navigation_entry_screenshot_manager.h revision 1320f92c476a1ad9d19dba2a48c72b75566198e9 
1// Copyright 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_BROWSER_FRAME_HOST_NAVIGATION_ENTRY_SCREENSHOT_MANAGER_H_
6#define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_ENTRY_SCREENSHOT_MANAGER_H_
7
8#include "base/compiler_specific.h"
9#include "base/memory/weak_ptr.h"
10#include "base/time/time.h"
11#include "content/common/content_export.h"
12
13class SkBitmap;
14
15namespace content {
16
17class NavigationControllerImpl;
18class NavigationEntryImpl;
19class RenderViewHost;
20class ScreenshotData;
21
22// NavigationEntryScreenshotManager takes care of taking image-captures for the
23// current navigation entry of a NavigationControllerImpl, and managing these
24// captured images. These image-captures are used for history navigation using
25// overscroll gestures.
26class CONTENT_EXPORT NavigationEntryScreenshotManager {
27 public:
28  explicit NavigationEntryScreenshotManager(
29      NavigationControllerImpl* controller);
30  virtual ~NavigationEntryScreenshotManager();
31
32  // Takes a screenshot of the last-committed entry of the controller.
33  void TakeScreenshot();
34
35  // Clears screenshots of all navigation entries.
36  void ClearAllScreenshots();
37
38 protected:
39  virtual void TakeScreenshotImpl(RenderViewHost* host,
40                                  NavigationEntryImpl* entry);
41
42  // Called after a screenshot has been set on an NavigationEntryImpl.
43  // Overridden in tests to get notified of when a screenshot is set.
44  virtual void OnScreenshotSet(NavigationEntryImpl* entry);
45
46  NavigationControllerImpl* owner() { return owner_; }
47
48  void SetMinScreenshotIntervalMS(int interval_ms);
49
50  // The callback invoked when taking the screenshot of the page is complete.
51  // This sets the screenshot on the navigation entry.
52  void OnScreenshotTaken(int unique_id,
53                         bool success,
54                         const SkBitmap& bitmap);
55
56  // Returns the number of entries with screenshots.
57  int GetScreenshotCount() const;
58
59 private:
60  // This is called when the screenshot data has beene encoded to PNG in a
61  // worker thread.
62  void OnScreenshotEncodeComplete(int unique_id,
63                                  scoped_refptr<ScreenshotData> data);
64
65  // Removes the screenshot for the entry, returning true if the entry had a
66  // screenshot.
67  bool ClearScreenshot(NavigationEntryImpl* entry);
68
69  // The screenshots in the NavigationEntryImpls can accumulate and consume a
70  // large amount of memory. This function makes sure that the memory
71  // consumption is within a certain limit.
72  void PurgeScreenshotsIfNecessary();
73
74  // The navigation controller that owns this screenshot-manager.
75  NavigationControllerImpl* owner_;
76
77  base::Time last_screenshot_time_;
78  int min_screenshot_interval_ms_;
79
80  // Taking a screenshot and encoding them can be async. So use a weakptr for
81  // the callback to make sure that the screenshot/encoding completion callback
82  // does not trigger on a destroyed NavigationEntryScreenshotManager.
83  base::WeakPtrFactory<NavigationEntryScreenshotManager> screenshot_factory_;
84
85  DISALLOW_COPY_AND_ASSIGN(NavigationEntryScreenshotManager);
86};
87
88}  // namespace content
89
90#endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_ENTRY_SCREENSHOT_MANAGER_H_
91