RectType ... const int* fXDivs; const int* fYDivs; const RectType* fRectTypes; int fXCount; int fYCount; const SkIRect* fBounds; const SkColor* fColors; }; ## Lattice divides Bitmap or Image into a rectangular grid. Grid entries on even columns and even rows are fixed; these entries are always drawn at their original size if the destination is large enough. If the destination side is too small to hold the fixed entries, all fixed entries are proportionately scaled down to fit. The grid entries not on even columns and rows are scaled to fit the remaining space, if any. #Enum RectType #Code enum RectType : uint8_t { kDefault = 0, kTransparent, kFixedColor, }; ## Optional setting per rectangular grid entry to make it transparent, or to fill the grid entry with a color. #Const kDefault 0 Draws Bitmap into lattice rectangle. ## #Const kTransparent 1 Skips lattice rectangle by making it transparent. ## #Const kFixedColor 2 Draws one of fColors into lattice rectangle. ## ## #Member const int* fXDivs Array of x-coordinates that divide the bitmap vertically. Array entries must be unique, increasing, greater than or equal to fBounds left edge, and less than fBounds right edge. Set the first element to fBounds left to collapse the left column of fixed grid entries. ## #Member const int* fYDivs Array of y-coordinates that divide the bitmap horizontally. Array entries must be unique, increasing, greater than or equal to fBounds top edge, and less than fBounds bottom edge. Set the first element to fBounds top to collapse the top row of fixed grid entries. ## #Member const RectType* fRectTypes Optional array of fill types, one per rectangular grid entry: array length must be #Formula (fXCount + 1) * (fYCount + 1) ## . Each RectType is one of: kDefault, kTransparent, kFixedColor. Array entries correspond to the rectangular grid entries, ascending left to right and then top to bottom. ## #Member int fXCount Number of entries in fXDivs array; one less than the number of horizontal divisions. ## #Member int fYCount Number of entries in fYDivs array; one less than the number of vertical divisions. ## #Member const SkIRect* fBounds Optional subset IRect source to draw from. If nullptr, source bounds is dimensions of Bitmap or Image. ## #Member const SkColor* fColors Optional array of colors, one per rectangular grid entry. Array length must be #Formula (fXCount + 1) * (fYCount + 1) ## . Array entries correspond to the rectangular grid entries, ascending left to right, then top to bottom. ## #Struct Lattice ## #Method void drawBitmapLattice(const SkBitmap& bitmap, const Lattice& lattice, const SkRect& dst, const SkPaint* paint = nullptr) Draw Bitmap bitmap stretched proportionally to fit into Rect dst. Lattice lattice divides bitmap into a rectangular grid. Each intersection of an even-numbered row and column is fixed; like the corners of drawBitmapNine, fixed lattice elements never scale larger than their initial size and shrink proportionately when all fixed elements exceed the bitmap dimension. All other grid elements scale to fill the available space, if any. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. #Param bitmap Bitmap containing pixels, dimensions, and format ## #Param lattice division of bitmap into fixed and variable rectangles ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 128 #Description The two leftmost bitmap draws has four corners and sides to the left and right of center. The leftmost bitmap draw scales the width of corners proportionately to fit. The third and fourth draw corners are not scaled; the sides are scaled to fill the remaining space; the center is transparent. The rightmost bitmap draw has four corners scaled vertically to fit, and uses sides above and below center to fill the remaining space. ## void draw(SkCanvas* canvas) { SkIRect center = { 20, 10, 50, 40 }; SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(60, 60)); SkCanvas bitCanvas(bitmap); SkPaint paint; SkColor gray = 0xFF000000; int left = 0; for (auto right: { center.fLeft, center.fRight, bitmap.width() } ) { int top = 0; for (auto bottom: { center.fTop, center.fBottom, bitmap.height() } ) { paint.setColor(gray); bitCanvas.drawIRect(SkIRect::MakeLTRB(left, top, right, bottom), paint); gray += 0x001f1f1f; top = bottom; } left = right; } const int xDivs[] = { center.fLeft, center.fRight }; const int yDivs[] = { center.fTop, center.fBottom }; SkCanvas::Lattice::RectType fillTypes[3][3]; memset(fillTypes, 0, sizeof(fillTypes)); fillTypes[1][1] = SkCanvas::Lattice::kTransparent; SkColor dummy[9]; // temporary pending bug fix SkCanvas::Lattice lattice = { xDivs, yDivs, fillTypes[0], SK_ARRAY_COUNT(xDivs), SK_ARRAY_COUNT(yDivs), nullptr, dummy }; for (auto dest: { 20, 30, 40, 60, 90 } ) { canvas->drawBitmapLattice(bitmap, lattice, SkRect::MakeWH(dest, 110 - dest), nullptr); canvas->translate(dest + 4, 0); } } ## #SeeAlso drawImageLattice drawBitmap drawBitmapNine Lattice ## # ------------------------------------------------------------------------------ #Method void drawImageLattice(const SkImage* image, const Lattice& lattice, const SkRect& dst, const SkPaint* paint = nullptr) Draw Image image stretched proportionally to fit into Rect dst. Lattice lattice divides image into a rectangular grid. Each intersection of an even-numbered row and column is fixed; like the corners of drawBitmapNine, fixed lattice elements never scale larger than their initial size and shrink proportionately when all fixed elements exceed the bitmap dimension. All other grid elements scale to fill the available space, if any. Additionally transform draw using Clip, Matrix, and optional Paint paint. If Paint paint is supplied, apply Color_Filter, Color_Alpha, Image_Filter, Blend_Mode, and Draw_Looper. If bitmap is kAlpha_8_SkColorType, apply Shader. If paint contains Mask_Filter, generate mask from bitmap bounds. If generated mask extends beyond bitmap bounds, replicate bitmap edge colors, just as Shader made from SkShader::MakeBitmapShader with SkShader::kClamp_TileMode set replicates the bitmap edge color when it samples outside of its bounds. #Param image Image containing pixels, dimensions, and format ## #Param lattice