Android 8.0 手机亮灭屏

本文主要跟踪分析通过按松power键来唤醒，熄灭屏幕的逻辑。下面是一些相关类的介绍

PowerManagerService.java：简称PMS，负责Andorid系统中电源管理方面的工作。作为系统核心服务之一，主要处理系统中与power相关的计算，然后决策系统该如何反应。同时PowerManagerService与其他服务及HAL层等都有交互关系，协调power如何与系统其他模块的交互，比如没有用户活动时屏幕变暗等。

DisplayPowerController.java：简称DPC管理Display设备的电源状态。仅在PowerManagerService中实例化了一个对象，它算是PowerManagerService的一部分，只不过是独立出来了而已。主要处理和距离传感器，

灯光传感器，以及包括关屏在内的一些动画，通过异步回调的方式来通知PowerManagerService某些事情发生了变化。

DisplayPowerState.java：简称DPS，在本质上类似于View，只不过用来描述一个display的属性，当这些属性发生变化时，可以通过一个序列化的命令，让这些和display电源状态的属性一起产生变化。

这个类的对象只能被DispalyPowerController的Looper持有。而这个Looper应该就是PowerManagerService中新建的一个HandlerThread中的Looper。和PowerManager相关的，

包括DisplayPowerState和DisplayPowerController相关的消息处理应该都可以通过这个HandlerThread进行运转的

Notifier.java：将power状态的重要变化，通过广播发送出去，并且参与了与AMS，WMS，IMP的交互。

ColorFade.java：负责屏幕由关到开，由开到关的一些GL动画，由DPC进行控制。

AutomaticBrightnessController.java：主要处理光传感器，将底层上传的参数进行处理计算，将计算的新的亮度值传给DPC。

RampAnimator.java：处理屏幕亮度渐变动画。

代码流程分析
1. Power事件上报跟踪

正常我们按下power键后，出触发Kernel关于该事件的中断。然后inputReader通过EventHub获取该事件，并做出事件处理，之后由inputdispatch进行事件分发。

因为power事件是key事件，会调用interceptKeyBeforeQueueing进行处理，通过如果流程

InputDispatcher.cpp

->com_android_server_input_InputManagerService.cpp

->InputManagerService.java

->InputMonitor.java

->WindowManagerPolicy.java

->PhoneWindowManager.java

PhoneWindowManager.java

最终由PhoneWindowManager.java的interceptKeyBeforeQueueing方法对该次事件进行处理，对power键以及屏幕状态进行判断，来决定亮屏还是灭屏等操作。当需要亮屏时，会调用PowerMangerService中的wakeup函数进行处理。

主要代码如下：

首先定义以下几个布尔值，主要是按键属性和屏幕状态

//是否亮屏状态，代码是否可以与用户交互

final boolean interactive = (policyFlags & FLAG_INTERACTIVE) != 0;

//按键事件是否为down事件

final boolean down = event.getAction() == KeyEvent.ACTION_DOWN;

//事件是否被取消

final boolean canceled = event.isCanceled();

//按键的keycode，不同按键 keycode不同，一般power 116

final int keyCode = event.getKeyCode();

//是否是输入事件

final boolean isInjected = (policyFlags & WindowManagerPolicy.FLAG_INJECTED) != 0;

//锁屏界面状态

final boolean keyguardActive = (mKeyguardDelegate == null ? false :(interactive ?isKeyguardShowingAndNotOccluded() :mKeyguardDelegate.isShowing()));

//flags有wake标记,或者按键(isWakeKey函数)为KEYCODE_BACK, KEYCODE_MENU, KEYCODE_WAKEUP, KEYCODE_PAIRING, KEYCODE_STEM_1, KEYCODE_STEM_2, KEYCODE_STEM_3设置isWakeKey为true

boolean isWakeKey = (policyFlags & WindowManagerPolicy.FLAG_WAKE) != 0 || event.isWakeKey();

if (isValidGlobalKey(keyCode)//有效的全局按键（KEYCODE_POWER:KEYCODE_WAKEUP:KeyEvent.KEYCODE_SLEEP:），

&& mGlobalKeyManager.shouldHandleGlobalKey(keyCode, event)) {//在com.android.internal.R.xml.global_keys 有定义

if (isWakeKey) {

wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY");唤醒屏幕

}

return result;

