本文主要是介绍Android4.1 关于Rotation相关的Configuration整体分析，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
关于Rotation方面在Android中有点会涉及到。
1. 在Settings->Display中有“Auto-rotate screen” 选项，当enable或者disable的时候都会影响到系统的Rotation
2. 当旋转手机的时候，系统会做怎么的操作去通知Activity要旋转界面了。
3. 当新启一个应用需要强制横屏或者竖屏的时候，系统是怎么去判断的。
1. 当我们enable或者disable “Auto-rotate screen”的时候，系统会做什么
1. RotationPolicy.setRotationLockForAccessibility()
1. 当用户enable或者disable “Auto-rotate screen”的时候，会调用RotationPolicy.setRotationLockForAccessibility()， 而在这个函数里面如果是enable就调用wm.freezeRotation(Suface.ROTATION_0); // goto 1.1
2. 否则就调用wm.thawRotation().
public static void setRotationLockForAccessibility(Context context, final boolean enabled) {Settings.System.putIntForUser(context.getContentResolver(),Settings.System.HIDE_ROTATION_LOCK_TOGGLE_FOR_ACCESSIBILITY, enabled ? 1 : 0,UserHandle.USER_CURRENT);AsyncTask.execute(new Runnable() {@Overridepublic void run() {try {IWindowManager wm = WindowManagerGlobal.getWindowManagerService();if (enabled) {wm.freezeRotation(Surface.ROTATION_0);} else {wm.thawRotation();}} catch (RemoteException exc) {Log.w(TAG, "Unable to save auto-rotate setting");}}});}
1.1 WindowManagerService.freezeRotation()
1. mPolicy.setUserRotationMode 通过PhoneWindowManager.setUserRotationMode()去设置Settings.System相关的数据库值，在PhoneWindowManager中会有一个Observe去监听Settings.System的数值变化，如果有变动就去调用SettingsObserver.onChange() //goto 1.1.1
2. updateRotationUnchecked(false, false); // goto 1.1.2
public void freezeRotation(int rotation) {... ...if (DEBUG_ORIENTATION) Slog.v(TAG, "freezeRotation: mRotation=" + mRotation);mPolicy.setUserRotationMode(WindowManagerPolicy.USER_ROTATION_LOCKED,rotation == -1 ? mRotation : rotation);updateRotationUnchecked(false, false);}1.1.1 SettingsObserver.onChange()
1. updateSettings(); 跟新系统相关的设置 //goto 1.1.1.1
2. updateRotation(false);
@Override public void onChange(boolean selfChange) {updateSettings();updateRotation(false);}
1.1.2 WindowManagerService.updateRotationUnchecked()
这是freezeRotation里面做的第二个动作，为什么要把它写在前面，因为在debug的时候，发现这个函数中会调用policy中函数请求mLock的锁，然后block住1.1.1.1 PhoneWindowManager.updateSettings()。
1. updateRotationUncheckedLocked(false); 如果返回的是false，就去直接执行performLayoutAndPlaceSurfacesLocked 去进行后续的刷新工作 // goto 1.1.2.1
2. 如果满足相应的条件， performLayoutAndPlaceSurfacesLocked() //
3. 如果Configuration有变化或者明确要求sendConfiguration，就调用sendNewConfiguration(); 让AMS去updateConfiguration。 //这时候还不会执行
public void updateRotationUnchecked(boolean alwaysSendConfiguration, boolean forceRelayout) {long origId = Binder.clearCallingIdentity();boolean changed;synchronized(mWindowMap) {changed = updateRotationUncheckedLocked(false); // goto 1.1.2.1if (!changed || forceRelayout) {getDefaultDisplayContentLocked().layoutNeeded = true;performLayoutAndPlaceSurfacesLocked(); //后续分析}}if (changed || alwaysSendConfiguration) {sendNewConfiguration();}}
1.1.2.1 WindowManagerService.updateRotationUncheckedLocked()
1. mPolicy.rotationForOrientationLw(mForcedAppOrientation, mRotation); // 返回0 goto 1.1.2.1.1
2. mPolicy.rotationHasCompatibleMetricsLw
3. 如果roataion 和altOrientataion都没有发生变化就直接返回 false. （这种情况是在portrait模式下enable rotation），如果是landscape模式下就应该往下走了。
4. computeScreenConfigurationLocked(null); // Update application display metrics. 跟新屏幕相关的信息。
