Android 7.0 Power 按键处理流程

Android 7.0  Power 按键处理流程

 

Power按键的处理逻辑由PhoneWindowManager来完成，本文只关注PhoneWindowManager中与Power键相关的内容，其他系统按键的处理类似也是在PhoneWindowManager中处理的。理解了power按键的处理再看其他系统按键的逻辑会容易的多也简单的多。

一、Power按键的上报

Power按键的上报流程与其余的按键处理流程一致，在按下power按键后驱动上报按键经InputManagerService处理按键事件，最终将会传递到PhoneWindowManager的interceptKeyBeforeQueueing函数来做具体的业务逻辑。（具体处理 Input system 做详细介绍）本篇侧重power的业务逻辑处理，这里简单介绍下power 按键的上报流程如下图： 

 

 

1-4：在power 按键按下时驱动会上报按键事件，EventHub读取到事件后转给InputReader来做处理。

5-9：InputReader根据上报的事件类型（此处是按键事件），交给KeyBoardInputMapper来做按键映射，根据驱动上报的按键值来映射为android framework的按键值（即KeyEvent.KEYCODE_POWER 和相应的flag），并通知上层。

10-16：经过层调用最后到PhoneWindowManager的interceptKeyBeforeQueueing（）函数来做具体的业务处理。这是本文的重点，下面具体分析。

17-18：通过PowerManagerService来唤醒系统。

 

二、Power 按键处理

PhoneWindowManager的interceptKeyBeforeQueueing（）函数处理具体的业务逻辑，从这个函数开始进行分析。

按键的事件分为按下和抬起两个，framework的处理也是分为按下和抬起来不同的事件分别由不同的函数来处理。

public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {    if (!mSystemBooted) {        // If we have not yet booted, don't let key events do anything.        return 0;    }    //是否点亮屏幕    final boolean interactive = (policyFlags & FLAG_INTERACTIVE) != 0;    final boolean down = event.getAction() == KeyEvent.ACTION_DOWN;    final boolean canceled = event.isCanceled();    //获取按键对应的android framework层的按键编码    final int keyCode = event.getKeyCode();    .................    switch (keyCode) {        ...........        case KeyEvent.KEYCODE_POWER: {            result &= ~ACTION_PASS_TO_USER;            isWakeKey = false; // wake-up will be handled separately            if (down) {                //处理Power键按下                interceptPowerKeyDown(event, interactive);            } else {                //处理Power键松开                interceptPowerKeyUp(event, interactive, canceled);            }             break;        }    }    ..............    if (isWakeKey) {        //按power键时，isWakeKey置为false，于是不会调用wakeUp函数，即不会唤醒系统点亮屏幕        wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY");    }    return result;} 

 

扩展：由上可知 isWakeKey 用来控制是否唤醒系统并点亮屏幕，如果需要添加按键需要实现点亮屏幕功能，可以在此处理 ^_^。

接下来，我们分别看一下interceptPowerKeyDown和interceptPowerKeyUp函数。

1、Power按键按下（interceptPowerKeyDown）

interceptPowerKeyDown（）用于处理按下Power键(还未抬起)对应的事件。

A: Power按键按下处理时序图

 

 

 

