winform 根据两点求出线上所有点及画出这条线

找出所有点：

根据斜率按照一个方向递增，求出对应的另一个方向的整数值。

Point pStart = new Point(0, 2);
            Point pEnd = new Point(8, 2);
            //定义线上的点
            List<Point> linePoint = new List<Point>();
            //定义x坐标的大小
            Point pointMaxX = new Point();
            Point pointMinX = new Point();
            //给x坐标大的点和小的点赋值
            if (Math.Max(pStart.X, pEnd.X) == pStart.X)
            {
                pointMaxX = pStart;
                pointMinX = pEnd;
            }
            else
            {
                pointMaxX = pEnd;
                pointMinX = pStart;
            }
            // 循环x坐标(循环满足x坐标为整数的y坐标)或者y坐标均可
            for (int i = pointMinX.X + 1; i < pointMaxX.X; i++)
            {
                // 计算斜率
                double k = ((double)(pointMinX.Y - pointMaxX.Y)) / (pointMinX.X - pointMaxX.X);
                // 根据斜率,计算y坐标
                double y = k * (i - pointMinX.X) + pointMinX.Y;
                // 简单判断一下y是不是整数
                double d = y - (int)y;
                if (0.001 > d && d > -0.001)
                {
                    linePoint.Add(new Point(i,(int)d));
                }
            }
            //打印点
            foreach (var item in linePoint)
            {
                Console.WriteLine(item.X + @"," + item.Y);
            }

画线

依据某个端点，找出这个端点方向的下一个三个周围点，找出最符合斜率的点。

public bool DrawLineOnPicture(Color c, Point start, Point end)
        {
            if (MyBitmapData == null) { return false; }
            int x, y;
            int dstStride = MyBitmapData.Stride;
            //Object thisLock = new Object();
            //lock (thisLock){
            System.IntPtr dstScan0 = MyBitmapData.Scan0;
            try
            {
                if (start.X > end.X)
                {
                    Point temp = start;
                    start = end;
                    end = temp;
                }
                int step;
                if (start.Y < end.Y)
                    step = 1;
                else
                    step = -1;
                x = start.X;
                y = start.Y;
                unsafe
                {
                    byte* pDst = (byte*)(void*)dstScan0;

                    while ((x != end.X) || (y != end.Y))
                    {

                        pDst[x * 3 + y * dstStride] = c.R;
                        pDst[x * 3 + y * dstStride + 1] = c.G;
                        pDst[x * 3 + y * dstStride + 2] = c.B;

                        Point p1 = new Point(x + 1, y);
                        Point p2 = new Point(x, y + step);
                        Point p3 = new Point(x + 1, y + step);

                        double distance1 = DistanceToLine(p1, start, end);
                        double distance2 = DistanceToLine(p2, start, end);
                        double distance3 = DistanceToLine(p3, start, end);

                        double distance = Math.Min(Math.Min(distance1, distance3), distance2);
                        if (distance == distance1)
                        {
                            x = p1.X;
                            y = p1.Y;
                        }
                        else if (distance == distance2)
                        {
                            x = p2.X;
                            y = p2.Y;
                        }
                        else
                        {
                            x = p3.X;
                            y = p3.Y;
                        }
                    }
                }
            }
            catch (Exception )
            {
                //DBConnection.LevelTrace(TraceLevel.Error, "MyImage-->DrawLineOnPicture failed with:" + e);
                return false;
            }
            //}
            return true;
        }

private double DistanceToLine(Point p, Point lineStart, Point lineEnd)
        {
            if (lineStart.X == lineEnd.X)
                return (Math.Abs(p.X - lineEnd.X));
            else if (lineStart.Y == lineEnd.Y)
                return (Math.Abs(p.Y - lineEnd.Y));
            else
            {
                double a = 1.0 * (lineEnd.Y - lineStart.Y) / (lineEnd.X - lineStart.X);
                double b = lineStart.Y - a * lineStart.X;
                double b2 = p.Y - a * p.X;
                return (Math.Abs(b2 - b));
            }
        }