在前面兩部分已經(jīng)對繪制windows與設置設備狀態(tài)進行了詳細講解. 之后接著就該對亮度值進行設置, 實現(xiàn)亮屏動作了.

在DisplayPowerController中的animateScreenBrightness函數(shù)通過亮度漸變動畫來將亮度設置到目標亮度.

[java]?view plain?copy

//?Brightness?animation?ramp?rate?in?brightness?units?per?second.??

private?static?final?int?BRIGHTNESS_RAMP_RATE_SLOW?=?40;?????//亮度漸變動畫較慢的速率,?每秒變化40個亮度單位???

??

????mBrightnessRampRateFast?=?resources.getInteger(??

????????????com.android.internal.R.integer.config_brightness_ramp_rate_fast);???//從配置文件中獲取較快的亮度速率??

??

????//?Animate?the?screen?brightness?when?the?screen?is?on?or?dozing.??

????//?Skip?the?animation?when?the?screen?is?off?or?suspended.??

????if?(!mPendingScreenOff)?{??

????????if?(state?==?Display.STATE_ON?||?state?==?Display.STATE_DOZE)?{??

????????????animateScreenBrightness(brightness,??????//當亮屏或doze狀態(tài)時有亮度漸變動畫??

????????????????????slowChange???BRIGHTNESS_RAMP_RATE_SLOW?:?mBrightnessRampRateFast);??

????????}?else?{??

????????????animateScreenBrightness(brightness,?0);???//滅屏時沒有亮度漸變動畫,直接將亮度設置為0??

????????}??

????}??

在animateScreenBrightness函數(shù)中調(diào)用動畫mScreenBrightnessRampAnimator對亮度值處理, 而mScreenBrightnessRampAnimator是在initialize()函數(shù)中進行初始化的, 在構(gòu)造函數(shù)中將DisplayPowerState和DisplayPowerState.SCREEN_BRIGHTNESS傳輸過去.

[java]?view plain?copy

??private?void?initialize()?{??

??????//....??

????????mScreenBrightnessRampAnimator?=?new?RampAnimator<DisplayPowerState>(??//泛型為DisplayPowerState??

????????????????mPowerState,?DisplayPowerState.SCREEN_BRIGHTNESS);??

????????mScreenBrightnessRampAnimator.setListener(mRampAnimatorListener);??

?????//...??

}??

??

????private?void?animateScreenBrightness(int?target,?int?rate)?{??

????????if?(DEBUG)?{??

????????????Slog.d(TAG,?"Animating?brightness:?target="?+?target?+",?rate="?+?rate);??

????????}??

????????if?(mScreenBrightnessRampAnimator.animateTo(target,?rate))?{????//動畫處理亮度值??

????????????try?{??

????????????????mBatteryStats.noteScreenBrightness(target);??

????????????}?catch?(RemoteException?ex)?{??

????????????????//?same?process??

????????????}??

????????}??

????}??

在RampAnimator的構(gòu)造函數(shù)中將DisplayPowerState賦值給mObject,?DisplayPowerState.SCREEN_BRIGHTNESS賦值給mProperty, 并且創(chuàng)建mChoreographer實例.

[java]?view plain?copy

public?RampAnimator(T?object,?IntProperty<T>?property)?{??

????mObject?=?object;??

????mProperty?=?property;??

????mChoreographer?=?Choreographer.getInstance();??

}??

下面重點講解animateTo函數(shù).

[java]?view plain?copy

public?boolean?animateTo(int?target,?int?rate)?{??

????//?Immediately?jump?to?the?target?the?first?time.??

????if?(mFirstTime?||?rate?<=?0)?{???//當?shù)谝淮握{(diào)用animateTo,?或者rate小于等于0時直接設置目標亮度.??

????????if?(mFirstTime?||?target?!=?mCurrentValue)?{??

????????????mFirstTime?=?false;???//之后就不是第一次調(diào)用該函數(shù)??

????????????mRate?=?0;??????????????//設置mRate為0??

????????????mTargetValue?=?target;???//設置目標亮度為target??

????????????mCurrentValue?=?target;??

????????????mProperty.setValue(mObject,?target);???//調(diào)用DisplayPowerState.SCREEN_BRIGHTNESS設置亮度值??

????????????if?(mAnimating)?{??

????????????????mAnimating?=?false;??

