How to Programmatically Control Screen Brightness on Android: A Step-by-Step Guide

Programmatically Adjusting System Brightness: A Comprehensive Guide

Changing the system brightness programmatically is a useful feature for applications that require controlling the device's display illumination. This article presents a detailed solution to this task.

Initial Approach: Setting Screen Brightness Attribute

Your initial approach using WindowManager.LayoutParams has limitations. The screenBrightness field only takes values from 0.0 to 1.0, not the expected maximum value of 255.

Alternative Solution: Utilizing Settings API

A more robust solution resides in the Settings API. By utilizing the ContentResolver and System class, you can manipulate the system's brightness settings directly. Here's how:

1. Initialization:

a. Define a private variable to store the brightness value.
b. Retrieve the ContentResolver and the current Window object.
c. Initialize the brightness variable with the current system brightness.

2. Monitoring Brightness Changes:

Write code to listen for and respond to brightness changes.

3. Updating Brightness:

a. Set the system brightness using Settings.System.putInt() and the updated brightness value.
b. Update the Window attributes by setting layoutpars.screenBrightness to the brightness value normalized to 1.0.
c. Apply the attribute changes to the window.

4. Manifest Permissions:

For Android Marshmallow and above, you need to request the WRITE_SETTINGS permission through the Settings Activity.

Example Code:

<code class="java">private ContentResolver cResolver;
private Window window;
private int brightness;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // Initialize settings and brightness.

    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) {
        Log.e("Error", "Cannot access system brightness");
        e.printStackTrace();
    }

    // Monitor brightness changes...

}

// Method to update brightness
public void setBrightness(int newBrightness) {
    // Update system brightness and window attributes.
}</code>

By following these steps, you can effectively change the system brightness programmatically, providing greater flexibility and customization options for your applications.

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