Change Brightness of a Screen Using SeekBar in Android Studio

Introduction

 

This article explains how to use a seek bar to change the screen brightness in Android Studio.

 

First, you need to use a SeekBar in an XML file and create its id in a Java class file. Now get the content resolver object by calling getContentResolver() and the current window by calling the getWindow() methods. To get the brightness of a screen use the getint() method that returns the current brightness of a system. You will the brightness to the setProgress() method as an argument. Now set the seekbar on setOnSeekBarChangeListener() to change the brightness of a screen.

 

In the onProgress() method set the progress of the seek bar in percentage.

 

Step 1

 

Now create an XML file and write this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:background="#475d5d"
   android:orientation="vertical" >
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_margin="5dp"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:background="#354d5d"
      android:orientation="vertical">
      <TextView
         android:layout_height="wrap_content"
         android:layout_width="wrap_content"
         android:text="BrighnessControl"
         android:layout_marginLeft="5dp"
         android:layout_marginTop="10dp"
         android:textColor="#ffffff"
         android:textStyle="bold">
      </TextView>
      <SeekBar
         android:layout_width="300dp"
         android:layout_height="wrap_content"
         android:id="@+id/seekBar"
         android:progress="0"
         android:max="100"
         android:layout_marginTop="20dp"
         android:indeterminate="false"
         />
      <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_width="fill_parent"
         android:layout_height="25dp"
         android:background="#354d5d"
         android:orientation="horizontal"
         android:layout_marginTop="20dp">
         <TextView
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="0"
            android:textStyle="bold"
            android:textSize="12dp"
            android:textColor="#ffffff"
            android:layout_marginLeft="25dp"/>
         <TextView
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:textSize="12dp"
            android:text="20"
            android:textColor="#ffffff"
            android:layout_marginLeft="30dp"/>
         <TextView
            android:layout_height="wrap_content"
            android:textSize="12dp"
            android:layout_width="wrap_content"
            android:text="40"
            android:textColor="#ffffff"
            android:layout_marginLeft="32dp"/>
         <TextView
            android:layout_height="wrap_content"
            android:textSize="12dp"
            android:layout_width="wrap_content"
            android:text="60"
            android:textColor="#ffffff"
            android:layout_marginLeft="36dp"/>
         <TextView
            android:textSize="12dp"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="80"
            android:textColor="#ffffff"
            android:layout_marginLeft="38dp"/>
         <TextView
            android:textSize="12dp"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="100"
            android:textColor="#ffffff"
            android:layout_marginLeft="42dp"/>
      </LinearLayout>
   </LinearLayout>
   <TextView
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text=""
      android:id="@+id/txtPercentage"/>
</LinearLayout>

Step 2

 

Now create a Java file and write this.

 

First, you need to use the SeekBar in the XML file and create its id in the Java class file. Now get the content resolver object by calling getContentResolver() and the current window by calling the getWindow() methods. To get the brightness of a screen use the getint() method that returns the current brightness of a system. You will the brightness to the setProgress() method as an argument. Now set the seekbar on setOnSeekBarChangeListener() to change the brightness of a screen. 

 

In the onProgress() method set the progress of the seek bar in percentage.

import android.app.Activity;
import android.content.ContentResolver;
import android.os.Bundle;
import android.provider.Settings.SettingNotFoundException;
import android.provider.Settings.System;
import android.util.Log;
import android.view.Window;
import android.view.WindowManager.LayoutParams;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;

public class MainActivity extends Activity {//UI objects//
    //Seek bar object
    private SeekBar seekBar;

    //Variable to store brightness value
    private int brightness;
    //Content resolver used as a handle to the system's settings
    private ContentResolver cResolver;
    //Window object, that will store a reference to the current window
    private Window window;

    TextView txtPerc;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Instantiate seekbar object
        seekBar = (SeekBar) findViewById(R.id.seekBar);

        txtPerc = (TextView) findViewById(R.id.txtPercentage);

        //Get the content resolver
        cResolver =  getContentResolver();

        //Get the current window
        window = getWindow();

        //Set the seekbar range between 0 and 255
        //seek bar settings//
        //sets the range between 0 and 255
        seekBar.setMax(255);
        //set the seek bar progress to 1
        seekBar.setKeyProgressIncrement(1);

        try
        {
            //Get the current system brightness
            brightness = System.getInt(cResolver, System.SCREEN_BRIGHTNESS);
        }
        catch (SettingNotFoundException e)
        {
            //Throw an error case it couldn't be retrieved
            Log.e("Error", "Cannot access system brightness");
            e.printStackTrace();
        }

        //Set the progress of the seek bar based on the system's brightness
        seekBar.setProgress(brightness);

        //Register OnSeekBarChangeListener, so it can actually change values
        seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener()
        {
            public void onStopTrackingTouch(SeekBar seekBar)
            {
                //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);
            }

            public void onStartTrackingTouch(SeekBar seekBar)
            {
                //Nothing handled here
            }

            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
            {
                //Set the minimal brightness level
                //if seek bar is 20 or any value below
                if(progress<=20)
                {
                    //Set the brightness to 20
                    brightness=20;
                }
                else //brightness is greater than 20
                {
                    //Set brightness variable based on the progress bar
                    brightness = progress;
                }
                //Calculate the brightness percentage
                float perc = (brightness /(float)255)*100;
                //Set the brightness percentage
                txtPerc.setText((int)perc +" %");
            }
        });
    }}

Step 3

 

Add permission to the Android Manifest.xml file.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.androidseekbarexample"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-permission android:name="android.permission.WRITE_SETTINGS"/>
    <uses-sdk
        android:minSdkVersion="7"
        android:targetSdkVersion="16" />

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

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

</manifest>

Step 4

 

When you run your project:

 

 

Step 5

 

When you change the position of a bar:

 

 

Step 6

 

When you set it to 100%: