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);
      105
      106         AsyncTask.execute(new Runnable() {
      107             @Override
      108             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());
        }
      }
    }