Android4.1 关于Rotation相关的Configuration整体分析

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() {
         @Override
         public 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 1.1.2.1
         if (!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 -1
         if (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 reason
         return;
     }
     //Could have been invoked due to screen turning on or off or
     //change of the currently visible window's orientation
     if (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 enabled
             if (!mOrientationSensorEnabled) {
                 mOrientationListener.enable();
                 if(localLOGV) Log.v(TAG, "Enabling listeners");
                 mOrientationSensorEnabled = true;
             }
         }
     }
     //check if sensors need to be disabled
     if (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) {