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