本篇从按下power按键后，按键事件从InputManagerService 传到PhoneWindowManager.java开始分析power 按键做屏幕亮灭过程的分析，关于power 按键的其他行为参考另一篇博文（Android 7.0 Power 按键处理流程）
（注：博客园显示的图片很模糊，上传的为大图，可以图片另存为查看）
言归正传，本篇涉及的几个模块（文件）如下，先做个简单的介绍有个直观大概的了解，方便后面流程细节的理解。
Ø PowerManagerService.Java：（/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java）
PMS，是Android系统中的电源处理服务，主要负责电源相关的计算和决策，如是否应该灭屏 或者让屏幕变暗，是否应该让系统休眠等等。
Ø DisplayPowerController.java：（/frameworks/base/services/core/java/com/android/server/display/DisplayPowerController.java）
DPC，管理显示设备（这里指的显示设备是屏幕）状态，主要处理距离传感器（如打电话时候靠近则灭屏，离开时候屏幕亮起）以及亮灭屏动画（包括根据光感传感器计算屏幕目标亮度值）。在DisplayManagerService.java(DMS)中实例化一个对象，以DMS为桥梁与PMS进行交互通过异步回调机制来通知PMS那些发生了改变。同时也与WMS进行交互。
Ø DisplayPowerState.java：（/frameworks/base/services/core/java/com/android/server/display/DisplayPowerState.java）
DPS，管理显示设备的状态仅在DPC中实例化一个对象，是DPC的一部分。
Ø Notifier.java：（ /frameworks/base/services/core/java/com/android/server/power/Notifier.java）
将电源状态的重要变化，通过广播通知出去。
Ø ColorFade.java：（/frameworks/base/services/core/java/com/android/server/display/ColorFade.java）
是负责屏幕由关到开，由开到关的一些GL动画，由DPC进行控制。
Ø AutomaticBrightnessController.java：（/frameworks/base/services/core/java/com/android/server/display/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来设定屏幕的亮度值（即根据环境的光线强度来计算屏幕的亮暗程度）。
Ø RampAnimator.java：（/frameworks/base/services/core/java/com/android/server/display/RampAnimator.java）
仅仅是屏幕亮度渐变动画。
一、Power按键的上报与处理
详细见【Android 7.0 Power 按键处理流程】此处仅略微的复习一下，方便了后面的理解。
1）Power按键的上报
在InputManagerService收到power按键事件经过一系列的处理和转换最终将会传递到PhoneWindowManager（PWM）的interceptKeyBeforeQueueing（）函数来做具体的业务逻辑.下图为上报的流程图。
2）power 按键关于量灭屏处理
关于量灭屏的处理主要在interceptKeyBeforeQueueing（）函数中。判断是否是isWakeKey，如果是则在此函数的最后通过调用wakeUp（）函数来具体处理，这就拉开了本文的序幕。
注：此函数很长本文删除无关的部分，仅仅保留部分和量灭屏相关的说明具体处理流程即可。详细参考【Android 7.0 Power 按键处理流程】
A: 按键处理判断是否要量灭屏
public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) { boolean isWakeKey = (policyFlags & WindowManagerPolicy.FLAG_WAKE) != 0 || event.isWakeKey(); if (interactive || (isInjected && !isWakeKey)) { // When the device is interactive or the key is injected pass the // key to the application. result = ACTION_PASS_TO_USER; isWakeKey = false; if (interactive) { // If the screen is awake, but the button pressed was the one that woke the device // then don't pass it to the application if (keyCode == mPendingWakeKey && !down) { result = 0; } // Reset the pending key mPendingWakeKey = PENDING_KEY_NULL; } } else if (!interactive && shouldDispatchInputWhenNonInteractive(event)) { // If we're currently dozing with the screen on and the keyguard showing, pass the key // to the application but preserve its wake key status to make sure we still move // from dozing to fully interactive if we would normally go from off to fully // interactive. result = ACTION_PASS_TO_USER; // Since we're dispatching the input, reset the pending key mPendingWakeKey = PENDING_KEY_NULL; } else { // When the screen is off and the key is not injected, determine whether // to wake the device but don't pass the key to the application. result = 0; if (isWakeKey && (!down || !isWakeKeyWhenScreenOff(keyCode))) { isWakeKey = false; } // Cache the wake key on down event so we can also avoid sending the up event to the app if (isWakeKey && down) { mPendingWakeKey = keyCode; } } // If the key would be handled globally, just return the result, don't worry about special // key processing. if (isValidGlobalKey(keyCode) && mGlobalKeyManager.shouldHandleGlobalKey(keyCode, event)) { if (isWakeKey) { wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY"); } return result; } .................... case KeyEvent.KEYCODE_ENDCALL: { result &= ~ACTION_PASS_TO_USER; if (down) { TelecomManager telecomManager = getTelecommService(); boolean hungUp = false; if (telecomManager != null) { hungUp = telecomManager.endCall(); } if (interactive && !hungUp) { mEndCallKeyHandled = false; mHandler.postDelayed(mEndCallLongPress, ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout()); } else { mEndCallKeyHandled = true; } } else { if (!mEndCallKeyHandled) { mHandler.removeCallbacks(mEndCallLongPress); if (!canceled) { if ((mEndcallBehavior & Settings.System.END_BUTTON_BEHAVIOR_HOME) != 0) { if (goHome()) { break; } } if ((mEndcallBehavior & Settings.System.END_BUTTON_BEHAVIOR_SLEEP) != 0) { mPowerManager.goToSleep(event.getEventTime(), PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0); isWakeKey = false; } } } } break; } .................... if (useHapticFeedback) { performHapticFeedbackLw(null, HapticFeedbackConstants.VIRTUAL_KEY, false); } if (isWakeKey) { wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY"); } return result; }
B：wakeUp处理量灭屏
private boolean wakeUp(long wakeTime, boolean wakeInTheaterMode, String reason) { final boolean theaterModeEnabled = isTheaterModeEnabled(); if (!wakeInTheaterMode && theaterModeEnabled) { return false; } if (theaterModeEnabled) { Settings.Global.putInt(mContext.getContentResolver(), Settings.Global.THEATER_MODE_ON, 0); } mPowerManager.wakeUp(wakeTime, reason); //调用PowerManagerService亮屏操作 return true; } }
二、PowerManagerService处理量灭屏过程
从上面的分析可知，在PWM中处理按键事件如果需要唤醒屏幕则会调用PWM的wakeUp（）函数，此函数会调用PMS 的wakeUp（）函数来具体处理。
从上面的分析可知，在PWM中处理按键事件如果需要唤醒屏幕则会调用PWM的wakeUp（）函数，此函数会调用PMS 的wakeUp（）函数来具体处理。
注：限于篇幅本文仅列出重要的函数和调用过程
首先来个概览，了解一下主要完成了如下三件事
1） 由Notifier根据系统的具体状态来发出广播
2） PMS 通过updatePowerStateLocked（）计算和更新电源的全局状态
3） PMS将最新的电源状态等传入DPC中，根据距离传感器和光感传感器，计算具体的屏幕亮度和量灭屏动画等
4） DPC通知PWM绘制keyguard与windows（此时会block等待绘制完成，灭屏时候无需绘制），绘制完成后通知DPC继续
5） DPC具体调用显示设备开启或关闭屏幕（执行量灭屏的动画效果）
1）PowerManagerService--wakeUpNoUpdateLocked()
PMS首先讲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) { if (DEBUG_SPEW) { Slog.d(TAG, "wakeUpNoUpdateLocked: eventTime=" + eventTime + ", uid=" + reasonUid); } if (eventTime < mLastSleepTime || mWakefulness == WAKEFULNESS_AWAKE || !mBootCompleted || !mSystemReady) { return false; //判断是否要去亮屏 } Trace.traceBegin(Trace.TRACE_TAG_POWER, "wakeUp"); try { switch (mWakefulness) { case WAKEFULNESS_ASLEEP: Slog.i(TAG, "Waking up from sleep due to"+opPackageName+" "+reason+" (uid " + reasonUid +")..."); break; case WAKEFULNESS_DREAMING: Slog.i(TAG, "Waking up from dream due to"+opPackageName+" "+reason+" (uid " + reasonUid +")..."); break; case WAKEFULNESS_DOZING: Slog.i(TAG, "Waking up from dozing due to"+opPackageName+" "+reason+" (uid " + reasonUid +")..."); break; } mLastWakeTime = eventTime; //设置最后一次唤醒的时间 setWakefulnessLocked(WAKEFULNESS_AWAKE, 0); //Notifier调用onWakefulnessChangeStarted发送亮屏广播 mNotifier.onWakeUp(reason, reasonUid, opPackageName, opUid); //调用Notifier通知battery处理 userActivityNoUpdateLocked( //更新最后一次用户事件时间 eventTime, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, reasonUid); } finally { Trace.traceEnd(Trace.TRACE_TAG_POWER); } return true; }
1）Notifier 发送量灭屏广播
Notifier发送广播前会与与AMS，WMS，IMS进行交互，通知各模块电源状态的改变，各模块会自行处理电源状态改变通知。
A:onWakefulnessChangeStarted()
public void onWakefulnessChangeStarted(final int wakefulness, int reason) { final boolean interactive = PowerManagerInternal.isInteractive(wakefulness); //亮屏true, 灭屏false if (DEBUG) { Slog.d(TAG, "onWakefulnessChangeStarted: wakefulness=" + wakefulness + ", reason=" + reason + ", interactive=" + interactive); } // Tell the activity manager about changes in wakefulness, not just interactivity. // It needs more granularity than other components. mHandler.post(new Runnable() { @Override public void run() { mActivityManagerInternal.onWakefulnessChanged(wakefulness); //与AMS交互处理 } }); // Handle