WPF 可触摸移动的ScrollViewer控件

 1     /// <summary>
 2     /// 可触摸滚动的ScrollViewer控件
 3     /// </summary>
 4     public class TouchableScrollViewer : ScrollViewer
 5     {
 6         //触摸点的坐标
 7         Point _startPosition;
 8         //滚动条当前位置
 9         double _startVerticalOffset;
10         double _startHorizontalOffset;
11         public TouchableScrollViewer()
12         {
13             TouchDown += TouchableScrollViewer_TouchDown;
14 
15             TouchUp += TouchableScrollViewer_TouchUp;
16         }
17         private void TouchableScrollViewer_TouchDown(object sender, TouchEventArgs e)
18         {
19             //添加触摸移动监听
20             TouchMove -= TouchableScrollViewer_TouchMove;
21             TouchMove += TouchableScrollViewer_TouchMove;
22 
23             //获取ScrollViewer滚动条当前位置
24             _startVerticalOffset = VerticalOffset;
25             _startHorizontalOffset = HorizontalOffset;
26 
27             //获取相对于ScrollViewer的触摸点位置
28             TouchPoint point = e.GetTouchPoint(this);
29             _startPosition = point.Position;
30         }
31 
32         private void TouchableScrollViewer_TouchUp(object sender, TouchEventArgs e)
33         {
34             //注销触摸移动监听
35             TouchMove -= TouchableScrollViewer_TouchMove;
36         }
37 
38         private void TouchableScrollViewer_TouchMove(object sender, TouchEventArgs e)
39         {
40             //获取相对于ScrollViewer的触摸点位置
41             TouchPoint endPoint = e.GetTouchPoint(this);
42             //计算相对位置
43             double diffOffsetY = endPoint.Position.Y - _startPosition.Y;
44             double diffOffsetX = endPoint.Position.X - _startPosition.X;
45 
46             //ScrollViewer滚动到指定位置(指定位置=起始位置-移动的偏移量，滚动方向和手势方向相反)
47             ScrollToVerticalOffset(_startVerticalOffset - diffOffsetY);
48             ScrollToHorizontalOffset(_startHorizontalOffset - diffOffsetX);
49         }
50     }