How to Increase/Decrease Screen Brightness using Volume Keys Programmatically in Android?

Screen brightness is one such factor that directly affects the Users as well as the Battery on a device. Android devices are Smart systems and have an inbuilt system for Auto-Brightness. But mostly this feature is unchecked by the users or set off by default. Irrespective of whether this feature is present, set on or off, or absent in any device, a developer must take this opportunity into consideration and develop an optimized application. Anything that is declared inside the application might have an effect on the outside space, i.e., if the screen brightness was changed programmatically from an application, the brightness value might stay unaltered even after exiting the application. So one must try to trace back the originals and set them before a user exits.

Where can we use this feature?

1. Non-Media: Non-media (music or video) applications could use the volume buttons to increase or decrease the brightness of a screen in steps.
2. Book Reader Applications: Reading books can sometimes be a moody choice, one can increase or decrease brightness directly from the application in steps.
3. News Paper Applications: One can increase or decrease brightness directly from the application in steps.

Through this article, we want you to know that volume buttons could be used for increasing and decreasing the brightness of a screen. A sample GIF is given below to get an idea about what we are going to do in this article. Note that we are going to implement this project using the Kotlin language.

Approach

Step 1: Create a New Project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language.

Step 2: Working with the AndroidManifest.xml file

Controlling the device screen brightness requires a change in root settings, for which declare a uses-permission of WRITE_SETTINGS in the AndroidManifest.xml file.

<uses-permission android:name=”android.permission.WRITE_SETTINGS”

       tools:ignore=”ProtectedPermissions” />

Below is the code for the AndroidManifest.xml file. 

XML

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="org.geeksforgeeks.screenbrightness_usingvolumekeys">

      <!--Add this permission-->
    <uses-permission android:name="android.permission.WRITE_SETTINGS"
        tools:ignore="ProtectedPermissions" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Step 3: Working with the activity_main.xml file

There is nothing to do with the activity_main.xml file. So keep the file as it is.

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Step 4: Working with the MainActivity.kt file

Finally, go to the MainActivity.kt file, and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin

import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Bundle
import android.provider.Settings
import android.view.KeyEvent
import android.widget.Toast
import androidx.annotation.RequiresApi
import androidx.appcompat.app.AppCompatActivity
import kotlin.math.round

class MainActivity : AppCompatActivity() {

    var brightnessValue = 255

    @RequiresApi(Build.VERSION_CODES.M)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    // Function to decrease the brightness
    @RequiresApi(Build.VERSION_CODES.M)
    fun decrease() { // Get app context object.

        val context = applicationContext

        // Check whether has the write settings permission or not.
        val settingsCanWrite = hasWriteSettingsPermission(context)

        // If do not have then open the Can modify system settings panel.
        if (!settingsCanWrite) {
            changeWriteSettingsPermission(context)
        } else {
            if (brightnessValue >= 11) {
                brightnessValue -= 10
                changeScreenBrightness(context, brightnessValue)
                val k = brightnessValue.toDouble() / 255
                Toast.makeText(
                    applicationContext, "Brightness : ${round(k * 100)}%",
                    Toast.LENGTH_SHORT
                ).show()
            }
        }
    }

    // Function to increase the brightness
    @RequiresApi(Build.VERSION_CODES.M)
    fun increase() {
        val context = applicationContext

        // Check whether has the write settings permission or not.
        val settingsCanWrite = hasWriteSettingsPermission(context)

        // If do not have then open the Can modify system settings panel.
        if (!settingsCanWrite) {
            changeWriteSettingsPermission(context)
        } else {
            if (brightnessValue <= 245) {
                brightnessValue += 10
                changeScreenBrightness(context, brightnessValue)
                val k = brightnessValue.toDouble() / 255
                Toast.makeText(
                    applicationContext, "Brightness : ${round(k * 100)}%",
                    Toast.LENGTH_SHORT
                ).show()
            }
        }
    }

    // Listen to the volume keys
    @RequiresApi(Build.VERSION_CODES.M)
    override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {

        // What happens when volume down key is pressed
        if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN) {
            decrease()
        }

        // What happens when volume up key is pressed
        if (keyCode == KeyEvent.KEYCODE_VOLUME_UP) {
            increase()
        }
        return true
    }

    // Check whether this app has android write settings permission.
    @RequiresApi(Build.VERSION_CODES.M)
    private fun hasWriteSettingsPermission(context: Context): Boolean {
        var ret = true
        // Get the result from below code.
        ret = Settings.System.canWrite(context)
        return ret
    }

    // Start can modify system settings panel to let
    // user change the write settings permission.
    private fun changeWriteSettingsPermission(context: Context) {
        val intent = Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS)
        context.startActivity(intent)
    }

    // This function only take effect in real physical android device,
    // it can not take effect in android emulator.
    private fun changeScreenBrightness(context: Context, screenBrightnessValue: Int) {
        // Change the screen brightness change mode to manual.
        Settings.System.putInt(
            context.contentResolver,
            Settings.System.SCREEN_BRIGHTNESS_MODE,
            Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL
        )
        // Apply the screen brightness value to the system, this will change
        // the value in Settings ---> Display ---> Brightness level.
        // It will also change the screen brightness for the device.
        Settings.System.putInt(
            context.contentResolver, Settings.System.SCREEN_BRIGHTNESS,
            screenBrightnessValue
        )
    }
}

Output: Run on Emulator

Note that before running the application make sure you have granted the required permissions otherwise the application will be crashed.