????????????????cancelAnimationCallback();??

????????????}??

????????????if?(mListener?!=?null)?{??

????????????????mListener.onAnimationEnd();??//動畫結(jié)束??

????????????}??

????????????return?true;??

????????}??

????????return?false;??

????}??

??

????//?Adjust?the?rate?based?on?the?closest?target.??

????//?If?a?faster?rate?is?specified,?then?use?the?new?rate?so?that?we?converge??

????//?more?rapidly?based?on?the?new?request.??

????//?If?a?slower?rate?is?specified,?then?use?the?new?rate?only?if?the?current??

????//?value?is?somewhere?in?between?the?new?and?the?old?target?meaning?that??

????//?we?will?be?ramping?in?a?different?direction?to?get?there.??

????//?Otherwise,?continue?at?the?previous?rate.??

????if?(!mAnimating??

????????????||?rate?>?mRate??

????????????||?(target?<=?mCurrentValue?&&?mCurrentValue?<=?mTargetValue)??

????????????||?(mTargetValue?<=?mCurrentValue?&&?mCurrentValue?<=?target))?{??

????????mRate?=?rate;???//重新調(diào)節(jié)亮度速率??

????}??

??

????final?boolean?changed?=?(mTargetValue?!=?target);??//如果當前亮度值不等于目標亮度值,說明亮度改變了??

????mTargetValue?=?target;????//重新設置mTargetValue??

??

????//?Start?animating.??開始動畫??

????if?(!mAnimating?&&?target?!=?mCurrentValue)?{????

????????mAnimating?=?true;??

????????mAnimatedValue?=?mCurrentValue;??

????????mLastFrameTimeNanos?=?System.nanoTime();??

????????postAnimationCallback();??

????}??

??

????return?changed;???

}??

在postAnimationCallback中調(diào)用Choreographer的postCallback函數(shù)處理, 調(diào)用完成后回調(diào)回mAnimationCallback的run函數(shù)

[java]?view plain?copy

private?void?postAnimationCallback()?{??

????mChoreographer.postCallback(Choreographer.CALLBACK_ANIMATION,?mAnimationCallback,?null);??

}??

??

private?final?Runnable?mAnimationCallback?=?new?Runnable()?{??

????@Override?//?Choreographer?callback??

????public?void?run()?{??

????????final?long?frameTimeNanos?=?mChoreographer.getFrameTimeNanos();??

????????final?float?timeDelta?=?(frameTimeNanos?-?mLastFrameTimeNanos)??

????????????????*?0.000000001f;??

????????mLastFrameTimeNanos?=?frameTimeNanos;??//記錄最后一次的frameTimeNanos??

??

????????//?Advance?the?animated?value?towards?the?target?at?the?specified?rate??

????????//?and?clamp?to?the?target.?This?gives?us?the?new?current?value?but??

????????//?we?keep?the?animated?value?around?to?allow?for?fractional?increments??

????????//?towards?the?target.??

????????final?float?scale?=?ValueAnimator.getDurationScale();??

????????if?(scale?==?0)?{??

????????????//?Animation?off.??

????????????mAnimatedValue?=?mTargetValue;???//讓scale為0時,?表示動畫停止了,?將mAnimatedValue設置為目標亮度??

????????}?else?{??

????????????final?float?amount?=?timeDelta?*?mRate?/?scale;??//計算每一次需要變化的亮度值??

????????????if?(mTargetValue?>?mCurrentValue)?{??

????????????????mAnimatedValue?=?Math.min(mAnimatedValue?+?amount,?mTargetValue);??//亮屏,每次增加亮度amount,不超過目標亮度??

????????????}?else?{??

????????????????mAnimatedValue?=?Math.max(mAnimatedValue?-?amount,?mTargetValue);?//暗屏,?每次減少amount個亮度,?不超過目標亮度??

????????????}??

????????}??

????????final?int?oldCurrentValue?=?mCurrentValue;??

????????mCurrentValue?=?Math.round(mAnimatedValue);??//獲取當前要達到的亮度值??

??

????????if?(oldCurrentValue?!=?mCurrentValue)?{??

????????????mProperty.setValue(mObject,?mCurrentValue);??//調(diào)用DisplayPowerState.SCREEN_BRIGHTNESS設置亮度值??

????????}??

