Upstream //ios/chrome/browser/snapshots

ios/chrome/browser/snapshots/snapshot_manager.h

+// Copyright 2012 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 IOS_CHROME_BROWSER_SNAPSHOTS_SNAPSHOT_MANAGER_H_
+#define IOS_CHROME_BROWSER_SNAPSHOTS_SNAPSHOT_MANAGER_H_
+
+#import <UIKit/UIKit.h>
+
+// Snapshot manager for contents of a tab. A snapshot is a full-screen image
+// of the contents of the page at the current scroll offset and zoom level,
+// used to stand in for the UIWebView if it has been purged from memory or when
+// quickly switching tabs. Uses |SnapshotCache| to cache (and persist)
+// snapshots.
+//
+// The snapshots are identified by a "session id" which is unique per tab. This
+// allows quick identification and replacement as a tab changes pages.
+@interface SnapshotManager : NSObject
+
+// Takes a snapshot for the supplied view. Returns an autoreleased image
+// cropped and scaled appropriately. The image is not yet cached.
+// The image can also contain overlays (if |overlays| is not nil and not empty).
+- (UIImage*)generateSnapshotForView:(UIView*)view
+                           withRect:(CGRect)rect
+                           overlays:(NSArray*)overlays;
+
+// TODO(shreyasv): Consider passing the sessionID into SnapshotManager from Tab
+// in the init method and simplifying the following methods.
+// Retrieve a cached snapshot for the |sessionID| and return it via the callback
+// if it exists. The callback is garanteed to be called synchronously if the
+// image is in memory. It will be called asynchronously if the image is on disk
+// or with nil if the image is not present at all.
+- (void)retrieveImageForSessionID:(NSString*)sessionID
+                         callback:(void (^)(UIImage*))callback;
+
+// Request the session's grey snapshot. If the image is already loaded in
+// memory, this will immediately call back on |callback|.  Otherwise, the grey
+// image will be loaded off disk or created by converting an existing color
+// snapshot to grey.
+- (void)retrieveGreyImageForSessionID:(NSString*)sessionID
+                             callback:(void (^)(UIImage*))callback;
+
+// Stores the supplied thumbnail for the specified |sessionID|.
+- (void)setImage:(UIImage*)img withSessionID:(NSString*)sessionID;
+
+// Removes the cached thumbnail for the specified |sessionID|.
+- (void)removeImageWithSessionID:(NSString*)sessionID;
+
+// Request the grey image from the in-memory cache only.
+- (void)greyImageForSessionID:(NSString*)sessionID
+                     callback:(void (^)(UIImage*))callback;
+@end
+
+#endif  // IOS_CHROME_BROWSER_SNAPSHOTS_SNAPSHOT_MANAGER_H_