《SystemUI》限制低電量打開手電筒

任務：當電流低於16%的時候，關閉手電，而且在提醒用戶不能打開。

監聽電量，實現關閉手電
手電圖標實如今FlashlightTile.java

監聽電量，通常會使用廣播，可是SystemUI BatteryController註冊了電量廣播，能夠利用BatteryController裏面有相關的操做監聽，

當電量低於16%，不能打開手電筒，並彈出提示框
當電量低於16%，若是手電筒處於開啓狀態，關閉手電筒。
public class FlashlightTile extends QSTileImpl<BooleanState> implements
        FlashlightController.FlashlightListener , 
+        BatteryController.BatteryStateChangeCallback
        {

    private final Icon mIcon = ResourceIcon.get(R.drawable.ic_signal_flashlight);
    private final FlashlightController mFlashlightController;

+    // add for PCAAO-1862
+    private int mLevel = 100;
+    private final int lowLevel = 16;
+    private final BatteryController mBatteryController;
+    // END.

    public FlashlightTile(QSHost host) {
        super(host);
        mFlashlightController = Dependency.get(FlashlightController.class);
+        mBatteryController = Dependency.get(BatteryController.class);
    }

    @Override
    public void handleSetListening(boolean listening) {
        Log.i("FlashlightTile","handleSetListening "+listening);
        if (listening) {
+           mFlashlightController.addCallback(this);
            mBatteryController.addCallback(this);
        } else {
            mFlashlightController.removeCallback(this);
+            mBatteryController.removeCallback(this);
        }
    }

        @Override
    protected void handleClick() {
        if (ActivityManager.isUserAMonkey()) {
            return;
        }
+        // add for PCAAO-1862
+        boolean flashLightEnable = mFlashlightController.isEnabled();
+        if (!flashLightEnable && mLevel <= lowLevel) {
+            SystemUIDialog dialog = new SystemUIDialog(mContext);
+            dialog.setTitle(R.string.airplane_dlg_title);
+            dialog.setMessage(R.string.flash_light_dlg_msg);
+            dialog.setPositiveButton(R.string.yes, null);
+            //dialog.setNegativeButton(R.string.cancel, null);
+            dialog.setShowForAllUsers(true);
+            dialog.show();
+            return;
+        }
+        // END.

        boolean newState = !mState.value;
        refreshState(newState);
        mFlashlightController.setFlashlight(newState);

    }
+        @Override
+    public void onBatteryLevelChanged(int level, boolean pluggedIn, boolean charging) {
+        mLevel = level;
+
+       //if 
+       boolean flashLightEnable = mFlashlightController.isEnabled();
+       Log.i("FlashlightTile","flashLightEnable ,mState.value"+flashLightEnable+","+mState.value);
+       if (mLevel <= lowLevel && flashLightEnable && mState.value){
+           refreshState(false);
+           if(mFlashlightController!=null){
+             mFlashlightController.setFlashlight(false);
+           }
+       }
+    }

}