division of bitmap into fixed and variable rectangles ## #Param dst destination Rect of image to draw to ## #Param paint Paint containing Blend_Mode, Color_Filter, Image_Filter, and so on; or nullptr ## #Example #Height 128 #Description The leftmost image is smaller than center; only corners are drawn, all scaled to fit. The second image equals the size of center; only corners are drawn without scaling. The remaining images are larger than center. All corners draw without scaling. The sides are scaled if needed to take up the remaining space; the center is transparent. ## void draw(SkCanvas* canvas) { SkIRect center = { 20, 10, 50, 40 }; SkBitmap bitmap; bitmap.allocPixels(SkImageInfo::MakeN32Premul(60, 60)); SkCanvas bitCanvas(bitmap); SkPaint paint; SkColor gray = 0xFF000000; int left = 0; for (auto right: { center.fLeft, center.fRight, bitmap.width() } ) { int top = 0; for (auto bottom: { center.fTop, center.fBottom, bitmap.height() } ) { paint.setColor(gray); bitCanvas.drawIRect(SkIRect::MakeLTRB(left, top, right, bottom), paint); gray += 0x001f1f1f; top = bottom; } left = right; } const int xDivs[] = { center.fLeft, center.fRight }; const int yDivs[] = { center.fTop, center.fBottom }; SkCanvas::Lattice::RectType fillTypes[3][3]; memset(fillTypes, 0, sizeof(fillTypes)); fillTypes[1][1] = SkCanvas::Lattice::kTransparent; SkColor dummy[9]; // temporary pending bug fix SkCanvas::Lattice lattice = { xDivs, yDivs, fillTypes[0], SK_ARRAY_COUNT(xDivs), SK_ARRAY_COUNT(yDivs), nullptr, dummy }; sk_sp image = SkImage::MakeFromBitmap(bitmap); SkImage* imagePtr = image.get(); for (auto dest: { 20, 30, 40, 60, 90 } ) { canvas->drawImageNine(imagePtr, center, SkRect::MakeWH(dest, dest), nullptr); canvas->translate(dest + 4, 0); } } ## #SeeAlso drawBitmapLattice drawImage drawImageNine Lattice ## #Topic Draw_Image ## # ------------------------------------------------------------------------------ #Method void drawText(const void* text, size_t byteLength, SkScalar x, SkScalar y, const SkPaint& paint) Draw text, with origin at (x, y), using Clip, Matrix, and Paint paint. text meaning depends on Paint_Text_Encoding; by default, text is encoded as UTF-8. x and y meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default text draws left to right, positioning the first glyph left side bearing at x and its baseline at y. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. #Param text character code points or Glyphs drawn ## #Param byteLength byte length of text array ## #Param x start of text on x-axis ## #Param y start of text on y-axis ## #Param paint text size, blend, color, and so on, used to draw ## #Example #Height 200 #Description The same text is drawn varying Paint_Text_Size and varying Matrix. ## void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); float textSizes[] = { 12, 18, 24, 36 }; for (auto size: textSizes ) { paint.setTextSize(size); canvas->drawText("Aa", 2, 10, 20, paint); canvas->translate(0, size * 2); } paint.reset(); paint.setAntiAlias(true); float yPos = 20; for (auto size: textSizes ) { float scale = size / 12.f; canvas->resetMatrix(); canvas->translate(100, 0); canvas->scale(scale, scale); canvas->drawText("Aa", 2, 10 / scale, yPos / scale, paint); yPos += size * 2; } } ## #SeeAlso drawString drawPosText drawPosTextH drawTextBlob drawTextOnPath drawTextRSXform ## #Method void drawString(const char* string, SkScalar x, SkScalar y, const SkPaint& paint) Draw null terminated string, with origin at (x, y), using Clip, Matrix, and Paint paint. string meaning depends on Paint_Text_Encoding; by default, strings are encoded as UTF-8. Other values of Paint_Text_Encoding are unlikely to produce the desired results, since zero bytes may be embedded in the string. x and y meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default string draws left to right, positioning the first glyph left side bearing at x and its baseline at y. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. #Param string character code points or Glyphs drawn, ending with a char value of zero ## #Param x start of string on x-axis ## #Param y start of string on y-axis ## #Param paint text size, blend, color, and so on, used to draw ## #Example SkPaint paint; canvas->drawString("a small hello", 20, 20, paint); ## #SeeAlso drawText drawPosText drawPosTextH drawTextBlob drawTextOnPath drawTextRSXform ## #Method void drawString(const SkString& string, SkScalar x, SkScalar y, const SkPaint& paint) Draw null terminated string, with origin at (x, y), using Clip, Matrix, and Paint paint. string meaning depends on Paint_Text_Encoding; by default, strings are encoded as UTF-8. Other values of Paint_Text_Encoding are unlikely to produce the desired results, since zero bytes may be embedded in the string. x and y meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default string draws left to right, positioning the first glyph left side bearing at x and its baseline at y. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. #Param string character code points or Glyphs drawn, ending with a char value of zero ## #Param x start of string on x-axis ## #Param y start of string on y-axis ## #Param paint text size, blend, color, and so on, used to draw ## #Example SkPaint paint; SkString string("a small hello"); canvas->drawString(string, 20, 20, paint); ## #SeeAlso drawText drawPosText drawPosTextH drawTextBlob drawTextOnPath drawTextRSXform ## # ------------------------------------------------------------------------------ #Method void drawPosText(const void* text, size_t byteLength, const SkPoint pos[], const SkPaint& paint) Draw each glyph in text with the origin in pos array, using Clip, Matrix, and Paint paint. The number of entries in pos array must match the number of Glyphs described by byteLength of text. text meaning depends on Paint_Text_Encoding; by default, text is encoded as UTF-8. pos elements' meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default each glyph left side bearing is positioned at x and its baseline is positioned at y. