Refactor SkCanvas so that backends don't need to override it.

Methods or classes that should go away are marked deprecated. The only thing I know of that breaks backward compatibility is SkCanvas((SkDevice*)NULL), but that is fairly unlikely to occur in the wild because that constructor had a default value of NULL.

Review URL: http://codereview.appspot.com/2103045

git-svn-id: http://skia.googlecode.com/svn/trunk@604 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 63 insertions, 26 deletions

diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index 0ccc2dd999..6d995b8b55 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -29,6 +29,7 @@
 
 class SkBounder;
 class SkDevice;
+class SkDeviceFactory;
 class SkDraw;
 class SkDrawFilter;
 class SkPicture;
@@ -51,29 +52,37 @@ class SkShape;
 */
 class SkCanvas : public SkRefCnt {
 public:
-    /** Construct a canvas with the specified bitmap to draw into.
+    /** Construct a canvas with the given device factory.
+        @param factory  Specify the factory for generating additional devices.
+                        The factory may be null, in which case SkDeviceFactory
+                        will be used.
+    */
+    explicit SkCanvas(SkDeviceFactory* factory = NULL);
+
+    /** Construct a canvas with the specified device to draw into.  The device
+        factory will be retrieved from the passed device.
+        @param device   Specifies a device for the canvas to draw into.
+    */
+    explicit SkCanvas(SkDevice* device);
+
+    /** Deprecated - Construct a canvas with the specified bitmap to draw into.
         @param bitmap   Specifies a bitmap for the canvas to draw into. Its
                         structure are copied to the canvas.
     */
     explicit SkCanvas(const SkBitmap& bitmap);
-    /** Construct a canvas with the specified device to draw into.
-        @param device   Specifies a device for the canvas to draw into. The
-                        device may be null.
-    */
-    explicit SkCanvas(SkDevice* device = NULL);
     virtual ~SkCanvas();
 
     ///////////////////////////////////////////////////////////////////////////
 
-    /** If this subclass of SkCanvas supports GL viewports, return true and set
-        size (if not null) to the size of the viewport. If it is not supported,
-        ignore vp and return false.
+    /** If the Device supports GL viewports, return true and set size (if not
+        null) to the size of the viewport. If it is not supported, ignore size
+        and return false.
     */
     virtual bool getViewport(SkIPoint* size) const;
-    
-    /** If this subclass of SkCanvas supports GL viewports, return true and set
-        the viewport to the specified x and y dimensions. If it is not
-        supported, ignore x and y and return false.
+
+    /** If the Device supports GL viewports, return true and set the viewport
+        to the specified x and y dimensions. If it is not supported, ignore x
+        and y and return false.
     */
     virtual bool setViewport(int x, int y);
 
@@ -88,15 +97,16 @@ public:
         device, its reference count is decremented. The new device is returned.
     */
     SkDevice* setDevice(SkDevice* device);
-    
-    /** Specify a bitmap for the canvas to draw into. This is a help method for
-        setDevice(), and it creates a device for the bitmap by calling
-        createDevice(). The structure of the bitmap is copied into the device.
+
+    /** Deprecated - Specify a bitmap for the canvas to draw into. This is a
+        helper method for setDevice(), and it creates a device for the bitmap by
+        calling createDevice(). The structure of the bitmap is copied into the
+        device.
     */
     virtual SkDevice* setBitmapDevice(const SkBitmap& bitmap);
 
     ///////////////////////////////////////////////////////////////////////////
-    
+
     enum SaveFlags {
         /** save the matrix state, restoring it on restore() */
         kMatrix_SaveFlag            = 0x01,
@@ -749,6 +759,7 @@ private:
 
     SkBounder*  fBounder;
     SkDevice*   fLastDeviceToGainFocus;
+    SkDeviceFactory* fDeviceFactory;
 
     void prepareForDeviceDraw(SkDevice*);
     
diff --git a/include/core/SkDevice.h b/include/core/SkDevice.h
index 4d678c6a40..b7a9cbcb3a 100644
--- a/include/core/SkDevice.h
+++ b/include/core/SkDevice.h
@@ -22,26 +22,52 @@
 #include "SkCanvas.h"
 #include "SkColor.h"
 
+class SkDevice;
 class SkDraw;
 struct SkIRect;
 class SkMatrix;
 class SkRegion;
 
+/** \class SkDeviceFactory
+
+    Devices that extend SkDevice should also provide a SkDeviceFactory class
+    to pass into SkCanvas.  Doing so will eliminate the need to extend
+    SkCanvas as well.
+*/
+class SkDeviceFactory : public SkRefCnt {
+public:
+    virtual SkDevice* newDevice(SkBitmap::Config config, int width, int height,
+                                bool isOpaque, bool isForLayer) = 0;
+
+    enum Capabilities {
+        kGL_Capability    = 0x1,  //!< mask to indicate this device supports GL
+        kAll_Capabilities = 0x1
+    };
+    virtual uint32_t getDeviceCapabilities() = 0;
+};
+
+class SkRasterDeviceFactory : public SkDeviceFactory {
+public:
+    virtual SkDevice* newDevice(SkBitmap::Config config, int width, int height,
+                                bool isOpaque, bool isForLayer);
+    virtual uint32_t getDeviceCapabilities() { return 0; }
+};
+
 class SkDevice : public SkRefCnt {
 public:
     SkDevice();
-    /** Construct a new device, extracting the width/height/config/isOpaque values from
-        the bitmap. If transferPixelOwnership is true, and the bitmap claims to own its
-        own pixels (getOwnsPixels() == true), then transfer this responsibility to the
-        device, and call setOwnsPixels(false) on the bitmap.
-        
-        Subclasses may override the destructor, which is virtual, even though this class
-        doesn't have one. SkRefCnt does.
-    
+    /** Construct a new device, extracting the width/height/config/isOpaque
+        values from the bitmap.  Subclasses may override the destructor, which
+        is virtual, even though this class doesn't have one. SkRefCnt does.
+
         @param bitmap   A copy of this bitmap is made and stored in the device
     */
     SkDevice(const SkBitmap& bitmap);
 
+    virtual SkDeviceFactory* getDeviceFactory() {
+        return SkNEW(SkRasterDeviceFactory);
+    }
+
     /** Return the width of the device (in pixels).
     */
     int width() const { return fBitmap.width(); }