Android4.2距离感应器

先说现象，现象就是来电话，接通电话，把手机屏幕靠近脸部，遮挡住P-sensor，屏幕变黑了，不遮挡住P-sensor,屏幕就点亮了。接着我们来看看代码流程。

距离感应器与屏幕休眠可参考

http://blog.csdn.net/wds1181977/article/details/42125699

先来说说靠近P-sensor，不灭屏的正常的现象：

插入耳机
打开扬声器
打开蓝牙耳机
链接蓝牙键盘

步骤一：在PhoneGlobals.java文件中onCreate()方法中：

。。。。。。

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// lock used to keep the processor awake, when we don't care for the display.
mPartialWakeLock = mPowerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK
| PowerManager.ON_AFTER_RELEASE, LOG_TAG);
// Wake lock used to control proximity sensor behavior.
if (mPowerManager.isWakeLockLevelSupported(
PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK)) {
mProximityWakeLock = mPowerManager.newWakeLock(
PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, LOG_TAG);
}

。。。。。。

注意这个private PowerManager.WakeLock mProximityWakeLock;这个初始化变量，

这个mProximityWakeLock就是所说的P-Sensor锁，它是用来唤醒屏幕和使屏幕睡眠的锁。

步骤二：在PhoneGlobals.java文件中的onCreate()方法中：

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// create mAccelerometerListener only if we are using the proximity sensor
if (proximitySensorModeEnabled()) {
mAccelerometerListener = new AccelerometerListener(this, this);
}

创建加速度感应器。

步骤三：在更新Phone的状态的时候确定这个加速度的P-sensor感应器起作用；

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/**
* Notifies the phone app when the phone state changes.
*
* This method will updates various states inside Phone app (e.g. proximity sensor mode,
* accelerometer listener state, update-lock state, etc.)
*/
/* package */ void updatePhoneState(PhoneConstants.State state) {
if (state != mLastPhoneState) {
mLastPhoneState = state;
if (state == PhoneConstants.State.IDLE)
PhoneGlobals.getInstance().pokeUserActivity();
updateProximitySensorMode(state);
// Try to acquire or release UpdateLock.
//
// Watch out: we don't release the lock here when the screen is still in foreground.
// At that time InCallScreen will release it on onPause().
if (state != PhoneConstants.State.IDLE) {
// UpdateLock is a recursive lock, while we may get "acquire" request twice and
// "release" request once for a single call (RINGING + OFFHOOK and IDLE).
// We need to manually ensure the lock is just acquired once for each (and this
// will prevent other possible buggy situations too).
if (!mUpdateLock.isHeld()) {
mUpdateLock.acquire();
}
} else {
if (!isShowingCallScreen()) {
if (!mUpdateLock.isHeld()) {
mUpdateLock.release();
}
} else {
// For this case InCallScreen will take care of the release() call.
}
}
if (mAccelerometerListener != null) {
// use accelerometer to augment proximity sensor when in call
mOrientation = AccelerometerListener.ORIENTATION_UNKNOWN;
mAccelerometerListener.enable(state == PhoneConstants.State.OFFHOOK);
}
// clear our beginning call flag
mBeginningCall = false;
// While we are in call, the in-call screen should dismiss the keyguard.
// This allows the user to press Home to go directly home without going through
// an insecure lock screen.
// But we do not want to do this if there is no active call so we do not
// bypass the keyguard if the call is not answered or declined.
if (mInCallScreen != null) {
if (VDBG) Log.d(LOG_TAG, "updatePhoneState: state = " + state);
if (!PhoneUtils.isDMLocked())
mInCallScreen.updateKeyguardPolicy(state == PhoneConstants.State.OFFHOOK);
}
}
}

步骤四：用AccelerometerListener.java类中的监听事件来处理一些这个覆盖的改变，一共有2个状态，一个是

horizontal，一个是vertical的状态。在上述步骤三红色的调用部分注册这个监听事件:

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public void enable(boolean enable) {
if (DEBUG) Log.d(TAG, "enable(" + enable + ")");
synchronized (this) {
if (enable) {
mOrientation = ORIENTATION_UNKNOWN;
mPendingOrientation = ORIENTATION_UNKNOWN;
mSensorManager.registerListener(mSensorListener, mSensor,
SensorManager.SENSOR_DELAY_NORMAL);
} else {
mSensorManager.unregisterListener(mSensorListener);
mHandler.removeMessages(ORIENTATION_CHANGED);
}
}
}

步骤五：监听事件的相应的过程如下：

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SensorEventListener mSensorListener = new SensorEventListener() {
public void onSensorChanged(SensorEvent event) {
onSensorEvent(event.values[0], event.values[1], event.values[2]);
}
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// ignore
}
};

