Introduce the image_decoder service

chrome/utility/image_decoder_impl.cc

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "chrome/utility/image_decoder_impl.h"
-
-#include <string.h>
-
-#include <utility>
-
-#include "base/logging.h"
-#include "content/public/child/image_decoder_utils.h"
-#include "ipc/ipc_channel.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
-#include "skia/ext/image_operations.h"
-#include "third_party/skia/include/core/SkBitmap.h"
-#include "ui/gfx/geometry/size.h"
-
-#if defined(OS_CHROMEOS)
-#include "ui/gfx/chromeos/codec/jpeg_codec_robust_slow.h"
-#include "ui/gfx/codec/png_codec.h"
-#endif
-
-namespace {
-int64_t kMaxMessageSize = IPC::Channel::kMaximumMessageSize;
-int64_t kPadding = 64;
-}
-
-ImageDecoderImpl::ImageDecoderImpl() : ImageDecoderImpl(kMaxMessageSize) {}
-
-ImageDecoderImpl::ImageDecoderImpl(int64_t max_message_size)
-    : max_message_size_(max_message_size) {}
-
-ImageDecoderImpl::~ImageDecoderImpl() {
-}
-
-void ImageDecoderImpl::DecodeImage(const std::vector<uint8_t>& encoded_data,
-                                   mojom::ImageCodec codec,
-                                   bool shrink_to_fit,
-                                   const DecodeImageCallback& callback) {
-  if (encoded_data.empty()) {
-    callback.Run(SkBitmap());
-    return;
-  }
-
-  SkBitmap decoded_image;
-#if defined(OS_CHROMEOS)
-  if (codec == mojom::ImageCodec::ROBUST_JPEG) {
-    // Our robust jpeg decoding is using IJG libjpeg.
-    std::unique_ptr<SkBitmap> decoded_jpeg(gfx::JPEGCodecRobustSlow::Decode(
-        encoded_data.data(), encoded_data.size()));
-    if (decoded_jpeg.get() && !decoded_jpeg->empty())
-      decoded_image = *decoded_jpeg;
-  } else if (codec == mojom::ImageCodec::ROBUST_PNG) {
-    // Our robust PNG decoding is using libpng.
-    SkBitmap decoded_png;
-    if (gfx::PNGCodec::Decode(encoded_data.data(), encoded_data.size(),
-                              &decoded_png)) {
-      decoded_image = decoded_png;
-    }
-  }
-#endif  // defined(OS_CHROMEOS)
-  if (codec == mojom::ImageCodec::DEFAULT) {
-    decoded_image = content::DecodeImage(encoded_data.data(), gfx::Size(),
-                                         encoded_data.size());
-  }
-
-  if (!decoded_image.isNull()) {
-    // When serialized, the space taken up by a skia::mojom::Bitmap excluding
-    // the pixel data payload should be:
-    //   sizeof(skia::mojom::Bitmap::Data_) + pixel data array header (8 bytes)
-    // Use a bigger number in case we need padding at the end.
-    int64_t struct_size = sizeof(skia::mojom::Bitmap::Data_) + kPadding;
-    int64_t image_size = decoded_image.computeSize64();
-    int halves = 0;
-    while (struct_size + (image_size >> 2 * halves) > max_message_size_)
-      halves++;
-    if (halves) {
-      if (shrink_to_fit) {
-        // If decoded image is too large for IPC message, shrink it by halves.
-        // This prevents quality loss, and should never overshrink on displays
-        // smaller than 3600x2400.
-        // TODO (Issue 416916): Instead of shrinking, return via shared memory
-        decoded_image = skia::ImageOperations::Resize(
-            decoded_image, skia::ImageOperations::RESIZE_LANCZOS3,
-            decoded_image.width() >> halves, decoded_image.height() >> halves);
-      } else {
-        decoded_image.reset();
-      }
-    }
-  }
-
-  callback.Run(decoded_image);
-}