Can't apply system screen brightness programmatically in Android

Question

I'm using the following to set the system auto brightness mode and level:

    android.provider.Settings.System.putInt(y.getContentResolver(),Settings.System.SCREEN_BRIGHTNESS_MODE, 0);
    android.provider.Settings.System.putInt(y.getContentResolver(),Settings.System.SCREEN_BRIGHTNESS, y.brightness1);

I can change auto-brighess on and off, and set different levels. The settings seem to be applied properly -- I can go to into Settings --> Display --> Brightness, and whanever setting I set is actually shown correctly. However, the actual screen isn't changing its brightness. If i just tap on the slider in Display Settings, then everything gets applied.

I shoudl mention that I'm running an app withat a main activity, and these settings are getting applied in the BroadcastReceiver. I did try to create a dummy activity and tested the stuff there, but got the same results.

Answer 1

OK, found the answer here: Refreshing the display from a widget?

Basically, have to make a transparent activity that processes the brightness change. What's not mentioned in the post is that you have to do:

Settings.System.putInt(y.getContentResolver(),Settings.System.SCREEN_BRIGHTNESS_MODE, 0);
Settings.System.putInt(y.getContentResolver(),Settings.System.SCREEN_BRIGHTNESS, brightnessLevel); 

then do

WindowManager.LayoutParams lp = getWindow().getAttributes();
    lp.screenBrightness = brightness; 
    getWindow().setAttributes(lp);

And if you call finish() right after applying the changes, brightness will never actually change because the layout has to be created before the brightness settings is applied. So I ended up creating a thread that had a 300ms delay, then called finish().