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:
  1. <?xml version="1.0" encoding="utf-8"?>
  2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  3. android:layout_width="fill_parent"
  4. android:layout_height="fill_parent"
  5. android:background="#475d5d"
  6. android:orientation="vertical" >
  7. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  8. android:layout_margin="5dp"
  9. android:layout_width="fill_parent"
  10. android:layout_height="wrap_content"
  11. android:background="#354d5d"
  12. android:orientation="vertical">
  13. <TextView
  14. android:layout_height="wrap_content"
  15. android:layout_width="wrap_content"
  16. android:text="BrighnessControl"
  17. android:layout_marginLeft="5dp"
  18. android:layout_marginTop="10dp"
  19. android:textColor="#ffffff"
  20. android:textStyle="bold">
  21. </TextView>
  22. <SeekBar
  23. android:layout_width="300dp"
  24. android:layout_height="wrap_content"
  25. android:id="@+id/seekBar"
  26. android:progress="0"
  27. android:max="100"
  28. android:layout_marginTop="20dp"
  29. android:indeterminate="false"
  30. />
  31. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  32. android:layout_width="fill_parent"
  33. android:layout_height="25dp"
  34. android:background="#354d5d"
  35. android:orientation="horizontal"
  36. android:layout_marginTop="20dp">
  37. <TextView
  38. android:layout_height="wrap_content"
  39. android:layout_width="wrap_content"
  40. android:text="0"
  41. android:textStyle="bold"
  42. android:textSize="12dp"
  43. android:textColor="#ffffff"
  44. android:layout_marginLeft="25dp"/>
  45. <TextView
  46. android:layout_height="wrap_content"
  47. android:layout_width="wrap_content"
  48. android:textSize="12dp"
  49. android:text="20"
  50. android:textColor="#ffffff"
  51. android:layout_marginLeft="30dp"/>
  52. <TextView
  53. android:layout_height="wrap_content"
  54. android:textSize="12dp"
  55. android:layout_width="wrap_content"
  56. android:text="40"
  57. android:textColor="#ffffff"
  58. android:layout_marginLeft="32dp"/>
  59. <TextView
  60. android:layout_height="wrap_content"
  61. android:textSize="12dp"
  62. android:layout_width="wrap_content"
  63. android:text="60"
  64. android:textColor="#ffffff"
  65. android:layout_marginLeft="36dp"/>
  66. <TextView
  67. android:textSize="12dp"
  68. android:layout_height="wrap_content"
  69. android:layout_width="wrap_content"
  70. android:text="80"
  71. android:textColor="#ffffff"
  72. android:layout_marginLeft="38dp"/>
  73. <TextView
  74. android:textSize="12dp"
  75. android:layout_height="wrap_content"
  76. android:layout_width="wrap_content"
  77. android:text="100"
  78. android:textColor="#ffffff"
  79. android:layout_marginLeft="42dp"/>
  80. </LinearLayout>
  81. </LinearLayout>
  82. <TextView
  83. android:layout_width="fill_parent"
  84. android:layout_height="wrap_content"
  85. android:text=""
  86. android:id="@+id/txtPercentage"/>
  87. </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.
  1. import android.app.Activity;
  2. import android.content.ContentResolver;
  3. import android.os.Bundle;
  4. import android.provider.Settings.SettingNotFoundException;
  5. import android.provider.Settings.System;
  6. import android.util.Log;
  7. import android.view.Window;
  8. import android.view.WindowManager.LayoutParams;
  9. import android.widget.SeekBar;
  10. import android.widget.SeekBar.OnSeekBarChangeListener;
  11. import android.widget.TextView;
  13. public class MainActivity extends Activity {//UI objects//
  14. //Seek bar object
  15. private SeekBar seekBar;
  17. //Variable to store brightness value
  18. private int brightness;
  19. //Content resolver used as a handle to the system's settings
  20. private ContentResolver cResolver;
  21. //Window object, that will store a reference to the current window
  22. private Window window;
  24. TextView txtPerc;
  25. /** Called when the activity is first created. */
  26. @Override
  27. public void onCreate(Bundle savedInstanceState)
  28. {
  29. super.onCreate(savedInstanceState);
  30. setContentView(R.layout.activity_main);
  32. //Instantiate seekbar object
  33. seekBar = (SeekBar) findViewById(R.id.seekBar);
  35. txtPerc = (TextView) findViewById(R.id.txtPercentage);
  37. //Get the content resolver
  38. cResolver = getContentResolver();
  40. //Get the current window
  41. window = getWindow();
  43. //Set the seekbar range between 0 and 255
  44. //seek bar settings//
  45. //sets the range between 0 and 255
  46. seekBar.setMax(255);
  47. //set the seek bar progress to 1
  48. seekBar.setKeyProgressIncrement(1);
  50. try
  51. {
  52. //Get the current system brightness
  53. brightness = System.getInt(cResolver, System.SCREEN_BRIGHTNESS);
  54. }
  55. catch (SettingNotFoundException e)
  56. {
  57. //Throw an error case it couldn't be retrieved
  58. Log.e("Error", "Cannot access system brightness");
  59. e.printStackTrace();
  60. }
  62. //Set the progress of the seek bar based on the system's brightness
  63. seekBar.setProgress(brightness);
  65. //Register OnSeekBarChangeListener, so it can actually change values
  66. seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener()
  67. {
  68. public void onStopTrackingTouch(SeekBar seekBar)
  69. {
  70. //Set the system brightness using the brightness variable value
  71. System.putInt(cResolver, System.SCREEN_BRIGHTNESS, brightness);
  72. //Get the current window attributes
  73. LayoutParams layoutpars = window.getAttributes();
  74. //Set the brightness of this window
  75. layoutpars.screenBrightness = brightness / (float)255;
  76. //Apply attribute changes to this window
  77. window.setAttributes(layoutpars);
  78. }
  80. public void onStartTrackingTouch(SeekBar seekBar)
  81. {
  82. //Nothing handled here
  83. }
  85. public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
  86. {
  87. //Set the minimal brightness level
  88. //if seek bar is 20 or any value below
  89. if(progress<=20)
  90. {
  91. //Set the brightness to 20
  92. brightness=20;
  93. }
  94. else //brightness is greater than 20
  95. {
  96. //Set brightness variable based on the progress bar
  97. brightness = progress;
  98. }
  99. //Calculate the brightness percentage
  100. float perc = (brightness /(float)255)*100;
  101. //Set the brightness percentage
  102. txtPerc.setText((int)perc +" %");
  103. }
  104. });
  105. }}
Step 3
Add permission to the Android Manifest.xml file.
  1. <?xml version="1.0" encoding="utf-8"?>
  2. <manifest xmlns:android="http://schemas.android.com/apk/res/android"
  3. package="com.androidseekbarexample"
  4. android:versionCode="1"
  5. android:versionName="1.0" >
  7. <uses-permission android:name="android.permission.WRITE_SETTINGS"/>
  8. <uses-sdk
  9. android:minSdkVersion="7"
  10. android:targetSdkVersion="16" />
  12. <application
  13. android:allowBackup="true"
  14. android:icon="@drawable/ic_launcher"
  15. android:label="@string/app_name"
  16. android:theme="@style/AppTheme" >
  17. <activity
  18. android:name="com.androidseekbarexample.MainActivity"
  19. android:label="@string/app_name" >
  20. <intent-filter>
  21. <action android:name="android.intent.action.MAIN" />
  23. <category android:name="android.intent.category.LAUNCHER" />
  24. </intent-filter>
  25. </activity>
  26. </application>
  28. </manifest>
Step 4
When you run your project:
1.jpg
Step 5
When you change the position of a bar:
2.jpg
Step 6
When you set it to 100%:
3.jpg