android5.1 PowerManagerService和DisplayPowerControler、DisplayPowerState关系
PowerManagerService在updateDisplayPowerStateLocked中与DisplayPowerControler交互，详细看代码：
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();
// Determine appropriate screen brightness and auto-brightness adjustments.
int screenBrightness = mScreenBrightnessSettingDefault;
float screenAutoBrightnessAdjustment = 0.0f;
boolean autoBrightness = (mScreenBrightnessModeSetting ==
Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC);
if (isValidBrightness(mScreenBrightnessOverrideFromWindowManager)) {
screenBrightness = mScreenBrightnessOverrideFromWindowManager;
autoBrightness = false;
} else if (isValidBrightness(mTemporaryScreenBrightnessSettingOverride)) {
screenBrightness = mTemporaryScreenBrightnessSettingOverride;
} else if (isValidBrightness(mScreenBrightnessSetting)) {
screenBrightness = mScreenBrightnessSetting;
}
if (autoBrightness) {
screenBrightness = mScreenBrightnessSettingDefault;
if (isValidAutoBrightnessAdjustment(
mTemporaryScreenAutoBrightnessAdjustmentSettingOverride)) {
screenAutoBrightnessAdjustment =
mTemporaryScreenAutoBrightnessAdjustmentSettingOverride;
} else if (isValidAutoBrightnessAdjustment(
mScreenAutoBrightnessAdjustmentSetting)) {
screenAutoBrightnessAdjustment = mScreenAutoBrightnessAdjustmentSetting;
}
}
screenBrightness = Math.max(Math.min(screenBrightness,
mScreenBrightnessSettingMaximum), mScreenBrightnessSettingMinimum);
screenAutoBrightnessAdjustment = Math.max(Math.min(
screenAutoBrightnessAdjustment, 1.0f), -1.0f);
// Update display power request.
mDisplayPowerRequest.screenBrightness = screenBrightness;
mDisplayPowerRequest.screenAutoBrightnessAdjustment =
screenAutoBrightnessAdjustment;
mDisplayPowerRequest.useAutoBrightness = autoBrightness;
mDisplayPowerRequest.useProximitySensor = shouldUseProximitySensorLocked();
mDisplayPowerRequest.lowPowerMode = mLowPowerModeEnabled;
mDisplayPowerRequest.boostScreenBrightness = mScreenBrightnessBoostInProgress;
if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_DOZE) {
mDisplayPowerRequest.dozeScreenState = mDozeScreenStateOverrideFromDreamManager;
mDisplayPowerRequest.dozeScreenBrightness =
mDozeScreenBrightnessOverrideFromDreamManager;
} else {
mDisplayPowerRequest.dozeScreenState = Display.STATE_UNKNOWN;
mDisplayPowerRequest.dozeScreenBrightness = PowerManager.BRIGHTNESS_DEFAULT;
}
mDisplayReady = mDisplayManagerInternal.requestPowerState(mDisplayPowerRequest,//调用DisplayPowerControler的requestPowerstate接口
mRequestWaitForNegativeProximity);
mRequestWaitForNegativeProximity = false;
}
return mDisplayReady && !oldDisplayReady;
}
接下来我们再看看mDisplayManagerInternal这个成员变量：在systemready中
mDisplayManagerInternal = getLocalService(DisplayManagerInternal.class);
。。。。
mDisplayManagerInternal.initPowerManagement(
mDisplayPowerCallbacks, mHandler, sensorManager);
而DisplayPowerControler是在DisplayManagerService中定义，并且放在localservice中，publish出来。
private final class LocalService extends DisplayManagerInternal {
@Override
public void initPowerManagement(final DisplayPowerCallbacks callbacks, Handler handler,
SensorManager sensorManager) {
synchronized (mSyncRoot) {
DisplayBlanker blanker = new DisplayBlanker() {
@Override
public void requestDisplayState(int state) {
// The order of operations is important for legacy reasons.