??

????????if?(mTargetValue?!=?mCurrentValue)?{??

????????????postAnimationCallback();???//如果還沒有達到目標亮度,就會繼續(xù)調(diào)用postAnimationCallback循環(huán)設置亮度值??

????????}?else?{??

????????????mAnimating?=?false;??

????????????if?(mListener?!=?null)?{??

????????????????mListener.onAnimationEnd();??//否則,亮度動畫結(jié)束??

????????????}??

????????}??

????}??

};??

DisplayPowerState.SCREEN_BRIGHTNESS的setValue函數(shù)是在DisplayPowerState中實現(xiàn)的.

[java]?view plain?copy

public?static?final?IntProperty<DisplayPowerState>?SCREEN_BRIGHTNESS?=??

????????new?IntProperty<DisplayPowerState>("screenBrightness")?{??

????@Override??

????public?void?setValue(DisplayPowerState?object,?int?value)?{??

????????object.setScreenBrightness(value);??//調(diào)用DisplayPowerState的setScreenBrightness函數(shù),設置亮度值??

????}??

??

????@Override??

????public?Integer?get(DisplayPowerState?object)?{??

????????return?object.getScreenBrightness();??

????}??

};??

??

public?void?setScreenBrightness(int?brightness)?{??

????if?(mScreenBrightness?!=?brightness)?{??

????????if?(DEBUG)?{??

????????????Slog.d(TAG,?"setScreenBrightness:?brightness="?+?brightness);??

????????}??

??

????????mScreenBrightness?=?brightness;??//設置全局的亮度值??

????????if?(mScreenState?!=?Display.STATE_OFF)?{??

????????????mScreenReady?=?false;??

????????????scheduleScreenUpdate();???//如果不是滅屏狀態(tài),更新屏幕狀態(tài)??

????????}??

????}??

}??

scheduleScreenUpdate函數(shù)最終通過Handler發(fā)送mScreenUpdateRunnable對象來更新亮度值. 從run函數(shù)中可以看出只有當mColorFadeLevel > 0f時才能給brightness設置亮度值, 所以說當windows沒有繪制完成時就算mScreenBrightness有值不為0, 但是brightness仍然為0不能點亮屏幕.

[java]?view plain?copy

private?final?Runnable?mScreenUpdateRunnable?=?new?Runnable()?{??

????@Override??

????public?void?run()?{??

????????mScreenUpdatePending?=?false;??

??

????????int?brightness?=?mScreenState?!=?Display.STATE_OFF??

????????????????&&?mColorFadeLevel?>?0f???mScreenBrightness?:?0;????//判斷設置亮度值??

????????if?(mPhotonicModulator.setState(mScreenState,?brightness))?{??

????????????if?(DEBUG)?{??

????????????????Slog.d(TAG,?"Screen?ready");??

????????????}??

????????????mScreenReady?=?true;??

????????????invokeCleanListenerIfNeeded();??

????????}?else?{??

????????????if?(DEBUG)?{??

????????????????Slog.d(TAG,?"Screen?not?ready");??

????????????}??

????????}??

????}??

};??

之后的流程就與設置設置狀態(tài)的流程相同了, 調(diào)用DisplayManagerService中DisplayBlanker的requestDisplayState函數(shù).

[java]?view plain?copy

DisplayBlanker?blanker?=?new?DisplayBlanker()?{??

????@Override??

????public?void?requestDisplayState(int?state,?int?brightness)?{??

????????//?The?order?of?operations?is?important?for?legacy?reasons.??

????????if?(state?==?Display.STATE_OFF)?{??

????????????requestGlobalDisplayStateInternal(state,?brightness);??

????????}??

??

????????callbacks.onDisplayStateChange(state);??????

??

????????if?(state?!=?Display.STATE_OFF)?{??

????????????requestGlobalDisplayStateInternal(state,?brightness);??//亮屏調(diào)用設置狀態(tài),亮度??

????????}??

????}??

};??

[java]?view plain?copy

private?void?requestGlobalDisplayStateInternal(int?state,?int?brightness)?{??

????if?(state?==?Display.STATE_UNKNOWN)?{??

????????state?=?Display.STATE_ON;??

????}??

????if?(state?==?Display.STATE_OFF)?{??

????????brightness?=?PowerManager.BRIGHTNESS_OFF;??//滅屏設置屏幕亮度為0??

