JPEGImageDecoder RGB565 and downsample support and related Skia imagegenerator changes

third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 54 matching lines @@
 bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
     SkPMColor ctable[], int* ctableCount)
 {
     TRACE_EVENT1("blink", "DecodingImageGenerator::getPixels", "index", static_cast<int>(m_frameIndex));
 
     // Implementation doesn't support scaling yet so make sure we're not given a different size.
     if (info.width() != getInfo().width() || info.height() != getInfo().height())
         return false;
 
     if (info.colorType() != getInfo().colorType()) {
-        // ImageFrame may have changed the owning SkBitmap to kOpaque_SkAlphaType after sniffing the encoded data, so if we see a request
-        // for opaque, that is ok even if our initial alphatype was not opaque.
-        return false;
+        // So far, only one implemented is RGB565
+        if (info.colorType() != kRGB_565_SkColorType)
+            return false;
     }
 
     PlatformInstrumentation::willDecodeLazyPixelRef(m_generationId);
-    bool decoded = m_frameGenerator->decodeAndScale(getInfo(), m_frameIndex, pixels, rowBytes);
+    bool decoded = m_frameGenerator->decodeAndScale(info, m_frameIndex, pixels, rowBytes);
     PlatformInstrumentation::didDecodeLazyPixelRef();
 
     return decoded;
 }
 
 bool DecodingImageGenerator::onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3], SkYUVColorSpace* colorSpace)
 {
     if (!RuntimeEnabledFeatures::decodeToYUVEnabled())
         return false;
 
@@ skipping 26 matching lines @@
     const IntSize size = decoder->size();
     const SkImageInfo info = SkImageInfo::MakeN32Premul(size.width(), size.height());
 
     RefPtr<ImageFrameGenerator> frame = ImageFrameGenerator::create(SkISize::Make(size.width(), size.height()), buffer, true, false);
     if (!frame)
         return 0;
 
     return new DecodingImageGenerator(frame, info, 0);
 }
 
+bool DecodingImageGenerator::onCanDecodeAndScale(const SkColorType targetType, const SkScalar scale, SkISize *availableSize, SkISize *lowerSize)

[scroggo_chromium, 2015/10/19 20:41:36]

nit: I believe the "*" should go next to the type, rather than the name. (I do
not see this explicitly in the Blink style guide, though its examples use that
style, and Chromium's style guide requires it. It also matches the surrounding
code.)

[aleksandar.stojiljkovic, 2015/10/20 09:51:12]

Done.

+{
+    if (targetType == kRGB_565_SkColorType && targetType != getInfo().colorType() && scale == SK_Scalar1) {
+        return m_frameGenerator->canDecodeToRGB565();
+    }
+    return DecodingImageGenerator::onCanDecodeAndScale(targetType, scale, availableSize, lowerSize);

[scroggo_chromium, 2015/10/19 20:41:36]

This looks like infinite recursion, unless I'm missing something? Did you mean
to call SkImageGenerator::onCanDecodeAndScale?

[aleksandar.stojiljkovic, 2015/10/20 09:51:12]

Done.

+}
+
 } // namespace blink