}

接下来是对特殊按键的处理，这里只关注power键

switch (keyCode) {

case KeyEvent.KEYCODE_POWER: {

result &= ~ACTION_PASS_TO_USER;

isWakeKey = false; // wake-up will be handled separately

if (down) {

interceptPowerKeyDown(event, interactive);//处理power按下

} else {

interceptPowerKeyUp(event, interactive, canceled);//处理power松开

}

break;

}

power down 键的处理

private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {

// 获取wakelock，报错CPU唤醒状态

if (!mPowerKeyWakeLock.isHeld()) {

mPowerKeyWakeLock.acquire();

}

// 取消多次按下超时监测

if (mPowerKeyPressCounter != 0) {

mHandler.removeMessages(MSG_POWER_DELAYED_PRESS);

}

// Detect user pressing the power button in panic when an application has

// taken over the whole screen.

boolean panic = mImmersiveModeConfirmation.onPowerKeyDown(interactive,

SystemClock.elapsedRealtime(), isImmersiveMode(mLastSystemUiFlags),

isNavBarEmpty(mLastSystemUiFlags));

if (panic) {

mHandler.post(mHiddenNavPanic);

}

// Latch power key state to detect screenshot chord.

if (interactive && !mScreenshotChordPowerKeyTriggered

&& (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) {

mScreenshotChordPowerKeyTriggered = true;

mScreenshotChordPowerKeyTime = event.getDownTime();

interceptScreenshotChord();//屏幕截屏

interceptDisableTouchModeChord(); //添加口袋模式

}

// 当power键按下，停止电话响铃或者结束通话

TelecomManager telecomManager = getTelecommService();

boolean hungUp = false;

if (telecomManager != null) {

if (telecomManager.isRinging()) {

停止响铃

telecomManager.silenceRinger();

} else if ((mIncallPowerBehavior

& Settings.Secure.INCALL_POWER_BUTTON_BEHAVIOR_HANGUP) != 0

&& telecomManager.isInCall() && interactive) {

Setting数据库读取设置，如果开了挂断电话

hungUp = telecomManager.endCall();

}

SprdGestureLauncherService gestureService = LocalServices.getService(

SprdGestureLauncherService.class);

boolean gesturedServiceIntercepted = false;

if (gestureService != null) {

gesturedServiceIntercepted = gestureService.interceptPowerKeyDown(event, interactive,

mTmpBoolean);

if (mTmpBoolean.value && mGoingToSleep) {

mCameraGestureTriggeredDuringGoingToSleep = true;

}

// If the power key has still not yet been handled, then detect short

// 如果power键还没有被处理，判断是短按，多按，长按等场景并做出对应处理

mPowerKeyHandled = hungUp || mScreenshotChordVolumeDownKeyTriggered

|| mA11yShortcutChordVolumeUpKeyTriggered || gesturedServiceIntercepted;

if (!mPowerKeyHandled) {

if (interactive) {

//如果屏幕是亮的，长按动作处理对应的长按动作

if (hasLongPressOnPowerBehavior()) {

Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);

msg.setAsynchronous(true);

mHandler.sendMessageDelayed(msg,

ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());

}

} else {//屏幕休眠的状态，唤醒屏幕

wakeUpFromPowerKey(event.getDownTime());

if (mSupportLongPressPowerWhenNonInteractive && hasLongPressOnPowerBehavior()) {

Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);

msg.setAsynchronous(true);

mHandler.sendMessageDelayed(msg,//如果长按动作继续执行长按操作

ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());

mBeganFromNonInteractive = true;

} else {

final int maxCount = getMaxMultiPressPowerCount();

if (maxCount <= 1) {

mPowerKeyHandled = true;

} else {

mBeganFromNonInteractive = true;

......

