目的:检测绘制过程中的FPS数量。
获取DectorView的ViewTreeObserver,感知UI绘制的开始
private void addDrawListener(final Activity activity) {
activity.getWindow().getDecorView().post(new Runnable() { @Override public void run() { activity.getWindow().getDecorView().getViewTreeObserver().removeOnDrawListener(FPSTracer.this); activity.getWindow().getDecorView().getViewTreeObserver().addOnDrawListener(FPSTracer.this); } }); } @Override public void onDraw() { isDrawing = true; }复制代码通过Choreographer.FrameCallback,感知UI绘制的结束@Override
public void doFrame(long lastFrameNanos, long frameNanos) { if (!isInvalid && isDrawing && isEnterAnimationComplete() && mTraceConfig.isTargetScene(getScene())) { handleDoFrame(lastFrameNanos, frameNanos, getScene()); } isDrawing = false; }复制代码理论上用户更关心的是绘制过程中FPS过低导致的卡顿(UI静止的情况下,用户是感知不到FPS低的)在doFrame方法中,记录每一帧的数据,其中scene这个字段标识一个页面
@Override
public void onChange(final Activity activity, final Fragment fragment) { this.mScene = TraceConfig.getSceneForString(activity, fragment); }复制代码onChange的默认实现是通过Application的ActivityLifecycleCallbacks回调感知Activity的变化@Override
public void onActivityResumed(final Activity activity) { ... if (!activityHash.equals(mCurActivityHash)) { for (IObserver listener : mObservers) { listener.onChange(activity, null); } mCurActivityHash = activityHash; } ... }复制代码FPS数据默认是2分钟分析一次(前台情况下),切后台时后台轮询线程停止。/** * report FPS */ private void doReport() { ... //数据分析逻辑可行阅读 }