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1 // Copyright 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef CCFrameRateCounter_h | 5 // Temporary forwarding header |
6 #define CCFrameRateCounter_h | 6 #include "cc/frame_rate_counter.h" |
7 | |
8 #if USE(ACCELERATED_COMPOSITING) | |
9 | |
10 #include "base/basictypes.h" | |
11 #include <wtf/PassOwnPtr.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 (and standard deviation). | |
17 class CCFrameRateCounter { | |
18 public: | |
19 static PassOwnPtr<CCFrameRateCounter> create() | |
20 { | |
21 return adoptPtr(new CCFrameRateCounter()); | |
22 } | |
23 | |
24 void markBeginningOfFrame(double timestamp); | |
25 void markEndOfFrame(); | |
26 int currentFrameNumber() const { return m_currentFrameNumber; } | |
27 void getAverageFPSAndStandardDeviation(double& averageFPS, double& standardD
eviation) const; | |
28 int timeStampHistorySize() const { return kTimeStampHistorySize; } | |
29 | |
30 // n = 0 returns the oldest frame retained in the history, | |
31 // while n = timeStampHistorySize() - 1 returns the timestamp most recent fr
ame. | |
32 double timeStampOfRecentFrame(int /* n */); | |
33 | |
34 // This is a heuristic that can be used to ignore frames in a reasonable way
. Returns | |
35 // true if the given frame interval is too fast or too slow, based on consta
nt thresholds. | |
36 bool isBadFrameInterval(double intervalBetweenConsecutiveFrames) const; | |
37 | |
38 int droppedFrameCount() const { return m_droppedFrameCount; } | |
39 | |
40 private: | |
41 CCFrameRateCounter(); | |
42 | |
43 double frameInterval(int frameNumber) const; | |
44 int frameIndex(int frameNumber) const; | |
45 bool isBadFrame(int frameNumber) const; | |
46 | |
47 // Two thresholds (measured in seconds) that describe what is considered to
be a "no-op frame" that should not be counted. | |
48 // - if the frame is too fast, then given our compositor implementation, the
frame probably was a no-op and did not draw. | |
49 // - if the frame is too slow, then there is probably not animating content,
so we should not pollute the average. | |
50 static const double kFrameTooFast; | |
51 static const double kFrameTooSlow; | |
52 | |
53 // If a frame takes longer than this threshold (measured in seconds) then we | |
54 // (naively) assume that it missed a screen refresh; that is, we dropped a f
rame. | |
55 // FIXME: Determine this threshold based on monitor refresh rate, crbug.com/
138642. | |
56 static const double kDroppedFrameTime; | |
57 | |
58 static const int kTimeStampHistorySize = 120; | |
59 | |
60 int m_currentFrameNumber; | |
61 double m_timeStampHistory[kTimeStampHistorySize]; | |
62 | |
63 int m_droppedFrameCount; | |
64 | |
65 DISALLOW_COPY_AND_ASSIGN(CCFrameRateCounter); | |
66 }; | |
67 | |
68 } // namespace cc | |
69 | |
70 #endif // USE(ACCELERATED_COMPOSITING) | |
71 | |
72 #endif | |
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