c# picturebox上画图

在Form上添加 一个pictureBox,一个button控件

如图所示：

这样我们的绘画面板就弄好了，把pictureBox的dock属性设置为fill，按键为清屏的作用。

private Point p1, p2;//定义两个点（启点，终点）
private static bool drawing=false;//设置一个启动标志
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
                
              p1 = new Point(e.X, e.Y);
              p2 = new Point(e.X, e.Y);
                drawing = true;
            
        }

private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            drawing = false;
        }
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)

        {
          
            Graphics g = pictureBox1.CreateGraphics();
            if(e.Button ==MouseButtons.Left)
            {
                if (drawing)
                {
                    //drawing = true;
                    Point currentPoint = new Point(e.X, e.Y);
                    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;//消除锯齿
                    g.DrawLine(new Pen(Color.Blue, 2),  p2,currentPoint);
                    
                    p2.X = currentPoint.X;
                    p2.Y = currentPoint.Y;
                }

            }
            
        }
//清屏操作
private void button1_Click(object sender, EventArgs e)
        {
            Graphics g = pictureBox1.CreateGraphics();
            g.Clear(Color.White);
        }