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

third_party/WebKit/Source/platform/graphics/ImageBuffer.cpp

 /*
  * Copyright (c) 2008, Google Inc. All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
@@ skipping 130 matching lines @@
     if (m_client)
         m_client->notifySurfaceInvalid();
 }
 
 void ImageBuffer::resetCanvas(SkCanvas* canvas) const
 {
     if (m_client)
         m_client->restoreCanvasMatrixClipStack(canvas);
 }
 
-PassRefPtr<SkImage> ImageBuffer::newSkImageSnapshot() const
+PassRefPtr<SkImage> ImageBuffer::newSkImageSnapshot(AccelerationHint hint) const
 {
     if (m_snapshotState == InitialSnapshotState)
         m_snapshotState = DidAcquireSnapshot;
 
     if (!isSurfaceValid())
         return nullptr;
-    return m_surface->newImageSnapshot();
+    return m_surface->newImageSnapshot(hint);
 }
 
-PassRefPtr<Image> ImageBuffer::newImageSnapshot() const
+PassRefPtr<Image> ImageBuffer::newImageSnapshot(AccelerationHint hint) const
 {
-    RefPtr<SkImage> snapshot = newSkImageSnapshot();
+    RefPtr<SkImage> snapshot = newSkImageSnapshot(hint);
     if (!snapshot)
         return nullptr;
     return StaticBitmapImage::create(snapshot);
 }
 
 void ImageBuffer::didDraw(const FloatRect& rect) const
 {
     if (m_snapshotState == DidAcquireSnapshot)
         m_snapshotState = DrawnToAfterSnapshot;
     m_surface->didDraw(rect);
 }
 
 WebLayer* ImageBuffer::platformLayer() const
 {
     return m_surface->layer();
 }
 
 bool ImageBuffer::copyToPlatformTexture(WebGraphicsContext3D* context, Platform3DObject texture, GLenum internalFormat, GLenum destType, GLint level, bool premultiplyAlpha, bool flipY)
 {
-    if (!m_surface->isAccelerated() || !isSurfaceValid())
-        return false;
-
     if (!Extensions3DUtil::canUseCopyTextureCHROMIUM(GL_TEXTURE_2D, internalFormat, destType, level))
         return false;
 
-    RefPtr<const SkImage> textureImage = m_surface->newImageSnapshot();
+    if (!isSurfaceValid())
+        return false;
+
+    RefPtr<const SkImage> textureImage = m_surface->newImageSnapshot(PreferAcceleration);
     if (!textureImage)
         return false;
 
+    if (!m_surface->isAccelerated())
+        return false;
+
+
     ASSERT(textureImage->isTextureBacked()); // isAccelerated() check above should guarantee this
     // Get the texture ID, flushing pending operations if needed.
     Platform3DObject textureId = textureImage->getTextureHandle(true);
     if (!textureId)
         return false;
 
     OwnPtr<WebGraphicsContext3DProvider> provider = adoptPtr(Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
     if (!provider)
         return false;
     WebGraphicsContext3D* sharedContext = provider->context3d();
@@ skipping 77 matching lines @@
     dataSize *= rect.height();
     if (dataSize.hasOverflowed())
         return false;
 
     if (!isSurfaceValid()) {
         WTF::ArrayBufferContents result(rect.width() * rect.height(), 4, WTF::ArrayBufferContents::NotShared, WTF::ArrayBufferContents::ZeroInitialize);
         result.transfer(contents);
         return true;
     }
 
+    ASSERT(canvas());
+    RefPtr<SkImage> snapshot = m_surface->newImageSnapshot(PreferNoAcceleration);
+    if (!snapshot)
+        return false;
+
     const bool mayHaveStrayArea =
         m_surface->isAccelerated() // GPU readback may fail silently
         || rect.x() < 0
         || rect.y() < 0
         || rect.maxX() > m_surface->size().width()
         || rect.maxY() > m_surface->size().height();
     WTF::ArrayBufferContents result(
         rect.width() * rect.height(), 4,
         WTF::ArrayBufferContents::NotShared,
         mayHaveStrayArea
         ? WTF::ArrayBufferContents::ZeroInitialize
         : WTF::ArrayBufferContents::DontInitialize);
 
     SkAlphaType alphaType = (multiplied == Premultiplied) ? kPremul_SkAlphaType : kUnpremul_SkAlphaType;
     SkImageInfo info = SkImageInfo::Make(rect.width(), rect.height(), kRGBA_8888_SkColorType, alphaType);
 
-    ASSERT(canvas());
-    RefPtr<SkImage> snapshot = m_surface->newImageSnapshot();
-    if (!snapshot)
-        return false;
     snapshot->readPixels(info, result.data(), 4 * rect.width(), rect.x(), rect.y());
     result.transfer(contents);
     return true;
 }
 
 void ImageBuffer::putByteArray(Multiply multiplied, const unsigned char* source, const IntSize& sourceSize, const IntRect& sourceRect, const IntPoint& destPoint)
 {
     if (!isSurfaceValid())
         return;
 
@@ skipping 51 matching lines @@
     ASSERT(MIMETypeRegistry::isSupportedImageMIMETypeForEncoding(mimeType));
 
     Vector<char> encodedImage;
     if (!encodeImage(mimeType, quality, &encodedImage))
         return "data:,";
 
     return "data:" + mimeType + ";base64," + base64Encode(encodedImage);
 }
 
 } // namespace blink