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author | djsollen@google.com <djsollen@google.com@2bbb7eff-a529-9590-31e7-b0007b416f81> | 2013-08-29 19:29:09 +0000 |
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committer | djsollen@google.com <djsollen@google.com@2bbb7eff-a529-9590-31e7-b0007b416f81> | 2013-08-29 19:29:09 +0000 |
commit | 2ce9fce145c0b6cc80a02bf534fdea2798936265 (patch) | |
tree | 0b1c00ffaa7e6c012fb6e594228241546d291b63 /src/utils/SkCanvasStateUtils.cpp | |
parent | 6a7eecd92c58d2fe300ecc772531803116adc652 (diff) |
Create a semi-stable API for capturing the state of an SkCanvas and reconstructing that state across different versions of Skia.
R=joth@chromium.org, mtklein@google.com, reed@google.com, scroggo@google.com
Review URL: https://codereview.chromium.org/23545017
git-svn-id: http://skia.googlecode.com/svn/trunk@11010 2bbb7eff-a529-9590-31e7-b0007b416f81
Diffstat (limited to 'src/utils/SkCanvasStateUtils.cpp')
-rw-r--r-- | src/utils/SkCanvasStateUtils.cpp | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/src/utils/SkCanvasStateUtils.cpp b/src/utils/SkCanvasStateUtils.cpp new file mode 100644 index 0000000000..8abab6b5ae --- /dev/null +++ b/src/utils/SkCanvasStateUtils.cpp @@ -0,0 +1,339 @@ +/* + * Copyright 2013 Google Inc. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "SkCanvasStateUtils.h" +#include "SkCanvas.h" +#include "SkDevice.h" +#include "SkNWayCanvas.h" +#include "SkWriter32.h" + +#define CANVAS_STATE_VERSION 1 +/* + * WARNING: The structs below are part of a stable ABI and as such we explicitly + * use unambigious primitives (e.g. int32_t instead of an enum). + * + * ANY CHANGES TO THE STRUCTS BELOW THAT IMPACT THE ABI SHOULD RESULT IN AN + * UPDATE OF THE CANVAS_STATE_VERSION. SUCH CHANGES SHOULD ONLY BE MADE IF + * ABSOLUTELY NECESSARY! + */ +enum RasterConfigs { + kUnknown_RasterConfig = 0, + kRGB_565_RasterConfig = 1, + kARGB_8888_RasterConfig = 2 +}; +typedef int32_t RasterConfig; + +enum CanvasBackends { + kUnknown_CanvasBackend = 0, + kRaster_CanvasBackend = 1, + kGPU_CanvasBackend = 2, + kPDF_CanvasBackend = 3 +}; +typedef int32_t CanvasBackend; + +struct ClipRect { + int32_t left, top, right, bottom; +}; + +struct SkMCState { + float matrix[9]; + // NOTE: this only works for non-antialiased clips + int32_t clipRectCount; + ClipRect* clipRects; +}; + +// NOTE: If you add more members, bump CanvasState::version. +struct SkCanvasLayerState { + CanvasBackend type; + int32_t x, y; + int32_t width; + int32_t height; + + SkMCState mcState; + + union { + struct { + RasterConfig config; // pixel format: a value from RasterConfigs. + uint32_t rowBytes; // Number of bytes from start of one line to next. + void* pixels; // The pixels, all (height * rowBytes) of them. + } raster; + struct { + int32_t textureID; + } gpu; + }; +}; + +class SkCanvasState { +public: + SkCanvasState(SkCanvas* canvas) { + SkASSERT(canvas); + version = CANVAS_STATE_VERSION; + width = canvas->getDeviceSize().width(); + height = canvas->getDeviceSize().height(); + layerCount = 0; + layers = NULL; + originalCanvas = SkRef(canvas); + + mcState.clipRectCount = 0; + mcState.clipRects = NULL; + } + + ~SkCanvasState() { + // loop through the layers and free the data allocated to the clipRects + for (int i = 0; i < layerCount; ++i) { + sk_free(layers[i].mcState.clipRects); + } + + sk_free(mcState.clipRects); + sk_free(layers); + + // it is now safe to free the canvas since there should be no remaining + // references to the content that is referenced by this canvas (e.g. pixels) + originalCanvas->unref(); + } + + /** + * The version this struct was built with. This field must always appear + * first in the struct so