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. Layout engines such as Harfbuzz typically position each glyph rather than using the font advance widths. #Param text character code points or Glyphs drawn ## #Param byteLength byte length of text array ## #Param pos array of glyph origins ## #Param paint text size, blend, color, and so on, used to draw ## #Example #Height 120 void draw(SkCanvas* canvas) { const char hello[] = "HeLLo!"; const SkPoint pos[] = { {40, 100}, {82, 95}, {115, 110}, {130, 95}, {145, 85}, {172, 100} }; SkPaint paint; paint.setTextSize(60); canvas->drawPosText(hello, strlen(hello), pos, paint); } ## #SeeAlso drawText drawPosTextH drawTextBlob drawTextOnPath drawTextRSXform ## # ------------------------------------------------------------------------------ #Method void drawPosTextH(const void* text, size_t byteLength, const SkScalar xpos[], SkScalar constY, const SkPaint& paint) Draw each glyph in text with its (x, y) origin composed from xpos array and constY, using Clip, Matrix, and Paint paint. The number of entries in xpos array must match the number of Glyphs described by byteLength of text. text meaning depends on Paint_Text_Encoding; by default, text is encoded as UTF-8. xpos elements' meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default each glyph left side bearing is positioned at an xpos element and its baseline is positioned at constY. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. Layout engines such as Harfbuzz typically position each glyph rather than using the font advance widths if all Glyphs share the same baseline. #Param text character code points or Glyphs drawn ## #Param byteLength byte length of text array ## #Param xpos array of x positions, used to position each glyph ## #Param constY shared y coordinate for all of x positions ## #Param paint text size, blend, color, and so on, used to draw ## #Example #Height 40 void draw(SkCanvas* canvas) { SkScalar xpos[] = { 20, 40, 80, 160 }; SkPaint paint; canvas->drawPosTextH("XXXX", 4, xpos, 20, paint); } ## #SeeAlso drawText drawPosText drawTextBlob drawTextOnPath drawTextRSXform ## # ------------------------------------------------------------------------------ #Method void drawTextOnPathHV(const void* text, size_t byteLength, const SkPath& path, SkScalar hOffset, SkScalar vOffset, const SkPaint& paint) Draw text on Path path, using Clip, Matrix, and Paint paint. Origin of text is at distance hOffset along the path, offset by a perpendicular vector of length vOffset. If the path section corresponding the glyph advance is curved, the glyph is drawn curved to match; control points in the glyph are mapped to projected points parallel to the path. If the text advance is larger than the path length, the excess text is clipped. text meaning depends on Paint_Text_Encoding; by default, text is encoded as UTF-8. Origin meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default text positions the first glyph left side bearing at origin x and its baseline at origin y. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. #Param text character code points or Glyphs drawn ## #Param byteLength byte length of text array ## #Param path Path providing text baseline ## #Param hOffset distance along path to offset origin ## #Param vOffset offset of text above (if negative) or below (if positive) the path ## #Param paint text size, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { const char aero[] = "correo a" "\xC3" "\xA9" "reo"; const size_t len = sizeof(aero) - 1; SkPath path; path.addOval({43-26, 43-26, 43+26, 43+26}, SkPath::kCW_Direction, 3); SkPaint paint; paint.setTextSize(24); for (auto offset : { 0, 10, 20 } ) { canvas->drawTextOnPathHV(aero, len, path, 0, -offset, paint); canvas->translate(70 + offset, 70 + offset); } } ## #SeeAlso drawTextOnPath drawText drawPosTextH drawTextBlob drawTextRSXform ## # ------------------------------------------------------------------------------ #Method void drawTextOnPath(const void* text, size_t byteLength, const SkPath& path, const SkMatrix* matrix, const SkPaint& paint) Draw text on Path path, using Clip, Matrix, and Paint paint. Origin of text is at beginning of path offset by matrix, if provided, before it is mapped to path. If the path section corresponding the glyph advance is curved, the glyph is drawn curved to match; control points in the glyph are mapped to projected points parallel to the path. If the text advance is larger than the path length, the excess text is clipped. text meaning depends on Paint_Text_Encoding; by default, text is encoded as UTF-8. Origin meaning depends on Paint_Text_Align and Paint_Vertical_Text; by default text positions the first glyph left side bearing at origin x and its baseline at origin y. Text size is affected by Matrix and Paint_Text_Size. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. #Param text character code points or Glyphs drawn ## #Param byteLength byte length of text array ## #Param path Path providing text baseline ## #Param matrix transform of Glyphs before mapping to path; may be nullptr to use identity Matrix ## #Param paint text size, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { const char roller[] = "rollercoaster"; const size_t len = sizeof(roller) - 1; SkPath path; path.cubicTo(40, -80, 120, 80, 160, -40); SkPaint paint; paint.setTextSize(32); paint.setStyle(SkPaint::kStroke_Style); SkMatrix matrix; matrix.setIdentity(); for (int i = 0; i < 3; ++i) { canvas->translate(25, 60); canvas->drawPath(path, paint); canvas->drawTextOnPath(roller, len, path, &matrix, paint); matrix.preTranslate(0, 10); } } ## #SeeAlso drawTextOnPathHV drawText drawPosTextH drawTextBlob drawTextRSXform ## # ------------------------------------------------------------------------------ #Method void drawTextRSXform(const void* text, size_t byteLength, const SkRSXform xform[], const SkRect* cullRect, const SkPaint& paint) Draw text, transforming each glyph by the corresponding SkRSXform, using Clip, Matrix, and Paint paint. RSXform array specifies a separate square scale, rotation, and translation for each glyph. Optional Rect cullRect is a conservative bounds of text, taking into account RSXform and paint. If cullRect is outside of Clip, canvas can skip drawing. All elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to text. By default, draws