android 7.1 双击power按键唤醒camera功能调查
最近项目要求实现一个一定短时间内连续点击3次power按键进行某个特殊动作的需求，基于的base是android 7.1。以前没有听说过这个新功能，最初的想法是在PhoneWindowmanager.java的interceptKeyBeforeQueueing(KeyEvent event, int policyFlags)方法中对powerkey进行判断处理，这样做的话所有关于连续点击以及点击时间间隔的逻辑都要自己来实现，费了半天劲写了点逻辑，烧写进去后测试。
发现双击power按键的时候竟然触发了camera功能！！！这是什么鬼？？？
继续往上游查找，会找到GestureLauncherService.java中的interceptPowerKeyDown(KeyEvent event, boolean interactive, MutableBoolean outLaunched)。
一看到名字已经很熟悉了，联想所有hardkey事件相关都是从PhoneWindowManager.java中转发处理的，所以猜测这个方法应该是在PhoneWindowManager.java调过来的。
这句很关键，这样我们就跟最初调查的地方联系上了。
至此逻辑调用关系调查清楚，我们只需要在interceptPowerKeyDown方法中进行相应的定制就可以了。
发现双击power按键的时候竟然触发了camera功能！！！这是什么鬼？？？
百度之后竟然发现“关闭双击 Power 打开 Camera 功能”的相关资料，查了下发现原来android 7.1已经帮你实现了双击power按键的逻辑处理，研究了一下，特将这部分的逻辑处理进行说明。
02-26 14:02:32.115 1965 2066 I ActivityManager: START u0 {act=android.media.action.STILL_IMAGE_CAMERA flg=0x14000000 cmp=com.android.camera/.Camera} from uid 10038 on display 0adb pull /data/system/packages.list .com.android.systemui 10038 0 /data/user_de/0/com.android.systemui platform:privapp 3002,1023,1015,3001,3006PhoneStatusBar.java (base\packages\systemui\src\com\android\systemui\statusbar\phone):
@Override
public void onCameraLaunchGestureDetected(int source) {
mLastCameraLaunchSource = source;
if (mStartedGoingToSleep) {
mLaunchCameraOnFinishedGoingToSleep = true;
return;
}
if (!mNotificationPanel.canCameraGestureBeLaunched(
mStatusBarKeyguardViewManager.isShowing() && mExpandedVisible)) {
return;
}
if (!mDeviceInteractive) {
PowerManager pm = mContext.getSystemService(PowerManager.class);
pm.wakeUp(SystemClock.uptimeMillis(), "com.android.systemui:CAMERA_GESTURE");
mStatusBarKeyguardViewManager.notifyDeviceWakeUpRequested();
}
vibrateForCameraGesture();
if (!mStatusBarKeyguardViewManager.isShowing()) {
startActivity(KeyguardBottomAreaView.INSECURE_CAMERA_INTENT,
true /* dismissShade */);
} else {
if (!mDeviceInteractive) {
// Avoid flickering of the scrim when we instant launch the camera and the bouncer
// comes on.
mScrimController.dontAnimateBouncerChangesUntilNextFrame();
mGestureWakeLock.acquire(LAUNCH_TRANSITION_TIMEOUT_MS + 1000L);
}
if (mScreenTurningOn || mStatusBarKeyguardViewManager.isScreenTurnedOn()) {
mNotificationPanel.launchCamera(mDeviceInteractive /* animate */, source);
} else {
// We need to defer the camera launch until the screen comes on, since otherwise
// we will dismiss us too early since we are waiting on an activity to be drawn and
// incorrectly get notified because of the screen on event (which resumes and pauses
// some activities)
mLaunchCameraOnScreenTurningOn = true;
}
}
}startActivity(KeyguardBottomAreaView.INSECURE_CAMERA_INTENT,
true /* dismissShade */);StatusBarManagerService.java (base\services\core\java\com\android\server\statusbar):
@Override
public void onCameraLaunchGestureDetected(int source) {
if (mBar != null) {
try {
mBar.onCameraLaunchGestureDetected(source);
} catch (RemoteException e) {
}
}
}GestureLauncherService.java (base\services\core\java\com\android\server):
private boolean handleCameraLaunchGesture(boolean useWakelock, int source) {
boolean userSetupComplete = Settings.Secure.getIntForUser(mContext.getContentResolver(),
Settings.Secure.USER_SETUP_COMPLETE, 0, UserHandle.USER_CURRENT) != 0;
if (!userSetupComplete) {
if (DBG) Slog.d(TAG, String.format(
"userSetupComplete = %s, ignoring camera launch gesture.",
userSetupComplete));
return false;
}
if (DBG) Slog.d(TAG, String.format(
"userSetupComplete = %s, performing camera launch gesture.",
userSetupComplete));
if (useWakelock) {
// Make sure we don't sleep too early
mWakeLock.acquire(500L);
}
StatusBarManagerInternal service = LocalServices.getService(
StatusBarManagerInternal.class);
service.onCameraLaunchGestureDetected(source);
return true;
}继续往上游查找，会找到GestureLauncherService.java中的interceptPowerKeyDown(KeyEvent event, boolean interactive, MutableBoolean outLaunched)。
一看到名字已经很熟悉了，联想所有hardkey事件相关都是从PhoneWindowManager.java中转发处理的，所以猜测这个方法应该是在PhoneWindowManager.java调过来的。
PhoneWindowManager.java (base\services\core\java\com\android\server\policy):
private void interceptPowerKeyDown(KeyEvent event, boolean interactive) {
// Hold a wake lock until the power key is released.
if (!mPowerKeyWakeLock.isHeld()) {
mPowerKeyWakeLock.acquire();
}
// Cancel multi-press detection timeout.
