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      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 
     13 class SkBitmap;
     14 
     15 namespace content {
     16 
     17 class NavigationControllerImpl;
     18 class NavigationEntryImpl;
     19 class RenderViewHost;
     20 class 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.
     26 class 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   // Taking a screenshot and encoding them can be async. So use a weakptr for
     78   // the callback to make sure that the screenshot/encoding completion callback
     79   // does not trigger on a destroyed NavigationEntryScreenshotManager.
     80   base::WeakPtrFactory<NavigationEntryScreenshotManager> screenshot_factory_;
     81 
     82   base::Time last_screenshot_time_;
     83   int min_screenshot_interval_ms_;
     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