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   virtual ~ImageLoadingHelper();
  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
  36   // Requests to download an image. When done, the ImageLoadingHelper
  37   // is notified by way of DidDownloadImage. Returns true if the
  38   // request was successfully started, false otherwise. id is used to
  39   // uniquely identify the request and passed back to the
  40   // DidDownloadImage method. If the image is a favicon, cookies will not be
  41   // sent nor accepted during download. If the image has multiple frames, all
  42   // the frames whose size <= |max_image_size| are returned. If all of the
  43   // frames are larger than |max_image_size|, the smallest frame is resized to
  44   // |max_image_size| and is the only result. |max_image_size| == 0 is
  45   // interpreted as no max image size.
  46   bool DownloadImage(int id,
  47                      const GURL& image_url,
  48                      bool is_favicon,
  49                      uint32_t max_image_size);
  50
  51   // This callback is triggered when DownloadImage completes, either
  52   // succesfully or with a failure. See DownloadImage for more
  53   // details.
  54   void DidDownloadImage(
  55       uint32_t max_image_size,
  56       MultiResolutionImageResourceFetcher* fetcher,
  57       const std::vector<SkBitmap>& images);
  58
  59   // Decodes a data: URL image or returns an empty image in case of failure.
  60   SkBitmap ImageFromDataUrl(const GURL&) const;
  61
  62   // RenderFrameObserver implementation.
  63   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
  64
  65   typedef ScopedVector<MultiResolutionImageResourceFetcher>
  66       ImageResourceFetcherList;
  67
  68   // ImageResourceFetchers schedule via DownloadImage.
  69   ImageResourceFetcherList image_fetchers_;
  70
  71   DISALLOW_COPY_AND_ASSIGN(ImageLoadingHelper);
  72 };
  73
  74 }  // namespace content
  75
  76 #endif  // CONTENT_RENDERER_IMAGE_LOADING_HELPER_H_
  77