power up 键的处理

private void interceptPowerKeyUp(KeyEvent event, boolean interactive, boolean canceled) {

final boolean handled = canceled || mPowerKeyHandled; //power键是否被处理了

mScreenshotChordPowerKeyTriggered = false;

cancelPendingScreenshotChordAction();

cancelPendingPowerKeyAction();

if (!handled) {

// power press 加1

mPowerKeyPressCounter += 1;

final int maxCount = getMaxMultiPressPowerCount();//多按的次数

final long eventTime = event.getDownTime();//press power 时间

if (mPowerKeyPressCounter < maxCount) {

// 这种情况可能是一个多次按键事件，等待一会做确认处理

Message msg = mHandler.obtainMessage(MSG_POWER_DELAYED_PRESS,

interactive ? 1 : 0, mPowerKeyPressCounter, eventTime);

msg.setAsynchronous(true);

mHandler.sendMessageDelayed(msg, ViewConfiguration.getDoubleTapTimeout());

return;

}

// 没有其他action，继续处理power按下事件

powerPress(eventTime, interactive, mPowerKeyPressCounter);

}

// Done. Reset our state.

finishPowerKeyPress();//power按键处理结束

}

private void finishPowerKeyPress() {

mBeganFromNonInteractive = false;

mPowerKeyPressCounter = 0;

if (mPowerKeyWakeLock.isHeld()) {

mPowerKeyWakeLock.release();//释放wakelock

}

下面继续跟踪powerPress函数

private void powerPress(long eventTime, boolean interactive, int count) {

if (mScreenOnEarly && !mScreenOnFully) {

Slog.i(TAG, "Suppressed redundant power key press while "

+ "already in the process of turning the screen on.");

return;

}

if (count == 2) {//按两次power事件

powerMultiPressAction(eventTime, interactive, mDoublePressOnPowerBehavior);

} else if (count == 3) {//按三次power事件

powerMultiPressAction(eventTime, interactive, mTriplePressOnPowerBehavior);

} else if (interactive && !mBeganFromNonInteractive) {//屏幕如果亮着而且mBeganFromNonInteractive为false会执行下面操作

switch (mShortPressOnPowerBehavior) {//根据配置om.android.internal.R.integer.config_shortPressOnPowerBehavior 决定对应值此处为1

case SHORT_PRESS_POWER_NOTHING:

break;

case SHORT_PRESS_POWER_GO_TO_SLEEP:

mPowerManager.goToSleep(eventTime,

PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0);//执行灭屏操作

break;

......

}

我们继续跟踪亮屏操作，从power down事件处理可知，调用wakeUpFromPowerKey点亮屏幕

private void wakeUpFromPowerKey(long eventTime) {

Slog.d(TAG, "wake Up From Power Key"); // 此处会打印这句log，可作为分析问题是注意点

wakeUp(eventTime, mAllowTheaterModeWakeFromPowerKey, "android.policy:POWER");//调用wakeup继续执行亮屏操作，注意调用mPowerManager.wakeUp操作

}

PowerManager.wakeUp

下面我们看下PowerManager.wakeUp的相关处理

public void wakeUp(long time) {

try {

mService.wakeUp(time, "wakeUp", mContext.getOpPackageName());//调用到PWM.wakeUpInternal->PWM.wakeUpNoUpdateLocked

} catch (RemoteException e) {

throw e.rethrowFromSystemServer();

}

当power接收到亮灭屏调用后，会先进行设置手机wakefullness状态. 之后发送亮灭屏广播通知其他应用手机处于亮屏还是灭屏状态。

private boolean wakeUpNoUpdateLocked(long eventTime, String reason, int reasonUid,

String opPackageName, int opUid) {

//mWakefulness标识系统当前状态共有四种定义：

WAKEFULNESS_ASLEEP：表示系统当前处于休眠状态，只能被wakeUp()调用唤醒。

WAKEFULNESS_AWAKE：表示系统目前处于正常运行状态。

WAKEFULNESS_DREAMING：表示系统当前正处于互动屏保的状态。

WAKEFULNESS_DOZING：表示系统正处于“doze”状态

if (eventTime < mLastSleepTime || mWakefulness == WAKEFULNESS_AWAKE

|| !mBootCompleted || !mSystemReady) {//按键时间在睡下去之前，屏幕是正常状态，没有完成开机流程，系统没有准备完成，这四种情况不继续执行唤醒流程

return false;

}

try {//系统不是点亮状态，打出相关log

switch (mWakefulness) {

case WAKEFULNESS_ASLEEP:

case WAKEFULNESS_DREAMING:

case WAKEFULNESS_DOZING:

Slog.i(TAG, "Waking up from dozing due to"+opPackageName+" "+reason+" (uid " + reasonUid +")...");

break;

}

mLastWakeTime = eventTime;//更新wake时间

setWakefulnessLocked(WAKEFULNESS_AWAKE, 0);//更新mWakefulness，并调用Notifier.onWakefulnessChangeStarted发送亮屏广播

mNotifier.onWakeUp(reason, reasonUid, opPackageName, opUid);//调用Notifier通知battery处理

userActivityNoUpdateLocked(eventTime, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, reasonUid);//更新最后一次用户事件的时间

} finally {

}

return true;

}

Notifier.java

然后主要就是在Notifier.java中与AMS，window，input进行交互，通知各模块手机状态发生了改变，根据屏幕状态各自进行处理, 最后发送亮灭屏广播, 通知相关的模块.

private void setWakefulnessLocked(int wakefulness, int reason) {

if (mWakefulness != wakefulness) {

mWakefulness = wakefulness;//更新mWakefulness变量

mWakefulnessChanging = true;

mDirty |= DIRTY_WAKEFULNESS;

mNotifier.onWakefulnessChangeStarted(wakefulness, reason);//调用Notify的函数onWakefulnessChangeStarted 发广播通知

}

public void onWakefulnessChangeStarted(final int wakefulness, int reason) {

//获取交互模式变量，亮屏为true, 灭屏为false

final boolean interactive = PowerManagerInternal.isInteractive(wakefulness);

通知AMS wakefulness状态的变化

mHandler.post(new Runnable() {

@Override

public void run() {

mActivityManagerInternal.onWakefulnessChanged(wakefulness);

}

});

//interactive 变化时才会执行里面的逻辑

if (mInteractive != interactive) {

// Finish up late behaviors if needed.

if (mInteractiveChanging) {

handleLateInteractiveChange();

}

//在input中记录现在的屏幕状态

mInputManagerInternal.setInteractive(interactive);

mInputMethodManagerInternal.setInteractive(interactive);

//唤醒battery状态

try {

mBatteryStats.noteInteractive(interactive);

} catch (RemoteException ex) { }

// Handle early behaviors.

mInteractive = interactive;

mInteractiveChangeReason = reason;

mInteractiveChanging = true;

handleEarlyInteractiveChange();//处理交互模式改变

}

private void handleEarlyInteractiveChange() {

synchronized (mLock) {

if (mInteractive) {//mInteractive 为true代表要执行亮屏逻辑

// Waking up...

mHandler.post(new Runnable() {

@Override

public void run() {

// Note a SCREEN tron event is logged in PowerManagerService.

mPolicy.startedWakingUp();//调用PhoneWindowManager 方法开始亮屏流程

}

});

// 更新亮屏广播

mPendingInteractiveState = INTERACTIVE_STATE_AWAKE;

mPendingWakeUpBroadcast = true;

updatePendingBroadcastLocked();//mSuspendBlocker.acquire();持有partial 锁

} else {//mInteractive 为false代表要执行灭屏逻辑

final int why = translateOffReason(mInteractiveChangeReason);

mHandler.post(new Runnable() {

@Override

public void run() {

mPolicy.startedGoingToSleep(why);//调用PhoneWindowManager 方法开始灭屏流程

}

});

}

广播更新的流程

调用updatePendingBroadcastLocked函数发出handle msg 消息

Message msg = mHandler.obtainMessage(MSG_BROADCAST);

msg.setAsynchronous(true);

mHandler.sendMessage(msg);

然后handle收到后执行sendNextBroadcast函数

case MSG_BROADCAST:

sendNextBroadcast();

break;

private void sendNextBroadcast() {

final int powerState;

//mBroadcastedInteractiveState 这个变量记录当前的系统亮灭屏情况

synchronized (mLock) {

if (mBroadcastedInteractiveState == INTERACTIVE_STATE_UNKNOWN) {

// 当前状态位置更新为唤醒状态

mPendingWakeUpBroadcast = false;

mBroadcastedInteractiveState = INTERACTIVE_STATE_AWAKE;

