Implement image-rendering:pixelated for accelerated 2D canvases.

Source/core/html/HTMLCanvasElement.cpp

Index: Source/core/html/HTMLCanvasElement.cpp
diff --git a/Source/core/html/HTMLCanvasElement.cpp b/Source/core/html/HTMLCanvasElement.cpp
index 9cecdc45291136d9fab1fc1e9739d9b22dd1018c..cf37383deccf4f017e6b05a193c0c4d12f77c165 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -87,6 +87,7 @@ inline HTMLCanvasElement::HTMLCanvasElement(Document& document)
     , m_didFailToCreateImageBuffer(false)
     , m_didClearImageBuffer(false)
 {
+    setHasCustomStyleCallbacks();
 }
 
 DEFINE_NODE_FACTORY(HTMLCanvasElement)
@@ -120,6 +121,13 @@ RenderObject* HTMLCanvasElement::createRenderer(RenderStyle* style)
     return HTMLElement::createRenderer(style);
 }
 
+void HTMLCanvasElement::didRecalcStyle(StyleRecalcChange)
+{
+    if (!hasImageBuffer())
+        return;
+    m_imageBuffer->setFilterLevel(computedStyle()->imageRendering() == ImageRenderingPixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel);
+}
+
 Node::InsertionNotificationRequest HTMLCanvasElement::insertedInto(ContainerNode* node)
 {
     setIsInCanvasSubtree(true);
@@ -534,7 +542,7 @@ PassOwnPtr<ImageBufferSurface> HTMLCanvasElement::createImageBufferSurface(const
 
     OwnPtr<RecordingImageBufferFallbackSurfaceFactory> surfaceFactory = createSurfaceFactory(deviceSize, msaaSampleCount);
 
-    if (RuntimeEnabledFeatures::displayList2dCanvasEnabled()) {
+    if (RuntimeEnabledFeatures::displayList2dCanvasEnabled() && false) {

[Justin Novosad, 2014/11/18 16:32:50]

Do not hard-code disable the displayList2dCanvas feature.  If you do not intend
to fix this right now, you should file a separate bug for making
ImageRenderingPixelated work correctly with display lists.

[jackhou1, 2014/12/01 07:00:08]

Removed.

Sorry, added this when I was debugging.

         OwnPtr<ImageBufferSurface> surface = adoptPtr(new RecordingImageBufferSurface(deviceSize, surfaceFactory.release(), opacityMode));
         if (surface->isValid())
             return surface.release();
@@ -576,6 +584,7 @@ void HTMLCanvasElement::createImageBufferInternal()
 
     m_imageBuffer = ImageBuffer::create(surface.release());
     m_imageBuffer->setClient(this);
+    m_imageBuffer->setFilterLevel(computedStyle()->imageRendering() == ImageRenderingPixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel);
 
     m_didFailToCreateImageBuffer = false;
 
@@ -589,7 +598,7 @@ void HTMLCanvasElement::createImageBufferInternal()
     m_imageBuffer->setClient(this);
     m_imageBuffer->context()->setShouldClampToSourceRect(false);
     m_imageBuffer->context()->disableAntialiasingOptimizationForHairlineImages();
-    m_imageBuffer->context()->setImageInterpolationQuality(CanvasDefaultInterpolationQuality);
+    m_imageBuffer->context()->setImageInterpolationQuality(computedStyle()->imageRendering() == ImageRenderingOptimizeContrast ? InterpolationLow : CanvasDefaultInterpolationQuality);
     // Enabling MSAA overrides a request to disable antialiasing. This is true regardless of whether the
     // rendering mode is accelerated or not. For consistency, we don't want to apply AA in accelerated
     // canvases but not in unaccelerated canvases.
@@ -769,6 +778,8 @@ PassRefPtr<Image> HTMLCanvasElement::getSourceImageForCanvas(SourceImageMode mod
         return nullptr;
     }
 
+    m_imageBuffer->willAccessPixels();
+
     if (m_context && m_context->is3d()) {
         m_context->paintRenderingResultsToCanvas();
         *status = ExternalSourceImageStatus;