绪论
可以导致手机亮灭屏的因素有多种，而在本文中主要讲解按power键亮灭屏过程以及来电亮屏。在亮灭屏过程power中主要的实现类与功能如下所述：
PowerManagerService.java：以下简称PMS或者PowerMS，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：以下简称DPC或者DisplayPC，管理display设备状态，在DisplayManagerService.java(简称DMS)中实例化一个对象，以DMS为桥梁与PMS进行交互。主要处理距离传感器，亮灭屏动画，以及计算屏幕目标亮度值。通过异步回调机制来通知PMS那些事情发生了改变。同时也与WMS进行交互。
DisplayPowerState.java：以下简称DPS，power通过其与系统进行交互，如调用其它模块设置屏幕状态与亮度。仅在DPC中实例化一个对象，它算是DPC的一部分只不过将其独立出来了。
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。
亮屏总览
在点击power键亮屏过程中，主要流程就是input对按键事件的传输，传送到上层处理。之后就是在power中进行对亮屏状态的处理，计算一系列的数值，并且与AMS，WMS等模块进行交互，最后调用底层LCD进行最终的设备状态与亮度的设置。在下面将会对各流程详细讲解。
Input传输Power键
当触发power键，kernel会将该事件中断，然后InputReader通过EventHub获取事件，并且对输入事件进行处理，之后交由InputDispatcher进行分发。如果该事件为key事件会先调用interceptKeyBeforeQueueing，提前对需要系统处理的事件进行处理。最终调到PhoneWindowManager类中的interceptKeyBeforeQueueing函数对该事件优先处理，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。
从底层到上层的具体代码调用流程 InputReader.cpp->InputDispatcher.cpp->com_android_server_input_InputManagerService.cpp->InputManagerService.java->InputMonitor.java->WindowManagerPolicy.java->PhoneWindowManager.java最终来到java层处理按键事件.
public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {
if (!mSystemBooted) { //系统还没有启动完成,不处理任何按键事件
// If we have not yet booted, don't let key events do anything.
return 0;
}
final boolean interactive = (policyFlags & FLAG_INTERACTIVE) != 0; //是否能与用户交互, 如果亮屏为true
final boolean down = event.getAction() == KeyEvent.ACTION_DOWN; //按键down事件
final boolean canceled = event.isCanceled(); //事件被取消
final int keyCode = event.getKeyCode(); //按键事件的code
final boolean isInjected = (policyFlags & WindowManagerPolicy.FLAG_INJECTED) != 0;
// Basic policy based on interactive state.
int result;
boolean isWakeKey = (policyFlags & WindowManagerPolicy.FLAG_WAKE) != 0
|| event.isWakeKey(); //flags有wake标记,或者按键为KEYCODE_BACK, KEYCODE_MENU, KEYCODE_WAKEUP, KEYCODE_PAIRING, KEYCODE_STEM_1, KEYCODE_STEM_2, KEYCODE_STEM_3设置isWakeKey为true. power ,home键属于systemKey
// 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) { //如果按键时间有效, 并且在com.android.internal.R.xml.global_keys文件中配置了keycode. 如果是唤醒键就调用wakeUp唤醒屏幕
wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY");
}
return result;
}
// Handle special keys. //处理特殊的按键事件 ,这里主要讲解power键事件
switch (keyCode) {
case KeyEvent.KEYCODE_BACK: //back键
case KeyEvent.KEYCODE_VOLUME_DOWN: //音量下键
case KeyEvent.KEYCODE_VOLUME_UP: //音量上键
case KeyEvent.KEYCODE_VOLUME_MUTE: //静音键
case KeyEvent.KEYCODE_ENDCALL: //挂断电话键
case KeyEvent.KEYCODE_POWER: { //电源键
result &= ~ACTION_PASS_TO_USER;
isWakeKey = false; // wake-up will be handled separately
if (down) { //power按下事件
interceptPowerKeyDown(event, interactive); //处理power下键
} else { //power键松开
interceptPowerKeyUp(event, interactive, canceled); //处理power上键
}
break;
}
case KeyEvent.KEYCODE_SLEEP:
case KeyEvent.KEYCODE_SOFT_SLEEP:
case KeyEvent.KEYCODE_WAKEUP:
case KeyEvent.KEYCODE_MEDIA_PLAY:
case KeyEvent.KEYCODE_MEDIA_PAUSE:
case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE:
case KeyEvent.KEYCODE_HEADSETHOOK:
case KeyEvent.KEYCODE_MUTE:
