整理一下项目文件

AIStudio.Wpf.DiagramDesigner/Helpers/SegmentHelper.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Windows;
+using System.Windows.Media;
+
+namespace AIStudio.Wpf.DiagramDesigner
+{
+    public class SegmentHelper
+    {
+        /// <summary>
+        /// 获得贝塞尔曲线
+        /// </summary>
+        /// <param name="currentPt">当前点</param>
+        /// <param name="lastPt">上一个点</param>
+        /// <param name="nextPt1">下一个点1</param>
+        /// <param name="nextPt2">下一个点2</param>
+        /// <returns></returns>
+        public static BezierSegment GetBezierSegment(Point currentPt, Point lastPt, Point nextPt1, Point nextPt2)
+        {
+            //计算中点
+            var lastC = GetCenterPoint(lastPt, currentPt);
+            var nextC1 = GetCenterPoint(currentPt, nextPt1); //贝塞尔控制点
+            var nextC2 = GetCenterPoint(nextPt1, nextPt2);
+
+            //计算相邻中点连线跟目的点的垂足
+            //效果并不算太好，因为可能点在两个线上或者线的延长线上，计算会有误差
+            //所以就直接使用中点平移方法。
+            //var C1 = GetFootPoint(lastC, nextC1, currentPt);
+            //var C2 = GetFootPoint(nextC1, nextC2, nextPt1);
+
+
+            //计算“相邻中点”的中点
+            var c1 = GetCenterPoint(lastC, nextC1);
+            var c2 = GetCenterPoint(nextC1, nextC2);
+
+
+            //计算【"中点"的中点】需要的点位移
+            var controlPtOffset1 = currentPt - c1;
+            var controlPtOffset2 = nextPt1 - c2;
+
+            //移动控制点
+            var controlPt1 = nextC1 + controlPtOffset1;
+            var controlPt2 = nextC1 + controlPtOffset2;
+
+            //如果觉得曲线幅度太大，可以将控制点向当前点靠近一定的系数。
+            controlPt1 = controlPt1 + 0 * (currentPt - controlPt1);
+            controlPt2 = controlPt2 + 0 * (nextPt1 - controlPt2);
+
+            var bzs = new BezierSegment(controlPt1, controlPt2, nextPt1, true);
+            return bzs;
+        }
+
+        /// <summary>
+        ///     过c点做A和B连线的垂足
+        /// </summary>
+        /// <param name="aPoint"></param>
+        /// <param name="bPoint"></param>
+        /// <param name="cPoint"></param>
+        /// <returns></returns>
+        private static Point GetFootPoint(Point aPoint, Point bPoint, Point cPoint)
+        {
+            //设三点坐标是A，B，C，AB构成直线，C是线外的点
+            //三点对边距离是a,b,c,垂足为D，
+            //根据距离推导公式得：AD距离是（b平方-a平方+c平方）/2c
+            //本人数学不好，可能没考虑点c在线ab上的情况
+            var offsetADist = (Math.Pow(cPoint.X - aPoint.X, 2) + Math.Pow(cPoint.Y - aPoint.Y, 2) - Math.Pow(bPoint.X - cPoint.X, 2) - Math.Pow(bPoint.Y - cPoint.Y, 2) + Math.Pow(aPoint.X - bPoint.X, 2) + Math.Pow(aPoint.Y - bPoint.Y, 2)) / (2 * GetDistance(aPoint, bPoint));
+
+            var v = bPoint - aPoint;
+            var distab = GetDistance(aPoint, bPoint);
+            var offsetVector = v * offsetADist / distab;
+            return aPoint + offsetVector;
+        }
+
+        private static Point GetCenterPoint(Point pt1, Point pt2)
+        {
+            return new Point((pt1.X + pt2.X) / 2, (pt1.Y + pt2.Y) / 2);
+        }
+
+        private static double GetDistance(Point pt1, Point pt2)
+        {
+            return Math.Sqrt(Math.Pow(pt1.X - pt2.X, 2) + Math.Pow(pt1.Y - pt2.Y, 2));
+        }
+    }
+}