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

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 94 matching lines @@
     : HTMLElement(canvasTag, document)
     , DocumentVisibilityObserver(document)
     , m_size(DefaultWidth, DefaultHeight)
     , m_ignoreReset(false)
     , m_accelerationDisabled(false)
     , m_externallyAllocatedMemory(0)
     , m_originClean(true)
     , m_didFailToCreateImageBuffer(false)
     , m_imageBufferIsClear(false)
 {
+    setHasCustomStyleCallbacks();
 }
 
 DEFINE_NODE_FACTORY(HTMLCanvasElement)
 
 HTMLCanvasElement::~HTMLCanvasElement()
 {
     resetDirtyRect();
     v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(-m_externallyAllocatedMemory);
 #if !ENABLE(OILPAN)
     for (CanvasObserver* canvasObserver : m_observers)
         canvasObserver->canvasDestroyed(this);
     // Ensure these go away before the ImageBuffer.
     m_contextStateSaver.clear();
     m_context.clear();
 #endif
 }
 
 void HTMLCanvasElement::parseAttribute(const QualifiedName& name, const AtomicString& value)
 {
     if (name == widthAttr || name == heightAttr)
         reset();
     HTMLElement::parseAttribute(name, value);
 }
 
 RenderObject* HTMLCanvasElement::createRenderer(RenderStyle* style)
 {
+    if (hasImageBuffer())
+        m_imageBuffer->setFilterLevel(style->imageRendering() == ImageRenderingPixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel);

[esprehn, 2014/12/15 20:24:51]

If you have code in ::didRecalcStyle, you shouldn't need this too.

[jackhou1, 2014/12/15 23:17:24]

Done.

This was added for the case where a canvas is created off screen and then
appended to the DOM. But that seems to work without this now, so maybe there was
a bug in whatever commit I was based off.

     LocalFrame* frame = document().frame();
     if (frame && frame->script().canExecuteScripts(NotAboutToExecuteScript))
         return new RenderHTMLCanvas(this);
     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);
     return HTMLElement::insertedInto(node);
 }
 
 void HTMLCanvasElement::addObserver(CanvasObserver* observer)
 {
     m_observers.add(observer);
 }
@@ skipping 429 matching lines @@
     m_imageBufferIsClear = true;
 
     if (!canCreateImageBuffer(size()))
         return;
 
     int msaaSampleCount;
     OwnPtr<ImageBufferSurface> surface = createImageBufferSurface(size(), &msaaSampleCount);
     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);

[esprehn, 2014/12/15 20:24:51]

Why can't this just wait until didRecalcStyle to run?

[jackhou1, 2014/12/15 23:17:24]

It doesn't seem like didRecalcStyle will always run after this, even if I move
the updateRenderTreeIfNeeded after ImageBuffer::create.

 
     m_didFailToCreateImageBuffer = false;
 
     updateExternallyAllocatedMemory();
 
     if (is3D()) {
         // Early out for WebGL canvases
         return;
     }
 
     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.
     if (!msaaSampleCount && document().settings() && !document().settings()->antialiased2dCanvasEnabled())
         m_imageBuffer->context()->setShouldAntialias(false);
     // GraphicsContext's defaults don't always agree with the 2d canvas spec.
     // See CanvasRenderingContext2D::State::State() for more information.
     m_imageBuffer->context()->setMiterLimit(10);
     m_imageBuffer->context()->setStrokeThickness(1);
 #if ENABLE(ASSERT)
@@ skipping 150 matching lines @@
     if (!isPaintable()) {
         *status = InvalidSourceImageStatus;
         return nullptr;
     }
 
     if (!m_context) {
         *status = NormalSourceImageStatus;
         return createTransparentImage(size());
     }
 
+    m_imageBuffer->willAccessPixels();
+
     if (m_context->is3d()) {
         m_context->paintRenderingResultsToCanvas(BackBuffer);
         *status = ExternalSourceImageStatus;
 
         // can't create SkImage from WebGLImageBufferSurface (contains only SkBitmap)
         return buffer()->copyImage(DontCopyBackingStore, Unscaled);
     }
 
     RefPtr<SkImage> image = buffer()->newImageSnapshot();
     if (image) {
         *status = NormalSourceImageStatus;
         return StaticBitmapImage::create(image.release());
     }
 
     *status = InvalidSourceImageStatus;
     return nullptr;
 }
 
 bool HTMLCanvasElement::wouldTaintOrigin(SecurityOrigin*) const
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }