Implement resize option for createImageBitmap from ImageData

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/graphics/skia/SkiaUtils.h"
@@ skipping 345 matching lines @@
 }
 
 ImageBitmap::ImageBitmap(std::unique_ptr<uint8_t[]> data, uint32_t width, uint32_t height, bool isImageBitmapPremultiplied, bool isImageBitmapOriginClean)
 {
     SkImageInfo info = SkImageInfo::MakeN32(width, height, isImageBitmapPremultiplied ? kPremul_SkAlphaType : kUnpremul_SkAlphaType);
     m_image = StaticBitmapImage::create(fromSkSp(SkImage::MakeRasterCopy(SkPixmap(info, data.get(), info.bytesPerPixel() * width))));
     m_image->setPremultiplied(isImageBitmapPremultiplied);
     m_image->setOriginClean(isImageBitmapOriginClean);
 }
 
+static PassRefPtr<SkImage> scaleSkImage(PassRefPtr<SkImage> skImage, unsigned resizeWidth, unsigned resizeHeight, SkFilterQuality resizeQuality)
+{
+    SkImageInfo resizedInfo = SkImageInfo::Make(resizeWidth, resizeHeight, kBGRA_8888_SkColorType, kUnpremul_SkAlphaType);

[Justin Novosad, 2016/07/27 17:05:05]

Why BGRA instead of N32 (the platform-specific default)?

[xidachen, 2016/07/28 13:21:16]

Done, changed to N32. Swizzle is applied only when necessary, i.e. N32==BGRA.

+    std::unique_ptr<uint8_t[]> resizedPixels = wrapArrayUnique(new uint8_t[resizeWidth * resizeHeight * resizedInfo.bytesPerPixel()]);
+    SkPixmap pixmap(resizedInfo, resizedPixels.release(), resizeWidth * resizedInfo.bytesPerPixel());
+    skImage->scalePixels(pixmap, resizeQuality);
+    return fromSkSp(SkImage::MakeFromRaster(pixmap, [](const void* pixels, void*)
+        {
+            delete[] static_cast<const uint8_t*>(pixels);
+        }, nullptr));
+}
+
 ImageBitmap::ImageBitmap(ImageData* data, Optional<IntRect> cropRect, const ImageBitmapOptions& options)
 {
     // TODO(xidachen): implement the resize option
     IntRect dataSrcRect = IntRect(IntPoint(), data->size());
     ParsedOptions parsedOptions = parseOptions(options, cropRect, data->bitmapSourceSize());
     IntRect srcRect = cropRect ? intersection(parsedOptions.cropRect, dataSrcRect) : dataSrcRect;
 
     // treat non-premultiplyAlpha as a special case
     if (!parsedOptions.premultiplyAlpha) {
         unsigned char* srcAddr = data->data()->data();
         int srcHeight = data->size().height();
         int dstHeight = parsedOptions.cropRect.height();
         // TODO (xidachen): skia doesn't support SkImage::NewRasterCopy from a kRGBA color type.
         // For now, we swap R and B channel and uses kBGRA color type.
         SkImageInfo info = SkImageInfo::Make(parsedOptions.cropRect.width(), dstHeight, kBGRA_8888_SkColorType, kUnpremul_SkAlphaType);
         int srcPixelBytesPerRow = info.bytesPerPixel() * data->size().width();
         int dstPixelBytesPerRow = info.bytesPerPixel() * parsedOptions.cropRect.width();
+        RefPtr<SkImage> skImage;
         if (parsedOptions.cropRect == IntRect(IntPoint(), data->size())) {
             swizzleImageData(srcAddr, srcHeight, srcPixelBytesPerRow, parsedOptions.flipY);
-            m_image = StaticBitmapImage::create(fromSkSp(SkImage::MakeRasterCopy(SkPixmap(info, srcAddr, dstPixelBytesPerRow))));
+            skImage = fromSkSp(SkImage::MakeRasterCopy(SkPixmap(info, srcAddr, dstPixelBytesPerRow)));

[Justin Novosad, 2016/07/27 17:05:05]

It's a shame to have to make an make a copy here then another one when we
resize. Is there a reasonable way to avoid the double copy?  If it is
complicated, maybe file a bug and leave a comment.

[xidachen, 2016/07/28 13:21:16]

Not easy. SkSurface doesn't support un-premultiplied backing, so here we have
only one option, which is to create a SkImage directly from a raw ImageData.
Because SkImage cannot take ownership of the input ImageData, we would have to
make a copy here.

One way I can think of is this: we add a scale function to ImageData (not
trivial), which applies scaling to the input ImageData directly and produce a
scaled copy. Then we create a SkImage from that scaled copy, this time SkImage
can take the ownership of the scaled copy. However, I don't think add a scale
function to ImageData is trivial.

             // restore the original ImageData
             swizzleImageData(srcAddr, srcHeight, srcPixelBytesPerRow, parsedOptions.flipY);
         } else {
             std::unique_ptr<uint8_t[]> copiedDataBuffer = wrapArrayUnique(new uint8_t[dstHeight * dstPixelBytesPerRow]());
             if (!srcRect.isEmpty()) {
                 IntPoint srcPoint = IntPoint((parsedOptions.cropRect.x() > 0) ? parsedOptions.cropRect.x() : 0, (parsedOptions.cropRect.y() > 0) ? parsedOptions.cropRect.y() : 0);
                 IntPoint dstPoint = IntPoint((parsedOptions.cropRect.x() >= 0) ? 0 : -parsedOptions.cropRect.x(), (parsedOptions.cropRect.y() >= 0) ? 0 : -parsedOptions.cropRect.y());
                 int copyHeight = srcHeight - srcPoint.y();
                 if (parsedOptions.cropRect.height() < copyHeight)
                     copyHeight = parsedOptions.cropRect.height();
@@ skipping 11 matching lines @@
                     for (int j = 0; j < srcEndCopyPosition - srcStartCopyPosition; j++) {
                         if (j % 4 == 0)
                             copiedDataBuffer[dstStartCopyPosition + j] = srcAddr[srcStartCopyPosition + j + 2];
                         else if (j % 4 == 2)
                             copiedDataBuffer[dstStartCopyPosition + j] = srcAddr[srcStartCopyPosition + j - 2];
                         else
                             copiedDataBuffer[dstStartCopyPosition + j] = srcAddr[srcStartCopyPosition + j];
                     }
                 }
             }
-            m_image = StaticBitmapImage::create(newSkImageFromRaster(info, std::move(copiedDataBuffer), dstPixelBytesPerRow));
+            skImage = newSkImageFromRaster(info, std::move(copiedDataBuffer), dstPixelBytesPerRow);
         }
+        if (parsedOptions.shouldScaleInput)
+            m_image = StaticBitmapImage::create(scaleSkImage(skImage, parsedOptions.resizeWidth, parsedOptions.resizeHeight, parsedOptions.resizeQuality));
+        else
+            m_image = StaticBitmapImage::create(skImage);
         m_image->setPremultiplied(parsedOptions.premultiplyAlpha);
         return;
     }
 
     std::unique_ptr<ImageBuffer> buffer = ImageBuffer::create(parsedOptions.cropRect.size(), NonOpaque, DoNotInitializeImagePixels);
     if (!buffer)
         return;
 
     if (srcRect.isEmpty()) {
         m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration, SnapshotReasonUnknown));
         return;
     }
 
     IntPoint dstPoint = IntPoint(std::min(0, -parsedOptions.cropRect.x()), std::min(0, -parsedOptions.cropRect.y()));
     if (parsedOptions.cropRect.x() < 0)
         dstPoint.setX(-parsedOptions.cropRect.x());
     if (parsedOptions.cropRect.y() < 0)
         dstPoint.setY(-parsedOptions.cropRect.y());
     buffer->putByteArray(Unmultiplied, data->data()->data(), data->size(), srcRect, dstPoint);
+    RefPtr<SkImage> skImage = buffer->newSkImageSnapshot(PreferNoAcceleration, SnapshotReasonUnknown);
     if (parsedOptions.flipY)
-        m_image = StaticBitmapImage::create(flipSkImageVertically(buffer->newSkImageSnapshot(PreferNoAcceleration, SnapshotReasonUnknown).get(), PremultiplyAlpha));
-    else
-        m_image = StaticBitmapImage::create(buffer->newSkImageSnapshot(PreferNoAcceleration, SnapshotReasonUnknown));
+        skImage = flipSkImageVertically(skImage.get(), PremultiplyAlpha);
+    if (parsedOptions.shouldScaleInput) {
+        sk_sp<SkSurface> surface = SkSurface::MakeRasterN32Premul(parsedOptions.resizeWidth, parsedOptions.resizeHeight);
+        if (!surface)
+            return;
+        SkPaint paint;
+        paint.setFilterQuality(parsedOptions.resizeQuality);
+        SkRect dstDrawRect = SkRect::MakeWH(parsedOptions.resizeWidth, parsedOptions.resizeHeight);
+        surface->getCanvas()->drawImageRect(skImage.get(), dstDrawRect, &paint);
+        skImage = fromSkSp(surface->makeImageSnapshot());
+    }
+    m_image = StaticBitmapImage::create(skImage);
 }
 
 ImageBitmap::ImageBitmap(ImageBitmap* bitmap, Optional<IntRect> cropRect, const ImageBitmapOptions& options)
 {
     RefPtr<Image> input = bitmap->bitmapImage();
     if (!input)
         return;
     ParsedOptions parsedOptions = parseOptions(options, cropRect, input->size());
 
     m_image = cropImage(input.get(), parsedOptions, bitmap->isPremultiplied() ? PremultiplyAlpha : DontPremultiplyAlpha);
@@ skipping 155 matching lines @@
 FloatSize ImageBitmap::elementSize(const FloatSize&) const
 {
     return FloatSize(width(), height());
 }
 
 DEFINE_TRACE(ImageBitmap)
 {
 }
 
 } // namespace blink