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),
isNavBarEmpty(mLastSystemUiFlags));
if (panic) {
mHandler.post(mHiddenNavPanic);
}
// Latch power key state to detect screenshot chord.
if (interactive && !mScreenshotChordPowerKeyTriggered
&& (event.getFlags() & KeyEvent.FLAG_FALLBACK) == 0) {
mScreenshotChordPowerKeyTriggered = true;
mScreenshotChordPowerKeyTime = event.getDownTime();
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.
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.
hungUp = telecomManager.endCall();
}
}
GestureLauncherService gestureService = LocalServices.getService(
GestureLauncherService.class);
boolean gesturedServiceIntercepted = false;
if (gestureService != null) {
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;
if (!mPowerKeyHandled) {
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.
if (hasLongPressOnPowerBehavior()) {
Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
msg.setAsynchronous(true);
mHandler.sendMessageDelayed(msg,
ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
}
} else {
wakeUpFromPowerKey(event.getDownTime());
if (mSupportLongPressPowerWhenNonInteractive && hasLongPressOnPowerBehavior()) {
Message msg = mHandler.obtainMessage(MSG_POWER_LONG_PRESS);
msg.setAsynchronous(true);
mHandler.sendMessageDelayed(msg,
ViewConfiguration.get(mContext).getDeviceGlobalActionKeyTimeout());
mBeganFromNonInteractive = true;
} else {
final int maxCount = getMaxMultiPressPowerCount();
if (maxCount <= 1) {
mPowerKeyHandled = true;
} else {
mBeganFromNonInteractive = true;
}
}
}
}
}
这句很关键，这样我们就跟最初调查的地方联系上了。
PhoneWindowManager.java (base\services\core\java\com\android\server\policy):
/** {@inheritDoc} */
@Override
public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {
......
// Handle special keys.
switch (keyCode) {
......
case KeyEvent.KEYCODE_POWER: {
result &= ~ACTION_PASS_TO_USER;
isWakeKey = false; // wake-up will be handled separately
if (down) {
interceptPowerKeyDown(event, interactive);
} else {
interceptPowerKeyUp(event, interactive, canceled);
}
break;
}
......
}
if (useHapticFeedback) {
performHapticFeedbackLw(null, HapticFeedbackConstants.VIRTUAL_KEY, false);
}
if (isWakeKey) {
wakeUp(event.getEventTime(), mAllowTheaterModeWakeFromKey, "android.policy:KEY");
}
return result;
}至此逻辑调用关系调查清楚，我们只需要在interceptPowerKeyDown方法中进行相应的定制就可以了。
GestureLauncherService.java (base\services\core\java\com\android\server):
public boolean interceptPowerKeyDown(KeyEvent event, boolean interactive,
MutableBoolean outLaunched) {
boolean launched = false;
boolean intercept = false;
long doubleTapInterval;
synchronized (this) {
doubleTapInterval = event.getEventTime() - mLastPowerDown;
if (mIsEmergencyOnPowerKeyTapEnabled) {
//mIsEmergencyOnPowerKeyTapEnabled的值可以用来enable或disable三击的功能
System.arraycopy(mHits, 1, mHits, 0, mHits.length-1);
mHits[mHits.length-1] = SystemClock.uptimeMillis();
for (int i = 0 ; i < mHits.length ; i++) {
Slog.i(TAG, "mHits[" + i + "] = " + mHits[i] + "ms");
}
if (mHits[0] >=
(SystemClock.uptimeMillis()-mDuration)) {
//此处是对三击的时间进行判断，利用一个array来存储每次点击down的时间，然后进行判断是否在mDuration时间之类连续点击了3次。
launched = true;
intercept = interactive;
Arrays.fill(mHits,0);
}
} else if (mCameraDoubleTapPowerEnabled//mCameraDoubleTapPowerEnabled的值可以用来enable或disable双击启动camera的功能
&& doubleTapInterval < CAMERA_POWER_DOUBLE_TAP_MAX_TIME_MS) {
launched = true;
intercept = interactive;
}
mLastPowerDown = event.getEventTime();
}
if (launched) {
if (mIsEmergencyOnPowerKeyTapEnabled &&
!TextUtils.isEmpty(mEmergencyNumber)) {
Slog.i(TAG, "Power button Triple tap gesture detected, launching Emergency Call");
Intent intent = new Intent(Intent.ACTION_CALL_PRIVILEGED,
Uri.fromParts("tel", mEmergencyNumber, null));
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getContext().startActivityAsUser(intent, UserHandle.CURRENT);
} else {
Slog.i(TAG, "Power button double tap gesture detected, launching camera. Interval="
+ doubleTapInterval + "ms");
launched = handleCameraLaunchGesture(false /* useWakelock */,
StatusBarManager.CAMERA_LAUNCH_SOURCE_POWER_DOUBLE_TAP);
if (launched) {
MetricsLogger.action(mContext,
MetricsEvent.ACTION_DOUBLE_TAP_POWER_CAMERA_GESTURE,
(int) doubleTapInterval);
}
}
}
MetricsLogger.histogram(mContext, "power_double_tap_interval", (int) doubleTapInterval);
outLaunched.value = launched;
return intercept && launched;
}