Implement ImageBitmap options premultiplyAlpha

third_party/WebKit/Source/core/frame/ImageBitmap.cpp

 // Copyright 2013 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 "core/frame/ImageBitmap.h"
 
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/html/ImageData.h"
+#include "platform/image-decoders/ImageDecoder.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
+// The following two functions are helpers used in cropImage
 static inline IntRect normalizeRect(const IntRect& rect)
 {
     return IntRect(std::min(rect.x(), rect.maxX()),
         std::min(rect.y(), rect.maxY()),
         std::max(rect.width(), -rect.width()),
         std::max(rect.height(), -rect.height()));
 }
 
-static PassRefPtr<StaticBitmapImage> cropImage(Image* image, const IntRect& cropRect)
+static bool frameIsValid(const SkBitmap& frameBitmap)
+{
+    return !frameBitmap.isNull()
+        && !frameBitmap.empty()
+        && frameBitmap.isImmutable()
+        && frameBitmap.colorType() == kN32_SkColorType;
+}
+
+static PassRefPtr<StaticBitmapImage> cropImage(Image* image, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
     ASSERT(image);
 
     IntRect imgRect(IntPoint(), IntSize(image->width(), image->height()));
     const IntRect srcRect = intersection(imgRect, cropRect);
 
+    RefPtr<SkImage> skiaImage = image->imageForCurrentFrame();
+    // Attempt to get raw unpremultiplied image data.
+    if (((!options.premultiplyAlpha() && !skiaImage->isOpaque()) || !skiaImage) && image->data()) {
+        OwnPtr<ImageDecoder> decoder(ImageDecoder::create(
+            *(image->data()), ImageDecoder::AlphaNotPremultiplied,
+            ImageDecoder::GammaAndColorProfileIgnored));
+        if (!decoder)
+            return nullptr;
+        decoder->setData(image->data(), true);
+        if (!decoder->frameCount())
+            return nullptr;
+        ImageFrame* frame = decoder->frameBufferAtIndex(0);
+        if (!frame || frame->status() != ImageFrame::FrameComplete)
+            return nullptr;
+        SkBitmap bitmap = frame->bitmap();
+        if (!frameIsValid(bitmap))
+            return nullptr;
+        ASSERT(bitmap.isImmutable());
+        skiaImage = adoptRef(SkImage::NewFromBitmap(bitmap));
+    }
+
     if (cropRect == srcRect)
-        return StaticBitmapImage::create(adoptRef(image->imageForCurrentFrame()->newSubset(srcRect)));
+        return StaticBitmapImage::create(adoptRef(skiaImage->newSubset(srcRect)));
 
-    RefPtr<SkSurface> surface = adoptRef(SkSurface::NewRasterN32Premul(cropRect.width(), cropRect.height()));
+    RefPtr<SkSurface> surface;
+    if (options.premultiplyAlpha()) {
+        surface = adoptRef(SkSurface::NewRasterN32Premul(cropRect.width(), cropRect.height()));
+    } else {
+        SkImageInfo info = SkImageInfo::MakeN32(cropRect.width(), cropRect.height(), kUnpremul_SkAlphaType);
+        surface = adoptRef(SkSurface::NewRaster(info));
+    }
 
     if (srcRect.isEmpty())
         return StaticBitmapImage::create(adoptRef(surface->newImageSnapshot()));
 
     SkScalar dstLeft = std::min(0, -cropRect.x());
     SkScalar dstTop = std::min(0, -cropRect.y());
     if (cropRect.x() < 0)
         dstLeft = -cropRect.x();
     if (cropRect.y() < 0)
         dstTop = -cropRect.y();
-    surface->getCanvas()->drawImage(image->imageForCurrentFrame().get(), dstLeft, dstTop);
+
+    surface->getCanvas()->drawImage(skiaImage.get(), dstLeft, dstTop);

[xidachen, 2016/01/20 02:29:07]

This program could crash at this point. It is because this skiaImage is created
from a SkBitmap in the case when premultiplyAlpha=false, and this line of code
will trigger a call to SkBitmapDevice::SkBitmapDevice and goes to line 81 of
SkBitmapDevice which is a SkASSERT, that SkASSERT always fail because it
requires the alpha type is either kPremul_SkAlphaType or kOpaque_SkAlphaType.
But in our case, it is kUnpremul_SkAlphaType.

