Android7.0 PowerManagerService亮灭屏分析(二)

最新推荐文章于 2025-06-25 17:10:10 发布

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最新推荐文章于 2025-06-25 17:10:10 发布 · 1w 阅读

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本文深入分析Android7.0 PowerManagerService如何处理亮屏操作，涉及DisplayPowerController、DisplayPowerState、PhoneWindowManager和WindowManagerService的角色。在亮屏过程中，系统等待所有窗口绘制完成，通过DisplayManagerService请求电源状态，更新屏幕亮度，并利用渐变动画点亮屏幕。关键步骤包括设置ScreenState、更新设备状态以及调用SurfaceControl设置显示功率模式。

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在PowerManagerService中对各种状态进行判断后，将其数值封装进DisplayPowerRequest中传入DisplayPowerController中进一步处理。在亮屏过程中DisplayPowerController会根据传过来的数值来设置新的电源状态为亮屏，然后调用DisplayPowerState来对状态进行设置，在分析DisplayPowerState时会具体讲解。由于此时ColorFade level(就是在手机屏幕的一层surface，当level为0是为一层黑帧，level为1.0时为透明)的值为0，表示屏幕还没有绘制好，所以此时需要block screen直到window界面绘制完成。当需要亮屏时调用PhoneWindowManager的screenTurningOn函数，通知window屏幕就要点亮了。然后调用WMS中函数waitForAllWindowsDrawn函数等待将所有需要绘制的window绘制完成后回调回来，超时时间为1000ms。在WMS中获取需要绘制的window将其加入mWaitingForDrawn中等待绘制，通过检查mWaitingForDrawn是否为空来判断，window是否绘制完成。此时screenTurningOn函数就执行完了，剩下的就是等待windows绘制完成。

DisplayManagerService.java中的LocalService继承了DisplayManagerInternal.java, 所以就会调用LocalService的requestPowerState函数请求电源状态.

    private final class LocalService extends DisplayManagerInternal {
        @Override
        public void initPowerManagement(final DisplayPowerCallbacks callbacks, Handler handler,
                SensorManager sensorManager) {    //初始化函数在PowerManagerService的systemReady函数中调用
            synchronized (mSyncRoot) {
                DisplayBlanker blanker = new DisplayBlanker() {   //创建blanker对象
                    @Override
                    public void requestDisplayState(int state, int brightness) {
                        // The order of operations is important for legacy reasons.
                        if (state == Display.STATE_OFF) {
                            requestGlobalDisplayStateInternal(state, brightness);
                        }

                        callbacks.onDisplayStateChange(state);

                        if (state != Display.STATE_OFF) {
                            requestGlobalDisplayStateInternal(state, brightness);
                        }
                    }
                };
                mDisplayPowerController = new DisplayPowerController(    //创建DisplayPowerController对象
                        mContext, callbacks, handler, sensorManager, blanker);
            }
        }

        @Override
        public boolean requestPowerState(DisplayPowerRequest request,
                boolean waitForNegativeProximity) {
            return mDisplayPowerController.requestPowerState(request,
                    waitForNegativeProximity);     //调用DisplayPowerController请求电源状态
        }
       //.....
}

在DisplayPowerController中通过Handler发送MSG_UPDATE_POWER_STATE消息调用updatePowerState来更新电源状态. updatePowerState也是一个非常核心的函数,在该函数中将PowerManagerService中传过来的参数获取出来根据policy获取设备的请求状态是ON, OFF还是DOZE, 应用距离传感器, 将最终的请求状态调用DisplayPowerState进行设置. 判断设备是否打开了自动亮度调节, 计算最终屏幕要达到的目标亮度并通过亮度渐变动画慢慢的点亮屏幕,最终变为高亮.

    private void updatePowerState() {
        // Update the power state request.
        final boolean mustNotify;
        boolean mustInitialize = false;
        boolean autoBrightnessAdjustmentChanged = false;

        synchronized (mLock) {
            mPendingUpdatePowerStateLocked = false;
            if (mPendingRequestLocked == null) {
                return; // wait until first actual power request
            }

            if (mPowerRequest == null) { //判断mPowerRequest是否为NULL,如果为空新创建一个, 否则直接将mPendingRequestLocked复制给他  
                mPowerRequest = new DisplayPowerRequest(mPendingRequestLocked);
                mWaitingForNegativeProximity = mPendingWaitForNegativeProximityLocked;
                mPendingWaitForNegativeProximityLocked = false;
                mPendingRequestChangedLocked = false;
                mustInitialize = true;
            } else if (mPendingRequestChangedLocked) {
                autoBrightnessAdjustmentChanged = (mPowerRequest.screenAutoBrightnessAdjustment
                        != mPendingRequestLocked.screenAutoBrightnessAdjustment);
                mPowerRequest.copyFrom(mPendingRequestLocked);
                mWaitingForNegativeProximity |= mPendingWaitForNegativeProximityLocked;
                mPendingWaitForNegativeProximityLocked = false;
                mPendingRequestChangedLocked = false;
                mDisplayReadyLocked = false;
            }