????}?else?if?(brightness?<?0)?{??

????????brightness?=?PowerManager.BRIGHTNESS_DEFAULT;??//屏幕亮度小于0,設置為默認亮度??

????}?else?if?(brightness?>?PowerManager.BRIGHTNESS_ON)?{??

????????brightness?=?PowerManager.BRIGHTNESS_ON;????//屏幕亮度大于255設置最大亮度值255??

????}??

??

????synchronized?(mTempDisplayStateWorkQueue)?{??

????????try?{??

????????????//?Update?the?display?state?within?the?lock.??

????????????//?Note?that?we?do?not?need?to?schedule?traversals?here?although?it??

????????????//?may?happen?as?a?side-effect?of?displays?changing?state.??

????????????synchronized?(mSyncRoot)?{??

????????????????if?(mGlobalDisplayState?==?state??

????????????????????????&&?mGlobalDisplayBrightness?==?brightness)?{??

????????????????????return;?//?no?change?????亮度與狀態(tài)都沒有改變就return??

????????????????}??

??

????????????????Trace.traceBegin(Trace.TRACE_TAG_POWER,?"requestGlobalDisplayState("??

????????????????????????+?Display.stateToString(state)??

????????????????????????+?",?brightness="?+?brightness?+?")");??

????????????????mGlobalDisplayState?=?state;??

????????????????mGlobalDisplayBrightness?=?brightness;??

????????????????applyGlobalDisplayStateLocked(mTempDisplayStateWorkQueue);???//應用全局狀態(tài)??

????????????}??

??

????????????//?Setting?the?display?power?state?can?take?hundreds?of?milliseconds??

????????????//?to?complete?so?we?defer?the?most?expensive?part?of?the?work?until??

????????????//?after?we?have?exited?the?critical?section?to?avoid?blocking?other??

????????????//?threads?for?a?long?time.??

????????????for?(int?i?=?0;?i?<?mTempDisplayStateWorkQueue.size();?i++)?{??

????????????????mTempDisplayStateWorkQueue.get(i).run();??//運行mTempDisplayStateWorkQueue隊列中的runnable??

????????????}??

????????????Trace.traceEnd(Trace.TRACE_TAG_POWER);??

????????}?finally?{??

????????????mTempDisplayStateWorkQueue.clear();??

????????}??

????}??

}??

在applyGlobalDisplayStateLocked函數(shù)中獲取所有的devices, 調(diào)用對應設備的requestDisplayStateLocked函數(shù)更新請求狀態(tài). 啟動devices為LocalDisplayAdapter, 就會調(diào)用到該類的requestDisplayStateLocked獲得runnable.
[java]?view plain?copy

private?void?applyGlobalDisplayStateLocked(List<Runnable>?workQueue)?{??

????final?int?count?=?mDisplayDevices.size();??

????for?(int?i?=?0;?i?<?count;?i++)?{???//遍歷devices??

????????DisplayDevice?device?=?mDisplayDevices.get(i);??

????????Runnable?runnable?=?updateDisplayStateLocked(device);??//獲得devices中的runnable??

????????if?(runnable?!=?null)?{??

????????????workQueue.add(runnable);??//將runnable加入workQueue隊列,?即mTempDisplayStateWorkQueue隊列??

????????}??

????}??

}??

??

private?Runnable?updateDisplayStateLocked(DisplayDevice?device)?{??

????//?Blank?or?unblank?the?display?immediately?to?match?the?state?requested??

????//?by?the?display?power?controller?(if?known).??

????DisplayDeviceInfo?info?=?device.getDisplayDeviceInfoLocked();??//獲取devices信息??

????if?((info.flags?&?DisplayDeviceInfo.FLAG_NEVER_BLANK)?==?0)?{??

????????return?device.requestDisplayStateLocked(mGlobalDisplayState,?mGlobalDisplayBrightness);?//調(diào)用requestDisplayStateLocked函數(shù)??

????}??

????return?null;??

}??

在requestDisplayStateLocked中主要的任務就是創(chuàng)建一個runnable返回到DisplayManagerService中,并且等待回調(diào)run函數(shù).

[java]?view plain?copy

@Override??

public?Runnable?requestDisplayStateLocked(final?int?state,?final?int?brightness)?{??

