SeekBar

SeekBar的使用很简单，和其他控件一样，先在布局文件中声明，然后在Activity中使用。

下面演示下使用SeekBar改变图片的透明度：

1.java文件

 1 package gdp.seekbartest;
 2 
 3 import android.annotation.SuppressLint;
 4 import android.app.Activity;
 5 import android.os.Bundle;
 6 import android.view.Menu;
 7 import android.widget.ImageView;
 8 import android.widget.SeekBar;
 9 import android.widget.SeekBar.OnSeekBarChangeListener;
10 
11 public class MianActivity extends Activity {
12     private ImageView imageView ;
13     private SeekBar seekBar ;
14     @Override
15     protected void onCreate(Bundle savedInstanceState) {
16         super.onCreate(savedInstanceState);
17         setContentView(R.layout.mian);
18         
19         imageView = (ImageView)findViewById(R.id.imageView);
20         seekBar = (SeekBar)findViewById(R.id.seekBar);
21         seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
22             
23             @Override
24             public void onStopTrackingTouch(SeekBar arg0) {
25                 // TODO Auto-generated method stub
26                 
27             }
28             
29             @Override
30             public void onStartTrackingTouch(SeekBar arg0) {
31                 // TODO Auto-generated method stub
32                 
33             }
34             
35             @SuppressLint("NewApi")
36             @Override
37             public void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {
38                 // TODO Auto-generated method stub
39                 imageView.setImageAlpha(arg1);
40             }
41         });
42     }
43 
44     @Override
45     public boolean onCreateOptionsMenu(Menu menu) {
46         // Inflate the menu; this adds items to the action bar if it is present.
47         getMenuInflater().inflate(R.menu.mian, menu);
48         return true;
49     }
50 
51 }

2.xml文件

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     android:layout_width="fill_parent"
 3     android:layout_height="fill_parent"
 4     android:orientation="vertical" >
 5 
 6     <ImageView
 7         android:id="@+id/imageView"
 8         android:layout_width="match_parent"
 9         android:layout_height="wrap_content"
10         android:src="@drawable/home" />
11 
12     <!-- 定义seekbar，并改变滑块外观 -->
13 
14     <SeekBar
15         android:id="@+id/seekBar"
16         android:layout_width="fill_parent"
17         android:layout_height="wrap_content"
18         android:max="255"
19         android:progress="255"
20         />
21 </LinearLayout>