cc/debug/frame_rate_counter.h

   1 // Copyright 2012 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_DEBUG_FRAME_RATE_COUNTER_H_
   6 #define CC_DEBUG_FRAME_RATE_COUNTER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "base/time.h"
  11 #include "cc/debug/ring_buffer.h"
  12
  13 namespace cc {
  14
  15 // This class maintains a history of timestamps, and provides functionality to
  16 // intelligently compute average frames per second.
  17 class FrameRateCounter {
  18  public:
  19   static scoped_ptr<FrameRateCounter> Create(bool has_impl_thread);
  20
  21   int current_frame_number() const { return ring_buffer_.CurrentIndex(); }
  22   int dropped_frame_count() const { return dropped_frame_count_; }
  23   size_t time_stamp_history_size() const { return ring_buffer_.BufferSize(); }
  24
  25   void SaveTimeStamp(base::TimeTicks timestamp);
  26
  27   // n = 0 returns the oldest frame interval retained in the history, while n =
  28   // time_stamp_history_size() - 1 returns the most recent frame interval.
  29   base::TimeDelta RecentFrameInterval(size_t n) const;
  30
  31   // This is a heuristic that can be used to ignore frames in a reasonable way.
  32   // Returns true if the given frame interval is too fast or too slow, based on
  33   // constant thresholds.
  34   bool IsBadFrameInterval(
  35       base::TimeDelta interval_between_consecutive_frames) const;
  36
  37   void GetMinAndMaxFPS(double* min_fps, double* max_fps) const;
  38   double GetAverageFPS() const;
  39
  40   typedef RingBuffer<base::TimeTicks, 136> RingBufferType;
  41   RingBufferType::Iterator begin() const { return ring_buffer_.Begin(); }
  42   RingBufferType::Iterator end() const { return ring_buffer_.End(); }
  43
  44  private:
  45   explicit FrameRateCounter(bool has_impl_thread);
  46
  47   RingBufferType ring_buffer_;
  48
  49   bool has_impl_thread_;
  50   int dropped_frame_count_;
  51
  52   DISALLOW_COPY_AND_ASSIGN(FrameRateCounter);
  53 };
  54
  55 }  // namespace cc
  56
  57 #endif  // CC_DEBUG_FRAME_RATE_COUNTER_H_