结构intptr无法建立索引，因为它没有默认属性

Question

我正在尝试将code snippet from this answer转换为VB函数，并且遇到了以前从未见过的障碍。  我没有找到足够的细节，所以我正在寻找以太坊中的智慧。

Private Shared Function ConvertImage(filepath As String) As String
    Dim bmp As Bitmap = New Bitmap(filepath)
    Dim v As Byte = &HAA
    ' Lock the bitmap's bits. 
    Dim bmpData = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), Imaging.ImageLockMode.ReadWrite, Imaging.PixelFormat.Format1bppIndexed)
    Try
        Dim pBuffer As IntPtr = bmpData.Scan0
        For r As Integer = 0 To bmpData.Height Step 1
            Dim row As IntPtr = pBuffer + r * bmpData.Stride
            For c As Integer = 0 To bmpData.Stride Step 1
                row(c) = v
            Next
        Next

    Catch ex As Exception
    Finally
        bmp.UnlockBits(bmpData)
    End Try
    filepath = IO.Path.GetTempPath & "label.bmp"
    bmp.Save(filepath)
End Function

表明问题出在row(c) = v上。我该怎么做才能解决此问题？