that when the versions don't match (and the + * remaining contents and size are potentially different) we can still + * compare the version numbers. + */ + int32_t version; + + int32_t width; + int32_t height; + + SkMCState mcState; + + int32_t layerCount; + SkCanvasLayerState* layers; + +private: + SkCanvas* originalCanvas; +}; + +//////////////////////////////////////////////////////////////////////////////// + +class ClipValidator : public SkCanvas::ClipVisitor { +public: + ClipValidator() : fFailed(false) {} + bool failed() { return fFailed; } + + // ClipVisitor + virtual void clipRect(const SkRect& rect, SkRegion::Op op, bool antialias) SK_OVERRIDE { + fFailed |= antialias; + } + + virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) SK_OVERRIDE { + fFailed |= antialias; + } + +private: + bool fFailed; +}; + +static void setup_MC_state(SkMCState* state, const SkMatrix& matrix, const SkRegion& clip) { + // initialize the struct + state->clipRectCount = 0; + + // capture the matrix + for (int i = 0; i < 9; i++) { + state->matrix[i] = matrix.get(i); + } + + /* + * capture the clip + * + * storage is allocated on the stack for the first 4 rects. This value was + * chosen somewhat arbitrarily, but does allow us to represent simple clips + * and some more common complex clips (e.g. a clipRect with a sub-rect + * clipped out of its interior) without needing to malloc any additional memory. + */ + const int clipBufferSize = 4 * sizeof(ClipRect); + char clipBuffer[clipBufferSize]; + SkWriter32 clipWriter(sizeof(ClipRect), clipBuffer, clipBufferSize); + + if (!clip.isEmpty()) { + // only returns the b/w clip so aa clips fail + SkRegion::Iterator clip_iterator(clip); + for (; !clip_iterator.done(); clip_iterator.next()) { + // this assumes the SkIRect is stored in l,t,r,b ordering which + // matches the ordering of our ClipRect struct + clipWriter.writeIRect(clip_iterator.rect()); + state->clipRectCount++; + } + } + + // allocate memory for the clip then and copy them to the struct + state->clipRects = (ClipRect*) sk_malloc_throw(clipWriter.size()); + clipWriter.flatten(state->clipRects); +} + + + +SkCanvasState* SkCanvasStateUtils::CaptureCanvasState(SkCanvas* canvas) { + SkASSERT(canvas); + + // Check the clip can be decomposed into rectangles (i.e. no soft clips). + ClipValidator validator; + canvas->replayClips(&validator); + if (validator.failed()) { + SkDEBUGF(("CaptureCanvasState does not support canvases with antialiased clips.\n")); + return NULL; + } + + SkAutoTDelete<SkCanvasState> canvasState(SkNEW_ARGS(SkCanvasState, (canvas))); + + // decompose the total matrix and clip + setup_MC_state(&canvasState->mcState, canvas->getTotalMatrix(), canvas->getTotalClip()); + + /* + * decompose the layers + * + * storage is allocated on the stack for the first 3 layers. It is common in + * some view systems (e.g. Android) that a few non-clipped layers are present + * and we will not need to malloc any additional memory in those cases. + */ + const int layerBufferSize = 3 * sizeof(SkCanvasLayerState); + char layerBuffer[layerBufferSize]; + SkWriter32 layerWriter(sizeof(SkCanvasLayerState), layerBuffer, layerBufferSize); + int layerCount = 0; + for (SkCanvas::LayerIter layer(canvas, true/*skipEmptyClips*/); !layer.done(); layer.next()) { + + // we currently only work for bitmap backed devices + const SkBitmap& bitmap = layer.device()->accessBitmap(true/*changePixels*/); + if (bitmap.empty() || bitmap.isNull() || !bitmap.lockPixelsAreWritable()) { + return NULL; + } + + SkCanvasLayerState* layerState = + (SkCanvasLayerState*) layerWriter.reserve(sizeof(SkCanvasLayerState)); + layerState->type = kRaster_CanvasBackend; + layerState->x = layer.x(); + layerState->y = layer.y(); + layerState->width = bitmap.width(); + layerState->height = bitmap.height(); + + switch (bitmap.config()) { + case SkBitmap::kARGB_8888_Config: + layerState->raster.config = kARGB_8888_RasterConfig; + break; + case SkBitmap::kRGB_565_Config: + layerState->raster.config = kRGB_565_RasterConfig; + break; + default: + return NULL; + } + layerState->raster.rowBytes = bitmap.rowBytes(); + layerState->raster.pixels = bitmap.getPixels(); + + setup_MC_state(&layerState->mcState, layer.matrix(), layer.clip()); + layerCount++; + } + + // allocate memory for the layers and then and copy them to the struct + SkASSERT(layerWriter.size() == layerCount * sizeof(SkCanvasLayerState)); + canvasState->layerCount = layerCount; + canvasState->layers = (SkCanvasLayerState*) sk_malloc_throw(layerWriter.size()); + layerWriter.flatten(canvasState->layers); + + // for now, just ignore any client supplied DrawFilter. + if (canvas->getDrawFilter()) { + SkDEBUGF(("CaptureCanvasState will ignore the canvases draw filter.\n")); + } + + return canvasState.detach(); +} + +//////////////////////////////////////////////////////////////////////////////// + +static void setup_canvas_from_MC_state(const SkMCState& state, SkCanvas* canvas) { + // reconstruct the matrix + SkMatrix matrix; + for (int i = 0; i < 9; i++) { + matrix.set(i, state.matrix[i]); + } + + // reconstruct the clip + SkRegion clip; + for (int i = 0; i < state.clipRectCount; ++i) { + clip.op(SkIRect::MakeLTRB(state.clipRects[i].left, + state.clipRects[i].top, + state.clipRects[i].right, + state.clipRects[i].bottom), + SkRegion::kUnion_Op); + } + + canvas->setMatrix(matrix); + canvas->setClipRegion(clip); +} + +static SkCanvas* create_canvas_from_canvas_layer(const SkCanvasLayerState& layerState) { + SkASSERT(kRaster_CanvasBackend == layerState.type); + + SkBitmap bitmap; + SkBitmap::Config config = + layerState.raster.config == kARGB_8888_RasterConfig ? SkBitmap::kARGB_8888_Config : + layerState.raster.config == kRGB_565_RasterConfig ? SkBitmap::kRGB_565_Config : + SkBitmap::kNo_Config; + + if (config == SkBitmap::kNo_Config) { + return NULL; + } + + bitmap.setConfig(config, layerState.width, layerState.height, + layerState.raster.rowBytes); + bitmap.setPixels(layerState.raster.pixels); + + SkASSERT(!bitmap.empty()); + SkASSERT(!bitmap.isNull()); + + // create a device & canvas + SkAutoTUnref<SkDevice> device(SkNEW_ARGS(SkDevice, (bitmap))); + SkAutoTUnref<SkCanvas> canvas(SkNEW_ARGS(SkCanvas, (device.get()))); + + // setup the matrix and clip + setup_canvas_from_MC_state(layerState.mcState, canvas.get()); + + return canvas.detach(); +} + +SkCanvas* SkCanvasStateUtils::CreateFromCanvasState(const SkCanvasState* state) { + SkASSERT(state); + + // check that the versions match + if (CANVAS_STATE_VERSION != state->version) { + SkDebugf("CreateFromCanvasState version does not match the one use to create the input"); + return NULL; + } + + if (state->layerCount < 1) { + return NULL; + } + + SkAutoTUnref<SkNWayCanvas> canvas(SkNEW_ARGS(SkNWayCanvas, (state->width, state->height))); + + // setup the matrix and clip on the n-way canvas + setup_canvas_from_MC_state(state->mcState, canvas); + + // Iterate over the layers and add them to the n-way canvas + for (int i = 0; i < state->layerCount; ++i) { + SkAutoTUnref<SkCanvas> canvasLayer(create_canvas_from_canvas_layer(state->layers[i])); + if (!canvasLayer.get()) { + return NULL; + } + canvas->addCanvas(canvasLayer.get()); + } + + return canvas.detach(); +} + +//////////////////////////////////////////////////////////////////////////////// + +void SkCanvasStateUtils::ReleaseCanvasState(SkCanvasState* state) { + SkDELETE(state); +} |