src/chrome/browser/fav_icon_helper.h

// Copyright (c) 2006-2008 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.

#ifndef CHROME_BROWSER_FAV_ICON_HELPER_H__
#define CHROME_BROWSER_FAV_ICON_HELPER_H__

#include <map>

#include "base/basictypes.h"
#include "base/ref_counted.h"
#include "chrome/browser/cancelable_request.h"
#include "chrome/browser/history/history.h"
#include "chrome/browser/profile.h"
#include "googleurl/src/gurl.h"

class NavigationEntry;
class SkBitmap;
class WebContents;

// FavIconHelper is used to fetch the favicon for WebContents.
//
// FetchFavIcon requests the favicon from the history database. At this point
// we only know the URL of the page, and not necessarily the url of the
// favicon. To ensure we handle reloading stale favicons as well as
// reloading a favicon on page reload we always request the favicon from
// history regardless of whether the NavigationEntry has a favicon.
//
// After the navigation two types of events are delivered (which is
// first depends upon who is faster): notification from the history
// db on our request for the favicon (OnFavIconDataForInitialURL),
// or a message from the renderer giving us the URL of the favicon for
// the page (SetFavIconURL).
// . If the history db has a valid up to date favicon for the page, we update
//   the NavigationEntry and use the favicon.
// . When we receive the favicon url if it matches that of the NavigationEntry
//   and the NavigationEntry's favicon is set, we do nothing (everything is
//   ok).
// . On the other hand if the database does not know the favicon for url, or
//   the favicon is out date, or the URL from the renderer does not match that
//   NavigationEntry we proceed to DownloadFavIconOrAskHistory. Before we
//   invoke DownloadFavIconOrAskHistory we wait until we've received both
//   the favicon url and the callback from history. We wait to ensure we
//   truly know both the favicon url and the state of the database.
//
// DownloadFavIconOrAskHistory does the following:
// . If we have a valid favicon, but it is expired we ask the renderer to
//   download the favicon.
// . Otherwise we ask the history database to update the mapping from
//   page url to favicon url and call us back with the favicon. Remember, it is
//   possible for the db to already have the favicon, just not the mapping
//   between page to favicon url. The callback for this is OnFavIconData.
//
// OnFavIconData either updates the favicon of the NavigationEntry (if the
// db knew about the favicon), or requests the renderer to download the
// favicon.
//
// When the renderer downloads the favicon SetFavIconImageData is invoked,
// at which point we update the favicon of the NavigationEntry and notify
// the database to save the favicon.

class FavIconHelper {
 public:
  explicit FavIconHelper(WebContents* web_contents);

  // Initiates loading the favicon for the specified url.
  void FetchFavIcon(const GURL& url);

  // Sets the url of the favicon for the specified page. This is invoked some
  // time after FetchFavIcon.
  void SetFavIconURL(const GURL& icon_url);

  // Sets the image data for the favicon. This is invoked asynchronously after
  // we request the WebContents to download the favicon.
  void SetFavIcon(int download_id,
                  const GURL& icon_url,
                  const SkBitmap& image);

  // Invoked when a request to download the favicon failed.
  void FavIconDownloadFailed(int download_id);

  // Converts the image data to an SkBitmap and sets it on the NavigationEntry.
  // If the WebContents has a delegate, it is notified of the new favicon
  // (INVALIDATE_FAVICON).
  void UpdateFavIcon(NavigationEntry* entry,
                     const std::vector<unsigned char>& data);
  void UpdateFavIcon(NavigationEntry* entry, const SkBitmap& image);

 private:
  struct DownloadRequest {
    DownloadRequest() {}
    DownloadRequest(const GURL& url,
                    const GURL& fav_icon_url)
        : url(url),
          fav_icon_url(fav_icon_url) { }

    GURL url;
    GURL fav_icon_url;
  };

  // Return the NavigationEntry for the active entry, or NULL if the active
  // entries URL does not match that of the URL last passed to FetchFavIcon.
  NavigationEntry* GetEntry();

  Profile* profile();

  HistoryService* GetHistoryService();

  // See description above class for details.
  void OnFavIconDataForInitialURL(HistoryService::Handle handle,
                                  bool know_favicon,
                                  scoped_refptr<RefCountedBytes> data,
                                  bool expired,
                                  GURL icon_url);

  // If the favicon has expired, asks the renderer to download the favicon.
  // Otherwise asks history to update the mapping between page url and icon
  // url with a callback to OnFavIconData when done.
  void DownloadFavIconOrAskHistory(NavigationEntry* entry);

  // See description above class for details.
  void OnFavIconData(HistoryService::Handle handle,
                     bool know_favicon,
                     scoped_refptr<RefCountedBytes> data,
                     bool expired,
                     GURL icon_url);

  // Schedules a download for the specified entry. This adds the request to
  // download_requests_.
  void ScheduleDownload(NavigationEntry* entry);

  // Scales the image such that either the width and/or height is 16 pixels
  // wide. Does nothing if the image is empty.
  SkBitmap ConvertToFavIconSize(const SkBitmap& image);

  // Hosting WebContents. We callback into this when done.
  WebContents* web_contents_;

  // Used for history requests.
  CancelableRequestConsumer cancelable_consumer_;

  // URL of the page we're requesting the favicon for.
  GURL url_;

  // Whether we got the url for the page back from the renderer.
  // See "Favicon Details" in web_contents.cc for more details.
  bool got_fav_icon_url_;

  // Whether we got the initial response for the favicon back from the renderer.
  // See "Favicon Details" in web_contents.cc for more details.
  bool got_fav_icon_from_history_;

  // Whether the favicon is out of date. If true, it means history knows about
  // the favicon, but we need to download the favicon because the icon has
  // expired.
  // See "Favicon Details" in web_contents.cc for more details.
  bool fav_icon_expired_;

  // Requests to the renderer to download favicons.
  typedef std::map<int,DownloadRequest> DownloadRequests;
  DownloadRequests download_requests_;

  DISALLOW_EVIL_CONSTRUCTORS(FavIconHelper);
};

#endif  // CHROME_BROWSER_FAV_ICON_HELPER_H__