User60291871 posted
I had the same problem! Spent hours researching to try and resolve this and eventually wrote this code in VB. Works well for me, hope you find it useful.
You will need a ASPX form with a FileUpload control, a label, an image control and a button to use the code below.
Regards Sean.
Imports
System.IO
Imports System.Drawing
Partial Class _Default
Inherits System.Web.UI.Page
Protected Sub btnUpload_Click(ByVal sender
As Object,
ByVal e As System.EventArgs)
Handles btnUpload.Click
Const bmpW = 300 'New image target width
Const bmpH = 226 'New Image target height
If (FileUpload1.HasFile)
Then
'Clear the error label text
lblError.Text = ""
'Check to make sure the file to upload has a picture file format extention and set the target width and height
If (CheckFileType(FileUpload1.FileName))
Then
Dim newWidth
As Integer = bmpW
Dim newHeight
As Integer = bmpH
'Use the uploaded filename for saving without the '.' extension
Dim upName
As String = Mid(FileUpload1.FileName, 1, (InStr(FileUpload1.FileName,
".") - 1))
'Set the save path of the resized image, you will need this directory already created in your web site
Dim filePath As
String = "~/Upload/" & upName &
".png"
'Create a new Bitmap using the uploaded picture as a Stream
'Set the new bitmap resolution to 72 pixels per inch
Dim upBmp As Bitmap = Bitmap.FromStream(FileUpload1.PostedFile.InputStream)
Dim newBmp
As Bitmap = New Bitmap(newWidth, newHeight, Imaging.PixelFormat.Format24bppRgb)
newBmp.SetResolution(72, 72)
'Get the uploaded image width and height
Dim upWidth
As Integer = upBmp.Width
Dim upHeight
As Integer = upBmp.Height
Dim newX As
Integer = 0
'Set the new top left drawing position on the image canvas
Dim newY As
Integer = 0
Dim reDuce
As Decimal
'Keep the aspect ratio of image the same if not 4:3 and work out the newX and newY positions
'to ensure the image is always in the centre of the canvas vertically and horizontally
If upWidth > upHeight
Then 'Landscape picture
reDuce = newWidth / upWidth
'calculate the width percentage reduction as decimal
newHeight = Int(upHeight * reDuce)
'reduce the uploaded image height by the reduce amount
newY = Int((bmpH - newHeight) / 2)
'Position the image centrally down the canvas
newX = 0 'Picture will be full width
ElseIf upWidth < upHeight
Then 'Portrait picture
reDuce = newHeight / upHeight
'calculate the height percentage reduction as decimal
newWidth = Int(upWidth * reDuce)
'reduce the uploaded image height by the reduce amount
newX = Int((bmpW - newWidth) / 2)
'Position the image centrally across the canvas
newY = 0 'Picture will be full hieght
ElseIf upWidth = upHeight
Then 'square picture
reDuce = newHeight / upHeight
'calculate the height percentage reduction as decimal
newWidth = Int(upWidth * reDuce)
'reduce the uploaded image height by the reduce amount
newX = Int((bmpW - newWidth) / 2) 'Position the image centrally across the canvas
newY = Int((bmpH - newHeight) / 2) 'Position the image centrally down the canvas
End If
'Create a new image from the uploaded picture using the Graphics class
'Clear the graphic and set the background colour to white
'Use Antialias and High Quality Bicubic to maintain a good quality picture
'Save the new bitmap image using 'Png' picture format and the calculated canvas positioning
Dim newGraphic
As Graphics = Graphics.FromImage(newBmp)
Try
newGraphic.Clear(Color.White)
newGraphic.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
newGraphic.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic
newGraphic.DrawImage(upBmp, newX, newY, newWidth, newHeight)
newBmp.Save(MapPath(filePath), Imaging.ImageFormat.Png)
'Show the uploaded resized picture in the image control
Image1.ImageUrl = filePath
Image1.Visible = True
Catch ex As Exception
lblError.Text = ex.ToString
Finally
upBmp.Dispose()
newBmp.Dispose()
newGraphic.Dispose()
End Try
Else
lblError.Text = "Please select a picture with a file format extension of either Bmp, Jpg, Jpeg, Gif or Png."
End If
End If
End Sub
Function CheckFileType(ByVal fileName
As String)
As Boolean
Dim ext As
String = Path.GetExtension(fileName)
Select Case ext.ToLower()
Case ".gif"
Return True
Case ".png"
Return True
Case ".jpg"
Return True
Case ".jpeg"
Return True
Case ".bmp"
Return True
Case Else
Return False
End Select
End Function
End
Class
