GDI+
看看我大一的時候的課程設計
諸如這樣的程式碼就可以啦：
            for (int counter = 0; counter <= 24; counter++)
            {
                Pen mypen = new Pen(Color.Green, 3);
                Graphics myGraphics = this.tabPage3.CreateGraphics();
                Point drawPoint = new Point(30 + (700 * counter / 24), 350 - mydblData[counter] * (300 / 10));
                ENDPOINT = drawPoint;
                myGraphics.DrawLine(mypen, STARTPOINT, ENDPOINT);
                STARTPOINT = drawPoint;
            }

//////////////////////////////////////////////////////////////////////////////////////////

public void DrawMapXY(Bitmap imageTemp, Pen DrawPen, float XNum, float YNum, int X1Num, int Y1Num)//指定座標兩點畫線
{
    Graphics g = Graphics.FromImage(imageTemp);
    g.DrawLine(DrawPen, new PointF(XNum, YNum), new PointF(X1Num, Y1Num));
}

Bitmap imageTemp = new Bitmap(100,100);
DrawMapXY(imageTemp, new Pen(Color.Blue, 1), 20, 20, 80, 80)
image.Save("c://1.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);