case KeyEvent.KEYCODE_MEDIA_STOP:
case KeyEvent.KEYCODE_MEDIA_NEXT:
case KeyEvent.KEYCODE_MEDIA_PREVIOUS:
case KeyEvent.KEYCODE_MEDIA_REWIND:
case KeyEvent.KEYCODE_MEDIA_RECORD:
case KeyEvent.KEYCODE_MEDIA_FAST_FORWARD:
case KeyEvent.KEYCODE_MEDIA_AUDIO_TRACK:
case KeyEvent.KEYCODE_CALL:
case KeyEvent.KEYCODE_VOICE_ASSIST:
case KeyEvent.KEYCODE_WINDOW:
}
}
if (isWakeKey) { //如果除了power键, 别的按键也需要亮屏,就调用WakeUp亮屏
wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY");
}
return result;
} private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {
// Hold a wake lock until the power key is released.
if (!mPowerKeyWakeLock.isHeld()) {
mPowerKeyWakeLock.acquire(); //获取wakeLock,保持cpu唤醒状态
}
// 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
}
// Stop ringing or end call if configured to do so when power is pressed.
TelecomManager telecomManager = getTelecommService(); //获取telecom
boolean hungUp = false;
if (telecomManager != null) {
if (telecomManager.isRinging()) { //如果来电过程中,按power键手机将静音,停止响铃
// Pressing Power while there's a ringing incoming
// call should silence the ringer.
telecomManager.silenceRinger();
} else if ((mIncallPowerBehavior
& Settings.Secure.INCALL_POWER_BUTTON_BEHAVIOR_HANGUP) != 0
&& telecomManager.isInCall() && interactive) {
// Otherwise, if "Power button ends call" is enabled,
// the Power button will hang up any current active call.
hungUp = telecomManager.endCall(); //如果在Setting数据库中配置了,按power键挂断电话, 就将电话挂断
}
}
//................
// If the power key has still not yet been handled, then detect short
// press, long press, or multi press and decide what to do. //如果power键还没有被处理,就判断是短按, 长按,还是多按来决定如何处理
mPowerKeyHandled = hungUp || mScreenshotChordVolumeDownKeyTriggered
|| mScreenshotChordVolumeUpKeyTriggered || gesturedServiceIntercepted;
if (!mPowerKeyHandled) {
if (interactive) {
// When interactive, we're already awake.
// Wait for a long press or for the button to be released to decide what to do.
if (hasLongPressOnPowerBehavior()) { //如果屏幕是亮这的,长按power键 ,就处理长按事件
Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
msg.setAsynchronous(true);
mHandler.sendMessageDelayed(msg,
ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
}
} else {
wakeUpFromPowerKey(event.getDownTime()); //如果屏幕是休眠状态,就唤醒屏幕
if (mSupportLongPressPowerWhenNonInteractive && hasLongPressOnPowerBehavior()) {
Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
msg.setAsynchronous(true);
mHandler.sendMessageDelayed(msg, //如果还是长按power键, 就再处理长按事件
ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
mBeganFromNonInteractive = true;
} else {
final int maxCount = getMaxMultiPressPowerCount();
if (maxCount <= 1) {
mPowerKeyHandled = true;
} else {
mBeganFromNonInteractive = true;
}
}
}
}
} private void interceptPowerKeyUp(KeyEvent event, boolean interactive, boolean canceled) {
final boolean handled = canceled || mPowerKeyHandled;
mScreenshotChordPowerKeyTriggered = false;
cancelPendingScreenshotChordAction();
cancelPendingPowerKeyAction();
if (!handled) { //power键还没被处理
// Figure out how to handle the key now that it has been released.
