回弹效果HorizontalScrollview

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.widget.HorizontalScrollView;

public class BouncyHScrollView extends HorizontalScrollView {

private static final int MAX_X_OVERSCROLL_DISTANCE = 200;
private Context mContext;
private int mMaxXOverscrollDistance;

public BouncyHScrollView(Context context) {
super(context);
// TODO Auto-generated constructor stub
mContext = context;
initBounceDistance();
}
public BouncyHScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
mContext = context;
initBounceDistance();
}
public BouncyHScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
mContext = context;
initBounceDistance();
}

private void initBounceDistance(){
final DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
mMaxXOverscrollDistance = (int) (metrics.density * MAX_X_OVERSCROLL_DISTANCE);
}

@Override
protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent){
//这块是关键性代码
return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, mMaxXOverscrollDistance, maxOverScrollY, isTouchEvent);
}

}

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.HorizontalScrollView;

public class ElasticHorizontalScrollView extends HorizontalScrollView {
private View inner;
private Rect normal = new Rect();
private float x;

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

public ElasticHorizontalScrollView(Context context) {
super(context);
}

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

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

private void commOnTouchEvent(MotionEvent ev) {
int action = ev.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
x = ev.getX();
break;
case MotionEvent.ACTION_UP:
if (isNeedAnimation()) {
animation();
}
break;
case MotionEvent.ACTION_MOVE:
final float preX = x;
float nowX = ev.getX();
int distanceX = (int) (preX - nowX);
scrollBy(distanceX, 0);
x = nowX;
if (isNeedMove()) {
if (normal.isEmpty()) {
normal.set(inner.getLeft(), inner.getTop(), inner.getRight(), inner.getBottom());
}
inner.layout(inner.getLeft() - distanceX, inner.getTop(), inner.getRight() - distanceX, inner.getBottom());
}

break;

default:
break;
}
}

private void animation() {
TranslateAnimation mTranslateAnimation = new TranslateAnimation(inner.getLeft(), 0, normal.left, 0);
mTranslateAnimation.setDuration(50);
inner.setAnimation(mTranslateAnimation);
inner.layout(normal.left, normal.top, normal.right, normal.bottom);
normal.setEmpty();

}

private boolean isNeedAnimation() {
return !normal.isEmpty();
}

private boolean isNeedMove() {
int offset = inner.getMeasuredWidth() - getWidth();
int scrollX = getScrollX();
if (scrollX == 0 || offset == scrollX)
return true;
return false;
}
}