I had the need to upload images to my blog as well as create a thumbnail based on the image. I had the code written at www.jasncab.com, but it was in an EXE.

So I was left with converting it just a little.

First the code to upload the image:

The only real line here to pay attention to is
Call ProcessImage(filepath)

Private Sub cmdUpload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdUpload.Click        Dim theFile As String = txtFile.PostedFile.FileName        Dim filename As String        filename = theFile.Substring(theFile.LastIndexOf("\") + 1)

        Dim filepath As String = MapPath("db/images/") _            & filename        Try            txtFile.PostedFile.SaveAs(filepath)            Call ProcessImage(filepath)

            lblError.Text &= "Image Uploaded"            Call SetupPage()        Catch ex As Exception            lblError.Text &= ex.Message        End Try

    End Sub

Then I needed to actually create the thumbnail. There a couple nuances here. You need a callback function delegate and I created a couple of functions to figure out the height and width for me as well based on 100 as the largest side.

deletegatetest is the only thing here to watch for. You need it for a callback, but it really doesnt need to do anything.

#Region "Imagestuff"    Private Sub DeleteImage(ByVal strImage As String)        If System.IO.File.Exists(MapPath("db/images/" & strImage)) Then            System.IO.File.Delete(MapPath("db/images/" & strImage))        End If        If System.IO.File.Exists(MapPath("db/images/thumbnails/" & strImage.Replace(".jpg", "_thumb.jpg"))) Then            System.IO.File.Delete(MapPath("db/images/thumbnails/" & strImage.Replace(".jpg", "_thumb.jpg")))        End If    End Sub    Private Sub ProcessImage(ByVal strImage As String)        Dim imgSource As System.Drawing.Image        Dim imgOutput As System.Drawing.Image        Dim dummyCallBack As System.Drawing.Image.GetThumbnailImageAbort        Dim strDestDir As String

        strDestDir = MapPath("db/images/thumbnails/") + strImage.Substring(strImage.LastIndexOf("\") + 1)        lblError.Text &= strDestDir        dummyCallBack = New _              System.Drawing.Image.GetThumbnailImageAbort(AddressOf delegatetest)        Try            imgSource = System.Drawing.Image.FromFile(strImage)            imgOutput = imgSource.GetThumbnailImage(GetImageWidth(imgSource), GetImageHeight(imgSource), dummyCallBack, IntPtr.Zero)

            imgOutput.Save(strDestDir.Replace(".jpg", "_Thumb.jpg"), Imaging.ImageFormat.Jpeg)

            imgSource.Dispose()            imgOutput.Dispose()        Catch e As Exception            'I dont care.            lblError.Text &= e.Message        End Try        imgSource = Nothing        imgOutput = Nothing

    End Sub    Public Function delegatetest() As Boolean        Return False    End Function    Public Function GetImageWidth(ByVal imgS As System.Drawing.Image) As Integer        Dim aspR As Double        If imgS.Width > imgS.Height Then            GetImageWidth = 100        Else            aspR = 100 / imgS.Height            GetImageWidth = CType(imgS.Width * aspR, Integer)        End If    End Function    Public Function GetImageHeight(ByVal imgS As System.Drawing.Image) As Integer        Dim aspR As Double        If imgS.Width > imgS.Height Then            aspR = 100 / imgS.Width            GetImageHeight = CType(imgS.Height * aspR, Integer)        Else            GetImageHeight = 100        End If    End Function#End Region

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