How to Programmatically Adjust System Brightness in Android?

Adjusting System Brightness Programmatically

Despite setting the screenBrightness attribute of the window layout parameters, no change in brightness is observed. This issue prompts the exploration of alternative methods for programmatically altering system brightness.

Solution:

To effectively adjust system brightness, consider the following steps:

1. Declare the following instance variables in your activity class:

   private int brightness;
   private ContentResolver cResolver;
   private Window window;

2. Within the onCreate method, retrieve the content resolver, window reference, and the current system brightness:

   cResolver = getContentResolver();
   window = getWindow();
   
   try {
       Settings.System.putInt(cResolver, Settings.System.SCREEN_BRIGHTNESS_MODE, Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
       brightness = Settings.System.getInt(cResolver, Settings.System.SCREEN_BRIGHTNESS);
   } catch (SettingNotFoundException e) {
       // Handle the error gracefully
   }

3. Implement a mechanism to monitor changes in brightness (e.g., a SeekBar listener).

4. When adjusting the brightness, set the system brightness using the updated brightness variable and update the window attributes:

   Settings.System.putInt(cResolver, Settings.System.SCREEN_BRIGHTNESS, brightness);
   
   LayoutParams layoutpars = window.getAttributes();
   layoutpars.screenBrightness = brightness / 255f;
   window.setAttributes(layoutpars);

5. Don't forget to declare the necessary permission in the AndroidManifest.xml file:

   <code class="xml"><uses-permission android:name="android.permission.WRITE_SETTINGS" /></code>

Note:

For API levels greater than or equal to 23 (Android 6.0 Marshmallow), you'll need to request the WRITE_SETTINGS permission through a Settings Activity or via the Activity Compatibility Library (ActivityCompat).

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