处理流程：

1）  判断是否power按键与音量按键“同时”按下需要做截屏动作，是则触发截屏。

2）  是否为响铃或通话状态，是则执行与之相关配置的动作（默认响铃会静音，如果设置按power挂断电话则挂断）。

3）  判断是否为长按，是则根据配置执行长按行为的动作。

B: 代码分析

private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {    // Hold a wake lock until the power key is released.    // mPowerKeyWakeLock为PARTIAL_WAKE_LOCK级别的锁    if (!mPowerKeyWakeLock.isHeld()) {        //将调用到PMS的acquire WakeLock流程        mPowerKeyWakeLock.acquire();    }    // Cancel multi-press detection timeout.    //处理多次按power键的场景    //每次power up时，发送MSG_POWER_DELAYED_PRESS的延迟消息    //如果延迟消息被处理，说明一次完整的Power键处理结束（按下去，弹起来）    if (mPowerKeyPressCounter != 0) {        mHandler.removeMessages(MSG_POWER_DELAYED_PRESS);    }    // Detect user pressing the power button in panic when an application has    // taken over the whole screen.    boolean panic = mImmersiveModeConfirmation.onPowerKeyDown(interactive,        SystemClock.elapsedRealtime(), isImmersiveMode(mLastSystemUiFlags));    if (panic) {        mHandler.post(mHiddenNavPanic);    }    // Latch power key state to detect screenshot chord.    //屏状态，满足触发截屏的条件则触发截屏功能    if (interactive && !mScreenshotChordPowerKeyTriggered            && (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) {        mScreenshotChordPowerKeyTriggered = true;        mScreenshotChordPowerKeyTime = event.getDownTime();        //触发截屏功能        interceptScreenshotChord();    }    // Stop ringing or end call if configured to do so when power is pressed.    TelecomManager telecomManager = getTelecommService();    boolean hungUp = false;    if (telecomManager != null) {        if (telecomManager.isRinging()) {            // Pressing Power while there's a ringing incoming            // call should silence the ringer.            //有电话拨入且响铃状态，默认设置静音            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.            //如果正在接听电话，且配置了Power键挂断电话的话，按Power按键挂断正在接听的电话            hungUp = telecomManager.endCall();        }    }     GestureLauncherService gestureService = LocalServices.getService(            GestureLauncherService.class);    boolean gesturedServiceIntercepted = false;    if (gestureService != null) {        //手势对应的服务，尝试拦截处理Power键动作事件        gesturedServiceIntercepted = gestureService.interceptPowerKeyDown(event, interactive,mTmpBoolean);        if (mTmpBoolean.value && mGoingToSleep) {            mCameraGestureTriggeredDuringGoingToSleep = true;        }    }    // If the power key has still not yet been handled, then detect short    // press, long press, or multi press and decide what to do.    mPowerKeyHandled = hungUp ||mScreenshotChordVolumeDownKeyTriggered||mScreenshotChordVolumeUpKeyTriggered || gesturedServiceIntercepted;    //Power键事件未被消耗掉    if (!mPowerKeyHandled) {       //屏幕还是亮的        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.            //1、 判断是否支持长按的行为            if (hasLongPressOnPowerBehavior()) {            //2、 亮屏状态，长按Power键将触发MSG_POWER_LONG_PRESS消息                Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);                msg.setAsynchronous(true);                mHandler.sendMessageDelayed(msg,                        ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());            }        } else {            //3、灭屏状态先唤醒系统，这个会调用到PMS的wakeUp            wakeUpFromPowerKey(event.getDownTime());            //支持熄屏长按，mSupportLongPressPowerWhenNonInteractive读资源文件得到，默认为false            if (mSupportLongPressPowerWhenNonInteractive && hasLongPressOnPowerBehavior()) {                Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);                msg.setAsynchronous(true);                mHandler.sendMessageDelayed(msg,                   ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());                mBeganFromNonInteractive = true;            } else {                //默认返回1                final int maxCount = getMaxMultiPressPowerCount();                if (maxCount <= 1) {                    //息屏时，按下power键（不弹起），仅消耗掉该事件                    mPowerKeyHandled = true;                } else {                    mBeganFromNonInteractive = true;                }            }        }    }}

 

1）是否支持长按hasLongPressOnPowerBehavior （）

hasLongPressOnPowerBehavior负责判断终端是否支持长按的行为，通过读取系统的配置文件来判断。

private boolean hasLongPressOnPowerBehavior() {    return getResolvedLongPressOnPowerBehavior() != LONG_PRESS_POWER_NOTHING;}private int getResolvedLongPressOnPowerBehavior() {    //取决与系统属性"factory.long_press_power_off"，此处默认为false    if (FactoryTest.isLongPressOnPowerOffEnabled()) {        return LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM;    }    return mLongPressOnPowerBehavior;}从上面的代码可以看出，终端是否支持长按行为，最终将由mLongPressOnPowerBehavior决定。.........mLongPressOnPowerBehavior = mContext.getResources().getInteger(      com.android.internal.R.integer.config_longPressOnPowerBehavior);.........