} else if (mBroadcastedInteractiveState == INTERACTIVE_STATE_AWAKE) {

// 当前是唤醒状态，更新为灭屏状态

if (mPendingWakeUpBroadcast || mPendingGoToSleepBroadcast

|| mPendingInteractiveState == INTERACTIVE_STATE_ASLEEP) {

mPendingGoToSleepBroadcast = false;

mBroadcastedInteractiveState = INTERACTIVE_STATE_ASLEEP;

} else {

finishPendingBroadcastLocked();//释放partial 锁

return;

}

} else {

// 当前是灭屏状态，更新为唤醒状态

if (mPendingWakeUpBroadcast || mPendingGoToSleepBroadcast

|| mPendingInteractiveState == INTERACTIVE_STATE_AWAKE) {

mPendingWakeUpBroadcast = false;

mBroadcastedInteractiveState = INTERACTIVE_STATE_AWAKE;

} else {

finishPendingBroadcastLocked();

return;

}

//记录下当前系统时间为广播开始时间

mBroadcastStartTime = SystemClock.uptimeMillis();

powerState = mBroadcastedInteractiveState;

}

EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_SEND, 1);//打出event log

if (powerState == INTERACTIVE_STATE_AWAKE) {//根据powerState的值决定发亮屏还是灭屏广播

sendWakeUpBroadcast();

} else {

sendGoToSleepBroadcast();

}

广播都是前台广播，然后其他模块收到广播后作出对应处理

mScreenOnIntent.addFlags(

Intent.FLAG_RECEIVER_REGISTERED_ONLY | Intent.FLAG_RECEIVER_FOREGROUND

| Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);

mScreenOffIntent.addFlags(

Intent.FLAG_RECEIVER_REGISTERED_ONLY | Intent.FLAG_RECEIVER_FOREGROUND

| Intent.FLAG_RECEIVER_VISIBLE_TO_INSTANT_APPS);

Notify 收到这个广播后会，继续调用sendNextBroadcast，因为mPendingWakeUpBroadcast值变化，会调用finishPendingBroadcastLocked();释放partial 锁

private final BroadcastReceiver mWakeUpBroadcastDone = new BroadcastReceiver() {

@Override

public void onReceive(Context context, Intent intent) {

EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_DONE, 1,

SystemClock.uptimeMillis() - mBroadcastStartTime, 1);

sendNextBroadcast();

}

};

总结：当power接收到亮灭屏调用后，会先进行设置手机wakefullness状态，之后发送亮灭屏广播通知其他模块手机处于亮屏还是灭屏状态。并且在发送广播过程中power也与AMS，window，input进行交互，通知各模块手机状态发生了改变，根据屏幕状态各自进行处理。其中发送亮灭屏广播的主要实现在Notifier.java中。

当wakefulness状态发生改变，AMS收到通知。如果亮屏操作，AMS就会通过函数comeOutOfSleepIfNeedLocked调用到ActivityStackSupervisor中，将sleep超时消息移除，最后将在栈顶的activity显示出来。

power是通过WindowManagerPolicy与PhoneWindowManager进行交互，当屏幕在唤醒时需要通知window进行更新手势监听，更新方向监听，更新锁屏超时时间。最后通知keyguard屏幕点亮了，进行刷新锁屏界面时间，之后通过回调接口，回调回PhoneWindowManager的onShown函数，通知window keyguard准备完成。

当亮屏时通过InputManagerService将当前屏幕状态传入JNI中进行记录，当再次发生power键事件可以方便确认该事件是需要亮屏还是灭屏。

Power状态的更新和处理

当广播处理完毕后就会调用PMS的内部函数updatePowerStateLocked来更新全局电源状态。其实在PMS中很多函数都只是对一些必须的属性进行赋值，大部分最终都会调用到updatePowerStateLocked函数中进行功能执行，其中更新电源状态主要依据就是变量mDirty。mDirty就是用来记录power state的变化的标记位，这样的状态变化在系统中一共定义了12个，每一个状态对应一个固定的数字，都是2的倍数。这样，若有多个状态一块变化，进行按位取或这样结果既是唯一的，又能准确标记出各个状态的变化。在updatePowerStateLocked中主要做了如下事情:

首先判断手机是否处于充电状态，如果标记位DIRTY_BATTERY_STATE发生改变时就证明电池状态发生了改变，然后通过对比判断(通过电池前后变化与充电状态的变化)，确认手机是否处于充电状态。如果手机处于充电状态会将表示充电的标记位记入mDirty中。当有USB插拔时我们也可以通过配置信息来决定是否需要点亮屏幕。并且是否在充电或者充电方式发生改变，系统都会认为发生了一次用户事件进行更新最后用户操作时间，以此来重新计算屏幕超时时间。

private void updateIsPoweredLocked(int dirty) {

if ((dirty & DIRTY_BATTERY_STATE) != 0) {

final boolean wasPowered = mIsPowered;//是否在充电

final int oldPlugType = mPlugType;//充电类型

final boolean oldLevelLow = mBatteryLevelLow;//低电模式

mIsPowered = mBatteryManagerInternal.isPowered(BatteryManager.BATTERY_PLUGGED_ANY);

mPlugType = mBatteryManagerInternal.getPlugType();

mBatteryLevel = mBatteryManagerInternal.getBatteryLevel();

mBatteryLevelLow = mBatteryManagerInternal.getBatteryLevelLow();

if (wasPowered != mIsPowered || oldPlugType != mPlugType) {

mDirty |= DIRTY_IS_POWERED;//如果充电中设置mDirty

/* < Bug#696466 optimization for sceenoff */

if (wasPowered != mIsPowered)

SystemProperties.set("sys.sprd.power.ispowered", (mIsPowered? "1": "0"));//设置属性sys.sprd.power.ispowered

/* Bug#696466 optimization for sceenoff > */

//无线充电

final boolean dockedOnWirelessCharger = mWirelessChargerDetector.update(

mIsPowered, mPlugType, mBatteryLevel);

final long now = SystemClock.uptimeMillis();

if (shouldWakeUpWhenPluggedOrUnpluggedLocked(wasPowered, oldPlugType,

dockedOnWirelessCharger)) {//插拔USB是否要点亮屏幕

wakeUpNoUpdateLocked(now, "android.server.power:POWER", Process.SYSTEM_UID,

mContext.getOpPackageName(), Process.SYSTEM_UID);

}

userActivityNoUpdateLocked(//插拔USB算一次用户事件,重新设置最后一次用户事件的时间点

now, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, Process.SYSTEM_UID);

// Tell the notifier whether wireless charging has started so that

// it can provide feedback to the user.

if (dockedOnWirelessCharger) {

mNotifier.onWirelessChargingStarted();

}

if (wasPowered != mIsPowered || oldLevelLow != mBatteryLevelLow) {//低电模式

if (oldLevelLow != mBatteryLevelLow && !mBatteryLevelLow) {

mAutoLowPowerModeSnoozing = false;

}

updateLowPowerModeLocked();//更新低电模式

}

更新wakefulness

for (;;) {

int dirtyPhase1 = mDirty;

dirtyPhase2 |= dirtyPhase1;

mDirty = 0;

updateWakeLockSummaryLocked(dirtyPhase1);

updateUserActivitySummaryLocked(now, dirtyPhase1);

if (!updateWakefulnessLocked(dirtyPhase1)) {

break;

}

updateWakeLockSummaryLocked函数将wakeLock的类型用mWakeLockSummary进行记录，最后与Wakefulness状态结合重新算出新的mWakeLockSummary值，再判断是否需要睡眠时会使用。

之后updateUserActivitySummaryLocked就会更新屏幕超时时间，根据最后一次的用户事件与屏幕超时时间与dim持续时间来计算屏幕超时的时间，然后与现在的时间进行对比，来决定屏幕要继续高亮，还是要变为dim状态。

PowerManagerHandler接收屏幕超时的消息, 并且调用handleUserActivityTimeout进行处理, 该函数之后就在Handler线程中运行

private final class PowerManagerHandler extends Handler {

public PowerManagerHandler(Looper looper) {

super(looper, null, true /*async*/);

}

@Override

public void handleMessage(Message msg) {

switch (msg.what) {

case MSG_USER_ACTIVITY_TIMEOUT:

handleUserActivityTimeout(); //处理用户超时事件

break;

case MSG_SANDMAN:

handleSandman();

break;

case MSG_SCREEN_BRIGHTNESS_BOOST_TIMEOUT:

handleScreenBrightnessBoostTimeout();

break;