mPowerKeyPressCounter += 1;
final int maxCount = getMaxMultiPressPowerCount(); //多按的次数
final long eventTime = event.getDownTime(); //按键发生的时间点
if (mPowerKeyPressCounter < maxCount) {
// This could be a multi-press. Wait a little bit longer to confirm.
// Continue holding the wake lock. //等待一会调用powerPress处理
Message msg = mHandler.obtainMessage(MSG_POWER_DELAYED_PRESS,
interactive ? 1 : 0, mPowerKeyPressCounter, eventTime);
msg.setAsynchronous(true);
mHandler.sendMessageDelayed(msg, ViewConfiguration.getDoubleTapTimeout());
return;
}
// No other actions. Handle it immediately.
powerPress(eventTime, interactive, mPowerKeyPressCounter); //没有的的处理, 立即处理power down事件
}
// Done. Reset our state.
finishPowerKeyPress(); //power键处理结束
}
private void finishPowerKeyPress() {
mBeganFromNonInteractive = false;
mPowerKeyPressCounter = 0;
if (mPowerKeyWakeLock.isHeld()) {
mPowerKeyWakeLock.release(); //释放wakLock
}
} 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) {
powerMultiPressAction(eventTime, interactive, mDoublePressOnPowerBehavior); //处理按两次power键事件
} else if (count == 3) {
powerMultiPressAction(eventTime, interactive, mTriplePressOnPowerBehavior); //处理按三次power键事件
} else if (interactive && !mBeganFromNonInteractive) {
switch (mShortPressOnPowerBehavior) {
case SHORT_PRESS_POWER_NOTHING:
break;
case SHORT_PRESS_POWER_GO_TO_SLEEP: //灭屏
mPowerManager.goToSleep(eventTime,
PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0);
break;
case SHORT_PRESS_POWER_REALLY_GO_TO_SLEEP: //灭屏,不经历doze流程
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, //灭屏,不经历doze流程, 并返回home界面
PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON,
PowerManager.GO_TO_SLEEP_FLAG_NO_DOZE);
launchHomeFromHotKey();
break;
case SHORT_PRESS_POWER_GO_HOME: //返回home界面
launchHomeFromHotKey(true /* awakenFromDreams */, false /*respectKeyguard*/);
break;
}
}
} private void wakeUpFromPowerKey(long eventTime) {
wakeUp(eventTime, mAllowTheaterModeWakeFromPowerKey, "android.policy:POWER");
}
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唤醒屏幕
return true;
}
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) {
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的时间
eventTime, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, reasonUid);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
return true;
} public void onWakefulnessChangeStarted(final int wakefulness, int reason) {
final boolean interactive = PowerManagerInternal.isInteractive(wakefulness); //获取交互模式,亮屏为true, 灭屏为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input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
}
} 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(); //通过PhoneWindowManager系统开始亮屏, 更新转向监听器,手势监听器等
}
});
// 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);
}
});
}
}
} 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; //亮屏状态
} 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; //灭屏状态
} else {
finishPendingBroadcastLocked(); //结束发送广播
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(); //发送亮屏广播
} else {
sendGoToSleepBroadcast();
}
} mScreenOnIntent = new Intent(Intent.ACTION_SCREEN_ON); //亮屏广播intent
mScreenOnIntent.addFlags( //前台广播
Intent.FLAG_RECEIVER_REGISTERED_ONLY | Intent.FLAG_RECEIVER_FOREGROUND);
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); //发送亮屏广播,并且其它模块全部处理完后, 自身接收亮屏广播
} else {
EventLog.writeEvent(EventLogTags.POWER_SCREEN_BROADCAST_STOP, 2, 1);
sendNextBroadcast();
}
}
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(); //自身接收到亮屏广播后, 之后会调用finishPendingBroadcastLocked,释放wakeLock
}
};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，如果抓的有partial锁，就将其释放，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。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。
更新Power全局状态
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:
一.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
// Update wireless dock detection state.
final boolean dockedOnWirelessCharger = mWirelessChargerDetector.update(
mIsPowered, mPlugType, mBatteryLevel); //无线充电
// Treat plugging and unplugging the devices as a user activity.
