如何使用SeekBar以编程方式调整设备亮度？

Question

我在我的设置应用程序中有两个seekbars，一个用于声音，一个用于亮度。我的声音搜索栏会根据需要更改媒体音量，并且在其他活动和应用程序中保持更改，但亮度seekbar在更改活动后不会保持更改，它只会更改设置页面中的亮度。我希望完成的任务是让他们都留在应用程序设置页面中设置的任何地方，即使在其他活动和应用程序中。

ApplicationSettings.java

public class ApplicationSettings extends AppCompatActivity { 

private SeekBar VolumeSeekbar = null; 
private SeekBar BrightnessSeekbar = null; 
private AudioManager audioManager = null; 
private float BackLightValue; 
//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; 



@Override 
public void onCreate(Bundle savedInstanceState) { 
    setVolumeControlStream(AudioManager.STREAM_MUSIC); 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_application_settings); 

    //Instantiate seekbar object 
    seekBar = (SeekBar) findViewById(R.id.BrightBar); 
    txtPerc = (TextView) findViewById(R.id.txtPercentage); 
    //Get the content resolver 
    cResolver = getContentResolver(); 
    //Get the current window 
    window = getWindow(); 

    VolumeControl(); 
    BrightnessControl(); 
} 


public void GoToMainScreenButton1 (View view) { 
    Intent intentStart = new Intent(this, MainScreen.class); 
    startActivity(intentStart); 
} 

private void VolumeControl() { 
    try { 
     VolumeSeekbar = (SeekBar) findViewById(R.id.SoundBar); 
     audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE); 
     VolumeSeekbar.setMax(audioManager 
       .getStreamMaxVolume(AudioManager.STREAM_MUSIC)); 
     VolumeSeekbar.setProgress(audioManager 
       .getStreamVolume(AudioManager.STREAM_MUSIC)); 
     VolumeSeekbar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { 
      @Override 
      public void onStopTrackingTouch(SeekBar arg0) { 
      } 
      @Override 
      public void onStartTrackingTouch(SeekBar arg0) { 
      } 
      @Override 
      public void onProgressChanged(SeekBar arg0, int progress, boolean arg2) { 
       audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, 
         progress, 0); 
      } 
     }); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

} 

private void BrightnessControl() { 
    //Set the seekbar range between 0 and 255 
    //seek bar settings// 
    //sets the range between 0 and 255 
    seekBar = (SeekBar) findViewById(R.id.BrightBar); 

    seekBar.setMax(255); 
    //set the seek bar progress to 1 
    seekBar.setKeyProgressIncrement(1); 

    try 
    { 
     //Get the current system brightness 
     brightness = Settings.System.getInt(cResolver, Settings.System.SCREEN_BRIGHTNESS); 
    } 
    catch (Settings.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 SeekBar.OnSeekBarChangeListener() 
    { 
     public void onStopTrackingTouch(SeekBar seekBar) 
     { 
      //Set the system brightness using the brightness variable value 
      Settings.System.putInt(cResolver, Settings.System.SCREEN_BRIGHTNESS, brightness); 
      //Get the current window attributes 
      WindowManager.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 +" %"); 
     } 
    }); 
} 
} 

activity_application_settings.xml

<!--  android:background="#000000"--> 

<TextView 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=" Adjust the Sound volume" 
    android:id="@+id/SOUNDTEXT" 
    android:layout_alignParentTop="true" 
    android:layout_alignParentRight="true" 
    android:layout_alignParentEnd="true" 
    android:layout_marginTop="87dp" /> 

<SeekBar 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/SoundBar" 
    android:background="#87CEEB" 
    android:layout_gravity="center_vertical" 
    android:layout_alignParentStart="true" 
    android:layout_alignParentLeft="true" 
    android:layout_below="@+id/SOUNDTEXT" 
    android:layout_alignRight="@+id/Mainbutton11" 
    android:layout_alignEnd="@+id/Mainbutton11" /> 

<TextView 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="" 
    android:id="@+id/SoundPercentage" 
    android:background="#87CEEB" 
    android:layout_alignBottom="@+id/SoundBar" 
    android:layout_alignParentRight="true" 
    android:layout_alignParentEnd="true" 
    android:layout_toRightOf="@+id/SoundBar" 
    android:layout_toEndOf="@+id/SoundBar" /> 

<TextView 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=" Adjust the Brightness" 
    android:id="@+id/textView18" 
    android:layout_above="@+id/BrightBar" 
    android:layout_toStartOf="@+id/Mainbutton11" 
    android:layout_toLeftOf="@+id/Mainbutton11" 
    android:layout_alignParentRight="true" 
    android:layout_alignParentEnd="true" /> 

<SeekBar 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/BrightBar" 
    android:background="#87CEEB" 
    android:layout_gravity="left|bottom" 
    android:layout_centerVertical="true" 
    android:layout_toLeftOf="@+id/SoundPercentage" 
    android:layout_toStartOf="@+id/SoundPercentage" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/txtPercentage" 
    android:layout_alignTop="@+id/BrightBar" 
    android:layout_alignParentRight="true" 
    android:layout_alignParentEnd="true" 
    android:layout_alignLeft="@+id/SoundPercentage" 
    android:layout_alignStart="@+id/SoundPercentage" /> 

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="Go to chapters" 
    android:background="#FFE4B5" 
    android:onClick="GoToMainScreenButton1" 
    android:id="@+id/Mainbutton11" 
    android:layout_gravity="center_horizontal|top" 
    android:layout_alignParentBottom="true" 
    android:layout_centerHorizontal="true" /> 

Answer 1

你办理自动亮度模式？

Settings.System.putInt(cResolver, Settings.System.SCREEN_BRIGHTNESS_MODE, Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL); 

你也有清单许可？

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

PS：我会评论这些问题，但不能评论，但遗憾。