C# GDI练习 随机线段+随机圆

在form1.cs的事件中，点击

全局的结构

Random r = new Random();
        List<Point> listPoint = new List<Point>(300);//鼠标点击处生成的点的集合

Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;

            //随机产生不同颜色的线段
            for (int i = 0; i < 100; i++)
            {
                var x1 = r.Next(Width);
                var x2 = r.Next(Width);
                var y1 = r.Next(Height);
                var y2 = r.Next(Height);
                var ColorR = r.Next(256);
                var ColorG = r.Next(256);
                var ColorB = r.Next(256);
                Pen myPen = new Pen(Color.FromArgb(ColorR, ColorG, ColorB), 2);
                g.DrawLine(myPen, x1, y1, x2, y2);
            }
            
            SolidBrush blueBrush = new SolidBrush(Color.Blue);
            Pen redPen = new Pen(Color.LightBlue, 2);
            for (int i = 0; i < listPoint.Count; i++)
            {
                g.FillEllipse(blueBrush, new Rectangle(listPoint[i].X - 20, listPoint[i].Y - 20, 40, 40));
                if (i < listPoint.Count - 1)//连线
                {
                    g.DrawLine(redPen, listPoint[i].X, listPoint[i].Y, listPoint[i + 1].X, listPoint[i + 1].Y);
                }
            }
          
        }
        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            Point p = new Point(e.X, e.Y);
            listPoint.Add(p);
            Invalidate();
         
        }

为了不让页面有切换的感觉

结果：