屏幕会使用PowerManager自动唤醒。ON_AFTER_RELEASEakeLock

Question

In the following sample activity, the screen automatically wakes up right after the user switches it off (with power button), but only if I use the PowerManager.ON_AFTER_RELEASE flag. It doesn't happen if I don't use this flag.

public class TestActivity extends Activity {

    private WakeLock wakeLock;

    @Override
    protected void onResume() {
        super.onResume();

        wakeLock = ((PowerManager) getSystemService(Context.POWER_SERVICE)).newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK | PowerManager.ON_AFTER_RELEASE, "test");
        wakeLock.acquire();
    }

    @Override
    protected void onPause() {
        wakeLock.release();
        super.onPause();
    }

}

Is there a way to avoid this behaviour while still using the PowerManager.ON_AFTER_RELEASE flag ?

I have the same issue when using the MediaPlayer's setWakeMode() method (I checked in the source code and it also uses this PowerManager.ON_AFTER_RELEASE flag)

Or maybe I just misunderstand the purpose of this flag...what is it made for then ?

Answer 1

The WindowManager.LayoutParams class has a flag, FLAG_TURN_SCREEN_ON . It's documented as follows:

Window flag: when set as a window is being added or made visible, once the window has been shown then the system will poke the power manager's user activity (as if the user had woken up the device) to turn the screen on.

Try clearing this flag in your onResume :

getWindow().clearFlags( WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON );

and see if that makes the screen stay dark after the power button is hit. You could experiment with the flag in onPause too. Just a guess.

Answer 2

Ok, after many experiments it seems that there is no way to avoid this auto screen wakeup when using this PowerManager.ON_AFTER_RELEASE .

As a consequence it's not possible to use MediaPlayer.setWakeMode() without having this issue.