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 08bbb9b8ed8e510a2487914d4857ad8a741af137..b025c5c2b0f8108122a51cad95ed1e3b3179689f 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -148,11 +148,16 @@ RenderObject* HTMLCanvasElement::createRenderer(RenderStyle* style)
 
 void HTMLCanvasElement::didRecalcStyle(StyleRecalcChange)
 {
-    SkPaint::FilterLevel filterLevel = computedStyle()->imageRendering() == ImageRenderingPixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel;
+    bool pixelated = computedStyle()->imageRendering() == ImageRenderingPixelated;
+    SkPaint::FilterLevel filterLevel = pixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel;
     if (m_context && m_context->is3d()) {
         toWebGLRenderingContext(m_context.get())->setFilterLevel(filterLevel);
         setNeedsCompositingUpdate();
     }
+    if (hasImageBuffer()) {
+        m_imageBuffer->setFilterLevel(filterLevel);
+        m_imageBuffer->context()->setImageInterpolationQuality(pixelated ? InterpolationLow : CanvasDefaultInterpolationQuality);

[esprehn, 2014/12/17 23:05:19]

Did you add a test that this dynamically updates?

[jackhou1, 2014/12/18 03:48:07]

I have layout tests that cover changing the CSS property, but they pass without
this change. I guess either it's not necessary to set this for accelerated
canvases, or they're necessary for a case that's not yet tested. I think it's
better to remove this part for now and add it later if we discover a case that
actually requires it.

+    }
 }
 
 Node::InsertionNotificationRequest HTMLCanvasElement::insertedInto(ContainerNode* node)
@@ -624,8 +629,13 @@ void HTMLCanvasElement::createImageBufferInternal()
     if (!surface->isValid())
         return;
 
+    document().updateRenderTreeIfNeeded();
+    RenderStyle* style = computedStyle();
+    bool pixelated = style && (style->imageRendering() == ImageRenderingPixelated || style->imageRendering() == ImageRenderingOptimizeContrast);
+
     m_imageBuffer = ImageBuffer::create(surface.release());
     m_imageBuffer->setClient(this);
+    m_imageBuffer->setFilterLevel(pixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel);
 
     m_didFailToCreateImageBuffer = false;
 
@@ -639,7 +649,7 @@ 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(pixelated ? 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.
@@ -813,6 +823,8 @@ PassRefPtr<Image> HTMLCanvasElement::getSourceImageForCanvas(SourceImageMode mod
         return createTransparentImage(size());
     }
 
+    m_imageBuffer->willAccessPixels();
+
     if (m_context->is3d()) {
         m_context->paintRenderingResultsToCanvas(BackBuffer);
         *status = ExternalSourceImageStatus;