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private void onSensorEvent(double x, double y, double z) {
if (VDEBUG) Log.d(TAG, "onSensorEvent(" + x + ", " + y + ", " + z + ")");
// If some values are exactly zero, then likely the sensor is not powered up yet.
// ignore these events to avoid false horizontal positives.
if (x == 0.0 || y == 0.0 || z == 0.0) return;
// magnitude of the acceleration vector projected onto XY plane
double xy = Math.sqrt(x*x + y*y);
// compute the vertical angle
double angle = Math.atan2(xy, z);
// convert to degrees
angle = angle * 180.0 / Math.PI;
int orientation = (angle > VERTICAL_ANGLE ? ORIENTATION_VERTICAL : ORIENTATION_HORIZONTAL);
if (VDEBUG) Log.d(TAG, "angle: " + angle + " orientation: " + orientation);
setOrientation(orientation);
}
private void setOrientation(int orientation) {
synchronized (this) {
if (mPendingOrientation == orientation) {
// Pending orientation has not changed, so do nothing.
return;
}
// Cancel any pending messages.
// We will either start a new timer or cancel alltogether
// if the orientation has not changed.
mHandler.removeMessages(ORIENTATION_CHANGED);
if (mOrientation != orientation) {
// Set timer to send an event if the orientation has changed since its
// previously reported value.
mPendingOrientation = orientation;
Message m = mHandler.obtainMessage(ORIENTATION_CHANGED);
// set delay to our debounce timeout
int delay = (orientation == ORIENTATION_VERTICAL ? VERTICAL_DEBOUNCE
: HORIZONTAL_DEBOUNCE);
mHandler.sendMessageDelayed(m, delay);
} else {
// no message is pending
mPendingOrientation = ORIENTATION_UNKNOWN;
}
}
}

然后发送消息ORIENTATION_CHANGED这个改变的消息;这个消息会调用一个回调函数，然后根据状态判断，调用acquire和release（）方法；

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Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case ORIENTATION_CHANGED:
synchronized (this) {
mOrientation = mPendingOrientation;
if (DEBUG) {
Log.d(TAG, "orientation: " +
(mOrientation == ORIENTATION_HORIZONTAL ? "horizontal"
: (mOrientation == ORIENTATION_VERTICAL ? "vertical"
: "unknown")));
}
mListener.orientationChanged(mOrientation);
}
break;
}
}
};

步骤五：回调到PhoneGlobals.java这个类的 orientationChanged（）

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@Override
public void orientationChanged(int orientation) {
mOrientation = orientation;
updateProximitySensorMode(mCM.getState());
}

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<pre name="code" class="java">/**
* Updates the wake lock used to control proximity sensor behavior,
* based on the current state of the phone. This method is called
* from the CallNotifier on any phone state change.
*
* On devices that have a proximity sensor, to avoid false touches
* during a call, we hold a PROXIMITY_SCREEN_OFF_WAKE_LOCK wake lock
* whenever the phone is off hook. (When held, that wake lock causes
* the screen to turn off automatically when the sensor detects an
* object close to the screen.)
*
* This method is a no-op for devices that don't have a proximity
* sensor.
*
* Note this method doesn't care if the InCallScreen is the foreground
* activity or not. That's because we want the proximity sensor to be
* enabled any time the phone is in use, to avoid false cheek events
* for whatever app you happen to be running.
*
* Proximity wake lock will *not* be held if any one of the
* conditions is true while on a call:
* 1) If the audio is routed via Bluetooth
* 2) If a wired headset is connected
* 3) if the speaker is ON
* 4) If the slider is open(i.e. the hardkeyboard is *not* hidden)
*
* @param state current state of the phone (see {@link Phone#State})
*/
/* package */ void updateProximitySensorMode(PhoneConstants.State state) {
boolean isRingingWhenActive = false;//MTK81281 add isRingingWhenActive for Cr:ALPS00117091
if (VDBG) Log.d(LOG_TAG, "updateProximitySensorMode: state = " + state);
if (proximitySensorModeEnabled()) {
synchronized (mProximityWakeLock) {
// turn proximity sensor off and turn screen on immediately if
// we are using a headset, the keyboard is open, or the device
// is being held in a horizontal position.
boolean screenOnImmediately = (isHeadsetPlugged()
|| PhoneUtils.isSpeakerOn(this)
|| isBluetoothHeadsetAudioOn()
|| mIsHardKeyboardOpen);
if (FeatureOption.MTK_VT3G324M_SUPPORT) {
screenOnImmediately = screenOnImmediately ||
((!VTCallUtils.isVTIdle()) && (!VTCallUtils.isVTRinging()));
}
// We do not keep the screen off when the user is outside in-call screen and we are
// horizontal, but we do not force it on when we become horizontal until the
// proximity sensor goes negative.
// this horizontal is not the same portrait.
boolean horizontal =
(mOrientation == AccelerometerListener.ORIENTATION_HORIZONTAL);
screenOnImmediately |= !isShowingCallScreenForProximity() && horizontal;
if (VDBG) Log.d(LOG_TAG, "updateProximitySensorMode: mBeginningCall = " + mBeginningCall);
if (VDBG) Log.d(LOG_TAG, "updateProximitySensorMode: screenOnImmediately = " + screenOnImmediately);
//MTK81281 add isRingingWhenActive for Cr:ALPS00117091 start
//when a call is activeand p-sensor turn off the screen,
//another call or vtcall in we don't release the lock and acquire again
//(the prowermanagerservice will turn on and off the screen and it's a problem)
//instead ,we don't release the lock(prowermanagerservice will not turn on and off the screen)
isRingingWhenActive = (state == PhoneConstants.State.RINGING)
&& (mCM.getActiveFgCallState() == Call.State.ACTIVE)
&& (mCM.getFirstActiveRingingCall().getState() == Call.State.WAITING);
if (VDBG) Log.d(LOG_TAG, "updateProximitySensorMode: isRingingWhenActive = " + isRingingWhenActive);
//MTK81281 add isRingingWhenActive for Cr:ALPS00117091 end
//MTK81281 add isRingingWhenActive for Cr:ALPS00117091
if (((state == PhoneConstants.State.OFFHOOK) || mBeginningCall || isRingingWhenActive)
&& !screenOnImmediately) {
// Phone is in use! Arrange for the screen to turn off
// automatically when the sensor detects a close object.
if (!mProximityWakeLock.isHeld()) {
if (DBG) Log.d(LOG_TAG, "updateProximitySensorMode: acquiring...");
mProximityWakeLock.acquire();
} else {
if (VDBG) Log.d(LOG_TAG, "updateProximitySensorMode: lock already held.");
}
} else {
// Phone is either idle, or ringing. We don't want any
// special proximity sensor behavior in either case.
if (mProximityWakeLock.isHeld()) {
if (DBG) Log.d(LOG_TAG, "updateProximitySensorMode: releasing...");
// Wait until user has moved the phone away from his head if we are
// releasing due to the phone call ending.
// Qtherwise, turn screen on immediately
int flags =
(screenOnImmediately ? 0 : PowerManager.WAIT_FOR_PROXIMITY_NEGATIVE);
mProximityWakeLock.release(flags);
} else {
if (VDBG) {
Log.d(LOG_TAG, "updateProximitySensorMode: lock already released.");
}
}
}
}
}
}</pre>

