Android4.1 Rotation 小结

1, 操作Android 辅助功能：

获取启动时的旋转方向：

------->RotationPolicy.isRotationLocked() :packages/apps/Settings/src/com/android/settings/AccessibilitySettings.java ---->isRotationLocked() : frameworks/base/core/java/com/android/internal/view/RotationPolicy.java ----> Settings.System.ACCELEROMETER_ROTATION ----- 获取系统中的设置属性。

 61     /** 62      * Returns true if rotation lock is enabled. 63      */ 64     public static boolean isRotationLocked(Context context) { 65         return Settings.System.getInt(context.getContentResolver(), 66                 Settings.System.ACCELEROMETER_ROTATION, 0) == 0; 67     }

当 enable 或者 disable "Auto-rotate screen" 的时候

RotationPolicy.setRotationLockForAccessibility() : packages/apps/Settings/src/com/android/settings/AccessibilitySettings.java

setRotationLockForAccessibility() : frameworks/base/core/java/com/android/internal/view/RotationPolicy.java

102     public static void setRotationLockForAccessibility(Context context, final boolean enabled) {103         Settings.System.putInt(context.getContentResolver(),104                 Settings.System.HIDE_ROTATION_LOCK_TOGGLE_FOR_ACCESSIBILITY, enabled ? 1 : 0);105106         AsyncTask.execute(new Runnable() {107             @Override108             public void run() {109                 try {110                     IWindowManager wm = IWindowManager.Stub.asInterface(111                             ServiceManager.getService(Context.WINDOW_SERVICE));112                     if (enabled) {113                         wm.freezeRotation(Surface.ROTATION_0);114                     } else {115                         wm.thawRotation();116                     }117                 } catch (RemoteException exc) {118                     Log.w(TAG, "Unable to save auto-rotate setting");119                 }120             }121         });122     }

- 如果enable：调用WindowManagerService的freezeRotation()
- 否则调用wm.thawRotation() ----- 即WindowManagerService的thawRotation()
freezeRotation() ----------frameworks/base/services/java/com/android/server/wm/WindowManagerService.java

 5663     /** 5664      * Freeze rotation changes.  (Enable "rotation lock".) 5665      * Persists across reboots. 5666      * @param rotation The desired rotation to freeze to, or -1 to use the 5667      * current rotation. 5668      */ 5669     public void freezeRotation(int rotation) { 5670         if (!checkCallingPermission(android.Manifest.permission.SET_ORIENTATION, 5671                 "freezeRotation()")) { 5672             throw new SecurityException("Requires SET_ORIENTATION permission"); 5673         } 5674         if (rotation < -1 || rotation > Surface.ROTATION_270) { 5675             throw new IllegalArgumentException("Rotation argument must be -1 or a valid " 5676                     + "rotation constant."); 5677         } 5678 5679         if (DEBUG_ORIENTATION) Slog.v(TAG, "freezeRotation: mRotation=" + mRotation); 5680 5681         mPolicy.setUserRotationMode(WindowManagerPolicy.USER_ROTATION_LOCKED, 5682                 rotation == -1 ? mRotation : rotation); 5683         updateRotationUnchecked(false, false); 5684

setUserRotationMode() ------frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
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() .
updateRotationUnchecked -------WindowManagerService.updateRotationUnchecked()

分析：thawRotation() ----------- 释放rotation ----- 无论什么时候都使能旋转：调用setUserRotationMode() -----mPolicy.setUserRotationMode( WindowManagerPolicy.USER_ROTATION_FREE, 777); // rot not used 分析setUserRotationMode :

 public void setUserRotationMode(int mode, int rot) {        ContentResolver res = mContext.getContentResolver();        // mUserRotationMode and mUserRotation will be assigned by the content observer        if (mode == WindowManagerPolicy.USER_ROTATION_LOCKED) {            Settings.System.putIntForUser(res,                    Settings.System.USER_ROTATION,                    rot,                    UserHandle.USER_CURRENT);            Settings.System.putIntForUser(res,                    Settings.System.ACCELEROMETER_ROTATION,                    0,                    UserHandle.USER_CURRENT);        } else {            Settings.System.putIntForUser(res,                    Settings.System.ACCELEROMETER_ROTATION,                    1,                    UserHandle.USER_CURRENT);        }}

---------------- 也就是说，如果在启动系统之前，调用thawrotation(), 就是强制地执行 Settings.System.ACCELEROMETER_ROTATION；这样系统就会一直默认旋转。以前遇到有一个问题：在系统启动时，强制打开系统旋转，这样在辅助功能的设置就会无效，正是这个原因。

    private final class BootCompletedReceiver extends BroadcastReceiver {      @Override      public void onReceive(Context context, Intent intent) {        // At any given time accessories could be inserted        // one on the board, one on the dock and one on HDMI:        // observe three UEVENTs        init();  // set initial status   /*     try{          IWindowManager wm = IWindowManager.Stub.asInterface(                        ServiceManager.getService(Context.WINDOW_SERVICE));          wm.thawRotation();        }catch(Exception e){        }*/        for (int i = 0; i < uEventInfo.size(); ++i) {            UEventInfo uei = uEventInfo.get(i);            startObserving("DEVPATH="+uei.getDevPath());        }      }    }

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