Make 2D canvas smarter about chosing whether or not to use GPU acceleration

Source/modules/canvas2d/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012, 2013 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 1359 matching lines @@
 void CanvasRenderingContext2D::drawImage(CanvasImageSource* imageSource,
     float sx, float sy, float sw, float sh,
     float dx, float dy, float dw, float dh, ExceptionState& exceptionState)
 {
     if (!drawingCanvas())
         return;
 
     RefPtr<Image> image;
     SourceImageStatus sourceImageStatus = InvalidSourceImageStatus;
     if (!imageSource->isVideoElement()) {
-        image = imageSource->getSourceImageForCanvas(&sourceImageStatus);
+        AccelerationHint hint = canvas()->buffer()->isAccelerated() ? PreferAcceleration : PreferNoAcceleration;
+        image = imageSource->getSourceImageForCanvas(&sourceImageStatus, hint);
         if (sourceImageStatus == UndecodableSourceImageStatus)
             exceptionState.throwDOMException(InvalidStateError, "The HTMLImageElement provided is in the 'broken' state.");
         if (!image || !image->width() || !image->height())
             return;
     } else {
         if (!static_cast<HTMLVideoElement*>(imageSource)->hasAvailableVideoFrame())
             return;
     }
 
     if (!std::isfinite(dx) || !std::isfinite(dy) || !std::isfinite(dw) || !std::isfinite(dh)
@@ skipping 87 matching lines @@
 }
 
 CanvasPattern* CanvasRenderingContext2D::createPattern(const CanvasImageSourceUnion& imageSource, const String& repetitionType, ExceptionState& exceptionState)
 {
     Pattern::RepeatMode repeatMode = CanvasPattern::parseRepetitionType(repetitionType, exceptionState);
     if (exceptionState.hadException())
         return nullptr;
 
     SourceImageStatus status;
     CanvasImageSource* imageSourceInternal = toImageSourceInternal(imageSource);
-    RefPtr<Image> imageForRendering = imageSourceInternal->getSourceImageForCanvas(&status);
+    RefPtr<Image> imageForRendering = imageSourceInternal->getSourceImageForCanvas(&status, PreferNoAcceleration);
 
     switch (status) {
     case NormalSourceImageStatus:
         break;
     case ZeroSizeCanvasSourceImageStatus:
         exceptionState.throwDOMException(InvalidStateError, String::format("The canvas %s is 0.", imageSourceInternal->elementSize().width() ? "height" : "width"));
         return nullptr;
     case UndecodableSourceImageStatus:
         exceptionState.throwDOMException(InvalidStateError, "Source image is in the 'broken' state.");
         return nullptr;
@@ skipping 269 matching lines @@
 void CanvasRenderingContext2D::schedulePruneLocalFontCacheIfNeeded()
 {
     if (m_pruneLocalFontCacheScheduled)
         return;
     m_pruneLocalFontCacheScheduled = true;
     Platform::current()->currentThread()->addTaskObserver(this);
 }
 
 void CanvasRenderingContext2D::didProcessTask()
 {
+    // The rendering surface needs to be prepared now because it will be too late
+    // to create a layer once we are in the paint invalidation phase.
+    canvas()->prepareSurfaceForPaintingIfNeeded();
+
     pruneLocalFontCache(canvas()->document().canvasFontCache()->maxFonts());
     m_pruneLocalFontCacheScheduled = false;
     Platform::current()->currentThread()->removeTaskObserver(this);
 }
 
 void CanvasRenderingContext2D::pruneLocalFontCache(size_t targetSize)
 {
     if (targetSize == 0) {
         // Short cut: LRU does not matter when evicting everything
         m_fontLRUList.clear();
@@ skipping 532 matching lines @@
         if (imageType == CanvasRenderingContext2DState::NonOpaqueImage)
             return;
         if (alpha < 0xFF)
             return;
     }
 
     canvas()->buffer()->willOverwriteCanvas();
 }
 
 } // namespace blink