Calculating UpperLeft Cornor of Zoomed Image

[Drpills]

Hello, I am new to this community as well as Visual Basic. My class was assigned a project that is to use Panning and Zooming of a Image. However the code the teacher supplied us zooms to the Upper Left corner of the image instead of the Center of the Current Viewable area. I have tried to using AutoScrollPosition to adjust for zooming to the center however, I was unsuccesfull. Any help would be greatly apprecitated. I am using Visual Basic (From Visual Studio 2008)

Here is the code we were supplied with :

Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms

Public Class ZoomPicBox
    Inherits ScrollableControl

    Private _image As Image

    Public Property Image() As Image
        Get
            Return _image
        End Get

        Set(ByVal value As Image)
            _image = value
            UpdateScaleFactor()
            Invalidate()
        End Set
    End Property

    Private _zoom As Single = 1.0F

    Public Property Zoom() As Single
        Get
            Return _zoom
        End Get

        Set(ByVal value As Single)
            If value < 0 OrElse value < 0.00001 Then
                value = 0.00001F
            End If
            _zoom = value
            UpdateScaleFactor()
            Invalidate()
        End Set
    End Property

    Private Sub UpdateScaleFactor()
        If _image Is Nothing Then
            Me.AutoScrollMargin = Me.Size
        Else
            Me.AutoScrollMinSize = New Size(CInt(Me._image.Width * _zoom + 0.5F), CInt(Me._image.Height * _zoom + 0.5F))
        End If
    End Sub 'UpdateScaleFactor

    Private _interpolationMode As InterpolationMode = InterpolationMode.High

    Public Property InterpolationMode() As InterpolationMode
        Get
            Return _interpolationMode
        End Get

        Set(ByVal value As InterpolationMode)
            _interpolationMode = value
        End Set
    End Property

    Protected Overrides Sub OnPaintBackground(ByVal pevent As PaintEventArgs)

    End Sub 'OnPaintBackground

    Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        'if no image, don't bother
        If _image Is Nothing Then
            MyBase.OnPaintBackground(e)
            Return
        End If
        'Set up a zoom matrix
        Dim mx As New Matrix(_zoom, 0, 0, _zoom, 0, 0)
        mx.Translate(Me.AutoScrollPosition.X / _zoom, Me.AutoScrollPosition.Y / _zoom)
        e.Graphics.Transform = mx
        e.Graphics.InterpolationMode = _interpolationMode
        e.Graphics.DrawImage(_image, New Rectangle(0, 0, Me._image.Width, Me._image.Height), _
                             0, 0, _image.Width, _image.Height, GraphicsUnit.Pixel)
        MyBase.OnPaint(e)
    End Sub 'OnPaint

    Public Sub New()
        'Double buffer the control
        Me.SetStyle(ControlStyles.AllPaintingInWmPaint Or ControlStyles.UserPaint Or _
                    ControlStyles.ResizeRedraw Or ControlStyles.UserPaint Or ControlStyles.DoubleBuffer, True)
        Me.AutoScroll = True
    End Sub 'New

End Class

Edit: I Tried adjusting the AutoScrollPosition in the UpdateScaleFactor() Subroutine. I cannot figure out the actual arithmetic though.