GIF decoding to Index8, unit tests and misusing unit test as benchmark

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 53 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()) {
+    // if colorType declared in getInfo() fails, Skia would fetch N32 version
+    if (info.colorType() != getInfo().colorType() && info.colorType() != kN32_SkColorType) {
         // 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;
     }
 
     PlatformInstrumentation::willDecodeLazyPixelRef(m_generationId);
-    bool decoded = m_frameGenerator->decodeAndScale(getInfo(), m_frameIndex, pixels, rowBytes);
+    bool decoded = m_frameGenerator->decodeAndScale(info, m_frameIndex, pixels, rowBytes, ctable, ctableCount);
     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 17 matching lines @@
     // we only need the size, it doesn't really matter about premul or not, or gamma settings.
     OwnPtr<ImageDecoder> decoder = ImageDecoder::create(*buffer.get(), ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileApplied);
     if (!decoder)
         return 0;
 
     decoder->setData(buffer.get(), true);
     if (!decoder->isSizeAvailable())
         return 0;
 
     const IntSize size = decoder->size();
-    const SkImageInfo info = SkImageInfo::MakeN32Premul(size.width(), size.height());
+    const SkImageInfo info = decoder->canDecodeTo(0, ImageFrame::Index8)
+        ? SkImageInfo::Make(size.width(), size.height(), kIndex_8_SkColorType, kPremul_SkAlphaType)
+        : 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);
 }
 
+SkColorType DecodingImageGenerator::onGetColorType()
+{
+    // GIFDecoder: generator info is Index8 when constructed. but after downloading data this could
+    // change - it could turn out that some frames can be decoded only to N32.
+    if (m_frameGenerator->canDecodeTo(m_frameIndex, kIndex_8_SkColorType))
+        return kIndex_8_SkColorType;
+    return kN32_SkColorType;
+}
+
 } // namespace blink