if (state == Display.STATE_OFF) {
requestGlobalDisplayStateInternal(state);
}
callbacks.onDisplayStateChange(state);//注意这个接口后续会介绍
if (state != Display.STATE_OFF) {
requestGlobalDisplayStateInternal(state);
}
}
};
mDisplayPowerController = new DisplayPowerController(//new一个DisplayPowerController
mContext, callbacks, handler, sensorManager, blanker);
}
}
@Override
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
return mDisplayPowerController.requestPowerState(request,
waitForNegativeProximity);
}
。。。。。
好接下来我们先分析DisplayPowerControler中的requestPowerState函数：
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
synchronized (mLock) {
boolean changed = false;
if (waitForNegativeProximity
&& !mPendingWaitForNegativeProximityLocked) {
mPendingWaitForNegativeProximityLocked = true;
changed = true;
}
if (mPendingRequestLocked == null) {
mPendingRequestLocked = new DisplayPowerRequest(request);
changed = true;
} else if (!mPendingRequestLocked.equals(request)) {
mPendingRequestLocked.copyFrom(request);
changed = true;
}
if (changed) {
mDisplayReadyLocked = false;//注意有变化，返回的是false
}
if (changed && !mPendingRequestChangedLocked) {
mPendingRequestChangedLocked = true;
sendUpdatePowerStateLocked();//发送信号，到updatePowerState
}
return mDisplayReadyLocked;
}
}下面我们就来分析下DisplayPowerControler中的updatePowerState函数：
private void updatePowerState() {
// Update the power state request.
final boolean mustNotify;
boolean mustInitialize = false;
boolean autoBrightnessAdjustmentChanged = false;
synchronized (mLock) {
mPendingUpdatePowerStateLocked = false;
if (mPendingRequestLocked == null) {
return; // wait until first actual power request
}
if (mPowerRequest == null) {
mPowerRequest = new DisplayPowerRequest(mPendingRequestLocked);
mWaitingForNegativeProximity = mPendingWaitForNegativeProximityLocked;
mPendingWaitForNegativeProximityLocked = false;
mPendingRequestChangedLocked = false;
mustInitialize = true;
} else if (mPendingRequestChangedLocked) {
autoBrightnessAdjustmentChanged = (mPowerRequest.screenAutoBrightnessAdjustment
!= mPendingRequestLocked.screenAutoBrightnessAdjustment);
mPowerRequest.copyFrom(mPendingRequestLocked);
mWaitingForNegativeProximity |= mPendingWaitForNegativeProximityLocked;
mPendingWaitForNegativeProximityLocked = false;
mPendingRequestChangedLocked = false;
mDisplayReadyLocked = false;//这时候mDisplayReadyLocked还是false，这是requestPowerState的返回值
}
mustNotify = !mDisplayReadyLocked;
}
// Initialize things the first time the power state is changed.
if (mustInitialize) {
initialize();
}
// Compute the basic display state using the policy.
// We might override this below based on other factors.
int state;
int brightness = PowerManager.BRIGHTNESS_DEFAULT;
boolean performScreenOffTransition = false;
switch (mPowerRequest.policy) {//根据policy，得到显示的state
case DisplayPowerRequest.POLICY_OFF:
state = Display.STATE_OFF;
performScreenOffTransition = true;
break;
case DisplayPowerRequest.POLICY_DOZE:
if (mPowerRequest.dozeScreenState != Display.STATE_UNKNOWN) {
state = mPowerRequest.dozeScreenState;
} else {
state = Display.STATE_DOZE;
}
if (!mAllowAutoBrightnessWhileDozingConfig) {
brightness = mPowerRequest.dozeScreenBrightness;
}
break;
case DisplayPowerRequest.POLICY_DIM:
case DisplayPowerRequest.POLICY_BRIGHT:
default:
state = Display.STATE_ON;
break;
}
assert(state != Display.STATE_UNKNOWN);
// Apply the proximity sensor.这块是距离传感器
if (mProximitySensor != null) {
if (mPowerRequest.useProximitySensor && state != Display.STATE_OFF) {
setProximitySensorEnabled(true);
if (!mScreenOffBecauseOfProximity
&& mProximity == PROXIMITY_POSITIVE) {
mScreenOffBecauseOfProximity = true;
sendOnProximityPositiveWithWakelock();
}
} else if (mWaitingForNegativeProximity
&& mScreenOffBecauseOfProximity
&& mProximity == PROXIMITY_POSITIVE
&& state != Display.STATE_OFF) {
setProximitySensorEnabled(true);
} else {
setProximitySensorEnabled(false);
mWaitingForNegativeProximity = false;
}
if (mScreenOffBecauseOfProximity
&& mProximity != PROXIMITY_POSITIVE) {
mScreenOffBecauseOfProximity = false;
sendOnProximityNegativeWithWakelock();
}
} else {
mWaitingForNegativeProximity = false;
}
if (mScreenOffBecauseOfProximity) {
state = Display.STATE_OFF;
}
// 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.