到这已经把Phone层的P-sensor的亮屏和灭屏说完了，回头再来屡屡这个mProximityWakeLock在framework层怎么具体实现的亮屏和灭屏的；敬请期待。。。。。。

更正：上述的讲解是不正确的，后来经过打log，发现，这个mProximityWakeLock.acquire();和mProximityWakeLock.release(flags);只是申请这个锁，和释放这个锁，防止其他的调用，

其实，在4.2以前Phone模块的P-Sensor在PowerManagerServer.java中处理的，而Android4.2的时候，谷歌对代码进行了一些调整，所以Phone的模块的P-Sensor的控制的类在DisplayPowerController.java

路径:framework/base/services/java/com/android/server/power/DisplayPowerController.java中的：

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private final SensorEventListener mProximitySensorListener = new SensorEventListener() {
@Override
public void onSensorChanged(SensorEvent event) {
if (mProximitySensorEnabled) {
final long time = SystemClock.uptimeMillis();
final float distance = event.values[0];
boolean positive = distance >= 0.0f && distance < mProximityThreshold;
if (DEBUG) {
Slog.d(TAG, "P-Sensor Changed: " + positive);
}
handleProximitySensorEvent(time, positive);
}
}

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这个onSensorChanged（）就是距离感应器的；这个log：

P-Sensor Changed:true 表示：靠近手机，P-sensor被遮挡住；

P-Sensor Changed:false 表示：离开手机，P-sensor没有被遮挡住；

通过这个log也能帮我们分析一些问题；这个mProximitySensorListener的注册和反注册，大家可以自己在这个类中搜索就可以了；

补充：在PowserManagerServerice.java这个类中， private LightsService.Light mButtonLight;这个变量申请的就是按键灯，像：home，返回键，menu键的灯，申请这个灯的代码：

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private LightsService mLightsService;
。。。。。。
mButtonLight = mLightsService.getLight(LightsService.LIGHT_ID_BUTTONS);

通过LightService可以获得键盘灯的实例，

打开灯的方法：mButtonLight.setBrightness(120);//120可以是（0～255）任意数字；

关闭灯的方法：mButtonLight.turnOff();

需求：要想使Phone通话界面的P-Sensor亮灭屏幕和按键灯同步，当屏幕灭的时候，按键灯也灭，屏幕亮的时候，按键灯也亮；其实做法很简单了，在onSensorChanged（）的时候处理，扩一些接口，

具体设计的类我列举一下：

PowerManager.java
PowerManagerService.java
BridgetPowerManager.java
IPowerManager.adil
DisPlayPowerController.java

具体代码就不详细赘述了，还是“觉知此事要躬行”；

注意在

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mLastUserActivityButtonTime = SystemClock.uptimeMillis();
mButtonLight.setBrightness(102);

在设置打开按键灯的时候，设置一下最后一次用户触摸按钮的时间；至于为什么？？大家自已到时候打log就明白了。。。。。。

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mLastUserActivityButtonTime

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