filled 12 point black Glyphs. #Param text character code points or Glyphs drawn ## #Param byteLength byte length of text array ## #Param xform RSXform rotates, scales, and translates each glyph individually ## #Param cullRect Rect bounds of text for efficient clipping; or nullptr ## #Param paint text size, blend, color, and so on, used to draw ## #Example void draw(SkCanvas* canvas) { const int iterations = 26; SkRSXform transforms[iterations]; char alphabet[iterations]; SkScalar angle = 0; SkScalar scale = 1; for (size_t i = 0; i < SK_ARRAY_COUNT(transforms); ++i) { const SkScalar s = SkScalarSin(angle) * scale; const SkScalar c = SkScalarCos(angle) * scale; transforms[i] = SkRSXform::Make(-c, -s, -s * 16, c * 16); angle += .45; scale += .2; alphabet[i] = 'A' + i; } SkPaint paint; paint.setTextAlign(SkPaint::kCenter_Align); canvas->translate(110, 138); canvas->drawTextRSXform(alphabet, sizeof(alphabet), transforms, nullptr, paint); } ## #SeeAlso drawTextOnPath drawTextOnPathHV drawText drawPosText drawTextBlob ## # ------------------------------------------------------------------------------ #Method void drawTextBlob(const SkTextBlob* blob, SkScalar x, SkScalar y, const SkPaint& paint) Draw Text_Blob blob at (x, y), using Clip, Matrix, and Paint paint. blob contains Glyphs, their positions, and paint attributes specific to text: Typeface, Paint_Text_Size, Paint_Text_Scale_X, Paint_Text_Skew_X, Paint_Text_Align, Paint_Hinting, Anti-alias, Paint_Fake_Bold, Font_Embedded_Bitmaps, Full_Hinting_Spacing, LCD_Text, Linear_Text, Subpixel_Text, and Paint_Vertical_Text. Paint_Text_Encoding must be set to SkPaint::kGlyphID_TextEncoding. Elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to blob. #Param blob Glyphs, positions, and their paints' text size, typeface, and so on ## #Param x horizontal offset applied to blob ## #Param y vertical offset applied to blob ## #Param paint blend, color, stroking, and so on, used to draw ## #Example #Height 120 void draw(SkCanvas* canvas) { SkTextBlobBuilder textBlobBuilder; const char bunny[] = "/(^x^)\\"; const int len = sizeof(bunny) - 1; uint16_t glyphs[len]; SkPaint paint; paint.textToGlyphs(bunny, len, glyphs); paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); int runs[] = { 3, 1, 3 }; SkPoint textPos = { 20, 100 }; int glyphIndex = 0; for (auto runLen : runs) { paint.setTextSize(1 == runLen ? 20 : 50); const SkTextBlobBuilder::RunBuffer& run = textBlobBuilder.allocRun(paint, runLen, textPos.fX, textPos.fY); memcpy(run.glyphs, &glyphs[glyphIndex], sizeof(glyphs[0]) * runLen); textPos.fX += paint.measureText(&glyphs[glyphIndex], sizeof(glyphs[0]) * runLen, nullptr); glyphIndex += runLen; } sk_sp blob = textBlobBuilder.make(); paint.reset(); canvas->drawTextBlob(blob.get(), 0, 0, paint); } ## #SeeAlso drawText drawPosText drawPosTextH ## # ------------------------------------------------------------------------------ #Method void drawTextBlob(const sk_sp& blob, SkScalar x, SkScalar y, const SkPaint& paint) Draw Text_Blob blob at (x, y), using Clip, Matrix, and Paint paint. blob contains Glyphs, their positions, and paint attributes specific to text: Typeface, Paint_Text_Size, Paint_Text_Scale_X, Paint_Text_Skew_X, Paint_Text_Align, Paint_Hinting, Anti-alias, Paint_Fake_Bold, Font_Embedded_Bitmaps, Full_Hinting_Spacing, LCD_Text, Linear_Text, Subpixel_Text, and Paint_Vertical_Text. Paint_Text_Encoding must be set to SkPaint::kGlyphID_TextEncoding. Elements of paint: Path_Effect, Rasterizer, Mask_Filter, Shader, Color_Filter, Image_Filter, and Draw_Looper; apply to blob. #Param blob Glyphs, positions, and their paints' text size, typeface, and so on ## #Param x horizontal offset applied to blob ## #Param y vertical offset applied to blob ## #Param paint blend, color, stroking, and so on, used to draw ## #Example #Height 120 #Description Paint attributes unrelated to text, like color, have no effect on paint in allocated Text_Blob. Paint attributes related to text, like text size, have no effect on paint passed to drawTextBlob. ## void draw(SkCanvas* canvas) { SkTextBlobBuilder textBlobBuilder; SkPaint paint; paint.setTextSize(50); paint.setColor(SK_ColorRED); paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); const SkTextBlobBuilder::RunBuffer& run = textBlobBuilder.allocRun(paint, 1, 20, 100); run.glyphs[0] = 20; sk_sp blob = textBlobBuilder.make(); paint.setTextSize(10); paint.setColor(SK_ColorBLUE); canvas->drawTextBlob(blob.get(), 0, 0, paint); } ## #SeeAlso drawText drawPosText drawPosTextH ## # ------------------------------------------------------------------------------ #Method void drawPicture(const SkPicture* picture) Draw Picture picture, using Clip and Matrix. Clip and Matrix are unchanged by picture contents, as if save() was called before and restore() was called after drawPicture. Picture records a series of draw commands for later playback. #Param picture recorded drawing commands to play ## #Example void draw(SkCanvas* canvas) { SkPictureRecorder recorder; SkCanvas* recordingCanvas = recorder.beginRecording(50, 50); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xff007f00 } ) { SkPaint paint; paint.setColor(color); recordingCanvas->drawRect({10, 10, 30, 40}, paint); recordingCanvas->translate(10, 10); recordingCanvas->scale(1.2f, 1.4f); } sk_sp playback = recorder.finishRecordingAsPicture(); const SkPicture* playbackPtr = playback.get(); canvas->drawPicture(playback); canvas->scale(2, 2); canvas->translate(50, 0); canvas->drawPicture(playback); } ## #SeeAlso drawDrawable SkPicture SkPicture::playback ## # ------------------------------------------------------------------------------ #Method void drawPicture(const sk_sp& picture) Draw Picture picture, using Clip and Matrix. Clip and Matrix are unchanged by picture contents, as if save() was called before and restore() was called after drawPicture. Picture records a series of draw commands for later playback. #Param picture recorded drawing commands to play ## #Example void draw(SkCanvas* canvas) { SkPictureRecorder recorder; SkCanvas* recordingCanvas = recorder.beginRecording(50, 50); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xff007f00 } ) { SkPaint