????//?Assume?that?the?brightness?is?off?if?the?display?is?being?turned?off.??

????assert?state?!=?Display.STATE_OFF?||?brightness?==?PowerManager.BRIGHTNESS_OFF;??

??

????final?boolean?stateChanged?=?(mState?!=?state);??//狀態(tài)是否改變??

????final?boolean?brightnessChanged?=?(mBrightness?!=?brightness)?&&?mBacklight?!=?null;??//亮度值是否改變??

????if?(stateChanged?||?brightnessChanged)?{??//如果亮度值或者亮度狀態(tài)發(fā)生改變就重新設置對應值??

????????final?int?displayId?=?mBuiltInDisplayId;??

????????final?IBinder?token?=?getDisplayTokenLocked();??

????????final?int?oldState?=?mState;??

??

????????if?(stateChanged)?{???//設置亮度時.狀態(tài)已經(jīng)設置好,無變化??

????????????mState?=?state;??

????????????updateDeviceInfoLocked();??

????????}??

??

????????if?(brightnessChanged)?{??

????????????mBrightness?=?brightness;??//設置mBrightness??

????????}??

??

????????//?Defer?actually?setting?the?display?state?until?after?we?have?exited??

????????//?the?critical?section?since?it?can?take?hundreds?of?milliseconds??

????????//?to?complete.??

????????return?new?Runnable()?{????//新建一個runnable返回??

????????????@Override??

????????????public?void?run()?{??//在DisplayManagerService中調(diào)用run函數(shù)??

????????????????//?Exit?a?suspended?state?before?making?any?changes.????

????????????????int?currentState?=?oldState;??

????????????????if?(Display.isSuspendedState(oldState)????//判斷設置是否還是在suspend狀態(tài)??

????????????????????????||?oldState?==?Display.STATE_UNKNOWN)?{??

????????????????????if?(!Display.isSuspendedState(state))?{??

????????????????????????setDisplayState(state);??

????????????????????????currentState?=?state;??

????????????????????}?else?if?(state?==?Display.STATE_DOZE_SUSPEND??

????????????????????????????||?oldState?==?Display.STATE_DOZE_SUSPEND)?{??

????????????????????????setDisplayState(Display.STATE_DOZE);??

????????????????????????currentState?=?Display.STATE_DOZE;??

????????????????????}?else?{??

????????????????????????return;?//?old?state?and?new?state?is?off??

????????????????????}??

????????????????}??

??

????????????????//?Apply?brightness?changes?given?that?we?are?in?a?non-suspended?state.??

????????????????if?(brightnessChanged)?{??

????????????????????if?(isPowerDebug())?{??

????????????????????????Slog.d(TAG,?"set?display?brightness="?+?brightness);??

????????????????????}??

????????????????????setDisplayBrightness(brightness);????//設置屏幕亮度??

????????????????}??

??

????????????????//?Enter?the?final?desired?state,?possibly?suspended.??

????????????????if?(state?!=?currentState)?{??

????????????????????if(isPowerDebug())?{??

????????????????????????Slog.d(TAG,?"set?display?state="?+?state);??

????????????????????}??

????????????????????setDisplayState(state);??

????????????????}??

????????????}??

[java]?view plain?copy

????????????private?void?setDisplayBrightness(int?brightness)?{??

????????????????if?(DEBUG)?{??

????????????????????Slog.d(TAG,?"setDisplayBrightness("??

????????????????????????????+?"id="?+?displayId?+?",?brightness="?+?brightness?+?")");??

????????????????}??

??

????????????????Trace.traceBegin(Trace.TRACE_TAG_POWER,?"setDisplayBrightness("??

????????????????????????+?"id="?+?displayId?+?",?brightness="?+?brightness?+?")");??

????????????????try?{??

????????????????????mBacklight.setBrightness(brightness);???//調(diào)用LightService設置亮度??

????????????????}?finally?{??

????????????????????Trace.traceEnd(Trace.TRACE_TAG_POWER);??

????????????????}??

????????????}??

????????};??

????}??

????return?null;??

}??

[java]?view plain?copy

@Override??

public?void?setBrightness(int?brightness)?{??

????setBrightness(brightness,?BRIGHTNESS_MODE_USER);???//亮度模式默認為BRIGHTNESS_MODE_USER??

}??

??