// Users find it disconcerting when they plug or unplug the device
// and it shuts off right away.
// Some devices also wake the device when plugged or unplugged because
// they don't have a charging LED.
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) {
if (DEBUG_SPEW) {
Slog.d(TAG, "updateIsPoweredLocked: resetting low power snooze");
}
mAutoLowPowerModeSnoozing = false;
}
updateLowPowerModeLocked(); //更新低电模式
}
}
} mWakeUpWhenPluggedOrUnpluggedConfig = resources.getBoolean(
com.android.internal.R.bool.config_unplugTurnsOnScreen); //从xml文件中读取配置信息
private boolean shouldWakeUpWhenPluggedOrUnpluggedLocked(
boolean wasPowered, int oldPlugType, boolean dockedOnWirelessCharger) {
// Don't wake when powered unless configured to do so.
if (!mWakeUpWhenPluggedOrUnpluggedConfig) { //如果配置为true, 可能会亮屏
return false;
}
// Don't wake when undocked from wireless charger.
// See WirelessChargerDetector for justification.
if (wasPowered && !mIsPowered
&& oldPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS) {
return false;
}
// Don't wake when docked on wireless charger unless we are certain of it.
// See WirelessChargerDetector for justification.
if (!wasPowered && mIsPowered
&& mPlugType == BatteryManager.BATTERY_PLUGGED_WIRELESS
&& !dockedOnWirelessCharger) {
return false;
}
// If already dreaming and becoming powered, then don't wake.
if (mIsPowered && mWakefulness == WAKEFULNESS_DREAMING) {
return false;
}
// Don't wake while theater mode is enabled.
if (mTheaterModeEnabled && !mWakeUpWhenPluggedOrUnpluggedInTheaterModeConfig) {
return false;
}
// Otherwise wake up!
return true;
}二:更新wakefulness
for (;;) {
int dirtyPhase1 = mDirty;
dirtyPhase2 |= dirtyPhase1;
mDirty = 0; //将mDirty清零,不影响下个循环
updateWakeLockSummaryLocked(dirtyPhase1);
updateUserActivitySummaryLocked(now, dirtyPhase1);
if (!updateWakefulnessLocked(dirtyPhase1)) { //当updateWakefulnessLocked返回false跳出循环
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，在下面判断是否需要睡眠时会使用。
private void updateWakeLockSummaryLocked(int dirty) {
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_WAKEFULNESS)) != 0) {
mWakeLockSummary = 0;
final int numWakeLocks = mWakeLocks.size(); //获取所有的wakeLocks
for (int i = 0; i < numWakeLocks; i++) { //遍历所有的wakeLocks, 将wakeLocks记录在mWakeLockSummary中
final WakeLock wakeLock = mWakeLocks.get(i);
switch (wakeLock.mFlags & PowerManager.WAKE_LOCK_LEVEL_MASK) {
case PowerManager.PARTIAL_WAKE_LOCK:
if (!wakeLock.mDisabled) {
// We only respect this if the wake lock is not disabled.
