根据坐标在图片上绘制多边形边框

'''根据坐标的现有图片上绘制多边形
    Public Shared Function GetSelectedActionImage(ByVal imgurl As String, ByVal coords As String, ByVal colors As String) As Bitmap
        Dim bmp As New Bitmap(imgurl, True)
        Dim g As Graphics = Graphics.FromImage(bmp)
        Dim pens As New Pen(getColor(colors), 2)
        Dim arr As Array = Report.GetStrArray(coords, "|")
        Dim x As Array = Report.GetStrArray(arr.GetValue(0), ",")
        Dim y As Array = Report.GetStrArray(arr.GetValue(1), ",")
        Dim pen As New Pen(Color.Red, 2)
        Dim points As New ArrayList
        If x.Length = y.Length Then
            For j As Integer = 0 To x.Length - 1
                Dim pf As PointF = New PointF(x(j), y(j))
                points.Add(pf)
            Next
        End If
        Dim i As Integer
        For i = 0 To points.Count - 2
            g.DrawLine(pen, points(i).X, points(i).Y, points(i + 1).X, points(i + 1).Y)
        Next
        g.DrawLine(pen, points(i).X, points(i).Y, points(0).X, points(0).Y)
        g.Dispose()
        Return bmp
    End Function
    '''缩放图片
    Public Shared Function Zoom(ByVal myImage As Bitmap, ByVal nWidth As Integer, ByVal nHeight As Integer) As Bitmap
        Dim iX As Integer
        Dim iY As Integer
        Dim xMax As Integer
        Dim yMax As Integer
        If nWidth < myImage.Width Or nHeight < myImage.Height Then
            If myImage.Width / myImage.Height > nWidth / nHeight Then
                xMax = nWidth
                yMax = myImage.Height * nWidth / myImage.Width
            Else
                yMax = nHeight
                xMax = myImage.Width * nHeight / myImage.Height
            End If
        Else
            xMax = myImage.Width
            yMax = myImage.Height
        End If
        Dim tembmp As Bitmap = New Bitmap(myImage, xMax, yMax)
        Return tembmp
    End Function