@Override??

public?void?setBrightness(int?brightness,?int?brightnessMode)?{??

????synchronized?(this)?{??

????????int?color?=?brightness?&?0x000000ff;??

????????color?=?0xff000000?|?(color?<<?16)?|?(color?<<?8)?|?color;???//設置光顏色??

????????setLightLocked(color,?LIGHT_FLASH_NONE,?0,?0,?brightnessMode);??

????}??

}??

private?void?setLightLocked(int?color,?int?mode,?int?onMS,?int?offMS,?int?brightnessMode)?{??

????if?(!LightsUtilsFactory.getInstance().isBatteryOpenWhenNotificationCome(mId,?color)){??

????????if?(!mLocked?&&?(color?!=?mColor?||?mode?!=?mMode?||?onMS?!=?mOnMS?||?offMS?!=?mOffMS?||??

????????????????mBrightnessMode?!=?brightnessMode))?{??

????????????if?(DEBUG?||?isDebugNotifyLight())?Slog.v(TAG,?"setLight?#"?+?mId?+?":?color=#"??

????????????????????+?Integer.toHexString(color)?+?":?brightnessMode="?+?brightnessMode);??

????????????mLastColor?=?mColor;??

????????????mColor?=?color;??

????????????mMode?=?mode;??

????????????mOnMS?=?onMS;??

????????????mOffMS?=?offMS;??

????????????mLastBrightnessMode?=?mBrightnessMode;??

????????????mBrightnessMode?=?brightnessMode;??

????????????Trace.traceBegin(Trace.TRACE_TAG_POWER,?"setLight("?+?mId?+?",?0x"??

????????????????????+?Integer.toHexString(color)?+?")");??

????????????try?{??

????????????????setLight_native(mNativePointer,?mId,?color,?mode,?onMS,?offMS,?brightnessMode);??//調(diào)用jni層設置亮度??

????????????}?finally?{??

????????????????Trace.traceEnd(Trace.TRACE_TAG_POWER);??

????????????}??

????????}??

????}??

}??

通過JNI調(diào)用com_android_server_lights_LightsService.cpp的setLight_native函數(shù)
[java]?view plain?copy

static?void?setLight_native(JNIEnv*?/*?env?*/,?jobject?/*?clazz?*/,?jlong?ptr,??

????????jint?light,?jint?colorARGB,?jint?flashMode,?jint?onMS,?jint?offMS,?jint?brightnessMode)??

{??

????Devices*?devices?=?(Devices*)ptr;??

????light_state_t?state;??

??

????if?(light?<?0?||?light?>=?LIGHT_COUNT?||?devices->lights[light]?==?NULL)?{??

????????return?;??

????}??

??

????uint32_t?version?=?devices->lights[light]->common.version;??

??

????memset(&state,?0,?sizeof(light_state_t));??

??

????if?(brightnessMode?==?BRIGHTNESS_MODE_LOW_PERSISTENCE)?{??

????????if?(light?!=?LIGHT_INDEX_BACKLIGHT)?{??

????????????ALOGE("Cannot?set?low-persistence?mode?for?non-backlight?device.");??

????????????return;??

????????}??

????????if?(version?<?LIGHTS_DEVICE_API_VERSION_2_0)?{??

????????????//?HAL?impl?has?not?been?upgraded?to?support?this.??

????????????return;??

????????}??

????}?else?{??

????????//?Only?set?non-brightness?settings?when?not?in?low-persistence?mode??

????????state.color?=?colorARGB;??

????????state.flashMode?=?flashMode;??

????????state.flashOnMS?=?onMS;??

????????state.flashOffMS?=?offMS;??

????}??

??

????state.brightnessMode?=?brightnessMode;??

??

????{??

????????ALOGD_IF_SLOW(50,?"Excessive?delay?setting?light");???//當設置亮度耗時大于50ms,就會輸出該行l(wèi)og.??

????????devices->lights[light]->set_light(devices->lights[light],?&state);??

????}??

}??

之后調(diào)用BSP向亮度節(jié)點寫入亮度值. 從而點亮屏幕.

滅屏流程分析

滅屏總覽

? ? ? ? ? ? ? ? ? ?

