Android_调节屏幕亮度(背景灯)及保持背景灯常亮的方法

Android写的应用程序其实可以调节屏幕亮度的，查了一下资料发现WindowManager.LayoutParams这个类就包含了调节亮度的参数：

WindowManager.LayoutParams lp = getWindow().getAttributes();

lp.screenBrightness = 0.1f;

其中参数screenBrightness就是设置屏幕亮度的0.0f屏幕最暗，1.0f屏幕最亮

在此基础上我又加了一个SeekBar来调节屏幕亮度，

代码参考如下：

此外在回调函数中必须有如下这句话 getWindow().setAttributes(lp); 否则不起作用。我在开始的时候在onCreate()函数中直接设的值，没有这个函数，就能直接调节，但是在回调函数中不加上就不起作用

[java] view plain copy print ?

1. public class BLightActivity extends Activity {
2. /** Called when the activity is first created. */
3. int Max_Brightness = 100;
4. SeekBar bSeekBar = null;
5. float fBrightness = 0.0f;
6. WindowManager.LayoutParams lp = null;
7. @Override
8. public void onCreate(Bundle savedInstanceState) {
9. super.onCreate(savedInstanceState);
10. setContentView(R.layout.main);
12. bSeekBar = (SeekBar) findViewById(R.id.bLightBar);
13. bSeekBar.setOnSeekBarChangeListener(seekListener);
14. bSeekBar.setMax(Max_Brightness);
16. lp = getWindow().getAttributes();
17. // lp.screenBrightness = 0.1f;
18. }
20. OnSeekBarChangeListener seekListener = new OnSeekBarChangeListener() {
21. public void onStopTrackingTouch(SeekBar seekBar) {
22. // TODO Auto-generated method stub
23. }
24. public void onStartTrackingTouch(SeekBar seekBar) {
25. // TODO Auto-generated method stub
26. }
27. public void onProgressChanged(SeekBar seekBar, int progress,
28. boolean fromUser) {
29. // TODO Auto-generated method stub
30. fBrightness = (float)progress / (float)Max_Brightness;
31. lp.screenBrightness = fBrightness;
32. // 这句得加上，否则屏幕亮度不启作用
33. getWindow().setAttributes(lp);
34. System.out.println("FY_" + fBrightness);
35. }
36. };
37. }

public class BLightActivity extends Activity {
    /** Called when the activity is first created. */
int Max_Brightness = 100;
SeekBar bSeekBar = null;
float fBrightness = 0.0f;
WindowManager.LayoutParams lp = null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        bSeekBar = (SeekBar) findViewById(R.id.bLightBar);
        bSeekBar.setOnSeekBarChangeListener(seekListener);
        bSeekBar.setMax(Max_Brightness);
        
        lp = getWindow().getAttributes();
//        lp.screenBrightness = 0.1f;
    }
    
    OnSeekBarChangeListener seekListener = new OnSeekBarChangeListener() {
public void onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}
public void onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method stub
}
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
// TODO Auto-generated method stub
fBrightness = (float)progress / (float)Max_Brightness;
lp.screenBrightness = fBrightness;
// 这句得加上，否则屏幕亮度不启作用
getWindow().setAttributes(lp);
System.out.println("FY_" + fBrightness);
}
};
}

下面是介绍保持背景灯常量的方法：

首先是要获得权限 :

[html] view plain copy print ?

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

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

下面是控制代码实例

[java] view plain copy print ?

1. public class test extends Activity{
2. PowerManager powerManager = null;
3. WakeLock wakeLock = null;
4. @Override
5. protected void onCreate(Bundle savedInstanceState) {
6. super.onCreate(savedInstanceState);
7. this.setContentView(R.layout.main);
9. this.powerManager = (PowerManager)this.getSystemService(Context.POWER_SERVICE);
10. this.wakeLock = this.powerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Lock");
11. this.wakeLock.acquire();
12. }
13. @Override
14. protected void onResume() {
15. super.onResume();
16. // 重新获取
17. this.wakeLock.acquire();
18. }
19. @Override
20. protected void onPause() {
21. super.onPause();
22. // 在Activity销毁的时候释放wakeLock
23. this.wakeLock.release();
24. }
25. }

public class test extends Activity{     
	PowerManager powerManager = null;
    WakeLock wakeLock = null;
    @Override
	protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         this.setContentView(R.layout.main);
         
         this.powerManager = (PowerManager)this.getSystemService(Context.POWER_SERVICE);
         this.wakeLock = this.powerManager.newWakeLock(PowerManager.FULL_WAKE_LOCK, "My Lock");
		 this.wakeLock.acquire();
     }
    @Override
    protected void onResume() {
         super.onResume();
		 // 重新获取
         this.wakeLock.acquire();
     }
     @Override
     protected void onPause() {
         super.onPause();
		 // 在Activity销毁的时候释放wakeLock
         this.wakeLock.release();
     }
 }