//后面详细分析下这函数，主要设置显示的state，和displayPowerState交互。
animateScreenStateChange(state, performScreenOffTransition);
state = mPowerState.getScreenState();
// Use zero brightness when screen is off.
if (state == Display.STATE_OFF) {
brightness = PowerManager.BRIGHTNESS_OFF;
}
// Configure auto-brightness.
boolean autoBrightnessEnabled = false;
if (mAutomaticBrightnessController != null) {
final boolean autoBrightnessEnabledInDoze = mAllowAutoBrightnessWhileDozingConfig
&& (state == Display.STATE_DOZE || state == Display.STATE_DOZE_SUSPEND);
autoBrightnessEnabled = mPowerRequest.useAutoBrightness
&& (state == Display.STATE_ON || autoBrightnessEnabledInDoze)
&& brightness < 0;
mAutomaticBrightnessController.configure(autoBrightnessEnabled,
mPowerRequest.screenAutoBrightnessAdjustment, state != Display.STATE_ON);
}
// Apply brightness boost.
// We do this here after configuring auto-brightness so that we don't
// disable the light sensor during this temporary state. That way when
// boost ends we will be able to resume normal auto-brightness behavior
// without any delay.
if (mPowerRequest.boostScreenBrightness
&& brightness != PowerManager.BRIGHTNESS_OFF) {
brightness = PowerManager.BRIGHTNESS_ON;
}
// Apply auto-brightness.
boolean slowChange = false;
if (brightness < 0) {
if (autoBrightnessEnabled) {
brightness = mAutomaticBrightnessController.getAutomaticScreenBrightness();
}
if (brightness >= 0) {
// Use current auto-brightness value and slowly adjust to changes.
brightness = clampScreenBrightness(brightness);
if (mAppliedAutoBrightness && !autoBrightnessAdjustmentChanged) {
slowChange = true; // slowly adapt to auto-brightness
}
mAppliedAutoBrightness = true;
} else {
mAppliedAutoBrightness = false;
}
} else {
mAppliedAutoBrightness = false;
}
// Use default brightness when dozing unless overridden.
if (brightness < 0 && (state == Display.STATE_DOZE
|| state == Display.STATE_DOZE_SUSPEND)) {
brightness = mScreenBrightnessDozeConfig;
}
// Apply manual brightness.
// Use the current brightness setting from the request, which is expected
// provide a nominal default value for the case where auto-brightness
// is not ready yet.
if (brightness < 0) {
brightness = clampScreenBrightness(mPowerRequest.screenBrightness);
}
// Apply dimming by at least some minimum amount when user activity
// timeout is about to expire.
if (mPowerRequest.policy == DisplayPowerRequest.POLICY_DIM) {
if (brightness > mScreenBrightnessRangeMinimum) {
brightness = Math.max(Math.min(brightness - SCREEN_DIM_MINIMUM_REDUCTION,
mScreenBrightnessDimConfig), mScreenBrightnessRangeMinimum);
}
if (!mAppliedDimming) {
slowChange = false;
}
mAppliedDimming = true;
}
// If low power mode is enabled, cut the brightness level by half
// as long as it is above the minimum threshold.
if (mPowerRequest.lowPowerMode) {//低功耗模式
if (brightness > mScreenBrightnessRangeMinimum) {
brightness = Math.max(brightness / 2, mScreenBrightnessRangeMinimum);
}
if (!mAppliedLowPower) {
slowChange = false;
}
mAppliedLowPower = true;
}
// 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,
slowChange ? BRIGHTNESS_RAMP_RATE_SLOW : BRIGHTNESS_RAMP_RATE_FAST);
} else {
animateScreenBrightness(brightness, 0);
}
}
// Determine whether the display is ready for use in the newly requested state.
