Android7.0 PowerManagerService 之亮滅屏（一）
本篇從按下power按鍵後，按鍵事件從InputManagerService 傳到PhoneWindowManager.java開始分析power 按鍵做屏幕亮滅過程的分析，關於power 按鍵的其他行爲參考另一篇博文（Android 7.0 Power 按鍵處理流程）
（注：博客園顯示的圖片很模糊，上傳的爲大圖，可以圖片另存爲查看）
言歸正傳，本篇涉及的幾個模塊（文件）如下，先做個簡單的介紹有個直觀大概的瞭解，方便後面流程細節的理解。
Ø PowerManagerService.Java：（/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java）
PMS，是Android系統中的電源處理服務，主要負責電源相關的計算和決策，如是否應該滅屏 或者讓屏幕變暗，是否應該讓系統休眠等等。
Ø DisplayPowerController.java：（/frameworks/base/services/core/java/com/android/server/display/DisplayPowerController.java）
DPC，管理顯示設備（這裏指的顯示設備是屏幕）狀態，主要處理距離傳感器（如打電話時候靠近則滅屏，離開時候屏幕亮起）以及亮滅屏動畫（包括根據光感傳感器計算屏幕目標亮度值）。在DisplayManagerService.java(DMS)中實例化一個對象，以DMS爲橋樑與PMS進行交互通過異步回調機制來通知PMS那些發生了改變。同時也與WMS進行交互。
Ø DisplayPowerState.java：（/frameworks/base/services/core/java/com/android/server/display/DisplayPowerState.java）
DPS，管理顯示設備的狀態僅在DPC中實例化一個對象，是DPC的一部分。
Ø Notifier.java：（ /frameworks/base/services/core/java/com/android/server/power/Notifier.java）
將電源狀態的重要變化，通過廣播通知出去。
Ø ColorFade.java：（/frameworks/base/services/core/java/com/android/server/display/ColorFade.java）
是負責屏幕由關到開，由開到關的一些GL動畫，由DPC進行控制。
Ø AutomaticBrightnessController.java：（/frameworks/base/services/core/java/com/android/server/display/AutomaticBrightnessController.java）
主要處理光傳感器，將底層上傳的參數進行處理計算，將計算的新的亮度值傳給DPC來設定屏幕的亮度值（即根據環境的光線強度來計算屏幕的亮暗程度）。
Ø RampAnimator.java：（/frameworks/base/services/core/java/com/android/server/display/RampAnimator.java）
僅僅是屏幕亮度漸變動畫。
一、Power按鍵的上報與處理
詳細見【Android 7.0 Power 按鍵處理流程】此處僅略微的複習一下，方便了後面的理解。
1）Power按鍵的上報
在InputManagerService收到power按鍵事件經過一系列的處理和轉換最終將會傳遞到PhoneWindowManager（PWM）的interceptKeyBeforeQueueing（）函數來做具體的業務邏輯.下圖爲上報的流程圖。
2）power 按鍵關於量滅屏處理
關於量滅屏的處理主要在interceptKeyBeforeQueueing（）函數中。判斷是否是isWakeKey，如果是則在此函數的最後通過調用wakeUp（）函數來具體處理，這就拉開了本文的序幕。
注：此函數很長本文刪除無關的部分，僅僅保留部分和量滅屏相關的說明具體處理流程即可。詳細參考【Android 7.0 Power 按鍵處理流程】
A: 按鍵處理判斷是否要量滅屏
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處理量滅屏
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); //調用PowerManagerService亮屏操作
return true;
}
}
二、PowerManagerService處理量滅屏過程
從上面的分析可知，在PWM中處理按鍵事件如果需要喚醒屏幕則會調用PWM的wakeUp（）函數，此函數會調用PMS 的wakeUp（）函數來具體處理。
從上面的分析可知，在PWM中處理按鍵事件如果需要喚醒屏幕則會調用PWM的wakeUp（）函數，此函數會調用PMS 的wakeUp（）函數來具體處理。
注：限於篇幅本文僅列出重要的函數和調用過程
首先來個概覽，瞭解一下主要完成了如下三件事
1） 由Notifier根據系統的具體狀態來發出廣播
2） PMS 通過updatePowerStateLocked（）計算和更新電源的全局狀態
3） PMS將最新的電源狀態等傳入DPC中，根據距離傳感器和光感傳感器，計算具體的屏幕亮度和量滅屏動畫等
4） DPC通知PWM繪製keyguard與windows（此時會block等待繪製完成，滅屏時候無需繪製），繪製完成後通知DPC繼續
5） DPC具體調用顯示設備開啓或關閉屏幕（執行量滅屏的動畫效果）
1）PowerManagerService--wakeUpNoUpdateLocked()
PMS首先講wakefullness狀態. 之後發送亮滅屏廣播通知其他應用手機處於亮屏還是滅屏狀態。
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; //判斷是否要去亮屏
}
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; //設置最後一次喚醒的時間
setWakefulnessLocked(WAKEFULNESS_AWAKE, 0); //Notifier調用onWakefulnessChangeStarted發送亮屏廣播
mNotifier.onWakeUp(reason, reasonUid, opPackageName, opUid); //調用Notifier通知battery處理
userActivityNoUpdateLocked( //更新最後一次用戶事件時間
eventTime, PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, reasonUid);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
return true;
}
1）Notifier 發送量滅屏廣播
Notifier發送廣播前會與與AMS，WMS，IMS進行交互，通知各模塊電源狀態的改變，各模塊會自行處理電源狀態改變通知。
A:onWakefulnessChangeStarted()
public void onWakefulnessChangeStarted(final int wakefulness, int reason) {
final boolean interactive = PowerManagerInternal.isInteractive(wakefulness); //亮屏true, 滅屏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); //與AMS交互處理
}
});
// 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中記錄現在的屏幕狀態
mInputMethodManagerInternal.setInteractive(interactive);
// Notify battery stats.
try {
mBatteryStats.noteInteractive(interactive); //喚醒battery狀態
} catch (RemoteException ex) { }
// Handle early behaviors.
mInteractive = interactive;
mInteractiveChangeReason = reason;
mInteractiveChanging = true;
handleEarlyInteractiveChange(); //初期處理交互模式改變
}
}
B: handleEarlyInteractiveChange()
當屏幕在wakingup時需要通知window進行更新手勢監聽，更新方向監聽，更新鎖屏超時時間
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(); //更新亮屏廣播
} else {
// Going to sleep... //滅屏
// 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();//這裏發送亮屏廣播
} else {
sendGoToSleepBroadcast();
}
}
（3）sendWakeUpBroadcast()
注意：Notifier 自身也會接收亮屏廣播，其受到後會調用finishPendingBroadcastLocked()函數來釋放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();
}
}
