ios/chrome/browser/snapshots/snapshot_manager.h

   1 // Copyright 2012 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 IOS_CHROME_BROWSER_SNAPSHOTS_SNAPSHOT_MANAGER_H_
   6 #define IOS_CHROME_BROWSER_SNAPSHOTS_SNAPSHOT_MANAGER_H_
   7
   8 #import <UIKit/UIKit.h>
   9
  10 #include "ios/web/public/web_view_type.h"
  11
  12 // Snapshot manager for contents of a tab. A snapshot is a full-screen image
  13 // of the contents of the page at the current scroll offset and zoom level,
  14 // used to stand in for the web view if it has been purged from memory or when
  15 // quickly switching tabs. Uses |SnapshotCache| to cache (and persist)
  16 // snapshots.
  17 //
  18 // The snapshots are identified by a "session id" which is unique per tab. This
  19 // allows quick identification and replacement as a tab changes pages.
  20 @interface SnapshotManager : NSObject
  21
  22 // Takes a snapshot for the supplied view (which should correspond to the given
  23 // type of web view). Returns an autoreleased image cropped and scaled
  24 // appropriately.
  25 // The image is not yet cached.
  26 // The image can also contain overlays (if |overlays| is not nil and not empty).
  27 - (UIImage*)generateSnapshotForView:(UIView*)view
  28                            withRect:(CGRect)rect
  29                            overlays:(NSArray*)overlays;
  30
  31 // TODO(shreyasv): Consider passing the sessionID into SnapshotManager from Tab
  32 // in the init method and simplifying the following methods.
  33 // Retrieve a cached snapshot for the |sessionID| and return it via the callback
  34 // if it exists. The callback is garanteed to be called synchronously if the
  35 // image is in memory. It will be called asynchronously if the image is on disk
  36 // or with nil if the image is not present at all.
  37 - (void)retrieveImageForSessionID:(NSString*)sessionID
  38                          callback:(void (^)(UIImage*))callback;
  39
  40 // Request the session's grey snapshot. If the image is already loaded in
  41 // memory, this will immediately call back on |callback|.  Otherwise, the grey
  42 // image will be loaded off disk or created by converting an existing color
  43 // snapshot to grey.
  44 - (void)retrieveGreyImageForSessionID:(NSString*)sessionID
  45                              callback:(void (^)(UIImage*))callback;
  46
  47 // Stores the supplied thumbnail for the specified |sessionID|.
  48 - (void)setImage:(UIImage*)img withSessionID:(NSString*)sessionID;
  49
  50 // Removes the cached thumbnail for the specified |sessionID|.
  51 - (void)removeImageWithSessionID:(NSString*)sessionID;
  52
  53 // Request the grey image from the in-memory cache only.
  54 - (void)greyImageForSessionID:(NSString*)sessionID
  55                      callback:(void (^)(UIImage*))callback;
  56 @end
  57
  58 #endif  // IOS_CHROME_BROWSER_SNAPSHOTS_SNAPSHOT_MANAGER_H_