public boolean updateRotationUncheckedLocked(boolean inTransaction) {... ...int rotation = mPolicy.rotationForOrientationLw(mForcedAppOrientation, mRotation);boolean altOrientation = !mPolicy.rotationHasCompatibleMetricsLw(mForcedAppOrientation, rotation);if (mRotation == rotation && mAltOrientation == altOrientation) {// No change.return false;}mRotation = rotation;mAltOrientation = altOrientation;mPolicy.setRotationLw(mRotation);mWindowsFreezingScreen = true;mH.removeMessages(H.WINDOW_FREEZE_TIMEOUT);mH.sendMessageDelayed(mH.obtainMessage(H.WINDOW_FREEZE_TIMEOUT),WINDOW_FREEZE_TIMEOUT_DURATION);mWaitingForConfig = true;getDefaultDisplayContentLocked().layoutNeeded = true;startFreezingDisplayLocked(inTransaction, 0, 0);// startFreezingDisplayLocked can reset the ScreenRotationAnimation.screenRotationAnimation =mAnimator.getScreenRotationAnimationLocked(Display.DEFAULT_DISPLAY);// We need to update our screen size information to match the new// rotation. Note that this is redundant with the later call to// sendNewConfiguration() that must be called after this function// returns... however we need to do the screen size part of that// before then so we have the correct size to use when initializing// the rotation animation for the new rotation.computeScreenConfigurationLocked(null);final DisplayContent displayContent = getDefaultDisplayContentLocked();final DisplayInfo displayInfo = displayContent.getDisplayInfo();if (!inTransaction) {if (SHOW_TRANSACTIONS) {Slog.i(TAG, ">>> OPEN TRANSACTION setRotationUnchecked");}Surface.openTransaction();}try {// NOTE: We disable the rotation in the emulator because// it doesn't support hardware OpenGL emulation yet.if (CUSTOM_SCREEN_ROTATION && screenRotationAnimation != null&& screenRotationAnimation.hasScreenshot()) {if (screenRotationAnimation.setRotationInTransaction(rotation, mFxSession,MAX_ANIMATION_DURATION, mTransitionAnimationScale,displayInfo.logicalWidth, displayInfo.logicalHeight)) {updateLayoutToAnimationLocked();}}mDisplayManagerService.performTraversalInTransactionFromWindowManager();} finally {if (!inTransaction) {Surface.closeTransaction();if (SHOW_LIGHT_TRANSACTIONS) {Slog.i(TAG, "<<< CLOSE TRANSACTION setRotationUnchecked");}}}final WindowList windows = displayContent.getWindowList();for (int i = windows.size() - 1; i >= 0; i--) {WindowState w = windows.get(i);if (w.mHasSurface) {if (DEBUG_ORIENTATION) Slog.v(TAG, "Set mOrientationChanging of " + w);w.mOrientationChanging = true;mInnerFields.mOrientationChangeComplete = false;}}for (int i=mRotationWatchers.size()-1; i>=0; i--) {try {mRotationWatchers.get(i).onRotationChanged(rotation);} catch (RemoteException e) {}}scheduleNotifyRotationChangedIfNeededLocked(displayContent, rotation);return true;}
1.1.2.1.1 PhoneWindowManager.rotationForOrientationLw()
这个函数的主要作用是返回跟Orientation相关的rotation，如果没有固定的设置，系统会返回一个默认的Rotation值。
1. 先去调用mOrientationListener.getProposeRotation()去获取Sensor认为的合适的rotation值，通常是-1，我debug的时候返回的就是。mOrientationListener 为MyOrientationListener对象
2. 由于此时mUserRotationMode == WindowManagerPolicy.USER_ROTATION_LOCKED 所以把preferredRotation = mUserRotation; 然后跟据对应的orientation选择对应的Rotation返回，我们这个case是走到default里面把preferredRotation返回回去。
public int rotationForOrientationLw(int orientation, int lastRotation) {synchronized (mLock) {int sensorRotation = mOrientationListener.getProposedRotation(); // may be -1if (sensorRotation < 0) {sensorRotation = lastRotation;}final int preferredRotation;if (mLidState == LID_OPEN && mLidOpenRotation >= 0) {.... ...} else if (mUserRotationMode == WindowManagerPolicy.USER_ROTATION_LOCKED&& orientation != ActivityInfo.SCREEN_ORIENTATION_NOSENSOR) {// Apply rotation lock. Does not apply to NOSENSOR.// The idea is that the user rotation expresses a weak preference for the direction// of gravity and as NOSENSOR is never affected by gravity, then neither should// NOSENSOR be affected by rotation lock (although it will be affected by docks).preferredRotation = mUserRotation;} else {// No overriding preference.