content/renderer/image_loading_helper.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_RENDERER_IMAGE_LOADING_HELPER_H_
   6 #define CONTENT_RENDERER_IMAGE_LOADING_HELPER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/memory/scoped_vector.h"
  12 #include "content/public/renderer/render_frame_observer.h"
  13 #include "url/gurl.h"
  14
  15 class SkBitmap;
  16
  17 namespace content {
  18
  19 class MultiResolutionImageResourceFetcher;
  20
  21 // This class deals with image downloading.
  22 // One instance of ImageLoadingHelper is owned by RenderFrame.
  23 class ImageLoadingHelper : public RenderFrameObserver {
  24  public:
  25   explicit ImageLoadingHelper(RenderFrame* render_frame);
  26
  27  private:
  28   ~ImageLoadingHelper() override;
  29
  30   // Message handler.
  31   void OnDownloadImage(int id,
  32                        const GURL& image_url,
  33                        bool is_favicon,
  34                        uint32_t max_image_size,
  35                        bool bypass_cache);
  36
  37   // Requests to download an image. When done, the ImageLoadingHelper
  38   // is notified by way of DidDownloadImage. Returns true if the
  39   // request was successfully started, false otherwise. id is used to
  40   // uniquely identify the request and passed back to the
  41   // DidDownloadImage method. If the image is a favicon, cookies will not be
  42   // sent nor accepted during download. If the image has multiple frames, all
  43   // the frames whose size <= |max_image_size| are returned. If all of the
  44   // frames are larger than |max_image_size|, the smallest frame is resized to
  45   // |max_image_size| and is the only result. |max_image_size| == 0 is
  46   // interpreted as no max image size.
  47   bool DownloadImage(int id,
  48                      const GURL& image_url,
  49                      bool is_favicon,
  50                      uint32_t max_image_size,
  51                      bool bypass_cache);
  52
  53   // This callback is triggered when DownloadImage completes, either
  54   // succesfully or with a failure. See DownloadImage for more
  55   // details.
  56   void DidDownloadImage(
  57       uint32_t max_image_size,
  58       MultiResolutionImageResourceFetcher* fetcher,
  59       const std::vector<SkBitmap>& images);
  60
  61   // Decodes a data: URL image or returns an empty image in case of failure.
  62   SkBitmap ImageFromDataUrl(const GURL&) const;
  63
  64   // RenderFrameObserver implementation.
  65   bool OnMessageReceived(const IPC::Message& message) override;
  66
  67   typedef ScopedVector<MultiResolutionImageResourceFetcher>
  68       ImageResourceFetcherList;
  69
  70   // ImageResourceFetchers schedule via DownloadImage.
  71   ImageResourceFetcherList image_fetchers_;
  72
  73   DISALLOW_COPY_AND_ASSIGN(ImageLoadingHelper);
  74 };
  75
  76 }  // namespace content
  77
  78 #endif  // CONTENT_RENDERER_IMAGE_LOADING_HELPER_H_
  79