mWakeLockSummary |= WAKE_LOCK_CPU;
}
break;
case PowerManager.FULL_WAKE_LOCK: //屏幕键盘全部点亮
mWakeLockSummary |= WAKE_LOCK_SCREEN_BRIGHT | WAKE_LOCK_BUTTON_BRIGHT;
break;
case PowerManager.SCREEN_BRIGHT_WAKE_LOCK: //点亮屏幕
mWakeLockSummary |= WAKE_LOCK_SCREEN_BRIGHT;
break;
case PowerManager.SCREEN_DIM_WAKE_LOCK: //dim锁
mWakeLockSummary |= WAKE_LOCK_SCREEN_DIM;
break;
case PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK: //距离灭屏
mWakeLockSummary |= WAKE_LOCK_PROXIMITY_SCREEN_OFF;
break;
case PowerManager.DOZE_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_DOZE;
break;
case PowerManager.DRAW_WAKE_LOCK:
mWakeLockSummary |= WAKE_LOCK_DRAW;
break;
}
}
// Cancel wake locks that make no sense based on the current state.
if (mWakefulness != WAKEFULNESS_DOZING) { //根据当前的屏幕状态, 取消不必要的wakeLocks
mWakeLockSummary &= ~(WAKE_LOCK_DOZE | WAKE_LOCK_DRAW);
}
if (mWakefulness == WAKEFULNESS_ASLEEP //如果屏幕为休眠,就将屏幕高亮,dim锁取消
|| (mWakeLockSummary & WAKE_LOCK_DOZE) != 0) {
mWakeLockSummary &= ~(WAKE_LOCK_SCREEN_BRIGHT | WAKE_LOCK_SCREEN_DIM
| WAKE_LOCK_BUTTON_BRIGHT);
if (mWakefulness == WAKEFULNESS_ASLEEP) {
mWakeLockSummary &= ~WAKE_LOCK_PROXIMITY_SCREEN_OFF;
}
}
// Infer implied wake locks where necessary based on the current state.
if ((mWakeLockSummary & (WAKE_LOCK_SCREEN_BRIGHT | WAKE_LOCK_SCREEN_DIM)) != 0) {
if (mWakefulness == WAKEFULNESS_AWAKE) {
mWakeLockSummary |= WAKE_LOCK_CPU | WAKE_LOCK_STAY_AWAKE; //当WakeLock为亮屏锁或dim锁时，需要保持AWAKE状态。
} else if (mWakefulness == WAKEFULNESS_DREAMING) {
mWakeLockSummary |= WAKE_LOCK_CPU;
}
}
if ((mWakeLockSummary & WAKE_LOCK_DRAW) != 0) {
mWakeLockSummary |= WAKE_LOCK_CPU;
}
if (DEBUG_SPEW) {
Slog.d(TAG, "updateWakeLockSummaryLocked: mWakefulness="
+ PowerManagerInternal.wakefulnessToString(mWakefulness)
+ ", mWakeLockSummary=0x" + Integer.toHexString(mWakeLockSummary));
}
}
} private void updateUserActivitySummaryLocked(long now, int dirty) {
// Update the status of the user activity timeout timer.
