如何在完整多边形的两点之间的某处添加一个点

Question

我有一个点列表。我取第一个点和下一个点（第二点）并在第一点和第二点之间画一条线。

我想在现有点之间添加另一个顶点。

这是我的方法。

当用户双击在线时，应该在那里添加一个点。

找到由多边形生成的所有形状点。

检查 e.Location 是否在点列表中。

如果存在则检查该点的下限和上限。

在下限旁边插入 e.Location。

使用更新的列表重新绘制线条。

我正在计算直线的所有点。通过使用 y = mx + c。

我的问题是我能够获得所有垂直点 x = a、一些对角线点和水平点，但不是全部。我需要知道是什么原因以及如何解决它？
我正在创建由 ICImaging video grabber library.So 提供的位图叠加层，我只能通过整数点在屏幕上绘制。

   private void btnAddPoint_Click(object sender, EventArgs e)
    {
        //IsLineSelected = true;
        Debug.Print("Current Points in List ");
        foreach (System.Drawing.Point P in PathPoints)
        {
            Debug.Print(P.ToString());
        }
        for (int IndexI = 0; IndexI != PathPoints.Count - 1; IndexI++)
        {
            if (IndexI  == PathPoints.Count-1)
            {
                break;
            }
            else
            {
                Debug.Print("P1:" + PathPoints[IndexI].ToString() + "P2:"+ PathPoints[IndexI+1].ToString());
                ShapeDirectory.AllLinePoints(PathPoints[IndexI], PathPoints[IndexI + 1]);
            }

        }

        foreach (System.Drawing.Point P in ShapeDirectory.LinePoints)
        {
            PathPoints3.Add(P);
        }
        drawLinePoints = true;

    }        

    public static void AllLinePoints(Point p1, Point p2)
    {

        double YDiff = p2.Y - p1.Y;
        double XDiff = p2.X - p1.X;

        double SlopM = Math.Round(Math.Abs(YDiff / XDiff));

        double YinterceptB = Math.Round(Math.Abs(p1.Y - (SlopM * p1.X)));

        Debug.Print("Slop: " + SlopM.ToString() + "Y Intercept: " + YinterceptB.ToString());

        if (SlopM == 0)
        {

        }


        if (Double.IsNegativeInfinity(SlopM) || Double.IsPositiveInfinity(SlopM))
        {
            int LowerBoundX = 0;
            int LowerBoundY = 0;

            int upperBoundX;
            int upperBoundY;

            double distanceBetwwenP1andp2 = GetDistanceBetween2points(p1, p2);

            if (p1.X == p2.X )
            {
                LowerBoundX = p1.X;
                upperBoundX = p2.X;                   

            }

            if (p1.Y <= p2.Y)
            {
                LowerBoundY = p1.Y;
                upperBoundY = p2.Y;

            }
            else
            {
                LowerBoundY = p2.Y;
                upperBoundY = p1.Y;
            }

            //Vertical 

            for (int YIndex = LowerBoundY; YIndex <= upperBoundY; YIndex++)
            {

                        TempLinePoint.X = LowerBoundX;
                        TempLinePoint.Y = YIndex;

                        //Debug.Print("Current Line Points X: " + XIndex.ToString() + "Y: " + YIndex.ToString());
                        LinePoints.Add(TempLinePoint);                            
            }
        }
        else 
        {
            int LowerBoundX;
            int LowerBoundY;

            int upperBoundX;
            int upperBoundY;

            double distanceBetwwenP1andp2 = GetDistanceBetween2points(p1, p2);

            if (p1.X <= p2.X && p1.Y <= p2.Y)
            {
                LowerBoundX = p1.X;
                upperBoundX = p2.X;

                LowerBoundY = p1.Y;
                upperBoundY = p2.Y;

            }
            else
            {
                LowerBoundX = p2.X;
                upperBoundX = p1.X;

                LowerBoundY = p2.Y;
                upperBoundY = p1.Y;

