listview 反弹

package com.rebound.myscroll;

import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.TranslateAnimation;
import android.widget.ListView;
import android.widget.ScrollView;

/**
 * MyListView 
 * 
 */
public class MyListView extends ListView
{
    private View inner;

    private float y;

    private Rect normal = new Rect();;

    public MyListView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
       // this.smoothScrollTo(0, 0);
        this.scrollTo(0, 0);

    }

    @Override
    protected void onFinishInflate()
    {
       // if (getChildCount() > 0)
        //{
          //  inner = getChildAt(0);

        //}
     inner=this;
     System.out.println("inner//"+inner.toString());
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev)
    {
        if (inner == null)
        {
            return super.onTouchEvent(ev);
        }
        else
        {
            commOnTouchEvent(ev);
        }

        return super.onTouchEvent(ev);
    }

    public void commOnTouchEvent(MotionEvent ev)
    {
        int action = ev.getAction();
        switch (action)
        {
            case MotionEvent.ACTION_DOWN:
                y = ev.getY();
                break;
            case MotionEvent.ACTION_UP:

                if (isNeedAnimation())
                {
                    animation();
                }

                break;
            case MotionEvent.ACTION_MOVE:
                final float preY = y;
                float nowY = ev.getY();
                int deltaY = (int) (preY - nowY);
                System.out.println("移动的距离::///"+deltaY);
                // 下面的要注释掉，不然view会闪第一次，误用
//                scrollBy(0, deltaY);
                //scrollTo(0, deltaY);

                y = nowY;
                // 是否要改变位置
                if (isNeedMove())
                {
                    int left = inner.getLeft();
     int top = inner.getTop();
     int right = inner.getRight();
     int bottom = inner.getBottom();
     if (normal.isEmpty())
                    {
                        // 保存listview左上角这个坐标的位置，移动完后好回归原点
                        normal.set(left, top, right, bottom);
                        System.out.println("inner.getLeft()/inner.getTop()/inner.getRight()/inner.getBottom()"+left+"   "+top+"  "+right+" "+bottom);
                    }
                    // 改变listview的位置
                    inner.layout(left, top - deltaY, right, bottom - deltaY);
                }
                break;

            default:
                break;
        }
    }

    // 动画

    public void animation()
    {
        // 动画
        TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(), normal.top);
        ta.setDuration(200);
        inner.startAnimation(ta);
        // 回归最初位置
        inner.layout(normal.left, normal.top, normal.right, normal.bottom);

        normal.setEmpty();

    }

    // 看normal有没有保存listview的位置
    public boolean isNeedAnimation()
    {
        return !normal.isEmpty();
    }

    // 是否符合反弹的条件
    public boolean isNeedMove()
    {

      
          if (getFirstVisiblePosition()==0 || getLastVisiblePosition()==getAdapter().getCount()-1)
        {
         System.out.println("NeedMove");
            return true;
        }
        System.out.println("not   NeedMove");
        return false;
    }

}