paint; paint.setColor(color); recordingCanvas->drawRect({10, 10, 30, 40}, paint); recordingCanvas->translate(10, 10); recordingCanvas->scale(1.2f, 1.4f); } sk_sp playback = recorder.finishRecordingAsPicture(); canvas->drawPicture(playback); canvas->scale(2, 2); canvas->translate(50, 0); canvas->drawPicture(playback); } ## #SeeAlso drawDrawable SkPicture SkPicture::playback ## # ------------------------------------------------------------------------------ #Method void drawPicture(const SkPicture* picture, const SkMatrix* matrix, const SkPaint* paint) Draw Picture picture, using Clip and Matrix; transforming picture with Matrix matrix, if provided; and use Paint paint Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode, if provided. matrix transformation is equivalent to: save(), concat(), drawPicture, restore(). paint use is equivalent to: saveLayer, drawPicture, restore(). #Param picture recorded drawing commands to play ## #Param matrix Matrix to rotate, scale, translate, and so on; may be nullptr ## #Param paint Paint to apply transparency, filtering, and so on; may be nullptr ## #Example void draw(SkCanvas* canvas) { SkPaint paint; SkPictureRecorder recorder; SkCanvas* recordingCanvas = recorder.beginRecording(50, 50); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xff007f00 } ) { paint.setColor(color); recordingCanvas->drawRect({10, 10, 30, 40}, paint); recordingCanvas->translate(10, 10); recordingCanvas->scale(1.2f, 1.4f); } sk_sp playback = recorder.finishRecordingAsPicture(); const SkPicture* playbackPtr = playback.get(); SkMatrix matrix; matrix.reset(); for (auto alpha : { 70, 140, 210 } ) { paint.setAlpha(alpha); canvas->drawPicture(playbackPtr, &matrix, &paint); matrix.preTranslate(70, 70); } } ## #SeeAlso drawDrawable SkPicture SkPicture::playback ## # ------------------------------------------------------------------------------ #Method void drawPicture(const sk_sp& picture, const SkMatrix* matrix, const SkPaint* paint) Draw Picture picture, using Clip and Matrix; transforming picture with Matrix matrix, if provided; and use Paint paint Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode, if provided. matrix transformation is equivalent to: save(), concat(), drawPicture, restore(). paint use is equivalent to: saveLayer, drawPicture, restore(). #Param picture recorded drawing commands to play ## #Param matrix Matrix to rotate, scale, translate, and so on; may be nullptr ## #Param paint Paint to apply transparency, filtering, and so on; may be nullptr ## #Example void draw(SkCanvas* canvas) { SkPaint paint; SkPictureRecorder recorder; SkCanvas* recordingCanvas = recorder.beginRecording(50, 50); for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xff007f00 } ) { paint.setColor(color); recordingCanvas->drawRect({10, 10, 30, 40}, paint); recordingCanvas->translate(10, 10); recordingCanvas->scale(1.2f, 1.4f); } sk_sp playback = recorder.finishRecordingAsPicture(); SkMatrix matrix; matrix.reset(); for (auto alpha : { 70, 140, 210 } ) { paint.setAlpha(alpha); canvas->drawPicture(playback, &matrix, &paint); matrix.preTranslate(70, 70); } } ## #SeeAlso drawDrawable SkPicture SkPicture::playback ## # ------------------------------------------------------------------------------ #Method void drawVertices(const SkVertices* vertices, SkBlendMode mode, const SkPaint& paint) Draw Vertices vertices, a triangle mesh, using Clip and Matrix. If Vertices_Texs and Vertices_Colors are defined in vertices, and Paint paint contains Shader, Blend_Mode mode combines Vertices_Colors with Shader. #Param vertices triangle mesh to draw ## #Param mode combines Vertices_Colors with Shader, if both are present ## #Param paint specifies the Shader, used as Vertices texture; may be nullptr ## #Example void draw(SkCanvas* canvas) { SkPaint paint; SkPoint points[] = { { 0, 0 }, { 250, 0 }, { 100, 100 }, { 0, 250 } }; SkColor colors[] = { SK_ColorRED, SK_ColorBLUE, SK_ColorYELLOW, SK_ColorCYAN }; auto vertices = SkVertices::MakeCopy(SkVertices::kTriangleFan_VertexMode, SK_ARRAY_COUNT(points), points, nullptr, colors); canvas->drawVertices(vertices.get(), SkBlendMode::kSrc, paint); } ## #SeeAlso drawPatch drawPicture ## # ------------------------------------------------------------------------------ #Method void drawVertices(const sk_sp& vertices, SkBlendMode mode, const SkPaint& paint) Draw Vertices vertices, a triangle mesh, using Clip and Matrix. If Vertices_Texs and Vertices_Colors are defined in vertices, and Paint paint contains Shader, Blend_Mode mode combines Vertices_Colors with Shader. #Param vertices triangle mesh to draw ## #Param mode combines Vertices_Colors with Shader, if both are present ## #Param paint specifies the Shader, used as Vertices texture, may be nullptr ## #Example void draw(SkCanvas* canvas) { SkPaint paint; SkPoint points[] = { { 0, 0 }, { 250, 0 }, { 100, 100 }, { 0, 250 } }; SkPoint texs[] = { { 0, 0 }, { 0, 250 }, { 250, 250 }, { 250, 0 } }; SkColor colors[] = { SK_ColorRED, SK_ColorBLUE, SK_ColorYELLOW, SK_ColorCYAN }; paint.setShader(SkGradientShader::MakeLinear(points, colors, nullptr, 4, SkShader::kClamp_TileMode)); auto vertices = SkVertices::MakeCopy(SkVertices::kTriangleFan_VertexMode, SK_ARRAY_COUNT(points), points, texs, colors); canvas->drawVertices(vertices.get(), SkBlendMode::kDarken, paint); } ## #SeeAlso drawPatch drawPicture ## # ------------------------------------------------------------------------------ #Method void drawPatch(const SkPoint cubics[12], const SkColor colors[4], const SkPoint texCoords[4], SkBlendMode mode, const SkPaint& paint) Draws a Coons_Patch: the interpolation of four cubics with shared corners, associating a color, and optionally a texture coordinate, with each corner. Coons_Patch uses Clip and Matrix, paint Shader, Color_Filter, Color_Alpha, Image_Filter, and Blend_Mode. If Shader is provided it is treated as Coons_Patch texture; Blend_Mode mode combines Color colors and Shader if both are provided. Point array cubics specifies four Cubics starting at the top-left corner, in clockwise order, sharing every fourth point. The last Cubic ends at the first point. Color array color associates colors with corners in