// Note that we do not wait for the brightness ramp animation to complete before
// reporting the display is ready because we only need to ensure the screen is in the
// right power state even as it continues to converge on the desired brightness.
final boolean ready = mPendingScreenOnUnblocker == null
&& !mColorFadeOnAnimator.isStarted()
&& !mColorFadeOffAnimator.isStarted()
&& mPowerState.waitUntilClean(mCleanListener);
final boolean finished = ready
&& !mScreenBrightnessRampAnimator.isAnimating();
// Grab a wake lock if we have unfinished business.
if (!finished && !mUnfinishedBusiness) {
if (DEBUG) {
Slog.d(TAG, "Unfinished business...");
}
mCallbacks.acquireSuspendBlocker();//回调持cpu锁
mUnfinishedBusiness = true;//使用该变量，只能进一次该函数
}
// Notify the power manager when ready.
if (ready && mustNotify) {
// Send state change.
synchronized (mLock) {
if (!mPendingRequestChangedLocked) {
mDisplayReadyLocked = true;
if (DEBUG) {
Slog.d(TAG, "Display ready!");
}
}
}
sendOnStateChangedWithWakelock();//重新在PowerManagerService中调用updatePowerState函数
}
// Release the wake lock when we have no unfinished business.
if (finished && mUnfinishedBusiness) {
if (DEBUG) {
Slog.d(TAG, "Finished business...");
}
mUnfinishedBusiness = false;
mCallbacks.releaseSuspendBlocker();//释放cpu锁
}
}
我们先来看下在上面函数中调用的几个mCallbacks函数：
private final DisplayManagerInternal.DisplayPowerCallbacks mDisplayPowerCallbacks =
new DisplayManagerInternal.DisplayPowerCallbacks() {
private int mDisplayState = Display.STATE_UNKNOWN;
@Override
public void onStateChanged() {//只是重新调用下powerManagerService中的updatePowerStateLocked函数
synchronized (mLock) {
mDirty |= DIRTY_ACTUAL_DISPLAY_POWER_STATE_UPDATED;
updatePowerStateLocked();
}
}
@Override
public void onProximityPositive() {
synchronized (mLock) {
mProximityPositive = true;
mDirty |= DIRTY_PROXIMITY_POSITIVE;
updatePowerStateLocked();
}
}
@Override
public void onProximityNegative() {
synchronized (mLock) {
mProximityPositive = false;
mDirty |= DIRTY_PROXIMITY_POSITIVE;
userActivityNoUpdateLocked(SystemClock.uptimeMillis(),
PowerManager.USER_ACTIVITY_EVENT_OTHER, 0, Process.SYSTEM_UID);
updatePowerStateLocked();
}
}
@Override
public void onDisplayStateChange(int state) {
// This method is only needed to support legacy display blanking behavior
// where the display's power state is coupled to suspend or to the power HAL.
// The order of operations matters here.
synchronized (mLock) {
if (mDisplayState != state) {
mDisplayState = state;
if (state == Display.STATE_OFF) {
if (!mDecoupleHalInteractiveModeFromDisplayConfig) {
setHalInteractiveModeLocked(false);
}
if (!mDecoupleHalAutoSuspendModeFromDisplayConfig) {
setHalAutoSuspendModeLocked(true);
}
} else {
if (!mDecoupleHalAutoSuspendModeFromDisplayConfig) {
setHalAutoSuspendModeLocked(false);
}
if (!mDecoupleHalInteractiveModeFromDisplayConfig) {
setHalInteractiveModeLocked(true);
}
}
}
}
}
@Override
public void acquireSuspendBlocker() {
mDisplaySuspendBlocker.acquire();
}
@Override
public void releaseSuspendBlocker() {
mDisplaySuspendBlocker.release();
}
而sendOnStateChangedWithWakelock代码如下：
private void sendOnStateChangedWithWakelock() {
mCallbacks.acquireSuspendBlocker();
mHandler.post(mOnStateChangedRunnable);
}
private final Runnable mOnStateChangedRunnable = new Runnable() {直接在两个线程中，这个handler是PowerManagerService中的
@Override
public void run() {
mCallbacks.onStateChanged();
mCallbacks.releaseSuspendBlocker();
}
};
第一次调用requestPowerState时返回的mDisplayReadyLocked = false，然后在DisplayPowerControler中的updatePowerState函数全都好了，把变量mDisplayReadyLocked = true ，再调用PowerManagerService中的updatePowerLocked，再调的话mDisplayReadyLocked 就返回true了。
接下来我们来看animateScreenStateChange函数，主要是设置display的state。
private void animateScreenStateChange(int target, boolean performScreenOffTransition) {
// If there is already an animation in progress, don't interfere with it.
