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 49 matching lines @@
     if (buffer && allDataReceived)
         return SkData::NewWithCopy(buffer->data(), buffer->size());
     return 0;
 }
 
 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);
 }
 
+SkImageGenerator::Result DecodingImageGenerator::onCanDecodeAndScale(const SkColorType targetType,
+    const SkScalar scale, SkISize* availableSize, SkISize* lowerSize)
+{
+    SkColorType readC = targetType;
+    float desired = SkScalarToFloat(scale);
+    float read = desired;
+    float lower = 0;
+    m_frameGenerator->getAvailableDecodeAndScale(&readC, &read, &lower);
+    if (availableSize)
+        availableSize->set(static_cast<int>(ceil(getInfo().width() * read)), static_cast<int>(ceil(getInfo().height() * read)));
+    if (lowerSize)
+        lowerSize->set(static_cast<int>(ceil(getInfo().width() * lower)), static_cast<int>(ceil(getInfo().height() * lower)));
+
+    return static_cast<SkImageGenerator::Result>(((desired != 1.0f && read != 1.0f) ? SkImageGenerator::kScale : SkImageGenerator::kNotAvailable)
+        | ((readC == targetType) ? SkImageGenerator::kDecode : SkImageGenerator::kNotAvailable));
+}
+
 } // namespace blink