top-left, top-right, bottom-right, bottom-left order. If paint contains Shader, Point array texCoords maps Shader as texture to corners in top-left, top-right, bottom-right, bottom-left order. #Param cubics Path_Cubic array, sharing common points ## #Param colors Color array, one for each corner ## #Param texCoords Point array of texture coordinates, mapping Shader to corners; may be nullptr #Param ## #Param mode Blend_Mode for colors, and for Shader if paint has one ## #Param paint Shader, Color_Filter, Blend_Mode, used to draw ## #Example #Image 5 void draw(SkCanvas* canvas) { // SkBitmap source = cmbkygk; SkPaint paint; paint.setFilterQuality(kLow_SkFilterQuality); paint.setAntiAlias(true); SkPoint cubics[] = { { 3, 1 }, { 4, 2 }, { 5, 1 }, { 7, 3 }, /* { 7, 3 }, */ { 6, 4 }, { 7, 5 }, { 5, 7 }, /* { 5, 7 }, */ { 4, 6 }, { 3, 7 }, { 1, 5 }, /* { 1, 5 }, */ { 2, 4 }, { 1, 3 }, /* { 3, 1 } */ }; SkColor colors[] = { 0xbfff0000, 0xbf0000ff, 0xbfff00ff, 0xbf00ffff }; SkPoint texCoords[] = { { -30, -30 }, { 162, -30}, { 162, 162}, { -30, 162} }; paint.setShader(SkShader::MakeBitmapShader(source, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, nullptr)); canvas->scale(15, 15); for (auto blend : { SkBlendMode::kSrcOver, SkBlendMode::kModulate, SkBlendMode::kXor } ) { canvas->drawPatch(cubics, colors, texCoords, blend, paint); canvas->translate(4, 4); } } ## #ToDo can patch use image filter? ## #SeeAlso SeeAlso drawVertices drawPicture ## # ------------------------------------------------------------------------------ #Method void drawPatch(const SkPoint cubics[12], const SkColor colors[4], const SkPoint texCoords[4], const SkPaint& paint) Draws Cubic Coons_Patch: the interpolation of four cubics with shared corners, associating a color, and optionally a texture coordinate, with each corner. Coons_Patch uses Clip and Matrix, paint Shader, Color_Filter, Color_Alpha, Image_Filter, and Blend_Mode. If Shader is provided it is treated as Coons_Patch texture; Blend_Mode mode combines Color colors and Shader if both are provided. Point array cubics specifies four Cubics starting at the top-left corner, in clockwise order, sharing every fourth point. The last Cubic ends at the first point. Color array color associates colors with corners in top-left, top-right, bottom-right, bottom-left order. If paint contains Shader, Point array texCoords maps Shader as texture to corners in top-left, top-right, bottom-right, bottom-left order. #Param cubics Path_Cubic array, sharing common points ## #Param colors Color array, one for each corner ## #Param texCoords Point array of texture coordinates, mapping Shader to corners; may be nullptr #Param ## #Param paint Shader, Color_Filter, Blend_Mode, used to draw ## #Example void draw(SkCanvas* canvas) { SkPaint paint; paint.setAntiAlias(true); SkPoint cubics[] = { { 3, 1 }, { 4, 2 }, { 5, 1 }, { 7, 3 }, /* { 7, 3 }, */ { 6, 4 }, { 7, 5 }, { 5, 7 }, /* { 5, 7 }, */ { 4, 6 }, { 3, 7 }, { 1, 5 }, /* { 1, 5 }, */ { 2, 4 }, { 1, 3 }, /* { 3, 1 } */ }; SkColor colors[] = { SK_ColorRED, SK_ColorBLUE, SK_ColorYELLOW, SK_ColorCYAN }; canvas->scale(30, 30); canvas->drawPatch(cubics, colors, nullptr, paint); SkPoint text[] = { {3,0.9f}, {4,2.5f}, {5,0.9f}, {7.5f,3.2f}, {5.5f,4.2f}, {7.5f,5.2f}, {5,7.5f}, {4,5.9f}, {3,7.5f}, {0.5f,5.2f}, {2.5f,4.2f}, {0.5f,3.2f} }; paint.setTextSize(18.f / 30); paint.setTextAlign(SkPaint::kCenter_Align); for (int i = 0; i< 10; ++i) { char digit = '0' + i; canvas->drawText(&digit, 1, text[i].fX, text[i].fY, paint); } canvas->drawString("10", text[10].fX, text[10].fY, paint); canvas->drawString("11", text[11].fX, text[11].fY, paint); paint.setStyle(SkPaint::kStroke_Style); canvas->drawPoints(SkCanvas::kPolygon_PointMode, 12, cubics, paint); canvas->drawLine(cubics[11].fX, cubics[11].fY, cubics[0].fX, cubics[0].fY, paint); } ## #Example #Image 6 void draw(SkCanvas* canvas) { // SkBitmap source = checkerboard; SkPaint paint; paint.setFilterQuality(kLow_SkFilterQuality); paint.setAntiAlias(true); SkPoint cubics[] = { { 3, 1 }, { 4, 2 }, { 5, 1 }, { 7, 3 }, /* { 7, 3 }, */ { 6, 4 }, { 7, 5 }, { 5, 7 }, /* { 5, 7 }, */ { 4, 6 }, { 3, 7 }, { 1, 5 }, /* { 1, 5 }, */ { 2, 4 }, { 1, 3 }, /* { 3, 1 } */ }; SkPoint texCoords[] = { { 0, 0 }, { 0, 62}, { 62, 62}, { 62, 0 } }; paint.setShader(SkShader::MakeBitmapShader(source, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode, nullptr)); canvas->scale(30, 30); canvas->drawPatch(cubics, nullptr, texCoords, paint); } ## #ToDo can patch use image filter? ## #SeeAlso SeeAlso drawVertices drawPicture ## # ------------------------------------------------------------------------------ #Method void drawAtlas(const SkImage* atlas, const SkRSXform xform[], const SkRect tex[], const SkColor colors[], int count, SkBlendMode mode, const SkRect* cullRect, const SkPaint* paint) Draw a set of sprites from atlas, using Clip, Matrix, and optional Paint paint. paint uses Anti-alias, Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode to draw, if present. For each entry in the array, Rect tex locates sprite in atlas, and RSXform xform transforms it into destination space. xform, text, and colors if present, must contain count entries. Optional colors are applied for each sprite using Blend_Mode. Optional cullRect is a conservative bounds of all transformed sprites. If cullRect is outside of Clip, canvas can skip drawing. #Param atlas Image containing sprites ## #Param xform RSXform mappings for sprites in atlas ## #Param tex Rect locations of sprites in atlas ## #Param colors one per sprite, blended with sprite using Blend_Mode; may be nullptr ## #Param count number of sprites to draw ## #Param mode Blend_Mode combining colors and sprites ## #Param cullRect bounds of transformed sprites for efficient clipping; may be nullptr ## #Param paint Color_Filter, Image_Filter, Blend_Mode, and so on; may be nullptr ## #Example #Image 3 void draw(SkCanvas* canvas) { // SkBitmap source = mandrill; SkRSXform xforms[] = { { .5f, 0, 0, 0 }, {0, .5f, 200, 100 } }; SkRect tex[] = { { 0, 0, 250, 250 }, { 0, 0, 250, 250 } }; SkColor colors[] = { 0x7f55aa00, 0x7f3333bf }; const SkImage* imagePtr = image.get(); canvas->drawAtlas(imagePtr, xforms, tex, colors, 