Implementing ImageBitmap option imageOrientation of flipY

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 "third_party/skia/include/core/SkSurface.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 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)
+// TODO(xidachen): this function needs to be changed later on when implementing premultiplyAlpha option
+static SkImage* flipSkImageVertically(SkImage* input)
+{
+    int width = input->width();
+    int height = input->height();
+    SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
+    OwnPtr<uint8_t[]> imagePixels = adoptArrayPtr(new uint8_t[width * height * info.bytesPerPixel()]);
+    int imageRowBytes = info.bytesPerPixel() * width;
+    input->readPixels(info, imagePixels.get(), imageRowBytes, 0, 0);
+
+    for (int i = 0; i < height / 2; i++) {
+        int topFirstElement = i * imageRowBytes;
+        int topLastElement = (i + 1) * imageRowBytes;
+        int bottomFirstElement = (height - 1 - i) * imageRowBytes;
+        std::swap_ranges(imagePixels.get() + topFirstElement, imagePixels.get() + topLastElement, imagePixels.get() + bottomFirstElement);
+    }
+    return SkImage::NewRasterCopy(info, imagePixels.get(), imageRowBytes);
+}
+
+static PassRefPtr<StaticBitmapImage> cropImage(Image* image, const IntRect& cropRect, bool flipYEnabled)
 {
     ASSERT(image);
 
     IntRect imgRect(IntPoint(), IntSize(image->width(), image->height()));
     const IntRect srcRect = intersection(imgRect, cropRect);
 
-    if (cropRect == srcRect)
+    if (cropRect == srcRect) {
+        if (flipYEnabled)
+            return StaticBitmapImage::create(adoptRef(flipSkImageVertically(image->imageForCurrentFrame()->newSubset(srcRect))));
         return StaticBitmapImage::create(adoptRef(image->imageForCurrentFrame()->newSubset(srcRect)));
+    }
 
     RefPtr<SkSurface> surface = adoptRef(SkSurface::NewRasterN32Premul(cropRect.width(), cropRect.height()));
 
     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);
+    if (flipYEnabled)
+        return StaticBitmapImage::create(adoptRef(flipSkImageVertically(surface->newImageSnapshot())));
     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);
+    if (options.imageOrientation() == "flipY")

[Justin Novosad, 2016/02/03 14:32:52]

Put this string value in a constant.

[xidachen, 2016/02/03 15:29:51]

Thanks for pointing this out. It is now defined as a static const char*.

+        m_image = cropImage(image->cachedImage()->image(), cropRect, true);
+    else
+        m_image = cropImage(image->cachedImage()->image(), cropRect, false);
     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.imageOrientation() == "flipY")
+        m_image = StaticBitmapImage::create(adoptRef(flipSkImageVertically(buffer->newSkImageSnapshot(PreferNoAcceleration).get())));
+    else
+        m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
     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);
+    if (options.imageOrientation() == "flipY")
+        m_image = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration).get(), cropRect, true);
+    else
+        m_image = cropImage(canvas->copiedImage(BackBuffer, PreferAcceleration).get(), cropRect, false);
     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));
+    if (options.imageOrientation() == "flipY")
+        m_image = StaticBitmapImage::create(adoptRef(flipSkImageVertically(buffer->newSkImageSnapshot(PreferNoAcceleration).get())));
+    else
+        m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
 }
 
 ImageBitmap::ImageBitmap(ImageBitmap* bitmap, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
-    m_image = cropImage(bitmap->bitmapImage(), cropRect);
+    if (options.imageOrientation() == "flipY")
+        m_image = cropImage(bitmap->bitmapImage(), cropRect, true);
+    else
+        m_image = cropImage(bitmap->bitmapImage(), cropRect, false);
     m_image->setOriginClean(bitmap->originClean());
 }
 
 ImageBitmap::ImageBitmap(PassRefPtr<StaticBitmapImage> image, const IntRect& cropRect, const ImageBitmapOptions& options)
 {
-    m_image = cropImage(image.get(), cropRect);
+    if (options.imageOrientation() == "flipY")
+        m_image = cropImage(image.get(), cropRect, true);
+    else
+        m_image = cropImage(image.get(), cropRect, false);
     m_image->setOriginClean(image->originClean());
 }
 
 ImageBitmap::ImageBitmap(PassRefPtr<StaticBitmapImage> image)
 {
     m_image = image;
 }
 
 PassRefPtr<StaticBitmapImage> ImageBitmap::transfer()
 {
@@ skipping 107 matching lines @@
 {
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
     ImageLoaderClient::trace(visitor);
 }
 
 } // namespace blink