矩形

        Dim w As Integer = 400
        Dim h As Integer = 280
        Dim img As Bitmap = New Bitmap(w, h)
        Dim g As Graphics = Graphics.FromImage(img)
        Dim pen As New Pen(Color.Blue)
        g.DrawRectangle(pen, 50, 50, 200, 20)
        Dim ms As New MemoryStream()
        img.Save(ms, Imaging.ImageFormat.Gif)
        Response.ClearContent()
        Response.ContentType = "image/gif"
        Response.BinaryWrite(ms.ToArray)