            }

            //if Vertical 
            for (int YIndex = LowerBoundY; YIndex <= upperBoundY; YIndex++)
            {

                for (int XIndex = LowerBoundX; XIndex <= upperBoundX; XIndex++)
                {
                    if (YIndex == (SlopM * XIndex) + YinterceptB)
                    {
                        TempLinePoint.X = XIndex;
                        TempLinePoint.Y = YIndex;

                        //Debug.Print("Current Line Points X: " + XIndex.ToString() + "Y: " + YIndex.ToString());
                        LinePoints.Add(TempLinePoint);

                    }
                }
            }

        }

编辑

我改变了方法。

计算中心点。

将新的 MouseDoubleClicked e.Location 添加到 PathPoint 列表。

找出多边形每个顶点的角度。

按升序排列列表。

插入列表末尾的第一个 Point 以完成多边形。

代码在答案中。

Answer 1

    public static double GetAngleBetweenPoints(Point p1, Point p2)
    {           
        double xDiff = p2.X - p1.X;
        double yDiff = p1.Y - p2.Y;

        double Angle = Math.Atan2(yDiff, xDiff) * (180 / Math.PI);

        if (Angle < 0.0)
            Angle = Angle + 360.0;

        return Angle;
    }

 public static GenericList<Point> PointAddingByAngle(GenericList<Point> LinePoints2)
    {

        List<int> AnglefromCenterPointsofShapePoint = new List<int>();
        List<Point> Linepoints3 = new List<Point>(LinePoints2);
        List<Point> LinePoints = Linepoints3.Distinct().ToList();

        Point CenterPoint = new Point();
        CenterPoint.X = PolygonCenterX;
        CenterPoint.Y = PolygonCenterY;            

        for (int index = 0; index < LinePoints.Count; index++)
        {
            AnglefromCenterPointsofShapePoint.Add((int) Math.Round(GetAngleBetweenPoints(CenterPoint, LinePoints[index])));    
        }           


        AnglefromCenterPointsofShapePoint.Sort();

        int currentPointAngle = 0;

        for (int AngleListIndex = 0; AngleListIndex < AnglefromCenterPointsofShapePoint.Count; AngleListIndex++)
        {
            currentPointAngle = AnglefromCenterPointsofShapePoint[AngleListIndex];

            for (int index = 0; index < LinePoints.Count; index++)
            {
                if ((Math.Round(GetAngleBetweenPoints(CenterPoint, LinePoints[index]))) == currentPointAngle)
                {
                    SortedPoints.Add(LinePoints[index]);
                    break;
                }
            }
        }

        SortedPoints.Add(SortedPoints[0]);
        return SortedPoints;
    }


   private void pictureBox_MouseDoubleClick(object sender, MouseEventArgs e)
    {
        if (PathPoints.Count > 2)
        {
            PathPoints.Add(PathPoints[0]);
            IsPathComplete = true;
            IsPointSelected = false;
            StartingPoint = PathPoints[0];
            EndingPoint = PathPoints[PathPoints.Count - 1];
        }

        if (IsPathComplete && NewPointAdd)
        {

            System.Drawing.Point Centerpoint = new System.Drawing.Point();

            PathPoints.Add(e.Location);

            MinMaxFinder(PathPoints);

            Centerpoint.X = PolygonCenterX;
            Centerpoint.Y = PolygonCenterY;


            lblAngle.Text = Convert.ToString(Math.Round(ShapeDirectory.GetAngleBetweenPoints(Centerpoint, e.Location)));

            PathPoints3.Clear();

            PathPoints3 = ShapeDirectory.PointAddingByAngle(PathPoints);

            PathPoints.Clear();

            foreach (System.Drawing.Point p in PathPoints3)
            {
                PathPoints.Add(p);
            }

            PathPoints.Add(PathPoints3[0]);
            NewPointAddDraw = true;
        }
    }

如何在完整多边形的两点之间的某处添加一个点

How to add a point in somewhere between two points of a complete polygon

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