Home | History | Annotate | Download | only in web_contents 
      1 // Copyright (c) 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_WEB_CONTENTS_WEB_CONTENTS_SCREENSHOT_MANAGER_H_
      6 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_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 // WebContentsScreenshotManager 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 WebContentsScreenshotManager {
     27  public:
     28   explicit WebContentsScreenshotManager(NavigationControllerImpl* controller);
     29   virtual ~WebContentsScreenshotManager();
     30 
     31   // Takes a screenshot of the last-committed entry of the controller.
     32   void TakeScreenshot();
     33 
     34   // Clears screenshots of all navigation entries.
     35   void ClearAllScreenshots();
     36 
     37  protected:
     38   virtual void TakeScreenshotImpl(RenderViewHost* host,
     39                                   NavigationEntryImpl* entry);
     40 
     41   // Called after a screenshot has been set on an NavigationEntryImpl.
     42   // Overridden in tests to get notified of when a screenshot is set.
     43   virtual void OnScreenshotSet(NavigationEntryImpl* entry);
     44 
     45   NavigationControllerImpl* owner() { return owner_; }
     46 
     47   void SetMinScreenshotIntervalMS(int interval_ms);
     48 
     49   // The callback invoked when taking the screenshot of the page is complete.
     50   // This sets the screenshot on the navigation entry.
     51   void OnScreenshotTaken(int unique_id,
     52                          bool success,
     53                          const SkBitmap& bitmap);
     54 
     55   // Returns the number of entries with screenshots.
     56   int GetScreenshotCount() const;
     57 
     58  private:
     59   // This is called when the screenshot data has beene encoded to PNG in a
     60   // worker thread.
     61   void OnScreenshotEncodeComplete(int unique_id,
     62                                   scoped_refptr<ScreenshotData> data);
     63 
     64   // Removes the screenshot for the entry, returning true if the entry had a
     65   // screenshot.
     66   bool ClearScreenshot(NavigationEntryImpl* entry);
     67 
     68   // The screenshots in the NavigationEntryImpls can accumulate and consume a
     69   // large amount of memory. This function makes sure that the memory
     70   // consumption is within a certain limit.
     71   void PurgeScreenshotsIfNecessary();
     72 
     73   // The navigation controller that owns this screenshot-manager.
     74   NavigationControllerImpl* owner_;
     75 
     76   // Taking a screenshot and encoding them can be async. So use a weakptr for
     77   // the callback to make sure that the screenshot/encoding completion callback
     78   // does not trigger on a destroyed WebContentsScreenshotManager.
     79   base::WeakPtrFactory<WebContentsScreenshotManager> screenshot_factory_;
     80 
     81   base::Time last_screenshot_time_;
     82   int min_screenshot_interval_ms_;
     83 
     84   DISALLOW_COPY_AND_ASSIGN(WebContentsScreenshotManager);
     85 };
     86 
     87 }  // namespace content
     88 
     89 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_SCREENSHOT_MANAGER_H_
     90