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY
| DIRTY_WAKEFULNESS | DIRTY_SETTINGS)) != 0) {
mHandler.removeMessages(MSG_USER_ACTIVITY_TIMEOUT); //移除屏幕超时的Message
long nextTimeout = 0;
if (mWakefulness == WAKEFULNESS_AWAKE
|| mWakefulness == WAKEFULNESS_DREAMING
|| mWakefulness == WAKEFULNESS_DOZING) {
final int sleepTimeout = getSleepTimeoutLocked(); //获取睡眠超时时间
final int screenOffTimeout = getScreenOffTimeoutLocked(sleepTimeout); //获取屏幕超时时间
final int screenDimDuration = getScreenDimDurationLocked(screenOffTimeout); //获取dim持续时长
final boolean userInactiveOverride = mUserInactiveOverrideFromWindowManager;
mUserActivitySummary = 0;
if (mLastUserActivityTime >= mLastWakeTime) { //最后一次的用户时间大于最后一次屏幕醒来的时间
nextTimeout = mLastUserActivityTime //计算下一次屏幕要变为dim的时间
+ screenOffTimeout - screenDimDuration;
if (now < nextTimeout) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_BRIGHT; //现在还早于屏幕超时, 设置现在用户活动为屏幕高亮
} else {
nextTimeout = mLastUserActivityTime + screenOffTimeout; //重新设置屏幕超时时间,进入dim阶段
if (now < nextTimeout) { //进入dim阶段了
mUserActivitySummary = USER_ACTIVITY_SCREEN_DIM;
}
}
}
if (mUserActivitySummary == 0
&& mLastUserActivityTimeNoChangeLights >= mLastWakeTime) {
nextTimeout = mLastUserActivityTimeNoChangeLights + screenOffTimeout;
if (now < nextTimeout) { //根据请求的policy来判断屏幕是高亮,还是dim状态
if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_BRIGHT) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_BRIGHT;
} else if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_DIM) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DIM;
}
}
}
if (mUserActivitySummary == 0) { //如果mUserActivitySummary还没赋值
if (sleepTimeout >= 0) {
final long anyUserActivity = Math.max(mLastUserActivityTime,
mLastUserActivityTimeNoChangeLights);
if (anyUserActivity >= mLastWakeTime) {
nextTimeout = anyUserActivity + sleepTimeout;
if (now < nextTimeout) {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DREAM; //设置dream状态
}
}
} else {
mUserActivitySummary = USER_ACTIVITY_SCREEN_DREAM;
nextTimeout = -1;
}
}
if (mUserActivitySummary != USER_ACTIVITY_SCREEN_DREAM && userInactiveOverride) {
if ((mUserActivitySummary &
(USER_ACTIVITY_SCREEN_BRIGHT | USER_ACTIVITY_SCREEN_DIM)) != 0) {
// Device is being kept awake by recent user activity
if (nextTimeout >= now && mOverriddenTimeout == -1) {
// Save when the next timeout would have occurred
mOverriddenTimeout = nextTimeout;
}
}
mUserActivitySummary = USER_ACTIVITY_SCREEN_DREAM;
nextTimeout = -1;
}
if (mUserActivitySummary != 0 && nextTimeout >= 0) { //mUserActivitySummary有值, 并且nextTimeout大于等于0, 发超时消息
Message msg = mHandler.obtainMessage(MSG_USER_ACTIVITY_TIMEOUT);
msg.setAsynchronous(true);
mHandler.sendMessageAtTime(msg, nextTimeout); //发送屏幕超时的Message
}
} else {
mUserActivitySummary = 0;
}
if (DEBUG_SPEW) {
Slog.d(TAG, "updateUserActivitySummaryLocked: mWakefulness="
+ PowerManagerInternal.wakefulnessToString(mWakefulness)
+ ", mUserActivitySummary=0x" + Integer.toHexString(mUserActivitySummary)
+ ", nextTimeout=" + TimeUtils.formatUptime(nextTimeout));
}
}
}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.
/**
* Handler for asynchronous operations performed by the power manager.
*/
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
}
}
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;
} 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;
} 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);
} 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.
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。
private boolean updateDisplayPowerStateLocked(int dirty) {
final boolean oldDisplayReady = mDisplayReady;
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY | DIRTY_WAKEFULNESS
| DIRTY_ACTUAL_DISPLAY_POWER_STATE_UPDATED | DIRTY_BOOT_COMPLETED
| DIRTY_SETTINGS | DIRTY_SCREEN_BRIGHTNESS_BOOST)) != 0) {
mDisplayPowerRequest.policy = getDesiredScreenPolicyLocked(); //根据mWakefulness与mWakeLockSummary获得,设备新状态是DIM, BRIGHT, OFF还是DOZE
// Determine appropriate screen brightness and auto-brightness adjustments.