 

mLongPressOnPowerBehavior将在PhoneWindowManager初始化时，通过读取资源文件（定义在frameworks/base/res/res/values/config.xm 中）得到，一般情况下应该为1。 于是，hasLongPressOnPowerBehavior的值返回true，即终端支持Power键长按。

config.xm 中定义的power按键的长按、短按、双击 、三联按的行为

 

2）长按MSG_POWER_LONG_PRESS的处理 

从上面的代码，在亮屏时按Power键，会触发延迟的MSG_POWER_LONG_PRESS消息。 如果在MSG_POWER_LONG_PRESS超时前，Power键未被释放掉，那么此次操作被定义为长按Power键。

 

 

 

 

MSG_POWER_LONG_PRESS对应的处理函数为powerLongPress：

private void powerLongPress() {    //也是由资源文件得到，默认为1，即LONG_PRESS_POWER_GLOBAL_ACTIONS    final int behavior = getResolvedLongPressOnPowerBehavior();    switch (behavior) {        case LONG_PRESS_POWER_NOTHING:            break;        case LONG_PRESS_POWER_GLOBAL_ACTIONS:            mPowerKeyHandled = true;            //performHapticFeedbackLw进行震动反馈，不同的事件，定义了不同的震动模式            if (!performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false)) {                //如果没有震动反馈，尝试声音反馈，例如响一下按键音                performAuditoryFeedbackForAccessibilityIfNeed();            }            //弹出选择关机还是重启的对话框            showGlobalActionsInternal();            break;        case LONG_PRESS_POWER_SHUT_OFF:        case LONG_PRESS_POWER_SHUT_OFF_NO_CONFIRM:            mPowerKeyHandled = true;            performHapticFeedbackLw(null, HapticFeedbackConstants.LONG_PRESS, false);            //弹出系统关机界面     sendCloseSystemWindows(SYSTEM_DIALOG_REASON_GLOBAL_ACTIONS);            //调关机接口            mWindowManagerFuncs.shutdown(behavior == LONG_PRESS_POWER_SHUT_OFF);            break;        .........    }}

 

3）唤醒系统点亮屏幕wakeUpFromPowerKey （）

在息屏的状态下按下Power键，将调用wakeUpFromPowerKey函数唤醒系统：

private void wakeUpFromPowerKey(long eventTime) {    //从config.xml读mAllowTheaterModeWakeFromPowerKey默认为true    wakeUp(eventTime, mAllowTheaterModeWakeFromPowerKey, "android.policy:POWER");} private boolean wakeUp(long wakeTime, boolean wakeInTheaterMode, String reason) {    //取数据库的值    final boolean theaterModeEnabled = isTheaterModeEnabled();    //按Power键时，条件返回false    if (!wakeInTheaterMode && theaterModeEnabled) {        return false;    }    if (theaterModeEnabled) {        Settings.Global.putInt(mContext.getContentResolver(),                Settings.Global.THEATER_MODE_ON, 0);    }    //最终将调用到PMS的wakeUp函数    mPowerManager.wakeUp(wakeTime, reason);    return true;}我们跟进一下PMS的wakeUp函数：public void wakeUp(long eventTime, String reason, String opPackageName) {    ..........    try {        wakeUpInternal(eventTime, reason, uid, opPackageName, uid);    } finally {        ...............    }}private void wakeUpInternal(long eventTime, String reason, int uid, String opPackageName,        int opUid) {    synchronized (mLock) {        //更新Wakefullness的状态为WAKEFULNESS_AWAKE，记录一次UserActivity        if (wakeUpNoUpdateLocked(eventTime, reason, uid, opPackageName, opUid)) {            //如之前博客所述，对整个电源状态进行一次调整，将在需要时点亮屏幕            updatePowerStateLocked();        }    }}

 

2、Power抬起（interceptPowerKeyUp ）

A: Power抬起 时序图

interceptPowerKeyUp处理松开Power键后的流程：

 