}

private void handleUserActivityTimeout() { // runs on handler thread

synchronized (mLock) {

if (DEBUG_SPEW) {

Slog.d(TAG, "handleUserActivityTimeout");

}

mDirty |= DIRTY_USER_ACTIVITY; //设置有用户活动的mDirty值

updatePowerStateLocked(); //更新电源状态, 最后去判断是否要睡眠

}

根据前面流程图可以看出更新wakefulness过程是通过一个死循环来执行的，只有调用函数updateWakefulnessLocked返回false时才会跳出循环。在循环中对wakeLockSummary进行更新，并且更新自动灭屏时间后，进行判断系统是否该睡眠了，是否可以跳出循环。

在updateWakefulnessLocked中主要根据是否存在wakeLock，用户活动进行判断设备是否需要进入睡眠状态。从函数isBeingKeptAwakeLocked可以看出当device拿着一个wake lock，有用户事件，有距离传感器等都不会灭屏进行睡眠状态。如果需要睡眠就会往下面调用，最后跳出循环。

private boolean updateWakefulnessLocked(int dirty) {

boolean changed = false;

if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY | DIRTY_BOOT_COMPLETED

| DIRTY_WAKEFULNESS | DIRTY_STAY_ON | DIRTY_PROXIMITY_POSITIVE

| DIRTY_DOCK_STATE)) != 0) {

if (mWakefulness == WAKEFULNESS_AWAKE && isItBedTimeYetLocked()) { //mWakefulness为AWAKE, 并且到了睡觉时间, 就去睡觉

if (DEBUG_SPEW) {

Slog.d(TAG, "updateWakefulnessLocked: Bed time...");

}

final long time = SystemClock.uptimeMillis();

if (shouldNapAtBedTimeLocked()) {

changed = napNoUpdateLocked(time, Process.SYSTEM_UID); //睡觉前先小憩一会

} else {

changed = goToSleepNoUpdateLocked(time,

PowerManager.GO_TO_SLEEP_REASON_TIMEOUT, 0, Process.SYSTEM_UID); //直接睡觉

}

return changed;

}

[java] view plain copy

private boolean isItBedTimeYetLocked() {// 对所有该唤醒的情况取反, 就是该休眠了

return mBootCompleted && !isBeingKeptAwakeLocked();

}

private boolean isBeingKeptAwakeLocked() {

return mStayOn //设置了stay on

|| mProximityPositive //距离传感器返回一个positive结果,保持唤醒

|| (mWakeLockSummary & WAKE_LOCK_STAY_AWAKE) != 0 //当有wake lock时保持唤醒

|| (mUserActivitySummary & (USER_ACTIVITY_SCREEN_BRIGHT

| USER_ACTIVITY_SCREEN_DIM)) != 0 //有user activity时保持唤醒

|| mScreenBrightnessBoostInProgress;

}

[java] view plain copy

mDreamsActivateOnSleepSetting = (Settings.Secure.getIntForUser(resolver,

Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP,

mDreamsActivatedOnSleepByDefaultConfig ? 1 : 0,

UserHandle.USER_CURRENT) != 0); //从settings数据库获取对应值

mDreamsActivateOnDockSetting = (Settings.Secure.getIntForUser(resolver,

Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK,

mDreamsActivatedOnDockByDefaultConfig ? 1 : 0,

UserHandle.USER_CURRENT) != 0);

private boolean shouldNapAtBedTimeLocked() { //当返回true, 设备自动nap

return mDreamsActivateOnSleepSetting

|| (mDreamsActivateOnDockSetting

&& mDockState != Intent.EXTRA_DOCK_STATE_UNDOCKED);

}

[java] view plain copy

private boolean napNoUpdateLocked(long eventTime, int uid) {

if (DEBUG_SPEW) {

Slog.d(TAG, "napNoUpdateLocked: eventTime=" + eventTime + ", uid=" + uid);

}

if (eventTime < mLastWakeTime || mWakefulness != WAKEFULNESS_AWAKE

|| !mBootCompleted || !mSystemReady) {

return false;

}

Trace.traceBegin(Trace.TRACE_TAG_POWER, "nap");

try {

Slog.i(TAG, "Nap time (uid " + uid +")...");

mSandmanSummoned = true;

setWakefulnessLocked(WAKEFULNESS_DREAMING, 0); //设置WAKEFULNESS_DREAMING

} finally {

Trace.traceEnd(Trace.TRACE_TAG_POWER);

}

return true;

}

调用goToSleepNoUpdateLocked进行睡眠, 当按power键灭屏是也会调用该函数.

