Power按键流程分析

Posted zhenjie_chang

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从InputManagerService分析我们知道，当按下手机的Power键之后，按键事件会传到InputDispatcher 的notifyKey 方法，然后调用到调用了NativeInputManager的interceptKeyBeforeQueueing函数，最终在这个函数中会调用到PhoneWindowManager中的interceptKeyBeforeQueueing函数，以上主要属于InputManagerService的范畴，Power按键流程我们从PhoneWindowManager 的interceptKeyBeforeQueueing 方法开始分析。

方法interceptKeyBeforeQueueing关键步骤：

第一步：初始化关键变量

if (!mSystemBooted) 
            return 0;
        

        final boolean interactive = (policyFlags & FLAG_INTERACTIVE) != 0;
        final boolean down = event.getAction() == KeyEvent.ACTION_DOWN;
        final boolean canceled = event.isCanceled();
        final int keyCode = event.getKeyCode();

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

首先判断系统是否启动完成，然后就是初始化一些关键变量

Interactive 表示屏幕是否点亮，这个变量表示PowerManagerService关于屏幕的状态

Down 表示是否是ActionDown事件

Canceled 事件是否取消

keyCode 按键编码

第二步，根据interative的状态的处理一些基本逻辑

if (interactive || (isInjected && !isWakeKey)) 
            //事件传递给用户
            result = ACTION_PASS_TO_USER;
            isWakeKey = false;
         else if (!interactive && shouldDispatchInputWhenNonInteractive()) 
            result = ACTION_PASS_TO_USER;
         else 
            
            result = 0;
            if (isWakeKey && (!down || !isWakeKeyWhenScreenOff(keyCode))) 
                isWakeKey = false;
            
        
        if (isValidGlobalKey(keyCode)
                && mGlobalKeyManager.shouldHandleGlobalKey(keyCode, event)) 
            if (isWakeKey) 
                //直接唤醒系统
                wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, " android.policy:KEY");
            
            return result;

第三步，处理Power按键的事件

case KeyEvent.KEYCODE_POWER: 
                result &= ~ACTION_PASS_TO_USER;
                isWakeKey = false; // wake-up will be handled separately
                if (down) 
                    Power键按下
                    interceptPowerKeyDown(event, interactive);
                 else 
                    Power键释放
                    interceptPowerKeyUp(event, interactive, canceled);
                
                break;

首先是Power按键的事件的话，不再分发到应用，如果是ActionDown事件执行InterceptPowerKeyDown()方法，如果是ActionUP事件则执行InterceptPowerKeyUp()方法

下一步继续分析interceptPowerKeyDown方法

private void interceptPowerKeyDown(KeyEvent event, boolean interactive) 
        
        if (!mPowerKeyWakeLock.isHeld()) 
            mPowerKeyWakeLock.acquire();

获取Power按键的锁，直到释放Power键

……   

if (interactive && !mScreenshotChordPowerKeyTriggered
                && (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) 
            mScreenshotChordPowerKeyTriggered = true;
            mScreenshotChordPowerKeyTime = event.getDownTime();
            interceptScreenshotChord();

如果当前是亮屏状态，且满足触发截屏的条件，触发截屏功能

TelecomManager telecomManager = getTelecommService();
        boolean hungUp = false;
        if (telecomManager != null) 
            if (telecomManager.isRinging()) 
             
                telecomManager.silenceRinger();
             else if ((mIncallPowerBehavior
                    & Settings.Secure.INCALL_POWER_BUTTON_BEHAVIOR_HANGUP) != 0
                    && telecomManager.isInCall() && interactive) 
  
                hungUp = telecomManager.endCall();

如果有电话拨入，且电话铃声响起的话，这个时候按Power键，设置电话响铃静音

如果正在接听电话，且配置了Power键挂断电话的话，按Power按键挂断正在接听的电话

       ……

mPowerKeyHandled = hungUp || mScreenshotChordVolumeDownKeyTriggered
                || mScreenshotChordVolumeUpKeyTriggered || gesturedServiceIntercepted;

如果按Power按键执行了截图功能或者电话静音或者挂断电话等功能后，Power事件不在传递，表示已经消耗掉了Power事件 

if (!mPowerKeyHandled)

如果未消耗掉Power事件，继续执行此处逻辑

分为两种情况

1， 当前是亮屏状态

2， 当前是灭屏状态

if (interactive) 
                //是否支持长按功能
                if (hasLongPressOnPowerBehavior()) 
                    Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
                    msg.setAsynchronous(true);
                    //发送MSG_POWER_LONG_PRESS消息，有Handler来处理
                    mHandler.sendMessageDelayed(msg,
                            ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
                
             else 
                  //当前灭屏状态，此时按Power键，先唤醒系统
                   wakeUpFromPowerKey(event.getDownTime());
                  //是否支持灭屏下的长按功能
                  if (mSupportLongPressPowerWhenNonInteractive && hasLongPressOnPowerBehavior()) 
                    Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
                    msg.setAsynchronous(true);
                    mHandler.sendMessageDelayed(msg,
                            ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
                    mBeganFromNonInteractive = true;
                 else 
                    final int maxCount = getMaxMultiPressPowerCount();

                    if (maxCount <= 1) 
                        mPowerKeyHandled = true;
                     else 
                        mBeganFromNonInteractive = true;

当前亮屏状态

首先判断是否支持长按的行为

先来看看hasLongPressOnPowerBehavior函数

private boolean hasLongPressOnPowerBehavior() 
        return getResolvedLongPressOnPowerBehavior() != LONG_PRESS_POWER_NOTHING;

