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Using Saveas() method for Ajax asyncupload using VB.NET

Posted on 2010-08-22
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Last Modified: 2013-12-26
I am having trouble to find a VB.NET tutorial on how to use the SaveAs() method for the Ajax AsyncUpload control.

What I need to do when the upload is complete is:
  - I have to either pass a parameter or access a session variable (call the variable "pictype")
  - I need to validate what type the file is ("picformat" - ex: GIF or JPG)
  - I need to validate the width of the image, and rescale it to no more than 150px wide
  - I  need to save the image as a new file name which includes the session variable and fileformat (ex: filename = "pic" & session("pictype") & "01" & "." & picformat  

I need help with these points in my subroutine.

Thanks, Peter
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Question by:pbissegger
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by:sedgwick
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by:pbissegger
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Although this is in C (not VB), I think I can figure out the SaveAs() functionality from this. Thank you.

Do you have any idea how to address the other points in my message (filetype ? picture width ?)

Thanks, Peter
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by:sedgwick
sedgwick earned 500 total points
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check this post regarding image:

http://forums.asp.net/p/1572277/3943629.aspx
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pbissegger earned 0 total points
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OK, your last post didn't help ,e out that much, but I have bridged the gap between your inputs and a final solution. Please find attached my final solution.
Sub RescaleImage(ImageFilename as String)

    Nx = 150 ' max width for large thumbnail

    Ny = 150 ' max height for large thumbnail

        

    ' Load the Image

    Dim originalimg As System.Drawing.Image = System.Drawing.Image.FromFile(trim(ImageFilename)) 



    ' Work out the width/height for the thumbnail. Preserve aspect ratio and honour max width/height

    ' Note: if the original is smaller than the thumbnail size it will be scaled up

        

    If originalimg.Width <> Nx then



        ' Need to rescale image

        

        Try

            If (originalimg.Width / Nx) > (originalimg.Width / Ny) Then

                N2 = originalimg.Width

                newWidth = Nx

                newHeight = originalimg.Height * (Nx / N2)

                If newHeight > Ny Then

                    newWidth = newWidth * (Ny / newHeight)

                    newHeight = Ny

                End If

            Else

                N2 = originalimg.Height

                newHeight = Ny

                newWidth = originalimg.Width * (Ny / N2)

                If newWidth > Nx Then

                    newHeight = newHeight * (Nx / newWidth)

                    newWidth = Nx

                End If

            End If

	

            Dim thumb As New Bitmap(newWidth, newHeight)

	

            'Create a graphics object for the thumbnail

            Dim gr_dest As Graphics = Graphics.FromImage(thumb)

	

            ' just in case it's a transparent GIF force the bg to white

            Dim sb = New SolidBrush(System.Drawing.Color.White)

            gr_dest.FillRectangle(sb, 0, 0, thumb.Width, thumb.Height)

	

            ' Re-draw the image to the specified height and width

            gr_dest.DrawImage(originalimg, 0, 0, thumb.Width, thumb.Height)

 

            thumb.Save(ImageFilename, originalimg.RawFormat)

                

            ' House Keeping !

            If Not thumb Is Nothing Then

                thumb.Dispose()

                thumb = Nothing

            End If



            If Not originalimg Is Nothing Then

                originalimg.Dispose()

                originalimg = Nothing

            End If           

                

        Catch

            Outputmessage = "Sorry, there was a problem saving the image."

        End Try



End If

    

End Sub



Protected Sub AsyncFileUpload1_UploadedComplete(ByVal sender As Object, ByVal e As EventArgs)

    If AsyncFileUpload1.HasFile then

        ' Determine new file name

        fileExtension = System.IO.Path.GetExtension(AsyncFileUpload1.Filename).ToLower()

        newfilename = "elogo-" & Session("sponsor") & fileExtension

        FolderToSave = Server.MapPath("\") & "Userdata\L-" & Trim(Session("Leaguenum")) & "\Advertisement\"



        ' Validate file is of correct type

        fileOK = False

        Dim allowedExtensions As String() = {".jpg", ".jpeg", ".png", ".gif"}

        For i As Integer = 0 To allowedExtensions.Length - 1

            If fileExtension = allowedExtensions(i) Then

                fileOK = True

            End If

        Next

        

        ' Save the file    

        If fileOK Then

            Try

                AsyncFileUpload1.PostedFile.SaveAs(trim(FolderToSave & newfilename))

                Outputmessage = "File uploaded!"

            Catch ex As Exception

                Outputmessage = "File could not be uploaded."

            End Try

        Else

            Outputmessage = "Cannot accept files of this type."

        End If



        ' Update database entry to indicate new banner name

            cmd.Connection = MyConn

            cmd.Connection.Open()     

            cmd.CommandText = "Update sponsors set sponsorlogoeng = '" & newfilename & "' where sponsorid = " & Session("sponsor")

            cmd.ExecuteNonQuery()

            cmd.Connection.Close()



        ' Display the output message

        upload1Label.Text = Outputmessage

    End If



    ' RescaleImage(trim(FolderToSave & newfilename))



    englishlogo.ImageUrl = Foldertosave & newfilename

    Showenglishlogoimages.Visible = "true"



End Sub

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