Set brightness below the system limit using alpha and save value

Question

I've been trying to set the brightness under the limit of Android settings. There are two similar apps in Google Play doing this:

• Shades
• Screen Filter

The second one, even allows to use the phone with a black screen, just what I need in my app.

There are a lot of other questions about brightness but not to set it under this system limit, and I've found one question asking almost the same but not helping me: Brightness Screen Filter

So after a lot of search I've got following code:

int brightness=0; //0 to 255, so I set it to a low level (not enough for me)
ContentResolver cResolver = getContentResolver();  

//set the system brightness value, and if active, disable auto mode.
System.putInt(cResolver, System.SCREEN_BRIGHTNESS, brightness);  
System.putInt(cResolver, System.SCREEN_BRIGHTNESS_MODE, System.SCREEN_BRIGHTNESS_MODE_MANUAL);  

//previous lines don't set the brightness to the current screen so we set it like this: 
LayoutParams layoutpars = getWindow().getAttributes();  
layoutpars.screenBrightness = brightness / (float)255; 

//Now we have brightness to the minimum allowed by Android but
//to achieve what these apps do, I have to reduce alpha of the window to the min
//then the screen is black like I want, and totally usable!
layoutpars.alpha=0.05f;
window.setAttributes(layoutpars);

Here the alpha is the key, this is doing what I want, but only for current window/screen, and I need to save to the system this alpha as default, like I'm doing with the brightness and the Manual mode for applying everywhere.

Do you know how I should do this? I'm unable to find a value "System.SCREEN_ALPHA" to set it with System.putInt or another way to do this.

In the other question I linked before, pheelicks replied with a suggestion of using a transparent non-touchable over screen, but this is not working for me, and the result does not give the feeling of a turned off screen like previous apps.

Thanks.

Answer 1

I decided to implemented this feature just inside my app with alpha. So I couldn't solve the initial question at all....

Anyways, in the end seems that the solution to this question is the one Pheelicks replied here: https://stackoverflow.com/a/4287597/1667990

-This is launching an activity to be always on top,

-with alpha to 0.0f so it be transparent,

-that redirects the touch to the activity behind:

//Let touches go through to apps/activities underneath.
Window window = activity.getWindow();
window.addFlags(FLAG_NOT_TOUCHABLE);

-And most important thing not explained in the previous link, is to set the dim behind our window to 1 (like the dim in a messagebox, but setting to the max to be black behind :D )

window.setDimAmount ((float)1.0) ;
window.setFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND,
    WindowManager.LayoutParams.FLAG_DIM_BEHIND);

I haven't tried that and decided not to do it in my app as it could bring unexpected behavior in my circumstances, but I think it should definitely work, if anyone try please add your feedback!