            mustNotify = !mDisplayReadyLocked;
        }

        // Initialize things the first time the power state is changed.
        if (mustInitialize) {
            initialize();//power state第一次发生变化时需要做一些初始化,如:创建DisplayPowerState, 亮灭屏动画,亮度渐变动画实例等 
        }

        // Compute the basic display state using the policy.
        // We might override this below based on other factors.
        int state;
        int brightness = PowerManager.BRIGHTNESS_DEFAULT;//设置屏幕默认亮度
        boolean performScreenOffTransition = false;
        switch (mPowerRequest.policy) {
            case DisplayPowerRequest.POLICY_OFF: //设置设备状态为OFF 
                state = Display.STATE_OFF;
                performScreenOffTransition = true; //灭屏有过渡动画  
                break;
            case DisplayPowerRequest.POLICY_DOZE:  //设置设备状态为DOZE
                if (mPowerRequest.dozeScreenState != Display.STATE_UNKNOWN) {
                    state = mPowerRequest.dozeScreenState;
                } else {
                    state = Display.STATE_DOZE;
                }
                if (!mAllowAutoBrightnessWhileDozingConfig) {
                    brightness = mPowerRequest.dozeScreenBrightness;//如果在xml文件中配置了相关属性,就将dozeScreenBrightness赋给亮度值
                }
                break;
            case DisplayPowerRequest.POLICY_DIM:
            case DisplayPowerRequest.POLICY_BRIGHT:
            default:
                state = Display.STATE_ON;//如果policy为DIM, BRIGHT的话,设备状态都为ON
                break;
        }
        assert(state != Display.STATE_UNKNOWN);

        // Apply the proximity sensor.
        if (mProximitySensor != null) {  //距离传感器相关处理
            if (mPowerRequest.useProximitySensor && state != Display.STATE_OFF) {
                setProximitySensorEnabled(true);
                if (!mScreenOffBecauseOfProximity
                        && mProximity == PROXIMITY_POSITIVE) {
                    mScreenOffBecauseOfProximity = true;
                    sendOnProximityPositiveWithWakelock();
                }
            } else if (mWaitingForNegativeProximity
                    && mScreenOffBecauseOfProximity
                    && mProximity == PROXIMITY_POSITIVE
                    && state != Display.STATE_OFF) {
                setProximitySensorEnabled(true);
            } else {
                setProximitySensorEnabled(false);
                mWaitingForNegativeProximity = false;
            }
            if (mScreenOffBecauseOfProximity
                    && mProximity != PROXIMITY_POSITIVE) {
                mScreenOffBecauseOfProximity = false;
                sendOnProximityNegativeWithWakelock();
            }
        } else {
            mWaitingForNegativeProximity = false;
        }
        if (mScreenOffBecauseOfProximity) {
            state = Display.STATE_OFF;//如果因为距离传感器灭屏设置设备状态为OFF
        }

        // Animate the screen state change unless already animating.
        // The transition may be deferred, so after this point we will use the
        // actual state instead of the desired one.
        animateScreenStateChange(state, performScreenOffTransition);//处理屏幕状态改变
        state = mPowerState.getScreenState();//获取新的屏幕状态 

        // Use zero brightness when screen is off.
        if (state == Display.STATE_OFF) {
            brightness = PowerManager.BRIGHTNESS_OFF; //如果新的状态是灭屏的话设置brightness为0
        }

        // Configure auto-brightness.
        boolean autoBrightnessEnabled = false;
        if (mAutomaticBrightnessController != null) {
            final boolean autoBrightnessEnabledInDoze = mAllowAutoBrightnessWhileDozingConfig
                    && (state == Display.STATE_DOZE || state == Display.STATE_DOZE_SUSPEND);
            autoBrightnessEnabled = mPowerRequest.useAutoBrightness
                    && (state == Display.STATE_ON || autoBrightnessEnabledInDoze)
                    && brightness < 0;
            final boolean userInitiatedChange = autoBrightnessAdjustmentChanged
                    && mPowerRequest.brightnessSetByUser;
            mAutomaticBrightnessController.configure(autoBrightnessEnabled,
                    mPowerRe