c# 实例——绘制波浪线（附源码）

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 >= 2))
    {
      _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 = 4;
    private const int abundancepiexl = 3;
    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 = 0;
      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, 2) + math.pow(abundancepiexl, 2));
        //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[0], true, false);
        if (points.count % 2 == 0)
        {
          //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(0, points[0]);
          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 < 0 || 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
  }