content/renderer/image_downloader/image_downloader_impl.cc

// Copyright 2015 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 "content/renderer/image_downloader/image_downloader_impl.h"

#include <utility>

#include "base/bind.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread_task_runner_handle.h"
#include "content/child/image_decoder.h"
#include "content/public/renderer/render_frame.h"
#include "content/public/renderer/render_thread.h"
#include "content/renderer/fetchers/multi_resolution_image_resource_fetcher.h"
#include "mojo/common/url_type_converters.h"
#include "net/base/data_url.h"
#include "skia/ext/image_operations.h"
#include "third_party/WebKit/public/platform/WebURLRequest.h"
#include "third_party/WebKit/public/platform/WebVector.h"
#include "third_party/WebKit/public/web/WebLocalFrame.h"
#include "third_party/WebKit/public/web/WebView.h"
#include "ui/gfx/favicon_size.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/skbitmap_operations.h"
#include "url/url_constants.h"

using blink::WebCachePolicy;
using blink::WebFrame;
using blink::WebVector;
using blink::WebURL;
using blink::WebURLRequest;

namespace {

// Decodes a data: URL image or returns an empty image in case of failure.
SkBitmap ImageFromDataUrl(const GURL& url) {
  std::string mime_type, char_set, data;
  if (net::DataURL::Parse(url, &mime_type, &char_set, &data) && !data.empty()) {
    // Decode the image using Blink's image decoder.
    content::ImageDecoder decoder(
        gfx::Size(gfx::kFaviconSize, gfx::kFaviconSize));
    const unsigned char* src_data =
        reinterpret_cast<const unsigned char*>(data.data());

    return decoder.Decode(src_data, data.size());
  }
  return SkBitmap();
}

//  Proportionally resizes the |image| to fit in a box of size
// |max_image_size|.
SkBitmap ResizeImage(const SkBitmap& image, uint32_t max_image_size) {
  if (max_image_size == 0)
    return image;
  uint32_t max_dimension = std::max(image.width(), image.height());
  if (max_dimension <= max_image_size)
    return image;
  // Proportionally resize the minimal image to fit in a box of size
  // max_image_size.
  return skia::ImageOperations::Resize(
      image, skia::ImageOperations::RESIZE_BEST,
      static_cast<uint64_t>(image.width()) * max_image_size / max_dimension,
      static_cast<uint64_t>(image.height()) * max_image_size / max_dimension);
}

// Filters the array of bitmaps, removing all images that do not fit in a box of
// size |max_image_size|. Returns the result if it is not empty. Otherwise,
// find the smallest image in the array and resize it proportionally to fit
// in a box of size |max_image_size|.
// Sets |original_image_sizes| to the sizes of |images| before resizing.
void FilterAndResizeImagesForMaximalSize(
    const std::vector<SkBitmap>& unfiltered,
    uint32_t max_image_size,
    std::vector<SkBitmap>* images,
    std::vector<gfx::Size>* original_image_sizes) {
  images->clear();
  original_image_sizes->clear();

  if (!unfiltered.size())
    return;

  if (max_image_size == 0)
    max_image_size = std::numeric_limits<uint32_t>::max();

  const SkBitmap* min_image = NULL;
  uint32_t min_image_size = std::numeric_limits<uint32_t>::max();
  // Filter the images by |max_image_size|, and also identify the smallest image
  // in case all the images are bigger than |max_image_size|.
  for (std::vector<SkBitmap>::const_iterator it = unfiltered.begin();
       it != unfiltered.end(); ++it) {
    const SkBitmap& image = *it;
    uint32_t current_size = std::max(it->width(), it->height());
    if (current_size < min_image_size) {
      min_image = &image;
      min_image_size = current_size;
    }
    if (static_cast<uint32_t>(image.width()) <= max_image_size &&
        static_cast<uint32_t>(image.height()) <= max_image_size) {
      images->push_back(image);
      original_image_sizes->push_back(gfx::Size(image.width(), image.height()));
    }
  }
  DCHECK(min_image);
  if (images->size())
    return;
  // Proportionally resize the minimal image to fit in a box of size
  // |max_image_size|.
  images->push_back(ResizeImage(*min_image, max_image_size));
  original_image_sizes->push_back(
      gfx::Size(min_image->width(), min_image->height()));
}