在點擊power鍵滅屏過程中，主要流程就是input對按鍵事件的傳輸，傳送到上層處理。在PhoneWindowManager中判斷是否為滅屏事件, 之后就是在power中進行對亮屏狀態(tài)的處理，計算一系列的數(shù)值，并且與AMS，WMS等模塊進行交互，最后調(diào)用底層LCD進行最終的設備狀態(tài)與亮度的設置。滅屏流程與亮屏流程有很多共同流程，在這里只講解滅屏的獨特流程。
? ? ? ? ? ? ? ? ? ? ? ? ? ??
當wakefulness狀態(tài)發(fā)生改變，AMS收到通知。如果亮屏操作，AMS就會通過函數(shù)comeOutOfSleepIfNeedLocked調(diào)用到ActivityStackSupervisor中，將sleep超時消息移除，如果抓的有partial鎖，就將其釋放，最后將在棧頂?shù)腶ctivity顯示出來。
當亮屏時通過InputManagerService將當前屏幕狀態(tài)傳入JNI中進行記錄，當再次發(fā)生power鍵事件可以方便確認該事件是需要亮屏還是滅屏。
滅屏時首先在Notifier中通過PhoneWindowManager來通知keyguard系統(tǒng)開始滅屏。
滅屏動畫
在PowerManagerService中獲得屏幕的請求狀態(tài)為OFF，即設置state為Display.STATE_OFF，在這里將performScreenOffTransition為true。

[java]?view plain?copy

case?DisplayPowerRequest.POLICY_OFF:??

????state?=?Display.STATE_OFF;??

????performScreenOffTransition?=?true;??

????break;??

調(diào)用animateScreenStateChange進行處理屏幕狀態(tài)。
[java]?view plain?copy

//?Animate?the?screen?state?change?unless?already?animating.??

//?The?transition?may?be?deferred,?so?after?this?point?we?will?use?the??

//?actual?state?instead?of?the?desired?one.??

animateScreenStateChange(state,?performScreenOffTransition);??

state?=?mPowerState.getScreenState();??

如果目標亮度不為STATE_ON，STATE_DOZE，STATE_DOZE_SUSPEND屏幕就要去睡眠了。
[java]?view plain?copy

//?Want?screen?off.??

mPendingScreenOff?=?true;??

if?(mPowerState.getColorFadeLevel()?==?0.0f)?{??

????//?Turn?the?screen?off.??

????//?A?black?surface?is?already?hiding?the?contents?of?the?screen.??

????setScreenState(Display.STATE_OFF);??

????mPendingScreenOff?=?false;??

????mPowerState.dismissColorFadeResources();??

}?else?if?(performScreenOffTransition??

????????&&?mPowerState.prepareColorFade(mContext,??

????????????????mColorFadeFadesConfig????

????????????????????????ColorFade.MODE_FADE?:?ColorFade.MODE_COOL_DOWN)??

????????&&?mPowerState.getScreenState()?!=?Display.STATE_OFF)?{??

????//?Perform?the?screen?off?animation.??

????mColorFadeOffAnimator.start();??

}?else?{??

????//?Skip?the?screen?off?animation?and?add?a?black?surface?to?hide?the??

????//?contents?of?the?screen.??

????mColorFadeOffAnimator.end();??

}??

在這里就要判斷ColorFadeLevel是不是0.0，由于亮屏時將ColorFadeLevel設置為1.0所以走else語句，如果performScreenOffTransition為true并且將ColorFade準備好了就開始滅屏動畫將ColorFadeLevel從1.0漸變?yōu)?.0。但是前面知道將performScreenOffTransition設置為了false，所以就沒有了滅屏動畫，直接將ColorFadeLevel設置為0.0。之后就調(diào)用setScreenState設置狀態(tài)。
發(fā)送滅屏廣播
? ? ? ? ? ? ? ? ? ? ? ? ? ? ??

power是通過WindowManagerPolicy與PhoneWindowManager進行交互，當屏幕在finishedGoingToSleep時需要通知window進行更新手勢監(jiān)聽，更新方向監(jiān)聽，更新鎖屏超時時間。之后發(fā)送滅屏廣播通知關心滅屏事件的模塊。

到此為止亮滅屏流程講解完畢.

版權(quán)聲明：本文為博主原創(chuàng)文章，未經(jīng)博主允許不得轉(zhuǎn)載。 https://blog.csdn.net/fu_kevin0606/article/details/54427641

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