Add ImageBitmapRenderingContext (experimental)

third_party/WebKit/Source/modules/imagebitmap/ImageBitmapRenderingContext.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "modules/imagebitmap/ImageBitmapRenderingContext.h"
+
+#include "core/frame/ImageBitmap.h"
+#include "platform/graphics/GraphicsContext.h"
+#include "platform/graphics/StaticBitmapImage.h"
+#include "third_party/skia/include/core/SkImage.h"
+#include "third_party/skia/include/core/SkSurface.h"
+
+namespace blink {
+
+ImageBitmapRenderingContext::ImageBitmapRenderingContext(HTMLCanvasElement* canvas, CanvasContextCreationAttributes attrs, Document& document)
+    : CanvasRenderingContext(canvas)
+    , m_hasAlpha(attrs.alpha())
+{ }
+
+ImageBitmapRenderingContext::~ImageBitmapRenderingContext() { }
+
+void ImageBitmapRenderingContext::transferImageBitmap(ImageBitmap* imageBitmap)
+{
+    m_image = imageBitmap->bitmapImage();
+    if (!m_image)
+        return;
+
+    RefPtr<SkImage> skImage = m_image->imageForCurrentFrame();
+    if (skImage->isTextureBacked()) {
+        // TODO(junov): crbug.com/585607 Eliminate this readback and use an ExternalTextureLayer
+        RefPtr<SkSurface> surface = adoptRef(SkSurface::NewRasterN32Premul(skImage->width(), skImage->height()));
+        if (!surface) {
+            // silent failure
+            m_image.clear();
+            return;
+        }
+        surface->getCanvas()->drawImage(skImage.get(), 0, 0);
+        m_image = StaticBitmapImage::create(adoptRef(surface->newImageSnapshot()));
+    }
+    canvas()->didDraw(FloatRect(FloatPoint(), FloatSize(m_image->width(), m_image->height())));
+}
+
+bool ImageBitmapRenderingContext::paint(GraphicsContext& gc, const IntRect& r)
+{
+    if (!m_image)
+        return true;
+
+    // With impl-side painting, it is unsafe to use a gpu-backed SkImage
+    ASSERT(!m_image->imageForCurrentFrame()->isTextureBacked());
+    gc.drawImage(m_image.get(), r, m_hasAlpha ? SkXfermode::kSrcOver_Mode : SkXfermode::kSrc_Mode);
+
+    return true;
+}
+
+PassOwnPtrWillBeRawPtr<CanvasRenderingContext> ImageBitmapRenderingContext::Factory::create(HTMLCanvasElement* canvas, const CanvasContextCreationAttributes& attrs, Document& document)
+{
+    if (!RuntimeEnabledFeatures::experimentalCanvasFeaturesEnabled())
+        return nullptr;
+    return adoptPtrWillBeNoop(new ImageBitmapRenderingContext(canvas, attrs, document));
+}
+
+void ImageBitmapRenderingContext::stop()
+{
+    m_image.clear();
+}
+
+} // blink