使用SeekBar组件调节屏幕亮度

Android手机里也可以通过程序进行屏幕亮度的调节，而这种操作往往就是通过SeekBar组件实现的，而要想实现亮度调节功能就必须android.view.Window类的screenBrightness属性实现，而此属性的取值范围是0~1
(由暗到亮)




.xml

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
   
xmlns:tools="http://schemas.android.com/tools"
   
android:layout_width="match_parent"
   
android:layout_height="match_parent"
   
android:orientation="vertical"
   
tools:context=".MainActivity" >

   
<SeekBar 
   
   
android:id="@+id/seekbar"
   
   
android:layout_width="fill_parent"
   
   
android:layout_height="wrap_content"/>
 
  
   
<ImageView 
   
   
android:id="@+id/img"
   
   
android:layout_width="wrap_content"
   
   
android:layout_height="wrap_content"
   
   
android:src="@drawable/android_book"/>
   
<TextView 
   
   
android:id="@+id/light"
   
   
android:layout_width="fill_parent"
   
   
android:layout_height="wrap_content"/>

</LinearLayout>

.java

package
com.example.seekbardemo3adjustthelight;

import
android.os.Bundle;
import
android.app.Activity;
import
android.view.Menu;
import
android.view.Window;
import
android.view.WindowManager;
import
android.widget.SeekBar;
import
android.widget.SeekBar.OnSeekBarChangeListener;
import
android.widget.TextView;

public class MainActivity
extends Activity {
private SeekBar
seekbar=null;
private TextView
light=null;
@Override
protected void onCreate(Bundle
savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.light=(TextView)
super.findViewById(R.id.light);
this.seekbar=(SeekBar)
super.findViewById(R.id.seekbar);
this.seekbar.setMax(100);
this.seekbar.setOnSeekBarChangeListener(new
SeekBarChangeListenerImp());
}

public class
SeekBarChangeListenerImp implements
OnSeekBarChangeListener{

public void
onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser)
{
// TODO Auto-generated method
stub
int
cur=seekBar.getProgress();
MainActivity.this.setScreenBrightness(cur/100);
MainActivity.this.light.setText("当前屏幕亮度:"+cur/100);
}

public void
onStartTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method
stub
}

public void
onStopTrackingTouch(SeekBar seekBar) {
// TODO Auto-generated method
stub
}
}
//设置屏幕亮度的函数
private void
setScreenBrightness(float num){
WindowManager.LayoutParams
layoutParams=super.getWindow().getAttributes();
layoutParams.screenBrightness=num;//设置屏幕的亮度
super.getWindow().setAttributes(layoutParams);
}
}