Android ScrollView实现横向和竖向拖动回弹效果

本文实例为大家分享了Android ScrollView实现拖动回弹效果的具体代码，供大家参考，具体内容如下

原理

在android2.3版本中，View类中新增了一个方法：overScrollBy。通过覆盖该方法，就可以达到阻尼回弹的效果。

示例1、竖向滚动

public class ReboundScrollView extends ScrollView{
 private static final int MAX_SCROLL = 200;
 private static final float SCROLL_RATIO = 0.5f;// 阻尼系数 

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

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

 public ReboundScrollView(Context context, AttributeSet attrs, int defStyle)
 {
  super(context, attrs, defStyle);
 } 

 @Override
 protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent)
 {
  int newDeltaY = deltaY;
  int delta = (int) (deltaY * SCROLL_RATIO);
  if((scrollY+deltaY)==0 || (scrollY-scrollRangeY+deltaY)==0){
   newDeltaY = deltaY;  //回弹最后一次滚动，复位
  }else{
   newDeltaY = delta;  //增加阻尼效果
  }
  return super.overScrollBy(deltaX, newDeltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, maxOverScrollX, MAX_SCROLL, isTouchEvent);
 }
} 

示例2、横向滚动

public class ReboundHScrollView extends HorizontalScrollView{
 private static final int MAX_SCROLL = 200;
 private static final float SCROLL_RATIO = 0.5f;// 阻尼系数 

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

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

 public ReboundHScrollView(Context context, AttributeSet attrs, int defStyle)
 {
  super(context, attrs, defStyle);
 } 

 @Override
 protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent)
 {
  int newDeltaX = deltaX;
  int delta = (int) (deltaX * SCROLL_RATIO);
  if((scrollX+deltaX)==0 || (scrollX-scrollRangeX+deltaX)==0){
   newDeltaX = deltaX;  //回弹最后一次滚动，复位
  }else{
   newDeltaX = delta;  //增加阻尼效果
  }
  return super.overScrollBy(newDeltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, MAX_SCROLL, maxOverScrollY, isTouchEvent);
 }
}

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