Any suggestions?

     return StaticBitmapImage::create(adoptRef(surface->newImageSnapshot()));
 }
 
 ImageBitmap::ImageBitmap(HTMLImageElement* image, const IntRect& cropRect, Document* document, const ImageBitmapOptions& options)
 {
-    m_image = cropImage(image->cachedImage()->image(), cropRect);
+    m_image = cropImage(image->cachedImage()->image(), cropRect, options);
     m_image->setOriginClean(!image->wouldTaintOrigin(document->securityOrigin()));
 }
 
 ImageBitmap::ImageBitmap(HTMLVideoElement* video, const IntRect& cropRect, Document* document, const ImageBitmapOptions& options)
 {
     IntSize playerSize;
     if (video->webMediaPlayer())
         playerSize = video->webMediaPlayer()->naturalSize();
 
     IntRect videoRect = IntRect(IntPoint(), playerSize);
     IntRect srcRect = intersection(cropRect, videoRect);
     OwnPtr<ImageBuffer> buffer = ImageBuffer::create(cropRect.size(), NonOpaque, DoNotInitializeImagePixels);
     if (!buffer)
         return;
 
     IntPoint dstPoint = IntPoint(std::max(0, -cropRect.x()), std::max(0, -cropRect.y()));
     video->paintCurrentFrame(buffer->canvas(), IntRect(dstPoint, srcRect.size()), nullptr);
-    m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
+    if (options.premultiplyAlpha())
+        m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
+    else
+        m_image = cropImage(buffer->newImageSnapshot().get(), IntRect(IntPoint(0, 0), cropRect.size()), options);
     m_image->setOriginClean(!video->wouldTaintOrigin(document->securityOrigin()));
 }
 
 ImageBitmap::ImageBitmap(HTMLCanvasElement* canvas, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
     ASSERT(canvas->isPaintable());
-    m_image = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration).get(), cropRect);
+    m_image = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration).get(), cropRect, options);
     m_image->setOriginClean(canvas->originClean());
 }
 
 ImageBitmap::ImageBitmap(ImageData* data, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
     IntRect srcRect = intersection(cropRect, IntRect(IntPoint(), data->size()));
 
     OwnPtr<ImageBuffer> buffer = ImageBuffer::create(cropRect.size(), NonOpaque, DoNotInitializeImagePixels);
     if (!buffer)
         return;
 
     if (srcRect.isEmpty()) {
         m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
         return;
     }
 
     IntPoint dstPoint = IntPoint(std::min(0, -cropRect.x()), std::min(0, -cropRect.y()));
     if (cropRect.x() < 0)
         dstPoint.setX(-cropRect.x());
     if (cropRect.y() < 0)
         dstPoint.setY(-cropRect.y());
     buffer->putByteArray(Unmultiplied, data->data()->data(), data->size(), srcRect, dstPoint);
     m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
 }
 
 ImageBitmap::ImageBitmap(ImageBitmap* bitmap, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
-    m_image = cropImage(bitmap->bitmapImage(), cropRect);
+    m_image = cropImage(bitmap->bitmapImage(), cropRect, options);
     m_image->setOriginClean(bitmap->originClean());
 }
 
 ImageBitmap::ImageBitmap(PassRefPtr<StaticBitmapImage> image, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
-    m_image = cropImage(image.get(), cropRect);
+    m_image = cropImage(image.get(), cropRect, options);
     m_image->setOriginClean(image->originClean());
 }
 
 ImageBitmap::ImageBitmap(PassRefPtr<StaticBitmapImage> image)
 {
     m_image = image;
 }
 
 PassRefPtr<StaticBitmapImage> ImageBitmap::transfer()
 {
@@ skipping 98 matching lines @@
 {
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
     ImageLoaderClient::trace(visitor);
 }
 
 } // namespace blink