SeekBar拖动条

seekbar拖动条,通过滑块的位置值的改变,来对某些数据进行调节,比如音量调节; 改变滑块的外观可以通过android:thumb属性完成

实例:拖动滑块改变图片透明度

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

    <SeekBar
        android:id="@+id/sb"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="255"
        android:progress="255" />

    <ImageView
        android:id="@+id/iv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/ic_launcher" />

</LinearLayout>

public class MainActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.seek);
        
        SeekBar sb = (SeekBar) findViewById(R.id.sb);
        final ImageView iv = (ImageView) findViewById(R.id.iv);
        sb.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
            
            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
            }
            
            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
            }
            
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress,
                    boolean fromUser) {
                iv.setAlpha(progress);
            }
        });
    }

}