content/browser/frame_host/navigation_entry_screenshot_manager.h

   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_