一、使用GDI+画线

.Net中在System.Drawing命名空间下使用Graphics类画线。

有四种方法画线。

//绘制一条连接两个Point结构的线
DrawLine(Pen,Point,Point)

//绘制一条连接两个PointF结构的线
DrawLine(Pen,PointF,PointF)

//绘制一条连接由坐标对指定的两个点的线条
DrawLine(Pen,Int32,Int32,Int32,Int32)

//绘制一条连接由坐标对指定的两个点的线条
DrawLine(Pen,Single,Single,Single,Single)

private void Form1_Paint(object sender, PaintEventArgs e)
{
    //创建画板从Paint事件中的直接引用Graphics对象
    Graphics graphics = e.Graphics;
    //定义画笔
    Pen pen = new Pen(Color.Red, 3.0f);
    //定义两个点
    Point pointStart = new Point(100,100);
    Point pointEnd = new Point(100,500);
    //画线(线条粗线为3.0f,长度400，垂直于屏幕的一条直线)
    graphics.DrawLine(pen, pointStart, pointEnd);
}

private void Form1_Paint(object sender, PaintEventArgs e)
{
    //创建画板从Paint事件中的直接引用Graphics对象
    Graphics graphics = e.Graphics;
    //定义画笔
    Pen pen = new Pen(Color.Red, 3.0f);
    //定义两个点
    PointF pointStart = new PointF(100.0f,100.0f);
    PointF pointEnd = new PointF(100.0f,500.0f);
    //画线(线条粗线为3.0f,长度400，垂直于屏幕的一条直线)
    graphics.DrawLine(pen, pointStart, pointEnd);
}

private void Form1_Paint(object sender, PaintEventArgs e)
{
    //创建画板从Paint事件中的直接引用Graphics对象
    Graphics graphics = e.Graphics;
    //定义画笔
    Pen pen = new Pen(Color.Red, 3.0f);
    //定义点坐标
    int x1 = 100;
    int x2 = 100;
    int y1 = 100;
    int y2 = 500;
    //画线(线条粗线为3.0f,长度400，垂直于屏幕的一条直线)
    graphics.DrawLine(pen, x1,y1,x2,y2);
}

private void Form1_Paint(object sender, PaintEventArgs e)
{
    //创建画板从Paint事件中的直接引用Graphics对象
    Graphics graphics = e.Graphics;
    //定义画笔
    Pen pen = new Pen(Color.Red, 3.0f);
    //定义点坐标
    int x1 = 100.0f;
    int x2 = 100.0f;
    int y1 = 100.0f;
    int y2 = 500.0f;
    //画线(线条粗线为3.0f,长度400，垂直于屏幕的一条直线)
    graphics.DrawLine(pen, x1,y1,x2,y2);
}

四种方法，有Point,PointF,Int,Single四种类型，主要是坐标点，画线的时候确定好起始坐标和结束坐标即可。四种中的任何一种都一样。

效果图：