}  // namespace

namespace content {

ImageDownloaderImpl::ImageDownloaderImpl(
    RenderFrame* render_frame,
    mojo::InterfaceRequest<content::mojom::ImageDownloader> request)
    : RenderFrameObserver(render_frame), binding_(this, std::move(request)) {
  DCHECK(render_frame);
  RenderThread::Get()->AddObserver(this);
}

ImageDownloaderImpl::~ImageDownloaderImpl() {
  RenderThread::Get()->RemoveObserver(this);
}

// static
void ImageDownloaderImpl::CreateMojoService(
    RenderFrame* render_frame,
    mojo::InterfaceRequest<content::mojom::ImageDownloader> request) {
  DVLOG(1) << "ImageDownloaderImpl::CreateService";
  DCHECK(render_frame);

  new ImageDownloaderImpl(render_frame, std::move(request));
}

// Ensure all loaders cleared before calling blink::shutdown.
void ImageDownloaderImpl::OnRenderProcessShutdown() {
  image_fetchers_.clear();
}

// ImageDownloader methods:
void ImageDownloaderImpl::DownloadImage(const mojo::String& url,
                                        bool is_favicon,
                                        uint32_t max_bitmap_size,
                                        bool bypass_cache,
                                        const DownloadImageCallback& callback) {
  const GURL image_url = url.To<GURL>();

  std::vector<SkBitmap> result_images;
  std::vector<gfx::Size> result_original_image_sizes;

  if (image_url.SchemeIs(url::kDataScheme)) {
    SkBitmap data_image = ImageFromDataUrl(image_url);
    if (!data_image.empty()) {
      result_images.push_back(ResizeImage(data_image, max_bitmap_size));
      result_original_image_sizes.push_back(
          gfx::Size(data_image.width(), data_image.height()));
    }
  } else {
    if (FetchImage(image_url, is_favicon, max_bitmap_size, bypass_cache,
                   callback)) {
      // Will complete asynchronously via ImageDownloaderImpl::DidFetchImage
      return;
    }
  }

  ReplyDownloadResult(0, result_images, result_original_image_sizes, callback);
}

bool ImageDownloaderImpl::FetchImage(const GURL& image_url,
                                     bool is_favicon,
                                     uint32_t max_image_size,
                                     bool bypass_cache,
                                     const DownloadImageCallback& callback) {
  blink::WebLocalFrame* frame = render_frame()->GetWebFrame();
  DCHECK(frame);

  // Create an image resource fetcher and assign it with a call back object.
  image_fetchers_.push_back(new MultiResolutionImageResourceFetcher(
      image_url, frame, 0, is_favicon ? WebURLRequest::RequestContextFavicon
                                      : WebURLRequest::RequestContextImage,
      bypass_cache ? WebCachePolicy::BypassingCache
                   : WebCachePolicy::UseProtocolCachePolicy,
      base::Bind(&ImageDownloaderImpl::DidFetchImage, base::Unretained(this),
                 max_image_size, callback)));
  return true;
}

void ImageDownloaderImpl::DidFetchImage(
    uint32_t max_image_size,
    const DownloadImageCallback& callback,
    MultiResolutionImageResourceFetcher* fetcher,
    const std::vector<SkBitmap>& images) {
  std::vector<SkBitmap> result_images;
  std::vector<gfx::Size> result_original_image_sizes;
  FilterAndResizeImagesForMaximalSize(images, max_image_size, &result_images,
                                      &result_original_image_sizes);

  ReplyDownloadResult(fetcher->http_status_code(), result_images,
                      result_original_image_sizes, callback);

  // Remove the image fetcher from our pending list. We're in the callback from
  // MultiResolutionImageResourceFetcher, best to delay deletion.
  ImageResourceFetcherList::iterator iter =
      std::find(image_fetchers_.begin(), image_fetchers_.end(), fetcher);
  if (iter != image_fetchers_.end()) {
    image_fetchers_.weak_erase(iter);
    base::ThreadTaskRunnerHandle::Get()->DeleteSoon(FROM_HERE, fetcher);
  }
}

void ImageDownloaderImpl::ReplyDownloadResult(
    int32_t http_status_code,
    const std::vector<SkBitmap>& result_images,
    const std::vector<gfx::Size>& result_original_image_sizes,
    const DownloadImageCallback& callback) {
  callback.Run(http_status_code, mojo::Array<SkBitmap>::From(result_images),
               result_original_image_sizes);
}

void ImageDownloaderImpl::OnDestruct() {
  delete this;
}

}  // namespace content