if (mColorFadeOnAnimator.isStarted()
|| mColorFadeOffAnimator.isStarted()) {
return;
}
if (mPendingScreenOff && target != Display.STATE_OFF) {
setScreenState(Display.STATE_OFF);//设置display的state
mPendingScreenOff = false;
}
if (target == Display.STATE_ON) {
if (!setScreenState(Display.STATE_ON)) {
return; // screen on blocked
}
if (USE_COLOR_FADE_ON_ANIMATION && mPowerRequest.isBrightOrDim()) {
// Perform screen on animation.
if (mPowerState.getColorFadeLevel() == 1.0f) {
mPowerState.dismissColorFade();
} else if (mPowerState.prepareColorFade(mContext,
mColorFadeFadesConfig ?
ColorFade.MODE_FADE :
ColorFade.MODE_WARM_UP)) {
mColorFadeOnAnimator.start();
} else {
mColorFadeOnAnimator.end();
}
} else {
// Skip screen on animation.
mPowerState.setColorFadeLevel(1.0f);
mPowerState.dismissColorFade();
}
} else if (target == Display.STATE_DOZE) {
// Want screen dozing.
// Wait for brightness animation to complete beforehand when entering doze
// from screen on to prevent a perceptible jump because brightness may operate
// differently when the display is configured for dozing.
if (mScreenBrightnessRampAnimator.isAnimating()
&& mPowerState.getScreenState() == Display.STATE_ON) {
return;
}
// Set screen state.
if (!setScreenState(Display.STATE_DOZE)) {
return; // screen on blocked
}
。。。。。。。。。。
</pre><p>再看setScreenState函数</p><pre class="java" name="code"> private boolean setScreenState(int state) {
if (mPowerState.getScreenState() != state) {
final boolean wasOn = (mPowerState.getScreenState() != Display.STATE_OFF);
mPowerState.setScreenState(state);//调用DisplayPowerState的setScreenState
// Tell battery stats about the transition.
try {
mBatteryStats.noteScreenState(state);
} catch (RemoteException ex) {
// same process
}
// Tell the window manager what's happening.
// Temporarily block turning the screen on until the window manager is ready
// by leaving a black surface covering the screen. This surface is essentially
// the final state of the color fade animation.
boolean isOn = (state != Display.STATE_OFF);
if (wasOn && !isOn) {
unblockScreenOn();
mWindowManagerPolicy.screenTurnedOff();//通知window Manager
} else if (!wasOn && isOn) {
if (mPowerState.getColorFadeLevel() == 0.0f) {
blockScreenOn();
} else {
unblockScreenOn();
}
mWindowManagerPolicy.screenTurningOn(mPendingScreenOnUnblocker);
}
}
return mPendingScreenOnUnblocker == null;
}
好，接下来我们就主要分析DisPlayPowerRequest，先看setScreenState
public void setScreenState(int state) {
if (mScreenState != state) {
if (DEBUG) {
Slog.d(TAG, "setScreenState: state=" + state);
}
mScreenState = state;
mScreenReady = false;
scheduleScreenUpdate();
}
}
private void scheduleScreenUpdate() {
if (!mScreenUpdatePending) {
mScreenUpdatePending = true;
postScreenUpdateThreadSafe();
}
private void postScreenUpdateThreadSafe() {
mHandler.removeCallbacks(mScreenUpdateRunnable);
mHandler.post(mScreenUpdateRunnable);
}
private final Runnable mScreenUpdateRunnable = new Runnable() {
@Override
public void run() {
mScreenUpdatePending = false;
int brightness = mScreenState != Display.STATE_OFF
&& mColorFadeLevel > 0f ? mScreenBrightness : 0;
if (mPhotonicModulator.setState(mScreenState, brightness)) {//最后调用了线程的setState
if (DEBUG) {
Slog.d(TAG, "Screen ready");
}
mScreenReady = true;
invokeCleanListenerIfNeeded();
} else {
if (DEBUG) {
Slog.d(TAG, "Screen not ready");
}
}
}
};
下面我们分析下PhotonicModulator这个线程类：
private final class PhotonicModulator extends Thread {
private static final int INITIAL_SCREEN_STATE = Display.STATE_OFF; // unknown, assume off
private static final int INITIAL_BACKLIGHT = -1; // unknown
private final Object mLock = new Object();
private int mPendingState = INITIAL_SCREEN_STATE;
private int mPendingBacklight = INITIAL_BACKLIGHT;
private int mActualState = INITIAL_SCREEN_STATE;
private int mActualBacklight = INITIAL_BACKLIGHT;
private boolean mChangeInProgress;
public boolean setState(int state, int backlight) {
synchronized (mLock) {
if (state != mPendingState || backlight != mPendingBacklight) {
if (DEBUG) {
Slog.d(TAG, "Requesting new screen state: state="
+ Display.stateToString(state) + ", backlight=" + backlight);
}
mPendingState = state;//设置state
mPendingBacklight = backlight;
if (!mChangeInProgress) {
mChangeInProgress = true;
mLock.notifyAll();
}
}
return !mChangeInProgress;
}
}
@Override
public void run() {
for (;;) {//线程一直跑，状态改变就去PowerManagerService中调用setHalInteractiveModeLocked设置屏幕状态
// Get pending change.