2, SkBlendMode::kSrcOver, nullptr, nullptr); } ## #SeeAlso drawBitmap drawImage ## # ------------------------------------------------------------------------------ #Method void drawAtlas(const sk_sp& atlas, const SkRSXform xform[], const SkRect tex[], const SkColor colors[], int count, SkBlendMode mode, const SkRect* cullRect, const SkPaint* paint) Draw a set of sprites from atlas, using Clip, Matrix, and optional Paint paint. paint uses Anti-alias, Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode to draw, if present. For each entry in the array, Rect tex locates sprite in atlas, and RSXform xform transforms it into destination space. xform, text, and colors if present, must contain count entries. Optional colors is applied for each sprite using Blend_Mode. Optional cullRect is a conservative bounds of all transformed sprites. If cullRect is outside of Clip, canvas can skip drawing. #Param atlas Image containing sprites ## #Param xform RSXform mappings for sprites in atlas ## #Param tex Rect locations of sprites in atlas ## #Param colors one per sprite, blended with sprite using Blend_Mode; may be nullptr ## #Param count number of sprites to draw ## #Param mode Blend_Mode combining colors and sprites ## #Param cullRect bounds of transformed sprites for efficient clipping; may be nullptr ## #Param paint Color_Filter, Image_Filter, Blend_Mode, and so on; may be nullptr ## #Example #Image 3 void draw(SkCanvas* canvas) { // SkBitmap source = mandrill; SkRSXform xforms[] = { { .5f, 0, 0, 0 }, {0, .5f, 200, 100 } }; SkRect tex[] = { { 0, 0, 250, 250 }, { 0, 0, 250, 250 } }; SkColor colors[] = { 0x7f55aa00, 0x7f3333bf }; SkPaint paint; paint.setAlpha(127); canvas->drawAtlas(image, xforms, tex, colors, 2, SkBlendMode::kPlus, nullptr, &paint); } ## #ToDo bug in example on cpu side, gpu looks ok ## #SeeAlso drawBitmap drawImage ## # ------------------------------------------------------------------------------ #Method void drawAtlas(const SkImage* atlas, const SkRSXform xform[], const SkRect tex[], int count, const SkRect* cullRect, const SkPaint* paint) Draw a set of sprites from atlas, using Clip, Matrix, and optional Paint paint. paint uses Anti-alias, Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode to draw, if present. For each entry in the array, Rect tex locates sprite in atlas, and RSXform xform transforms it into destination space. xform and text must contain count entries. Optional cullRect is a conservative bounds of all transformed sprites. If cullRect is outside of Clip, canvas can skip drawing. #Param atlas Image containing sprites ## #Param xform RSXform mappings for sprites in atlas ## #Param tex Rect locations of sprites in atlas ## #Param count number of sprites to draw ## #Param cullRect bounds of transformed sprites for efficient clipping; may be nullptr ## #Param paint Color_Filter, Image_Filter, Blend_Mode, and so on; may be nullptr ## #Example #Image 3 void draw(SkCanvas* canvas) { // sk_sp image = mandrill; SkRSXform xforms[] = { { .5f, 0, 0, 0 }, {0, .5f, 200, 100 } }; SkRect tex[] = { { 0, 0, 250, 250 }, { 0, 0, 250, 250 } }; const SkImage* imagePtr = image.get(); canvas->drawAtlas(imagePtr, xforms, tex, 2, nullptr, nullptr); } ## #SeeAlso drawBitmap drawImage ## # ------------------------------------------------------------------------------ #Method void drawAtlas(const sk_sp& atlas, const SkRSXform xform[], const SkRect tex[], int count, const SkRect* cullRect, const SkPaint* paint) Draw a set of sprites from atlas, using Clip, Matrix, and optional Paint paint. paint uses Anti-alias, Color_Alpha, Color_Filter, Image_Filter, and Blend_Mode to draw, if present. For each entry in the array, Rect tex locates sprite in atlas, and RSXform xform transforms it into destination space. xform and text must contain count entries. Optional cullRect is a conservative bounds of all transformed sprites. If cullRect is outside of Clip, canvas can skip drawing. #Param atlas Image containing sprites ## #Param xform RSXform mappings for sprites in atlas ## #Param tex Rect locations of sprites in atlas ## #Param count number of sprites to draw ## #Param cullRect bounds of transformed sprites for efficient clipping; may be nullptr ## #Param paint Color_Filter, Image_Filter, Blend_Mode, and so on; may be nullptr ## #Example #Image 3 void draw(SkCanvas* canvas) { // sk_sp image = mandrill; SkRSXform xforms[] = { { 1, 0, 0, 0 }, {0, 1, 300, 100 } }; SkRect tex[] = { { 0, 0, 200, 200 }, { 200, 0, 400, 200 } }; canvas->drawAtlas(image, xforms, tex, 2, nullptr, nullptr); } ## #SeeAlso drawBitmap drawImage ## # ------------------------------------------------------------------------------ #Method void drawDrawable(SkDrawable* drawable, const SkMatrix* matrix = nullptr) Draw Drawable drawable using Clip and Matrix, concatenated with optional matrix. If Canvas has an asynchronous implementation, as is the case when it is recording into Picture, then drawable will be referenced, so that SkDrawable::draw() can be called when the operation is finalized. To force immediate drawing, call SkDrawable::draw() instead. #Param drawable custom struct encapsulating drawing commands ## #Param matrix transformation applied to drawing; may be nullptr ## #Example #Height 100 #Function struct MyDrawable : public SkDrawable { SkRect onGetBounds() override { return SkRect::MakeWH(50, 100); } void onDraw(SkCanvas* canvas) override { SkPath path; path.conicTo(10, 90, 50, 90, 0.9f); SkPaint paint; paint.setColor(SK_ColorBLUE); canvas->drawRect(path.getBounds(), paint); paint.setAntiAlias(true); paint.setColor(SK_ColorWHITE); canvas->drawPath(path, paint); } }; #Function ## void draw(SkCanvas* canvas) { sk_sp drawable(new MyDrawable); SkMatrix matrix; matrix.setTranslate(10, 10); canvas->drawDrawable(drawable.get(), &matrix); } ## #SeeAlso SkDrawable drawPicture ## # ------------------------------------------------------------------------------ #Method void drawDrawable(SkDrawable* drawable, SkScalar x, SkScalar y) Draw Drawable drawable using Clip and Matrix, offset by (x, y). If Canvas has an asynchronous implementation, as is the case when it is recording into Picture, then drawable will be