How can I change the Brightness of the screen in BroadcastReceiver?

Question

I want to change the Brightness, I can use this method:

public static void SetBright(int brightness, Context context) {
    if (isAutoBrightness(context)) {
        stopAutoBrightness(context);
    }
    WindowManager.LayoutParams lp = ((Activity) context).getWindow()
            .getAttributes();
    lp.screenBrightness = Float.valueOf(brightness) * (1f / 255f);
    ((Activity) context).getWindow().setAttributes(lp);
}

I need an Activity to pass into SetBright(int brightness, Context context);

But now I have to invoke the method SetBright(int brightness, Context context) in a Brocastreceiver. I can use the context in the method onReceive(Context context, Intent intent) but if I quit the app, it doesn't work.

Is there another method that I can use to change the brightness instead of useing an activity?

Answer 1

start dummy activity and set window parameter using brightness(0 to 1 range-1 for 255). run a timer of 50, 100 or 500 ms whatever. after that finish the activity.

TimerTask finishTask = new TimerTask() {

        @Override
        public void run() {
            BrightActivity.this.finish();
            timer.cancel();
            if (timer != null) {
                timer = null;
            }
        }
    };
    timer.schedule(finishTask,Constants.BRIGHTNESS_REFRESH_DELAY);

Answer 2

if you want to save then try this after setting brightness :

public static void saveBrightness(Context context, int brightness) {
   ContentResolver resolver= context.getContentResolver();
    Uri uri = android.provider.Settings.System
            .getUriFor("screen_brightness");
    android.provider.Settings.System.putInt(resolver, "screen_brightness",
            brightness);
    resolver.notifyChange(uri, null);
}

Answer 3

Primarily I used 500 ms for screen refresh time, but in galaxy s3 it does not work. but 1000 is ok. So screen refresh time is device dependent may be.