Implementing ImageBitmap option imageOrientation of flipY

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

Index: third_party/WebKit/Source/core/frame/ImageBitmap.cpp
diff --git a/third_party/WebKit/Source/core/frame/ImageBitmap.cpp b/third_party/WebKit/Source/core/frame/ImageBitmap.cpp
index 25580c042d55adc9947c3ec02bbd6ce6dcb5d34a..e918ddac939afee021cc0906d183ed7b8676e7c9 100644
--- a/third_party/WebKit/Source/core/frame/ImageBitmap.cpp
+++ b/third_party/WebKit/Source/core/frame/ImageBitmap.cpp
@@ -94,7 +94,12 @@ ImageBitmap::ImageBitmap(ImageData* data, const IntRect& cropRect, const ImageBi
         dstPoint.setX(-cropRect.x());
     if (cropRect.y() < 0)
         dstPoint.setY(-cropRect.y());
-    buffer->putByteArray(Unmultiplied, data->data()->data(), data->size(), srcRect, dstPoint);
+    if (options.orientation() == "flipY" || options.orientation() == "bottomLeft") {
+        OwnPtr<uint8_t[]> flippedData = copyFlippedSourceData(data->data()->data(), data->width(), data->height());
+        buffer->putByteArray(Unmultiplied, flippedData.get(), data->size(), srcRect, dstPoint);
+    } else {
+        buffer->putByteArray(Unmultiplied, data->data()->data(), data->size(), srcRect, dstPoint);
+    }
     m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration));
 }
 
@@ -115,6 +120,18 @@ ImageBitmap::ImageBitmap(PassRefPtr<StaticBitmapImage> image)
     m_image = image;
 }
 
+PassOwnPtr<uint8_t[]> ImageBitmap::copyFlippedSourceData(const unsigned char* source, int width, int height)

[jbroman, 2016/01/26 17:03:37]

This assumes 4-byte pixels, and that the row size is exactly width * 4. This
seems to be true for ImageData, but not generally. Please either make this take
the ImageData instead, or rename it so that it's clear that these expectations
apply, to avoid misuse.

Also, this does not need to be a member of ImageBitmap, so I'd rather this were
a free static function, like normalizeRect and cropImage at the top of this
file. (It will then not need to be declared in the header.)

[xidachen, 2016/02/03 02:17:19]

This function won't be needed anymore because we don't need to apply flip to the
source data.

+{
+    const size_t bytesPerRow = 4 * width;
+    OwnPtr<uint8_t[]> dstPixels = adoptArrayPtr(new uint8_t[width * height * 4]);
+    for (int i = 0; i < height; i++) {
+        const unsigned char* srcAddr = source + i * bytesPerRow;
+        unsigned char* dstAddr = dstPixels.get() + (height - 1 - i) * bytesPerRow;
+        memcpy(dstAddr, srcAddr, bytesPerRow);
+    }
+    return dstPixels.release();
+}
+
 PassRefPtr<StaticBitmapImage> ImageBitmap::transfer()
 {
     ASSERT(!isNeutered());