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
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 * 1.  Redistributions of source code must retain the above copyright
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 *     notice, this list of conditions and the following disclaimer in the
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 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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#include "platform/graphics/DecodingImageGenerator.h"

#include "platform/PlatformInstrumentation.h"
#include "platform/SharedBuffer.h"
#include "platform/graphics/ImageFrameGenerator.h"
#include "platform/image-decoders/ImageDecoder.h"
#include "platform/image-decoders/SegmentReader.h"
#include "platform/tracing/TraceEvent.h"
#include "third_party/skia/include/core/SkData.h"
#include <memory>

namespace blink {

DecodingImageGenerator::DecodingImageGenerator(
    PassRefPtr<ImageFrameGenerator> frameGenerator,
    const SkImageInfo& info,
    PassRefPtr<SegmentReader> data,
    bool allDataReceived,
    size_t index,
    uint32_t uniqueID)
    : SkImageGenerator(info, uniqueID),
      m_frameGenerator(frameGenerator),
      m_data(data),
      m_allDataReceived(allDataReceived),
      m_frameIndex(index),
      m_canYUVDecode(false) {}

DecodingImageGenerator::~DecodingImageGenerator() {}

SkData* DecodingImageGenerator::onRefEncodedData(GrContext* ctx) {
  TRACE_EVENT0("blink", "DecodingImageGenerator::refEncodedData");

  // The GPU only wants the data if it has all been received, since the GPU
  // only wants a complete texture. getAsSkData() may require copying, so
  // skip it and just return nullptr to avoid a slowdown. (See
  // crbug.com/568016 for details about such a slowdown.)
  // TODO (scroggo): Stop relying on the internal knowledge of how Skia uses
  // this. skbug.com/5485
  if (ctx && !m_allDataReceived)
    return nullptr;

  // Other clients are serializers, which want the data even if it requires
  // copying, and even if the data is incomplete. (Otherwise they would
  // potentially need to decode the partial image in order to re-encode it.)
  return m_data->getAsSkData().release();
}

bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info,
                                         void* pixels,
                                         size_t rowBytes,
                                         SkPMColor table[],
                                         int* tableCount) {
  TRACE_EVENT1("blink", "DecodingImageGenerator::getPixels", "frame 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()) {
    // blink::ImageFrame may have changed the owning SkBitmap to
    // kOpaque_SkAlphaType after fully decoding the image frame, so if we see a
    // request for opaque, that is ok even if our initial alpha type was not
    // opaque.
    return false;
  }

  PlatformInstrumentation::willDecodeLazyPixelRef(uniqueID());
  bool decoded = m_frameGenerator->decodeAndScale(
      m_data.get(), m_allDataReceived, m_frameIndex, getInfo(), pixels,
      rowBytes);
  PlatformInstrumentation::didDecodeLazyPixelRef();

  return decoded;
}

bool DecodingImageGenerator::onQueryYUV8(SkYUVSizeInfo* sizeInfo,
                                         SkYUVColorSpace* colorSpace) const {
  // YUV decoding does not currently support progressive decoding. See comment
  // in ImageFrameGenerator.h.
  if (!m_canYUVDecode || !m_allDataReceived)
    return false;

  TRACE_EVENT1("blink", "DecodingImageGenerator::queryYUV8", "sizes",
               static_cast<int>(m_frameIndex));

  if (colorSpace)
    *colorSpace = kJPEG_SkYUVColorSpace;

  return m_frameGenerator->getYUVComponentSizes(m_data.get(), sizeInfo);
}

bool DecodingImageGenerator::onGetYUV8Planes(const SkYUVSizeInfo& sizeInfo,
                                             void* planes[3]) {
  // YUV decoding does not currently support progressive decoding. See comment
  // in ImageFrameGenerator.h.
  ASSERT(m_canYUVDecode && m_allDataReceived);

  TRACE_EVENT1("blink", "DecodingImageGenerator::getYUV8Planes", "frame index",
               static_cast<int>(m_frameIndex));

  PlatformInstrumentation::willDecodeLazyPixelRef(uniqueID());
  bool decoded =
      m_frameGenerator->decodeToYUV(m_data.get(), m_frameIndex, sizeInfo.fSizes,
                                    planes, sizeInfo.fWidthBytes);
  PlatformInstrumentation::didDecodeLazyPixelRef();

  return decoded;
}

SkImageGenerator* DecodingImageGenerator::create(SkData* data) {
  RefPtr<SegmentReader> segmentReader =
      SegmentReader::createFromSkData(sk_ref_sp(data));
  // We just need the size of the image, so we have to temporarily create an
  // ImageDecoder. Since we only need the size, the premul and gamma settings
  // don't really matter.
  std::unique_ptr<ImageDecoder> decoder = ImageDecoder::create(
      segmentReader, true, ImageDecoder::AlphaPremultiplied,
      ImageDecoder::ColorSpaceApplied);
  if (!decoder || !decoder->isSizeAvailable())
    return nullptr;

  const IntSize size = decoder->size();
  const SkImageInfo info = SkImageInfo::MakeN32(
      size.width(), size.height(), kPremul_SkAlphaType, decoder->colorSpace());

  RefPtr<ImageFrameGenerator> frame = ImageFrameGenerator::create(
      SkISize::Make(size.width(), size.height()), decoder->colorSpace(), false);
  if (!frame)
    return nullptr;

  return new DecodingImageGenerator(frame, info, segmentReader.release(), true,
                                    0);
}

}  // namespace blink