android实现自动滚动的Gallary控件效果

import java.util.Timer;import java.util.TimerTask;import android.content.Context;import android.os.Handler;import android.util.AttributeSet;import android.util.Log;import android.view.KeyEvent;import android.view.MotionEvent;import android.widget.Gallery;public class HomeGallery extends Gallery{  /**   * 这里的数值，限制了每次滚动的最大长度，图片宽度为480PX。这里设置600效果好一些。 这个值越大，滚动的长度就越大。   * 也就是会出现一次滚动跨多个Image。这里限制长度后，每次滚动只能跨一个Image   */  private static final int timerAnimation = 1;  private static final int time = 2000;  private final Handler mHandler = new Handler()  {    public void handleMessage(android.os.Message msg)    {      switch (msg.what)      {      case timerAnimation:        int position = getSelectedItemPosition();        Log.i("msg", "position:"+position);        if (position >= (getCount() - 1))        {          onKeyDown(KeyEvent.KEYCODE_DPAD_LEFT, null);        } else        {          onKeyDown(KeyEvent.KEYCODE_DPAD_RIGHT, null);        }        break;      default:        break;      }    };  };  private final Timer timer = new Timer();  private final TimerTask task = new TimerTask()  {    public void run()    {      mHandler.sendEmptyMessage(timerAnimation);    }  };  public HomeGallery(Context paramContext)  {    super(paramContext);    timer.schedule(task, time, time);  }  public HomeGallery(Context paramContext, AttributeSet paramAttributeSet)  {    super(paramContext, paramAttributeSet);    timer.schedule(task, time, time);  }  public HomeGallery(Context paramContext, AttributeSet paramAttributeSet,      int paramInt)  {    super(paramContext, paramAttributeSet, paramInt);    timer.schedule(task, time, time);  }  private boolean isScrollingLeft(MotionEvent paramMotionEvent1,      MotionEvent paramMotionEvent2)  {    float f2 = paramMotionEvent2.getX();    float f1 = paramMotionEvent1.getX();    if (f2 > f1)      return true;    return false;  }  public boolean onFling(MotionEvent paramMotionEvent1,      MotionEvent paramMotionEvent2, float paramFloat1, float paramFloat2)  {    int keyCode;    if (isScrollingLeft(paramMotionEvent1, paramMotionEvent2))    {      keyCode = KeyEvent.KEYCODE_DPAD_LEFT;    } else    {      keyCode = KeyEvent.KEYCODE_DPAD_RIGHT;    }    onKeyDown(keyCode, null);    return true;  }  public void destroy()  {    timer.cancel();  }}