final int state;
final boolean stateChanged;
final int backlight;
final boolean backlightChanged;
synchronized (mLock) {
state = mPendingState;
stateChanged = (state != mActualState);//state是否改变
backlight = mPendingBacklight;
backlightChanged = (backlight != mActualBacklight);
if (!stateChanged && !backlightChanged) {
// All changed applied, notify outer class and wait for more.
mChangeInProgress = false;
postScreenUpdateThreadSafe();
try {
mLock.wait();
} catch (InterruptedException ex) { }
continue;
}
mActualState = state;
mActualBacklight = backlight;
}
// Apply pending change.
if (DEBUG) {
Slog.d(TAG, "Updating screen state: state="
+ Display.stateToString(state) + ", backlight=" + backlight);
}
boolean suspending = Display.isSuspendedState(state);
if (stateChanged && !suspending) {改变了就调用requestDisplayState函数
requestDisplayState(state);
}
if (backlightChanged) {
setBrightness(backlight);
}
if (stateChanged && suspending) {
requestDisplayState(state);
}
}
}
private void requestDisplayState(int state) {
Trace.traceBegin(Trace.TRACE_TAG_POWER, "requestDisplayState("
+ Display.stateToString(state) + ")");
try {
mBlanker.requestDisplayState(state);//其中的调用了PowerManagerService的函数，详细看下面
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
}
private void setBrightness(int backlight) {
Trace.traceBegin(Trace.TRACE_TAG_POWER, "setBrightness(" + backlight + ")");
try {
mBacklight.setBrightness(backlight);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
}
}
当display的state改变的时候调用了mBlanker的requestDisplayState函数，而这个blanker如下：
private final class LocalService extends DisplayManagerInternal {
@Override
public void initPowerManagement(final DisplayPowerCallbacks callbacks, Handler handler,
SensorManager sensorManager) {
synchronized (mSyncRoot) {
DisplayBlanker blanker = new DisplayBlanker() {
@Override
public void requestDisplayState(int state) {
// The order of operations is important for legacy reasons.
if (state == Display.STATE_OFF) {
requestGlobalDisplayStateInternal(state);
}
callbacks.onDisplayStateChange(state);//调用了PowerManagerService中的onDisplayStateChange
if (state != Display.STATE_OFF) {
requestGlobalDisplayStateInternal(state);
}
}
};
mDisplayPowerController = new DisplayPowerController(
mContext, callbacks, handler, sensorManager, blanker);
}
}
最终还是调用了PowerManagerService中的onDisplayStateChange，
@Override
public void onDisplayStateChange(int state) {
// This method is only needed to support legacy display blanking behavior
// where the display's power state is coupled to suspend or to the power HAL.
// The order of operations matters here.