referenced, so that SkDrawable::draw() can be called when the operation is finalized. To force immediate drawing, call SkDrawable::draw() instead. #Param drawable custom struct encapsulating drawing commands ## #Param x offset into Canvas writable pixels in x ## #Param y offset into Canvas writable pixels in y ## #Example #Height 100 #Function struct MyDrawable : public SkDrawable { SkRect onGetBounds() override { return SkRect::MakeWH(50, 100); } void onDraw(SkCanvas* canvas) override { SkPath path; path.conicTo(10, 90, 50, 90, 0.9f); SkPaint paint; paint.setColor(SK_ColorBLUE); canvas->drawRect(path.getBounds(), paint); paint.setAntiAlias(true); paint.setColor(SK_ColorWHITE); canvas->drawPath(path, paint); } }; #Function ## void draw(SkCanvas* canvas) { sk_sp drawable(new MyDrawable); canvas->drawDrawable(drawable.get(), 10, 10); } ## #SeeAlso SkDrawable drawPicture ## # ------------------------------------------------------------------------------ #Method void drawAnnotation(const SkRect& rect, const char key[], SkData* value) Associate Rect on Canvas when an annotation; a key-value pair, where the key is a null-terminated utf8 string, and optional value is stored as Data. Only some canvas implementations, such as recording to Picture, or drawing to Document_PDF, use annotations. #Param rect Rect extent of canvas to annotate ## #Param key string used for lookup ## #Param value data holding value stored in annotation ## #Example #Height 1 const char text[] = "Click this link!"; SkRect bounds; SkPaint paint; paint.setTextSize(40); (void)paint.measureText(text, strlen(text), &bounds); const char url[] = "https://www.google.com/"; sk_sp urlData(SkData::MakeWithCString(url)); canvas->drawAnnotation(bounds, "url_key", urlData.get()); ## #SeeAlso SkPicture SkDocument ## # ------------------------------------------------------------------------------ #Method void drawAnnotation(const SkRect& rect, const char key[], const sk_sp& value) Associate Rect on Canvas when an annotation; a key-value pair, where the key is a null-terminated utf8 string, and optional value is stored as Data. Only some canvas implementations, such as recording to Picture, or drawing to Document_PDF, use annotations. #Param rect Rect extent of canvas to annotate ## #Param key string used for lookup ## #Param value data holding value stored in annotation ## #Example #Height 1 const char text[] = "Click this link!"; SkRect bounds; SkPaint paint; paint.setTextSize(40); (void)paint.measureText(text, strlen(text), &bounds); const char url[] = "https://www.google.com/"; sk_sp urlData(SkData::MakeWithCString(url)); canvas->drawAnnotation(bounds, "url_key", urlData.get()); ## #SeeAlso SkPicture SkDocument ## #Method SkDrawFilter* getDrawFilter() const Legacy call to be deprecated. #Deprecated ## ## #Method virtual SkDrawFilter* setDrawFilter(SkDrawFilter* filter) Legacy call to be deprecated. #Deprecated ## ## # ------------------------------------------------------------------------------ #Method virtual bool isClipEmpty() const Returns true if Clip is empty; that is, nothing will draw. May do work when called; it should not be called more often than needed. However, once called, subsequent calls perform no work until Clip changes. #Return true if Clip is empty ## #Example void draw(SkCanvas* canvas) { SkDebugf("clip is%s empty\n", canvas->isClipEmpty() ? "" : " not"); SkPath path; canvas->clipPath(path); SkDebugf("clip is%s empty\n", canvas->isClipEmpty() ? "" : " not"); } #StdOut clip is not empty clip is empty ## ## #SeeAlso isClipRect getLocalClipBounds getDeviceClipBounds ## # ------------------------------------------------------------------------------ #Method virtual bool isClipRect() const Returns true if Clip is Rect and not empty. Returns false if the clip is empty, or if it is not Rect. #Return true if Clip is Rect and not empty ## #Example void draw(SkCanvas* canvas) { SkDebugf("clip is%s rect\n", canvas->isClipRect() ? "" : " not"); canvas->clipRect({0, 0, 0, 0}); SkDebugf("clip is%s rect\n", canvas->isClipRect() ? "" : " not"); } #StdOut clip is rect clip is not rect ## ## #SeeAlso isClipEmpty getLocalClipBounds getDeviceClipBounds ## #Class SkCanvas ## #Class SkAutoCanvasRestore Stack helper class calls SkCanvas::restoreToCount() when SkAutoCanvasRestore goes out of scope. Use this to guarantee that the canvas is restored to a known state. #Method SkAutoCanvasRestore(SkCanvas* canvas, bool doSave) Preserves Canvas save count. Optionally saves Canvas Clip and Matrix. #Param canvas Canvas to guard ## #Param doSave call SkCanvas::save() ## #Return utility to restore Canvas state on destructor ## #Example #Height 128 SkPaint p; p.setAntiAlias(true); p.setTextSize(64); for (SkScalar sx : { -1, 1 } ) { for (SkScalar sy : { -1, 1 } ) { SkAutoCanvasRestore autoRestore(canvas, true); SkMatrix m = SkMatrix::MakeAll(sx, 1, 96, 0, sy, 64, 0, 0, 1); canvas->concat(m); canvas->drawString("R", 0, 0, p); } } ## #SeeAlso SkCanvas::save SkCanvas::restore ## #Method ~SkAutoCanvasRestore() Restores Canvas to saved state. Destructor is called when container goes out of scope. #NoExample ## #SeeAlso SkCanvas::save SkCanvas::restore ## #Method void restore() Restores Canvas to saved state immediately. Subsequent calls and ~SkAutoCanvasRestore have no effect. #Example for (bool callRestore : { false, true } ) { for (bool saveCanvas : {false, true} ) { SkAutoCanvasRestore autoRestore(canvas, saveCanvas); if (!saveCanvas) { canvas->save(); } SkDebugf("saveCanvas: %s before restore: %d\n", saveCanvas ? "true" : "false", canvas->getSaveCount()); if (callRestore) autoRestore.restore(); SkDebugf("saveCanvas: %s after restore: %d\n", saveCanvas ? "true" : "false", canvas->getSaveCount()); } } SkDebugf("final count: %d\n", canvas->getSaveCount()); #StdOut saveCanvas: false before restore: 2 saveCanvas: false after restore: 2 saveCanvas: true before restore: 2 saveCanvas: true after restore: 2 saveCanvas: false before restore: 2 saveCanvas: false after restore: 1 saveCanvas: true before restore: 2 saveCanvas: true after restore: 1 final count: 1 ## ## #SeeAlso SkCanvas::save SkCanvas::restore ## #Class SkAutoCanvasRestore ## #Topic Canvas ##