[java] view plain copy

private boolean goToSleepNoUpdateLocked(long eventTime, int reason, int flags, int uid) {

if (DEBUG_SPEW) {

Slog.d(TAG, "goToSleepNoUpdateLocked: eventTime=" + eventTime

+ ", reason=" + reason + ", flags=" + flags + ", uid=" + uid);

}

if (eventTime < mLastWakeTime

|| mWakefulness == WAKEFULNESS_ASLEEP

|| mWakefulness == WAKEFULNESS_DOZING

|| !mBootCompleted || !mSystemReady) {

return false; //判断设备是否应该睡眠

}

Trace.traceBegin(Trace.TRACE_TAG_POWER, "goToSleep");

try {

switch (reason) { //输出灭屏的原因

case PowerManager.GO_TO_SLEEP_REASON_DEVICE_ADMIN:

Slog.i(TAG, "Going to sleep due to device administration policy "

+ "(uid " + uid +")...");

break;

case PowerManager.GO_TO_SLEEP_REASON_TIMEOUT:

Slog.i(TAG, "Going to sleep due to screen timeout (uid " + uid +")...");

break;

case PowerManager.GO_TO_SLEEP_REASON_LID_SWITCH:

Slog.i(TAG, "Going to sleep due to lid switch (uid " + uid +")...");

break;

case PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON:

Slog.i(TAG, "Going to sleep due to power button (uid " + uid +")...");

break;

case PowerManager.GO_TO_SLEEP_REASON_SLEEP_BUTTON:

Slog.i(TAG, "Going to sleep due to sleep button (uid " + uid +")...");

break;

case PowerManager.GO_TO_SLEEP_REASON_HDMI:

Slog.i(TAG, "Going to sleep due to HDMI standby (uid " + uid +")...");

break;

default:

Slog.i(TAG, "Going to sleep by application request (uid " + uid +")...");

reason = PowerManager.GO_TO_SLEEP_REASON_APPLICATION;

break;

}

mLastSleepTime = eventTime;

mSandmanSummoned = true;

setWakefulnessLocked(WAKEFULNESS_DOZING, reason);

// Report the number of wake locks that will be cleared by going to sleep.

int numWakeLocksCleared = 0;

final int numWakeLocks = mWakeLocks.size();

for (int i = 0; i < numWakeLocks; i++) { //遍历所有的wakeLocks, 将FULL, BRIGHT, DIM Locks,计入numWakeLocksCleared中

final WakeLock wakeLock = mWakeLocks.get(i);

switch (wakeLock.mFlags & PowerManager.WAKE_LOCK_LEVEL_MASK) {

case PowerManager.FULL_WAKE_LOCK:

case PowerManager.SCREEN_BRIGHT_WAKE_LOCK:

case PowerManager.SCREEN_DIM_WAKE_LOCK:

numWakeLocksCleared += 1;

break;

}

EventLog.writeEvent(EventLogTags.POWER_SLEEP_REQUESTED, numWakeLocksCleared);

// Skip dozing if requested.

if ((flags & PowerManager.GO_TO_SLEEP_FLAG_NO_DOZE) != 0) {

reallyGoToSleepNoUpdateLocked(eventTime, uid); //如果没有doze流程,直接设置WAKEFULNESS_ASLEEP

}

} finally {

Trace.traceEnd(Trace.TRACE_TAG_POWER);

}

return true; //返回true

}

当第一个for循环中将所有的状态都设置好了, 并且此时也没有重要的mDirty发生变化, 在下一次循环中mDirty的值为0, updateWakefulnessLocked返回false,就会跳出循环.

当跳出循环之后在函数updateDisplayPowerStateLocked中进行获取需要请求的设备电源状态是亮还是灭或者dim，判断是否开启了自动调节亮度开关，是否使用了距离传感器，并经过一系列的计算获取亮度值等，最终都记录到DisplayPowerRequest中，经过DMS传入DPC中，进行处理。

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。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。

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