private Point? _startPoint = null;

     private void ContainerCanvas_OnPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)

     {

         var position = e.GetPosition(ContainerCanvas);

         if (_startPoint == null)

         {

             _startPoint = position;

         }

         else

         {

             //删除预览

             if (_previewLineElement != null)

             {

                 ContainerCanvas.Children.Remove(_previewLineElement);

                 _previewLineElement = null;

                 _lastMovedPoint = null;

             }

             //确定结束点，绘制波浪线

             var myLineElement = new MyLineElement();

             myLineElement.DrawLine((Point)_startPoint, position);

             ContainerCanvas.Children.Add(myLineElement);

             _startPoint = null;

         }

     }

     private MyLineElement _previewLineElement = null;

     private Point? _lastMovedPoint = null;

     /// <summary>

     /// 波浪线绘制预览

     /// </summary>

     /// <param name="sender"></param>

     /// <param name="e"></param>

     private void ContainerCanvas_OnMouseMove(object sender, MouseEventArgs e)

     {

         var position = e.GetPosition(ContainerCanvas);

         if (_startPoint != null && (_lastMovedPoint == null || _lastMovedPoint != null & (position - (Point)_lastMovedPoint).Length >= ))

         {

             _lastMovedPoint = position;

             if (_previewLineElement != null)

             {

                 ContainerCanvas.Children.Remove(_previewLineElement);

             }

             var myLineElement = new MyLineElement();

             myLineElement.DrawLine((Point)_startPoint, position);

             ContainerCanvas.Children.Add(myLineElement);

             _previewLineElement = myLineElement;

         }

     }

     class MyLineElement : FrameworkElement

     {

         public MyLineElement()

         {

             _visualShape = new VisualCollection(this);

         }

         internal void DrawLine(Point startPoint, Point endPoint)

         {

             List<Point> points = ForgePoints(startPoint, endPoint);

             DrawLine(points);

         }

         private const int SeparatorPiexl = ;

         private const int AbundancePiexl = ;

         private List<Point> ForgePoints(Point startPoint, Point endPoint)

         {

             var points = new List<Point>();

             var lineVector = endPoint - startPoint;

             var lineDistance = lineVector.Length;

             var lineAngle = Math.Atan2(-(endPoint.Y - startPoint.Y), endPoint.X - startPoint.X);

             points.Add(startPoint);

             int index = ;

             bool isAbundanceUpward = true;

             while (index * SeparatorPiexl < lineDistance)

             {

                 index++;

                 //计算出间隔长度（模拟点到起始点）

                 var separatorDistance = index * SeparatorPiexl;

                 var abundancePiexl = AbundancePiexl;

                 var distanceToStartPoint = Math.Sqrt(Math.Pow(separatorDistance, ) + Math.Pow(abundancePiexl, ));

                 //计算出模拟点、起始点，与直线的角度

                 var separatorAngle = Math.Atan2(AbundancePiexl, separatorDistance);

                 separatorAngle = isAbundanceUpward ? separatorAngle : -separatorAngle;

                 isAbundanceUpward = !isAbundanceUpward;

                 //得到模拟点的水平角度

                 var mockPointAngle = lineAngle + separatorAngle;

                 //计算出模拟点坐标

                 var verticalDistance = distanceToStartPoint * Math.Sin(mockPointAngle);

                 var horizontalDistance = distanceToStartPoint * Math.Cos(mockPointAngle);

                 var mockPoint = new Point(startPoint.X + horizontalDistance, startPoint.Y - verticalDistance);

                 points.Add(mockPoint);

             }

             points.Add(endPoint);

             return points;

         }

         private void DrawLine(List<Point> points)

         {

             _visualShape.Clear();

             var geometryTest = new StreamGeometry();

             using (var ctx = geometryTest.Open())

             {

                 ctx.BeginFigure(points[], true, false);

                 if (points.Count %  == )

                 {

                     //绘制二阶贝塞尔函数，需要保证为偶数点

                     ctx.PolyQuadraticBezierTo(points, true, true);

                 }

                 else

                 {

                     //绘制二阶贝塞尔函数，需要保证为偶数点

                     points.Insert(, points[]);

                     ctx.PolyQuadraticBezierTo(points, true, true);

                 }

                 ctx.Close();

             }

             var visual = new DrawingVisual();

             using (var context = visual.RenderOpen())

             {

                 context.DrawGeometry(FillBrush, StrokePen, geometryTest);

             }

             _visualShape.Add(visual);

         }

         #region 内部方法

         [Obsolete]

         protected override void OnRender(DrawingContext drawingContext)

         {

             //弃用，改为_visualShape填充实现

             //drawingContext.DrawGeometry(FillBrush, StrokePen, BaseGeometry);

         }

         protected override int VisualChildrenCount => _visualShape.Count;

         protected override Visual GetVisualChild(int index)

         {

             if (index <  || index >= _visualShape.Count)

             {

                 throw new ArgumentOutOfRangeException();

             }

             return _visualShape[index];

         }

         #endregion

         #region 曲线属性

         private readonly VisualCollection _visualShape;

         protected Brush FillBrush { get; set; } = Brushes.Transparent;

         public Brush LineBrush { get; set; } = Brushes.DarkSeaGreen;

         protected double BorderThickness { get; set; } = 1.0;

         private Pen _defaultPen = null;

         protected Pen StrokePen

         {

             get

             {

                 if (_defaultPen == null)

                 {

                     _defaultPen = new Pen(LineBrush, BorderThickness);

                 }

                 return _defaultPen;

             }

             set => _defaultPen = value;

         }

         #endregion

     }