仿ios的滑动效果

package code.suibianchou.com.custormview2;

import android.annotation.SuppressLint;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.ScrollView;

/** * Created by Administrator on 2017/5/18 0018. */

public class BounceScrollView extends ScrollView {    private static final String TAG = "BounceScrollView";

private View inner;// 孩子View

private float y;// 点击时y坐标

private Rect normal = new Rect();// 矩形(这里只是个形式，只是用于判断是否需要动画.)

private boolean isCount = false;// 是否开始计算    private float lastX = 0;    private float lastY = 0;    private float currentX = 0;    private float currentY = 0;    private float distanceX = 0;    private float distanceY = 0;    private boolean upDownSlide = false; //判断上下滑动的flag

public BounceScrollView(Context context, AttributeSet attrs) {        super(context, attrs);    }

/***     * 根据 XML 生成视图工作完成.该函数在生成视图的最后调用，在所有子视图添加完之后. 即使子类覆盖了 onFinishInflate     * 方法，也应该调用父类的方法，使该方法得以执行.     */    @SuppressLint("MissingSuperCall")    @Override    protected void onFinishInflate() {        if (getChildCount() > 0) {            inner = getChildAt(0);            View view;        }    }

@Override    public boolean dispatchTouchEvent(MotionEvent ev) {        // TODO Auto-generated method stub

currentX = ev.getX();        currentY = ev.getY();        switch(ev.getAction()){            case MotionEvent.ACTION_DOWN:

break;            case MotionEvent.ACTION_MOVE:                distanceX = currentX - lastX;                distanceY = currentY - lastY;                if(Math.abs(distanceX)<Math.abs(distanceY) && Math.abs(distanceY)>12){

upDownSlide = true;                }                break;            case MotionEvent.ACTION_UP:

break;            default:                break;        }        lastX = currentX;        lastY = currentY;        if (upDownSlide && inner != null) commOnTouchEvent(ev);        return super.dispatchTouchEvent(ev);    }

@Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        // TODO Auto-generated method stub        return super.onInterceptTouchEvent(ev);    }

/***     * 监听touch     */    @Override    public boolean onTouchEvent(MotionEvent ev) {        return super.onTouchEvent(ev);    }

/***     * 触摸事件     *     * @param ev     */    public void commOnTouchEvent(MotionEvent ev) {        int action = ev.getAction();        switch (action) {            case MotionEvent.ACTION_DOWN:                break;            case MotionEvent.ACTION_UP:                // 手指松开.                if (isNeedAnimation()) {                    animation();                    isCount = false;                }                clear0();                break;            case MotionEvent.ACTION_MOVE:                final float preY = y;// 按下时的y坐标                float nowY = ev.getY();// 时时y坐标                int deltaY = (int) (preY - nowY);// 滑动距离                if (!isCount) {                    deltaY = 0; // 在这里要归0.                }

y = nowY;                // 当滚动到最上或者最下时就不会再滚动，这时移动布局                if (isNeedMove()) {                    // 初始化头部矩形                    if (normal.isEmpty()) {                        // 保存正常的布局位置                        normal.set(inner.getLeft(), inner.getTop(),                                inner.getRight(), inner.getBottom());                    }                    // 移动布局                    inner.layout(inner.getLeft(), inner.getTop() - deltaY / 2,                            inner.getRight(), inner.getBottom() - deltaY / 2);                }                isCount = true;                break;

default:                break;        }    }

/***     * 回缩动画     */    public void animation() {        // 开启移动动画        TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(),                normal.top);        ta.setDuration(200);        inner.startAnimation(ta);        // 设置回到正常的布局位置        inner.layout(normal.left, normal.top, normal.right, normal.bottom);

normal.setEmpty();

}

// 是否需要开启动画    public boolean isNeedAnimation() {        return !normal.isEmpty();    }

/***     * 是否需要移动布局 inner.getMeasuredHeight():获取的是控件的总高度     *     * getHeight()：获取的是屏幕的高度     *     * @return     */    public boolean isNeedMove() {        int offset = inner.getMeasuredHeight() - getHeight();        int scrollY = getScrollY();        // 0是顶部，后面那个是底部        if (scrollY == 0 || scrollY == offset) {            return true;        }        return false;    }

private void clear0(){        lastX = 0;        lastY = 0;        distanceX = 0;        distanceY = 0;        upDownSlide = false;    }}