再来看看getResolvedLongPressOnPowerBehavior函数

private int getResolvedLongPressOnPowerBehavior() 
        if (FactoryTest.isLongPressOnPowerOffEnabled()) 
            return LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM;
        
        return mLongPressOnPowerBehavior;

由于systemProperty中的factory.long_press_power_off" 配置为0，所以不支持灭屏长按功能，。因此只要看mLongPressOnPowerBehavior这个变量

mLongPreesOnPowerBehavior 默认配置获取为

mLongPressOnPowerBehavior = mContext.getResources().getInteger(
               com.android.internal.R.integer.config_longPressOnPowerBehavior);

config_longPressOnPowerBehavior 默认值为1，所以 mLongPressOnPowerBehavior  = 1， 最后hasLongPressOnPowerBehavior返回 true 


if (hasLongPressOnPowerBehavior()) 
                    Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
                    msg.setAsynchronous(true);
                    mHandler.sendMessageDelayed(msg,
                            ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());

当hasLongPressOnPowerBehavior返回true，则发送MSG_POWER_LONG_PRESS的Handler消息，Handler处理消息调用 powerLongPress()方法，接着我们来看下Handler处理消息的逻辑

private void powerLongPress() 
        final int behavior = getResolvedLongPressOnPowerBehavior();
        switch (behavior) 
        case LONG_PRESS_POWER_NOTHING:
            break;
        case LONG_PRESS_POWER_GLOBAL_ACTIONS:
            mPowerKeyHandled = true;
            if (!performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false)) 
                performAuditoryFeedbackForAccessibilityIfNeed();
            
            showGlobalActionsInternal();
            break;
       ……

由以上的分析指导getResolvedLongPressOnPowerBehavior的值为1，所以执行case LONG_PRESS_POWER_GLOBAL_ACTIONS,

将mPowerKeyHandled的值设置为true，表示处理了PowerDown事件，showGlobalActionsInternal()方法弹出关机，重启对话框

1. 当屏幕是灭屏状态

首先执行wakeUpFromPowerKey方法，唤醒手机系统，最终调用mPowerManager.wakeUp(wakeTime, reason)来唤醒手机

然后mSupportLongPressPowerWhenNonInteractive默认不支持，所以默认执行

final int maxCount = getMaxMultiPressPowerCount();
              if (maxCount <= 1) 
                    mPowerKeyHandled = true;
                else 
                    mBeganFromNonInteractive = true;
               

getMaxMultiPressPowerCount() ==1，默认不支持对此按键，所以将mPowerKeyHandled设置为true，表示处理了PowerDown事件
2，处理PowerUp事件
PowerUp事件也分为两种情况，分别对应PowerDown的亮屏和灭屏两种情况

private void interceptPowerKeyUp(KeyEvent event, boolean interactive, boolean canceled) 
        final boolean handled = canceled || mPowerKeyHandled;
      ……
        if (!handled) 
            mPowerKeyPressCounter += 1;
            final int maxCount = getMaxMultiPressPowerCount();
            final long eventTime = event.getDownTime();
            if (mPowerKeyPressCounter < maxCount) 
                Message msg = mHandler.obtainMessage(MSG_POWER_DELAYED_PRESS,
                        interactive ? 1 : 0, mPowerKeyPressCounter, eventTime);
                msg.setAsynchronous(true);
                mHandler.sendMessageDelayed(msg, ViewConfiguration.getDoubleTapTimeout());
                return;
            
            powerPress(eventTime, interactive, mPowerKeyPressCounter);
        
        finishPowerKeyPress();

在灭屏的时候，和亮屏长按的时候mPowerKeyHandled最后设置为true，即handle为true，直接执行finishPowerKeyPress方法，释放mPowerKeyWakeLock

在亮屏短按的时候，handled为false，由以上分析，手机默认不支持多次按键所以maxCount为1，mPowerKeyPressCounter=1，所以直接执行powerPress方法

private void powerPress(long eventTime, boolean interactive, int count) 
		
        if (count == 2) 
            powerMultiPressAction(eventTime, interactive,mDoublePressOnPowerBehavior);
         else if (count == 3) 
            powerMultiPressAction(eventTime, interactive, mTriplePressOnPowerBehavior);
         else if (interactive && !mBeganFromNonInteractive) 
            switch (mShortPressOnPowerBehavior) 
                case SHORT_PRESS_POWER_NOTHING:
                    break;
                case SHORT_PRESS_POWER_GO_TO_SLEEP:
                    mPowerManager.goToSleep(eventTime,
                            PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0);
                    break;
                case SHORT_PRESS_POWER_REALLY_GO_TO_SLEEP:
                    mPowerManager.goToSleep(eventTime,
                            PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON,
                            PowerManager.GO_TO_SLEEP_FLAG_NO_DOZE);
                    break;
                case SHORT_PRESS_POWER_REALLY_GO_TO_SLEEP_AND_GO_HOME:
                    mPowerManager.goToSleep(eventTime,
                            PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON,
                            PowerManager.GO_TO_SLEEP_FLAG_NO_DOZE);
                    launchHomeFromHotKey();
                    break;
                case SHORT_PRESS_POWER_GO_HOME:
                    launchHomeFromHotKey(true /* awakenFromDreams */, false 
                    break;

由于mPowerKeyPressCounter 为1，所以执行case  SHORT_PRESS_POWER_GO_TO_SLEEP,调用mPowerManager.goToSleep休眠系统

 

Power按键流程总结

Power按键

1.亮屏 down 

           长按 弹出关闭重启对话框

           短按 不做处理

   亮屏 up 

       长按 不做处理

        短按 调用goToSleep休眠系统

2. 灭屏 down

            调用wakeup 唤醒系统

     灭屏 up

            不做处理


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