synchronized (mLock) {
if (mDisplayState != state) {
mDisplayState = state;
if (state == Display.STATE_OFF) {
if (!mDecoupleHalInteractiveModeFromDisplayConfig) {
setHalInteractiveModeLocked(false);
}
if (!mDecoupleHalAutoSuspendModeFromDisplayConfig) {
setHalAutoSuspendModeLocked(true);
}
} else {
if (!mDecoupleHalAutoSuspendModeFromDisplayConfig) {
setHalAutoSuspendModeLocked(false);
}
if (!mDecoupleHalInteractiveModeFromDisplayConfig) {
setHalInteractiveModeLocked(true);
}
}
}
}
}
其中setHalInteractiveModeLocked是一个native函数，设置屏幕是否亮。
private void setHalInteractiveModeLocked(boolean enable) {
if (enable != mHalInteractiveModeEnabled) {
if (DEBUG) {
Slog.d(TAG, "Setting HAL interactive mode to " + enable);
}
mHalInteractiveModeEnabled = enable;
Trace.traceBegin(Trace.TRACE_TAG_POWER, "setHalInteractive(" + enable + ")");
try {
nativeSetInteractive(enable);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
}
}
我们再看下DisPlayPowerControler如何设置ScreenBrightness,是调用animateScreenBrightness函数：
private void animateScreenBrightness(int target, int rate) {
if (DEBUG) {
Slog.d(TAG, "Animating brightness: target=" + target +", rate=" + rate);
}
if (mScreenBrightnessRampAnimator.animateTo(target, rate)) {
try {
mBatteryStats.noteScreenBrightness(target);
} catch (RemoteException ex) {
// same process
}
}
}
直接看类RampAnimator<T> 的animateTo函数，其中调用了mProperty.setValue(mObject, target);
public boolean animateTo(int target, int rate) {
// Immediately jump to the target the first time.
if (mFirstTime || rate <= 0) {
if (mFirstTime || target != mCurrentValue) {
mFirstTime = false;
mRate = 0;
mTargetValue = target;
mCurrentValue = target;
mProperty.setValue(mObject, target);
if (mAnimating) {
mAnimating = false;
cancelAnimationCallback();
}
if (mListener != null) {
mListener.onAnimationEnd();
}
return true;
}
return false;
}
最后还是调用了DisplayPowerState的setScreenState函数
public void setScreenState(int state) {
if (mScreenState != state) {
if (DEBUG) {
Slog.d(TAG, "setScreenState: state=" + state);
}
mScreenState = state;
mScreenReady = false;
scheduleScreenUpdate();
}
}
这个函数分析大体和上面的setState差不多，最后也是在线程中调用setBrightness函数
public void run() {
for (;;) {
// Get pending change.
final int state;
final boolean stateChanged;
final int backlight;
final boolean backlightChanged;
synchronized (mLock) {
state = mPendingState;
stateChanged = (state != mActualState);
backlight = mPendingBacklight;
backlightChanged = (backlight != mActualBacklight);
if (!stateChanged && !backlightChanged) {
// All changed applied, notify outer class and wait for more.
mChangeInProgress = false;
postScreenUpdateThreadSafe();
try {
mLock.wait();
} catch (InterruptedException ex) { }
continue;
}
mActualState = state;
mActualBacklight = backlight;
}
// Apply pending change.
if (DEBUG) {
Slog.d(TAG, "Updating screen state: state="
+ Display.stateToString(state) + ", backlight=" + backlight);
}
boolean suspending = Display.isSuspendedState(state);
if (stateChanged && !suspending) {
requestDisplayState(state);
}
if (backlightChanged) {
setBrightness(backlight);
}
if (stateChanged && suspending) {
requestDisplayState(state);
}
}
private void setBrightness(int backlight) {
Trace.traceBegin(Trace.TRACE_TAG_POWER, "setBrightness(" + backlight + ")");
try {
mBacklight.setBrightness(backlight);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
}
而mBackLigth是LocalServices.getService(LightsManager.class);
最后调到LightsService中的setLightLocked函数。
private void setLightLocked(int color, int mode, int onMS, int offMS, int brightnessMode) {
if (color != mColor || mode != mMode || onMS != mOnMS || offMS != mOffMS) {
if (DEBUG) Slog.v(TAG, "setLight #" + mId + ": color=#"
+ Integer.toHexString(color));
mColor = color;
mMode = mode;
mOnMS = onMS;
mOffMS = offMS;
Trace.traceBegin(Trace.TRACE_TAG_POWER, "setLight(" + mId + ", " + color + ")");
try {
setLight_native(mNativePointer, mId, color, mode, onMS, offMS, brightnessMode);//native函数设置亮度
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}
}
}
总结下：PowerManagerService中updateDisplayPowerStateLocked函数调用DisplayPowerControler中的requestPowerState函数，直接返回一个false，然后再发送一个信号，调用DisplayPowerControler中的updatePowerstate，然后和DisplayPowerState进行交互，结束后将mDisplayReadyLocked = true ，再调用PowerManagerService的updatePowerStateLocked，重新调用DisplayPowerControler中的requestPowerState函数然后再返回true。