重写Gallery中方法去处理Gallery滑动时的惯性

Gallery在滑动的时候有一个脱手时候的速度，这个速度将会影响Gallery滑动的惯性，有时候我们需要对这个惯性进行处理，这个时候我们就得自己定义View了，自定义个Gallery继承Gallery，并且重写onFling()方法，如下：

public class GalleryDemo extends Gallery {

public GalleryDemo(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
// TODO Auto-generated method stub
return super.onFling(e1, e2, velocityX / 4, velocityY);
}

}

值得注意的是自己定义控件的时候得使用
public GalleryDemo(Context context, AttributeSet attrs)构造方法，要不则会出现莫名其妙的异常。

下面就是去使用这个自定义的Gallery了：

public class GalleryDemoActivity extends Activity {
private Gallery gl_main;
private GalleryAdapter adapter;
private int[] pics = new int[] { R.drawable.a1, R.drawable.a2, R.drawable.a3, R.drawable.a4, R.drawable.a5,
R.drawable.a6, R.drawable.a7, R.drawable.a8, R.drawable.a9, R.drawable.a10 };

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
gl_main = (Gallery) findViewById(R.id.gl_main);
adapter = new GalleryAdapter();
//gl_main.
gl_main.setAdapter(adapter);
}

private class GalleryAdapter extends BaseAdapter {

@Override
public int getCount() {
// TODO Auto-generated method stub
return pics.length;
}

@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}

@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
ImageView iv = new ImageView(GalleryDemoActivity.this);
iv.setLayoutParams(new Gallery.LayoutParams(160, 320));
iv.setImageResource(pics[position]);
return iv;
}
}
}