1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/layers/composite/FPSCounter.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,93 @@
1.4 +/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef mozilla_layers_opengl_FPSCounter_h_
1.10 +#define mozilla_layers_opengl_FPSCounter_h_
1.11 +
1.12 +#include <stddef.h> // for size_t
1.13 +#include <algorithm> // for min
1.14 +#include "GLDefs.h" // for GLuint
1.15 +#include "mozilla/TimeStamp.h" // for TimeStamp, TimeDuration
1.16 +#include "nsTArray.h" // for nsAutoTArray, nsTArray_Impl, etc
1.17 +#include "VBOArena.h" // for gl::VBOArena
1.18 +
1.19 +namespace mozilla {
1.20 +namespace gl {
1.21 +class GLContext;
1.22 +}
1.23 +namespace layers {
1.24 +
1.25 +class DataTextureSource;
1.26 +class ShaderProgramOGL;
1.27 +
1.28 +const double kFpsWindowMs = 250.0;
1.29 +const size_t kNumFrameTimeStamps = 16;
1.30 +struct FPSCounter {
1.31 + FPSCounter() : mCurrentFrameIndex(0) {
1.32 + mFrames.SetLength(kNumFrameTimeStamps);
1.33 + }
1.34 +
1.35 + // We keep a circular buffer of the time points at which the last K
1.36 + // frames were drawn. To estimate FPS, we count the number of
1.37 + // frames we've drawn within the last kFPSWindowMs milliseconds and
1.38 + // divide by the amount time since the first of those frames.
1.39 + nsAutoTArray<TimeStamp, kNumFrameTimeStamps> mFrames;
1.40 + size_t mCurrentFrameIndex;
1.41 +
1.42 + void AddFrame(TimeStamp aNewFrame) {
1.43 + mFrames[mCurrentFrameIndex] = aNewFrame;
1.44 + mCurrentFrameIndex = (mCurrentFrameIndex + 1) % kNumFrameTimeStamps;
1.45 + }
1.46 +
1.47 + double AddFrameAndGetFps(TimeStamp aCurrentFrame) {
1.48 + AddFrame(aCurrentFrame);
1.49 + return EstimateFps(aCurrentFrame);
1.50 + }
1.51 +
1.52 + double GetFpsAt(TimeStamp aNow) {
1.53 + return EstimateFps(aNow);
1.54 + }
1.55 +
1.56 +private:
1.57 + double EstimateFps(TimeStamp aNow) {
1.58 + TimeStamp beginningOfWindow =
1.59 + (aNow - TimeDuration::FromMilliseconds(kFpsWindowMs));
1.60 + TimeStamp earliestFrameInWindow = aNow;
1.61 + size_t numFramesDrawnInWindow = 0;
1.62 + for (size_t i = 0; i < kNumFrameTimeStamps; ++i) {
1.63 + const TimeStamp& frame = mFrames[i];
1.64 + if (!frame.IsNull() && frame > beginningOfWindow) {
1.65 + ++numFramesDrawnInWindow;
1.66 + earliestFrameInWindow = std::min(earliestFrameInWindow, frame);
1.67 + }
1.68 + }
1.69 + double realWindowSecs = (aNow - earliestFrameInWindow).ToSeconds();
1.70 + if (realWindowSecs == 0.0 || numFramesDrawnInWindow == 1) {
1.71 + return 0.0;
1.72 + }
1.73 + return double(numFramesDrawnInWindow - 1) / realWindowSecs;
1.74 + }
1.75 +};
1.76 +
1.77 +struct FPSState {
1.78 + FPSCounter mCompositionFps;
1.79 + FPSCounter mTransactionFps;
1.80 +
1.81 + FPSState() {}
1.82 +
1.83 + void DrawFPS(TimeStamp, unsigned, Compositor* aCompositor);
1.84 +
1.85 + void NotifyShadowTreeTransaction() {
1.86 + mTransactionFps.AddFrame(TimeStamp::Now());
1.87 + }
1.88 +
1.89 +private:
1.90 + RefPtr<DataTextureSource> mFPSTextureSource;
1.91 +};
1.92 +
1.93 +}
1.94 +}
1.95 +
1.96 +#endif // mozilla_layers_opengl_FPSCounter_h_