// We will do exactly what the application asked us to do.preferredRotation = -1;}switch (orientation) {case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT:// Return portrait unless overridden.if (isAnyPortrait(preferredRotation)) {return preferredRotation;}return mPortraitRotation;case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE:// Return landscape unless overridden.if (isLandscapeOrSeascape(preferredRotation)) {return preferredRotation;}return mLandscapeRotation;case ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT:// Return reverse portrait unless overridden.if (isAnyPortrait(preferredRotation)) {return preferredRotation;}return mUpsideDownRotation;case ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE:// Return seascape unless overridden.if (isLandscapeOrSeascape(preferredRotation)) {return preferredRotation;}return mSeascapeRotation;case ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE:// Return either landscape rotation.if (isLandscapeOrSeascape(preferredRotation)) {return preferredRotation;}if (isLandscapeOrSeascape(lastRotation)) {return lastRotation;}return mLandscapeRotation;case ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT:// Return either portrait rotation.if (isAnyPortrait(preferredRotation)) {return preferredRotation;}if (isAnyPortrait(lastRotation)) {return lastRotation;}return mPortraitRotation;default:// For USER, UNSPECIFIED, NOSENSOR, SENSOR and FULL_SENSOR,// just return the preferred orientation we already calculated.if (preferredRotation >= 0) {return preferredRotation;}return Surface.ROTATION_0;}}}
1.1.1.1 PhoneWindowManager.updateSettings()
当 1.1.2的lock释放之后，也就是 PhoneWindowManager.rotationForOrientationLw()执行完，updateSettings会等到mLock锁.
由于userRotation和userRotationMode都发生了变化，所以会先后执行
1. updateOrientationListenerLp(); // goto 1.1.1.1.1
2. updateRotation(true); //这个操作跟1.1.1.2是一样的，只不过这次需要去sendConfiguration了。
public void updateSettings() {ContentResolver resolver = mContext.getContentResolver();boolean updateRotation = false;synchronized (mLock) {... ...// Configure rotation lock.int userRotation = Settings.System.getIntForUser(resolver,Settings.System.USER_ROTATION, Surface.ROTATION_0,UserHandle.USER_CURRENT);if (mUserRotation != userRotation) {mUserRotation = userRotation;updateRotation = true;}int userRotationMode = Settings.System.getIntForUser(resolver,Settings.System.ACCELEROMETER_ROTATION, 0, UserHandle.USER_CURRENT) != 0 ?WindowManagerPolicy.USER_ROTATION_FREE :WindowManagerPolicy.USER_ROTATION_LOCKED;if (mUserRotationMode != userRotationMode) {mUserRotationMode = userRotationMode;updateRotation = true;updateOrientationListenerLp();}}if (updateRotation) {updateRotation(true);}}
1.1.1.1.1 PhoneWindowManager.updateOrientationListenerLp();
这是函数很简单，由于我们把Rotation打开了，所以就去enable mOrientationListener （MyOrientationListener），作为Sensor变化的一个listener的回调函数。
void updateOrientationListenerLp() {if (!mOrientationListener.canDetectOrientation()) {// If sensor is turned off or nonexistent for some reasonreturn;}//Could have been invoked due to screen turning on or off or//change of the currently visible window's orientationif (localLOGV) Log.v(TAG, "Screen status="+mScreenOnEarly+", current orientation="+mCurrentAppOrientation+", SensorEnabled="+mOrientationSensorEnabled);boolean disable = true;if (mScreenOnEarly) {if (needSensorRunningLp()) {disable = false;//enable listener if not already enabledif (!mOrientationSensorEnabled) {mOrientationListener.enable();if(localLOGV) Log.v(TAG, "Enabling listeners");mOrientationSensorEnabled = true;}} } //check if sensors need to be disabledif (disable && mOrientationSensorEnabled) {mOrientationListener.disable();if(localLOGV) Log.v(TAG, "Disabling listeners");mOrientationSensorEnabled = false;}1.1.1.1 PhoneWindowManager.sendNewConfiguration()
调用AMS去updateconfigurattion，后续分析
void sendNewConfiguration() {try {mActivityManager.updateConfiguration(null);} catch (RemoteException e) {}}
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