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      1 // Copyright 2011 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 CC_SCHEDULER_FRAME_RATE_CONTROLLER_H_
      6 #define CC_SCHEDULER_FRAME_RATE_CONTROLLER_H_
      7 
      8 #include "base/memory/ref_counted.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "base/memory/weak_ptr.h"
     11 #include "base/time/time.h"
     12 #include "cc/base/cc_export.h"
     13 #include "cc/output/begin_frame_args.h"
     14 
     15 namespace base { class SingleThreadTaskRunner; }
     16 
     17 namespace cc {
     18 
     19 class TimeSource;
     20 class FrameRateController;
     21 
     22 class CC_EXPORT FrameRateControllerClient {
     23  protected:
     24   virtual ~FrameRateControllerClient() {}
     25 
     26  public:
     27   // Throttled is true when we have a maximum number of frames pending.
     28   virtual void FrameRateControllerTick(bool throttled,
     29                                        const BeginFrameArgs& args) = 0;
     30 };
     31 
     32 class FrameRateControllerTimeSourceAdapter;
     33 
     34 // The FrameRateController is used in cases where we self-tick (i.e. BeginFrame
     35 // is not sent by a parent compositor.
     36 class CC_EXPORT FrameRateController {
     37  public:
     38   explicit FrameRateController(scoped_refptr<TimeSource> timer);
     39   // Alternate form of FrameRateController with unthrottled frame-rate.
     40   explicit FrameRateController(base::SingleThreadTaskRunner* task_runner);
     41   virtual ~FrameRateController();
     42 
     43   void SetClient(FrameRateControllerClient* client) { client_ = client; }
     44 
     45   // Returns a valid BeginFrame on activation to potentially be used
     46   // retroactively.
     47   BeginFrameArgs SetActive(bool active);
     48 
     49   bool IsActive() { return active_; }
     50 
     51   // Use the following methods to adjust target frame rate.
     52   //
     53   // Multiple frames can be in-progress, but for every DidSwapBuffers, a
     54   // DidFinishFrame should be posted.
     55   //
     56   // If the rendering pipeline crashes, call DidAbortAllPendingFrames.
     57   void DidSwapBuffers();
     58   void DidSwapBuffersComplete();
     59   void DidAbortAllPendingFrames();
     60   void SetMaxSwapsPending(int max_swaps_pending);  // 0 for unlimited.
     61   int MaxSwapsPending() const { return max_swaps_pending_; }
     62   int NumSwapsPendingForTesting() const { return num_frames_pending_; }
     63 
     64   void SetTimebaseAndInterval(base::TimeTicks timebase,
     65                               base::TimeDelta interval);
     66   void SetDeadlineAdjustment(base::TimeDelta delta);
     67 
     68  protected:
     69   friend class FrameRateControllerTimeSourceAdapter;
     70   void OnTimerTick();
     71 
     72   void PostManualTick();
     73   void ManualTick();
     74 
     75     // This returns null for unthrottled frame-rate.
     76   base::TimeTicks NextTickTime();
     77   // This returns now for unthrottled frame-rate.
     78   base::TimeTicks LastTickTime();
     79 
     80   FrameRateControllerClient* client_;
     81   int num_frames_pending_;
     82   int max_swaps_pending_;
     83   base::TimeDelta interval_;
     84   base::TimeDelta deadline_adjustment_;
     85   scoped_refptr<TimeSource> time_source_;
     86   scoped_ptr<FrameRateControllerTimeSourceAdapter> time_source_client_adapter_;
     87   bool active_;
     88 
     89   // Members for unthrottled frame-rate.
     90   bool is_time_source_throttling_;
     91   bool manual_tick_pending_;
     92   base::SingleThreadTaskRunner* task_runner_;
     93   base::WeakPtrFactory<FrameRateController> weak_factory_;
     94 
     95  private:
     96   DISALLOW_COPY_AND_ASSIGN(FrameRateController);
     97 };
     98 
     99 }  // namespace cc
    100 
    101 #endif  // CC_SCHEDULER_FRAME_RATE_CONTROLLER_H_
    102