Removing the dependency on GraphicsContext for drawing images in 2D canvas

Source/core/svg/graphics/SVGImage.cpp

Index: Source/core/svg/graphics/SVGImage.cpp
diff --git a/Source/core/svg/graphics/SVGImage.cpp b/Source/core/svg/graphics/SVGImage.cpp
index edf144eb476899707ddb53f71ca610ab8bcbec71..6a2461f3788de492929c6a17b9a11da741d08dd8 100644
--- a/Source/core/svg/graphics/SVGImage.cpp
+++ b/Source/core/svg/graphics/SVGImage.cpp
@@ -194,8 +194,8 @@ IntSize SVGImage::containerSize() const
     return IntSize(300, 150);
 }
 
-void SVGImage::drawForContainer(GraphicsContext* context, const FloatSize containerSize, float zoom, const FloatRect& dstRect,
-    const FloatRect& srcRect, SkXfermode::Mode compositeOp)
+void SVGImage::drawForContainer(SkCanvas* canvas, const SkPaint& paint, const FloatSize containerSize, float zoom, const FloatRect& dstRect,
+    const FloatRect& srcRect)
 {
     if (!m_page)
         return;
@@ -214,7 +214,8 @@ void SVGImage::drawForContainer(GraphicsContext* context, const FloatSize contai
     adjustedSrcSize.scale(roundedContainerSize.width() / containerSize.width(), roundedContainerSize.height() / containerSize.height());
     scaledSrc.setSize(adjustedSrcSize);
 
-    draw(context, dstRect, scaledSrc, compositeOp, DoNotRespectImageOrientation);
+    bool shouldClampToSourceRect = true;
+    draw(canvas, paint, dstRect, scaledSrc, DoNotRespectImageOrientation, shouldClampToSourceRect);
 }
 
 bool SVGImage::bitmapForCurrentFrame(SkBitmap* bitmap)
@@ -226,7 +227,8 @@ bool SVGImage::bitmapForCurrentFrame(SkBitmap* bitmap)
     if (!buffer)
         return false;
 
-    drawForContainer(buffer->context(), size(), 1, rect(), rect(), SkXfermode::kSrcOver_Mode);
+    SkPaint paint;
+    drawForContainer(buffer->canvas(), paint, size(), 1, rect(), rect());
 
     *bitmap = buffer->bitmap();
     return true;
@@ -252,7 +254,8 @@ void SVGImage::drawPatternForContainer(GraphicsContext* context, const FloatSize
             // When generating an expanded tile, make sure we don't draw into the spacing area.
             if (tile != spacedTile)
                 patternPicture.context().clip(tile);
-            drawForContainer(&patternPicture.context(), containerSize, zoom, tile, srcRect, SkXfermode::kSrcOver_Mode);
+            SkPaint paint;
+            drawForContainer(patternPicture.context().canvas(), paint, containerSize, zoom, tile, srcRect);
         }
     }
     RefPtr<const SkPicture> tilePicture = patternPicture.endRecording();
@@ -270,13 +273,25 @@ void SVGImage::drawPatternForContainer(GraphicsContext* context, const FloatSize
     context->drawRect(dstRect, paint);
 }
 
-void SVGImage::draw(GraphicsContext* context, const FloatRect& dstRect, const FloatRect& srcRect, SkXfermode::Mode compositeOp, RespectImageOrientationEnum)
+static bool drawNeedsLayer(const SkPaint& paint)
+{
+    if (SkColorGetA(paint.getColor()) < 255)
+        return true;
+
+    SkXfermode::Mode xfermode;
+    if (SkXfermode::AsMode(paint.getXfermode(), &xfermode)) {
+        if (xfermode != SkXfermode::kSrcOver_Mode)
+            return true;
+    }
+
+    return false;
+}
+
+void SVGImage::draw(SkCanvas* canvas, const SkPaint& paint, const FloatRect& dstRect, const FloatRect& srcRect, RespectImageOrientationEnum, bool /*shouldClampToSourceRect*/)
 {
     if (!m_page)
         return;
 
-    float opacity = context->getNormalizedAlpha() / 255.f;
-
     FrameView* view = frameView();
     view->resize(containerSize());
 
@@ -284,16 +299,9 @@ void SVGImage::draw(GraphicsContext* context, const FloatRect& dstRect, const Fl
     // there may have been a previous url/fragment that needs to be reset.
     view->scrollToFragment(m_url);
 
+    SkPictureBuilder imagePicture(dstRect);
     {
-        DisplayItemListContextRecorder contextRecorder(*context);
-        GraphicsContext& paintContext = contextRecorder.context();
-
-        ClipRecorder clipRecorder(paintContext, *this, DisplayItem::ClipNodeImage, LayoutRect(enclosingIntRect(dstRect)));
-
-        bool hasCompositing = compositeOp != SkXfermode::kSrcOver_Mode;
-        OwnPtr<CompositingRecorder> compositingRecorder;
-        if (hasCompositing || opacity < 1)
-            compositingRecorder = adoptPtr(new CompositingRecorder(paintContext, *this, compositeOp, opacity));
+        ClipRecorder clipRecorder(imagePicture.context(), *this, DisplayItem::ClipNodeImage, LayoutRect(enclosingIntRect(dstRect)));
 
         // We can only draw the entire frame, clipped to the rect we want. So compute where the top left
         // of the image would be if we were drawing without clipping, and translate accordingly.
@@ -302,13 +310,23 @@ void SVGImage::draw(GraphicsContext* context, const FloatRect& dstRect, const Fl
         FloatPoint destOffset = dstRect.location() - topLeftOffset;
         AffineTransform transform = AffineTransform::translation(destOffset.x(), destOffset.y());
         transform.scale(scale.width(), scale.height());
-        TransformRecorder transformRecorder(paintContext, *this, transform);
+        TransformRecorder transformRecorder(imagePicture.context(), *this, transform);
 
         view->updateLayoutAndStyleForPainting();
-        view->paint(&paintContext, enclosingIntRect(srcRect));
+        view->paint(&imagePicture.context(), enclosingIntRect(srcRect));
         ASSERT(!view->needsLayout());
     }
 
+    {
+        SkAutoCanvasRestore ar(canvas, false);
+        if (drawNeedsLayer(paint)) {
+            SkRect layerRect = dstRect;
+            canvas->saveLayer(&layerRect, &paint);
+        }
+        RefPtr<const SkPicture> recording = imagePicture.endRecording();
+        canvas->drawPicture(recording.get());
+    }
+
     if (imageObserver())
         imageObserver()->didDraw(this);