boolean brightnessSetByUser = true;
int screenBrightness = mScreenBrightnessSettingDefault;
float screenAutoBrightnessAdjustment = 0.0f; //自动亮度调节
boolean autoBrightness = (mScreenBrightnessModeSetting ==
Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC); //是否开启自动亮度
if (isValidBrightness(mScreenBrightnessOverrideFromWindowManager)) {
screenBrightness = mScreenBrightnessOverrideFromWindowManager;
autoBrightness = false;
brightnessSetByUser = false;
} else if (isValidBrightness(mTemporaryScreenBrightnessSettingOverride)) {
screenBrightness = mTemporaryScreenBrightnessSettingOverride;
} else if (isValidBrightness(mScreenBrightnessSetting)) {
screenBrightness = mScreenBrightnessSetting;
}
if (autoBrightness) {
screenBrightness = mScreenBrightnessSettingDefault; //自动亮度调节
if (isValidAutoBrightnessAdjustment(
mTemporaryScreenAutoBrightnessAdjustmentSettingOverride)) {
screenAutoBrightnessAdjustment =
mTemporaryScreenAutoBrightnessAdjustmentSettingOverride;
} else if (isValidAutoBrightnessAdjustment(
mScreenAutoBrightnessAdjustmentSetting)) {
screenAutoBrightnessAdjustment = mScreenAutoBrightnessAdjustmentSetting;
}
}
screenBrightness = Math.max(Math.min(screenBrightness, //获得请求亮度
mScreenBrightnessSettingMaximum), mScreenBrightnessSettingMinimum);
screenAutoBrightnessAdjustment = Math.max(Math.min(
screenAutoBrightnessAdjustment, 1.0f), -1.0f);
// Update display power request. //将数据记录在mDisplayPowerRequest中
mDisplayPowerRequest.screenBrightness = screenBrightness;
mDisplayPowerRequest.screenAutoBrightnessAdjustment =
screenAutoBrightnessAdjustment;
mDisplayPowerRequest.brightnessSetByUser = brightnessSetByUser;
mDisplayPowerRequest.useAutoBrightness = autoBrightness;
mDisplayPowerRequest.useProximitySensor = shouldUseProximitySensorLocked();
mDisplayPowerRequest.lowPowerMode = mLowPowerModeEnabled;
mDisplayPowerRequest.boostScreenBrightness = mScreenBrightnessBoostInProgress;
mDisplayPowerRequest.useTwilight = mBrightnessUseTwilight;
if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_DOZE) {
mDisplayPowerRequest.dozeScreenState = mDozeScreenStateOverrideFromDreamManager;
if (mDisplayPowerRequest.dozeScreenState == Display.STATE_DOZE_SUSPEND
&& (mWakeLockSummary & WAKE_LOCK_DRAW) != 0) {
mDisplayPowerRequest.dozeScreenState = Display.STATE_DOZE;
}
mDisplayPowerRequest.dozeScreenBrightness =
mDozeScreenBrightnessOverrideFromDreamManager;
} else {
mDisplayPowerRequest.dozeScreenState = Display.STATE_UNKNOWN;
mDisplayPowerRequest.dozeScreenBrightness = PowerManager.BRIGHTNESS_DEFAULT;
}
mDisplayReady = mDisplayManagerInternal.requestPowerState(mDisplayPowerRequest,
mRequestWaitForNegativeProximity); //调用requestPowerState请求电源状态
mRequestWaitForNegativeProximity = false;
if (DEBUG_SPEW) {
Slog.d(TAG, "updateDisplayPowerStateLocked: mDisplayReady=" + mDisplayReady
+ ", policy=" + mDisplayPowerRequest.policy
+ ", mWakefulness=" + mWakefulness
+ ", mWakeLockSummary=0x" + Integer.toHexString(mWakeLockSummary)
+ ", mUserActivitySummary=0x" + Integer.toHexString(mUserActivitySummary)
+ ", mBootCompleted=" + mBootCompleted
+ ", mScreenBrightnessBoostInProgress="
+ mScreenBrightnessBoostInProgress);
}
}
return mDisplayReady && !oldDisplayReady;
}