自定义ScrollView 下拉上拉回弹，阻尼效果

package com.customWidget;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;/** * 自定义ScrollView */public class MyScrollView extends ScrollView {private View inner;// 孩子private float y;// 坐标private Rect normal = new Rect();// 矩形空白public MyScrollView(Context context, AttributeSet attrs) {super(context, attrs);}// android:fadingEdge=”none”@Overridepublic void setFadingEdgeLength(int length) {// TODO Auto-generated method stublength = 0;super.setFadingEdgeLength(length);}/*** * 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. */@Overrideprotected void onFinishInflate() {if (getChildCount() > 0) {inner = getChildAt(0);// 获取其孩子}}@Overridepublic boolean onTouchEvent(MotionEvent ev) {if (inner != null) {commOnTouchEvent(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:y = ev.getY();// 获取点击y坐标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);// 获取滑动距离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()) {if (normal.isEmpty()) {// 填充矩形，目的：就是告诉this:我现在已经有了，你松开的时候记得要执行回归动画.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);}break;default:break;}}/*** * 开启动画移动 */public void animation() {// 开启移动动画TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(),normal.top);ta.setDuration(300);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();// 清空矩形}/*** * 是否需要开启动画 *  * 如果矩形不为空，返回true，否则返回false. *  *  * @return */public boolean isNeedAnimation() {return !normal.isEmpty();}/*** * 是否需要移动布局 inner.getMeasuredHeight():获取的是控件的高度 * getHeight()：获取的是当前控件在屏幕中显示的高度 *  * @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;}}package com.customWidget;import android.cont