Question: I want a dialog that adjusts brightness of the screen using `SeekBar`.

How to display custom dialog with `SeekBar` that adjusts brightness of screen?

Answer: 
[You can use this API](http://developer.android.com/reference/android/view/WindowManager.LayoutParams.html#screenBrightness). This will change screen brightness of your window and not of the whole system.

```
        // Make the screen full bright for this activity.
        WindowManager.LayoutParams lp = getWindow().getAttributes();
        lp.screenBrightness = 1.0f;

        getWindow().setAttributes(lp);

```
Hey you can set the system brightness like this:

```
 //Set the system brightness using the brightness variable value
System.putInt(cResolver, System.SCREEN_BRIGHTNESS, brightness);
//Get the current window attributes
LayoutParams layoutpars = window.getAttributes();
//Set the brightness of this window
layoutpars.screenBrightness = brightness / (float)255;
//Apply attribute changes to this window
window.setAttributes(layoutpars);

```

Or you may refer on this complete [tutorial](http://programondaspot.blogspot.com/2015/09/change-screen-brightness.html)