any early interactive state changes. // Finish pending incomplete ones from a previous cycle. if (mInteractive != interactive) { // Finish up late behaviors if needed. if (mInteractiveChanging) { handleLateInteractiveChange(); } // Start input as soon as we start waking up or going to sleep. mInputManagerInternal.setInteractive(interactive); //在IMS中记录现在的屏幕状态 mInputMethodManagerInternal.setInteractive(interactive); // Notify battery stats. try { mBatteryStats.noteInteractive(interactive); //唤醒battery状态 } catch (RemoteException ex) { } // Handle early behaviors. mInteractive = interactive; mInteractiveChangeReason = reason; mInteractiveChanging = true; handleEarlyInteractiveChange(); //初期处理交互模式改变 } }
B: handleEarlyInteractiveChange()
当屏幕在wakingup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
private void handleEarlyInteractiveChange() { synchronized (mLock) { if (mInteractive) { // Waking up... //亮屏 mHandler.post(new Runnable() { @Override public void run() { EventLog.writeEvent(EventLogTags.POWER_SCREEN_STATE, 1, 0, 0, 0); mPolicy.startedWakingUp(); } }); // Send interactive broadcast. mPendingInteractiveState = INTERACTIVE_STATE_AWAKE; mPendingWakeUpBroadcast = true; updatePendingBroadcastLocked(); //更新亮屏广播 } else { // Going to sleep... //灭屏 // Tell the policy that we started going to sleep. final int why = translateOffReason(mInteractiveChangeReason); mHandler.post(new Runnable() { @Override public void run() { mPolicy.startedGoingToSleep(why); } }); } }
(1):updatePendingBroadcastLocked()
private void updatePendingBroadcastLocked() { if (!mBroadcastInProgress && mPendingInteractiveState != INTERACTIVE_STATE_UNKNOWN && (mPendingWakeUpBroadcast || mPendingGoToSleepBroadcast || mPendingInteractiveState != mBroadcastedInteractiveState)) { mBroadcastInProgress = true; mSuspendBlocker.acquire(); Message msg = mHandler.obtainMessage(MSG_BROADCAST); msg.setAsynchronous(true); mHandler.sendMessage(msg); } }
(2)sendNextBroadcast()
private void sendNextBroadcast() { final int powerState; synchronized (mLock) { if (mBroadcastedInteractiveState == INTERACTIVE_STATE_UNKNOWN) { // Broadcasted power state is unknown. Send wake up. mPendingWakeUpBroadcast = false; mBroadcastedInteractiveState = INTERACTIVE_STATE_AWAKE; } else if (mBroadcastedInteractiveState == INTERACTIVE_STATE_AWAKE) { // Broadcasted power state is awake. Send asleep if needed. if (mPendingWakeUpBroadcast || mPendingGoToSleepBroadcast || mPendingInteractiveState == INTERACTIVE_STATE_ASLEEP) { mPendingGoToSleepBroadcast = false; mBroadcastedInteractiveState = INTERACTIVE_STATE_ASLEEP; } else { finishPendingBroadcastLocked(); return; } } else { // Broadcasted power state is asleep. Send awake if needed. if (mPendingWakeUpBroadcast || mPendingGoToSleepBroadcast || mPendingInteractiveState == INTERACTIVE_STATE_AWAKE) { mPendingWakeUpBroadcast = false; mBroadcastedInteractiveState = INTERACTIVE_STATE_AWAKE; } else { finishPendingBroadcastLocked(); return; } } mBroadcastStartTime = SystemClock.uptimeMillis(); powerState = mBroadcastedInteractiveState; } EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_SEND, 1); if (powerState == INTERACTIVE_STATE_AWAKE) { sendWakeUpBroadcast();//这里发送亮屏广播 } else { sendGoToSleepBroadcast(); } }
（3）sendWakeUpBroadcast()
注意：Notifier 自身也会接收亮屏广播，其受到后会调用finishPendingBroadcastLocked()函数来释放wakeLock
private void sendWakeUpBroadcast() { if (DEBUG) { Slog.d(TAG, "Sending wake up broadcast."); } if (ActivityManagerNative.isSystemReady()) { mContext.sendOrderedBroadcastAsUser(mScreenOnIntent, UserHandle.ALL, null, mWakeUpBroadcastDone, mHandler, 0, null, null); } else { EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_STOP, 2, 1); sendNextBroadcast(); } }
