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94 lines
2.8 KiB
C++
94 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_layers_opengl_FPSCounter_h_
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#define mozilla_layers_opengl_FPSCounter_h_
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#include <stddef.h> // for size_t
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#include <algorithm> // for min
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#include "GLDefs.h" // for GLuint
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#include "mozilla/TimeStamp.h" // for TimeStamp, TimeDuration
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#include "nsTArray.h" // for nsAutoTArray, nsTArray_Impl, etc
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#include "VBOArena.h" // for gl::VBOArena
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namespace mozilla {
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namespace gl {
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class GLContext;
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}
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namespace layers {
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class DataTextureSource;
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class ShaderProgramOGL;
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const double kFpsWindowMs = 250.0;
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const size_t kNumFrameTimeStamps = 16;
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struct FPSCounter {
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FPSCounter() : mCurrentFrameIndex(0) {
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mFrames.SetLength(kNumFrameTimeStamps);
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}
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// We keep a circular buffer of the time points at which the last K
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// frames were drawn. To estimate FPS, we count the number of
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// frames we've drawn within the last kFPSWindowMs milliseconds and
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// divide by the amount time since the first of those frames.
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nsAutoTArray<TimeStamp, kNumFrameTimeStamps> mFrames;
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size_t mCurrentFrameIndex;
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void AddFrame(TimeStamp aNewFrame) {
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mFrames[mCurrentFrameIndex] = aNewFrame;
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mCurrentFrameIndex = (mCurrentFrameIndex + 1) % kNumFrameTimeStamps;
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}
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double AddFrameAndGetFps(TimeStamp aCurrentFrame) {
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AddFrame(aCurrentFrame);
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return EstimateFps(aCurrentFrame);
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}
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double GetFpsAt(TimeStamp aNow) {
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return EstimateFps(aNow);
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}
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private:
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double EstimateFps(TimeStamp aNow) {
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TimeStamp beginningOfWindow =
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(aNow - TimeDuration::FromMilliseconds(kFpsWindowMs));
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TimeStamp earliestFrameInWindow = aNow;
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size_t numFramesDrawnInWindow = 0;
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for (size_t i = 0; i < kNumFrameTimeStamps; ++i) {
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const TimeStamp& frame = mFrames[i];
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if (!frame.IsNull() && frame > beginningOfWindow) {
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++numFramesDrawnInWindow;
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earliestFrameInWindow = std::min(earliestFrameInWindow, frame);
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}
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}
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double realWindowSecs = (aNow - earliestFrameInWindow).ToSeconds();
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if (realWindowSecs == 0.0 || numFramesDrawnInWindow == 1) {
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return 0.0;
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}
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return double(numFramesDrawnInWindow - 1) / realWindowSecs;
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}
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};
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struct FPSState {
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FPSCounter mCompositionFps;
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FPSCounter mTransactionFps;
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FPSState() {}
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void DrawFPS(TimeStamp, unsigned, Compositor* aCompositor);
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void NotifyShadowTreeTransaction() {
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mTransactionFps.AddFrame(TimeStamp::Now());
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}
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private:
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RefPtr<DataTextureSource> mFPSTextureSource;
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};
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}
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}
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#endif // mozilla_layers_opengl_FPSCounter_h_
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