Use SkImage as a backing store for copying 2d Contexts to ImageBitmaps.

Source/core/platform/graphics/ImageBuffer.cpp

Index: Source/core/platform/graphics/ImageBuffer.cpp
diff --git a/Source/core/platform/graphics/ImageBuffer.cpp b/Source/core/platform/graphics/ImageBuffer.cpp
index 48f2f54951c38fc7cdced7bee47c1be5477d7df3..9200a92b78e91ef91d40ce836375d467f0551aae 100644
--- a/Source/core/platform/graphics/ImageBuffer.cpp
+++ b/Source/core/platform/graphics/ImageBuffer.cpp
@@ -40,6 +40,7 @@
 #include "core/platform/graphics/GraphicsContext.h"
 #include "core/platform/graphics/GraphicsContext3D.h"
 #include "core/platform/graphics/IntRect.h"
+#include "core/platform/graphics/ReadOnlyBitmapImage.h"
 #include "core/platform/graphics/chromium/Canvas2DLayerBridge.h"
 #include "core/platform/graphics/gpu/SharedGraphicsContext3D.h"
 #include "core/platform/graphics/skia/NativeImageSkia.h"
@@ -61,23 +62,35 @@ using namespace std;
 
 namespace WebCore {
 
-static SkCanvas* createAcceleratedCanvas(const IntSize& size, OwnPtr<Canvas2DLayerBridge>* outLayerBridge, OpacityMode opacityMode)
+void ImageBuffer::createAcceleratedCanvas(const IntSize& size, OwnPtr<Canvas2DLayerBridge>* outLayerBridge, OpacityMode opacityMode)

[Justin Novosad, 2013/08/19 20:12:43]

This clashes with a refactoring I have in flight.  Let's not commit this right
away

[Stephen White, 2013/08/19 20:21:21]

If you don't need the SkCanvas* return value anymore, you should probably just
return a PassOwnPtr<Canvas2DLayerBridge> from this function.

[danakj, 2013/08/19 20:22:33]

SkCanvas is refcounted. Should it not go in a RefPtr?

 {
     RefPtr<GraphicsContext3D> context3D = SharedGraphicsContext3D::get();
     if (!context3D)
-        return 0;
+        return;
     Canvas2DLayerBridge::OpacityMode bridgeOpacityMode = opacityMode == Opaque ? Canvas2DLayerBridge::Opaque : Canvas2DLayerBridge::NonOpaque;
     *outLayerBridge = Canvas2DLayerBridge::create(context3D.release(), size, bridgeOpacityMode);
+
+    // FIXME: refactor Canvas2DLayerBridge so that SkSurface is accessible.
+    SkSurface* surface = 0;
+    m_surface = adoptPtr(surface);
+
     // If canvas buffer allocation failed, debug build will have asserted
     // For release builds, we must verify whether the device has a render target
-    return (*outLayerBridge) ? (*outLayerBridge)->getCanvas() : 0;
+    SkCanvas* canvas = (*outLayerBridge) ? (*outLayerBridge)->getCanvas() : 0;
+    m_canvas = adoptPtr(canvas);
 }
 
-static SkCanvas* createNonPlatformCanvas(const IntSize& size)
+void ImageBuffer::createNonPlatformCanvas(const IntSize& size)
 {
-    SkAutoTUnref<SkDevice> device(new SkDevice(SkBitmap::kARGB_8888_Config, size.width(), size.height()));
-    SkPixelRef* pixelRef = device->accessBitmap(false).pixelRef();
-    return pixelRef ? new SkCanvas(device) : 0;
+    SkImage::Info info;
+    info.fWidth = size.width();
+    info.fHeight = size.height();
+    info.fColorType = SkImage::kRGBA_8888_ColorType;
+    info.fAlphaType = SkImage::kPremul_AlphaType;
+    m_surface = adoptPtr(SkSurface::NewRaster(info));
+    if (!m_surface)
+        return;
+    m_canvas = adoptPtr(m_surface->getCanvas());
 }
 
 PassOwnPtr<ImageBuffer> ImageBuffer::createCompatibleBuffer(const IntSize& size, float resolutionScale, const GraphicsContext* context, bool hasAlpha)
@@ -125,13 +138,13 @@ ImageBuffer::ImageBuffer(const IntSize& size, float resolutionScale, RenderingMo
     , m_resolutionScale(resolutionScale)
 {
     if (renderingMode == Accelerated) {
-        m_canvas = adoptPtr(createAcceleratedCanvas(size, &m_layerBridge, opacityMode));
+        createAcceleratedCanvas(size, &m_layerBridge, opacityMode);
         if (!m_canvas)
             renderingMode = UnacceleratedNonPlatformBuffer;
     }
 
     if (renderingMode == UnacceleratedNonPlatformBuffer)
-        m_canvas = adoptPtr(createNonPlatformCanvas(size));
+        createNonPlatformCanvas(size);
 
     if (!m_canvas)
         m_canvas = adoptPtr(skia::TryCreateBitmapCanvas(size.width(), size.height(), false));
@@ -188,6 +201,22 @@ static SkBitmap deepSkBitmapCopy(const SkBitmap& bitmap)
     return tmp;
 }
 
+PassRefPtr<Image> ImageBuffer::imageSnapshot() const
+{
+    // A canvas without a surface indicates that a platform buffer is being used. imageSnapshot() on a platform
+    // buffer is not supported.
+    ASSERT(!m_canvas);
+
+    if (!isValid())
+        return BitmapImage::create(NativeImageSkia::create());
+
+    // FIXME: Case where canvas is acclerated. This should be removed once ImageBuffer holds a ref to the SkSurface.
+    if (!m_surface)
+        return copyImage(CopyBackingStore);
+
+    return ReadOnlyBitmapImage::create(m_surface->newImageSnapshot());
+}
+
 PassRefPtr<Image> ImageBuffer::copyImage(BackingStoreCopy copyBehavior, ScaleBehavior) const
 {
     if (!isValid())