Eliminate copies of encoded image data

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

Index: third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp b/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
index 64d6223d6af84d4c2aaed13b95cd5ae9f5164a10..963362f54c8fdb8261331a6c7cd3101d49818256 100644
--- a/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
+++ b/third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp
@@ -29,14 +29,18 @@
 #include "platform/SharedBuffer.h"
 #include "platform/TraceEvent.h"
 #include "platform/graphics/ImageFrameGenerator.h"
+#include "platform/image-decoders/DataSegmentReader.h"
 #include "platform/image-decoders/ImageDecoder.h"
 #include "third_party/skia/include/core/SkData.h"
+#include "third_party/skia/src/core/SkRWBuffer.h"
 
 namespace blink {
 
-DecodingImageGenerator::DecodingImageGenerator(PassRefPtr<ImageFrameGenerator> frameGenerator, const SkImageInfo& info, size_t index)
+DecodingImageGenerator::DecodingImageGenerator(PassRefPtr<ImageFrameGenerator> frameGenerator, const SkImageInfo& info, PassRefPtr<SegmentReader> data, bool allDataReceived, size_t index)
     : SkImageGenerator(info)
     , m_frameGenerator(frameGenerator)
+    , m_data(data)
+    , m_allDataReceived(allDataReceived)
     , m_frameIndex(index)
     , m_generationId(0)
     , m_canYUVDecode(false)
@@ -51,7 +55,10 @@ SkData* DecodingImageGenerator::onRefEncodedData()
 {
     TRACE_EVENT0("blink", "DecodingImageGenerator::refEncodedData");
 
-    return m_frameGenerator->refEncodedData();
+    if (!m_allDataReceived)
+        return nullptr;
+
+    return m_data->getAsSkData().leakRef();
 }
 
 bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, SkPMColor table[], int* tableCount)
@@ -69,7 +76,7 @@ bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels,
     }
 
     PlatformInstrumentation::willDecodeLazyPixelRef(m_generationId);
-    bool decoded = m_frameGenerator->decodeAndScale(m_frameIndex, getInfo(), pixels, rowBytes);
+    bool decoded = m_frameGenerator->decodeAndScale(m_data.get(), m_allDataReceived, m_frameIndex, getInfo(), pixels, rowBytes);
     PlatformInstrumentation::didDecodeLazyPixelRef();
 
     return decoded;
@@ -77,7 +84,7 @@ bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels,
 
 bool DecodingImageGenerator::onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3], SkYUVColorSpace* colorSpace)
 {
-    if (!m_canYUVDecode)
+    if (!m_canYUVDecode || !m_allDataReceived)
         return false;
 
     bool requestingYUVSizes = !planes || !planes[0];
@@ -85,13 +92,13 @@ bool DecodingImageGenerator::onGetYUV8Planes(SkISize sizes[3], void* planes[3],
     TRACE_EVENT1("blink", "DecodingImageGenerator::getYUV8Planes", requestingYUVSizes ? "sizes" : "frame index", static_cast<int>(m_frameIndex));
 
     if (requestingYUVSizes)
-        return m_frameGenerator->getYUVComponentSizes(sizes);
+        return m_frameGenerator->getYUVComponentSizes(m_data.get(), sizes);
 
     if (colorSpace)
         *colorSpace = kJPEG_SkYUVColorSpace;
 
     PlatformInstrumentation::willDecodeLazyPixelRef(m_generationId);
-    bool decoded = m_frameGenerator->decodeToYUV(m_frameIndex, sizes, planes, rowBytes);
+    bool decoded = m_frameGenerator->decodeToYUV(m_data.get(), m_frameIndex, sizes, planes, rowBytes);
     PlatformInstrumentation::didDecodeLazyPixelRef();
 
     return decoded;
@@ -99,26 +106,26 @@ bool DecodingImageGenerator::onGetYUV8Planes(SkISize sizes[3], void* planes[3],
 
 SkImageGenerator* DecodingImageGenerator::create(SkData* data)
 {
-    RefPtr<SharedBuffer> buffer = SharedBuffer::create(data->bytes(), data->size());
-
     // We just need the size of the image, so we have to temporarily create an ImageDecoder. Since
     // 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);
+    OwnPtr<ImageDecoder> decoder = ImageDecoder::create(static_cast<const char*>(data->data()), data->size(),
+        ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileApplied);
     if (!decoder)
         return 0;
 
-    decoder->setData(buffer.get(), true);
+    RefPtr<SegmentReader> segmentReader = adoptRef(new DataSegmentReader(data));
+    decoder->setData(segmentReader.get(), true);
     if (!decoder->isSizeAvailable())
         return 0;
 
     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);
+    RefPtr<ImageFrameGenerator> frame = ImageFrameGenerator::create(SkISize::Make(size.width(), size.height()), false);
     if (!frame)
         return 0;
 
-    return new DecodingImageGenerator(frame, info, 0);
+    return new DecodingImageGenerator(frame, info, segmentReader.release(), true, 0);
 }
 
 } // namespace blink