 

 

B: Power抬起代码分析

private void interceptPowerKeyUp(KeyEvent event, boolean interactive, boolean canceled) {    //事件被取消，或者在按下Power键时，该事件已被消耗掉    //那么就不用继续处理    final boolean handled = canceled || mPowerKeyHandled;    mScreenshotChordPowerKeyTriggered = false;    //退出截屏    cancelPendingScreenshotChordAction();    //取消MSG_POWER_LONG_PRESS事件，即在一定事件内Power键弹起，则表示这一次不是长按Power键    cancelPendingPowerKeyAction();    //从之前的代码，我们知道除了特殊功能外灭屏按Power键或亮屏长按时，均会消耗掉Power事件因此，只有亮屏短按Power键需要进行处理    if (!handled) {        // Figure out how to handle the key now that it has been released.        mPowerKeyPressCounter += 1;        final int maxCount = getMaxMultiPressPowerCount();        final long eventTime = event.getDownTime();        if (mPowerKeyPressCounter < maxCount) {            // This could be a multi-press.  Wait a little bit longer to confirm.            // Continue holding the wake lock.            // 与之前interceptPowerKeyDown，处理Power键被多次按下场景对应            // 每次被按下，均发送MSG_POWER_DELAYED_PRESS消息            // 实际上maxCount为1，不会进入该分支            Message msg = mHandler.obtainMessage(MSG_POWER_DELAYED_PRESS,                interactive ? 1 : 0, mPowerKeyPressCounter, eventTime);            msg.setAsynchronous(true);            mHandler.sendMessageDelayed(msg, ViewConfiguration.getDoubleTapTimeout());           return;        }        //1、No other actions.  Handle it immediately.        powerPress(eventTime, interactive, mPowerKeyPressCounter);    }    // 2、Done.  Reset our state.    finishPowerKeyPress();}

1）powerPress

powerPress函数根据屏幕状态和配置的条件，如果亮屏状态下短按power按键则调用PMS的goToSleep（）函数，执行灭屏并将系统休眠。

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) {//原生不进入powerMultiPressAction(eventTime, interactive, mDoublePressOnPowerBehavior);} else if (count == 3) {//原生不进入powerMultiPressAction(eventTime, interactive, mTriplePressOnPowerBehavior);} else if (interactive && !mBeganFromNonInteractive) {//亮屏时，将进入该分支//mShortPressOnPowerBehavior被配置为1switch (mShortPressOnPowerBehavior) {case SHORT_PRESS_POWER_NOTHING:break;case SHORT_PRESS_POWER_GO_TO_SLEEP://最终调用到PMS的goToSleep函数mPowerManager.goToSleep(eventTime,PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON, 0);break;...............}}}在亮屏状态下，短按一下Power键，最终将调用到PMS的goToSleep函数，使终端进入到休眠状态，与实际情况一致。 PMS的goToSleep函数public void goToSleep(long eventTime, int reason, int flags) {    ............    try {        goToSleepInternal(eventTime, reason, flags, uid);    } finally {        ...............    }} private void goToSleepInternal(long eventTime, int reason, int flags, int uid) {    synchronized (mLock) {    //没有触发用户事件，将mWakefullness置为WAKEFULNESS_DOZING    if (goToSleepNoUpdateLocked(eventTime, reason, flags, uid)) {        //执行整体的电源状态更新，将熄灭屏幕        updatePowerStateLocked();    }}

 

2）finishPowerKeyPress

每当处理一次完整的Power键按下、弹出操作后，interceptPowerKeyUp调用finishPowerKeyPress进行最后的状态复位操作：

private void finishPowerKeyPress() {    mBeganFromNonInteractive = false;    mPowerKeyPressCounter = 0;    if (mPowerKeyWakeLock.isHeld()) {        mPowerKeyWakeLock.release();    }}

 

从代码可以看出，主要的工作其实就是将状态变量恢复为初始值，同时释放掉最初申请的锁。

三、Power按键处理总流程

按键处理的总流程如下图：