ASP.NET Image Resizing and returning in Response.Output Stream

[Neil Woodvine]

***Scenario ...
I have a DataList with a hyperlink WebControl in the Item Template.
I want to display a 64x64 image in the Hyperlink and set the NavigateURL to
the full size image.

***Source Data Item for Databinding is a class with 2 props ...
URL
Description

***MyMainPage.a spx Page_Load Code ...
Dim myImages As ArrayList = New ArrayList
myImages.Add(Ne w ImageItem(URL As String =
"http://localhost/mywebapp/images/bigpic.bmp", Description As String = "My
bigpic")
DataList1.DataS ource = myImages
DataList1.DataB ind()

***Databing Code for Hyperlink in DataList1 on MyMainPage.aspx ...
*Tooltip = [DataBinder.Eval (Container.Data Item, "Descriptio n")
*NavigateURL = [DataBinder.Eval (Container.Data Item, "URL")
*ImageURL = ["ImageProcessor .aspx?filename= " &
DataBinder.Eval (Container.Data Item, "URL") & "&width=64&heig ht=64"]

***ImageProcess or.aspx Page_Load Code (Imports System.Drawing) ...
Dim imagePath As String = Request.Params( "filename")
Dim requestedWidth As Integer = Request.Params( "width")
Dim requestedHeight As Integer = Request.Params( "height")
Dim sourceImage As Image = Image.FromFile( imagePath)
Dim newImage As Bitmap = New Bitmap(requeste dWidth, requestedHeight ,
Imaging.PixelFo rmat.Format24bp pRgb)
newImage.SetRes olution(sourceI mage.Horizontal Resolution,
sourceImage.Ver ticalResolution )
Dim gr As Graphics = Graphics.FromIm age(newImage)
gr.Interpoloati onMode = Drawing2D.Inter polationMode.Hi ghQualityBicubi c
gr.DrawImage(so urceImage, _
New Rectangle(0, 0, requestedWidth, requestedHeight ), _
New Rectangle(0, 0, sourceImage.Wid th, sourceImage.Hei ght), _
GraphicsUnit.Pi xel)
gr.Dispose()
Response.Conten tType = "image/bmp"
newImage.Save(R esponse.OutputS tream, Imaging.ImageFo rmat.Bmp)

=============== =============== ====
When I run this code I get the hyperlink control with a 'X' in it because it
could not load
an image, but the link itself IS active and correctly takes me to a view of
the full size image.

I've tested the resizing code used in ImageProcessor. aspx on a Windows Form
with a
couple of picture boxes and all seems to be fine, so I conclude that my
problem lies in
how I am writing the resized image to the Response OutputStream (new ground
for me).

So, if anyone can spot my mistake I'd be very grateful.

Thanks,
Neil

[Neil Woodvine]

Sorted it.

Just read elsewhere that Response.Output Stream only likes GIFs or JPEGs, not
BMPs.

So I Changed ...
Response.Conten tType = "image/bmp"
newImage.Save(R esponse.OutputS tream, Imaging.ImageFo rmat.Bmp)
To ...
Response.Conten tType = "image/jpeg"
newImage.Save(R esponse.OutputS tream, Imaging.ImageFo rmat.Jpeg)

and all is just dandy!

Cheers,
Neil

"Neil Woodvine" <nR************ ****@btEinternM et.cEom> wrote in message
news:ce******** **@titan.btinte rnet.com...

***Scenario ...
I have a DataList with a hyperlink WebControl in the Item Template.
I want to display a 64x64 image in the Hyperlink and set the NavigateURL to the full size image.

***Source Data Item for Databinding is a class with 2 props ...
URL
Description

***MyMainPage.a spx Page_Load Code ...
Dim myImages As ArrayList = New ArrayList
myImages.Add(Ne w ImageItem(URL As String =
"http://localhost/mywebapp/images/bigpic.bmp", Description As String = "My
bigpic")
DataList1.DataS ource = myImages
DataList1.DataB ind()

***Databing Code for Hyperlink in DataList1 on MyMainPage.aspx ...
*Tooltip = [DataBinder.Eval (Container.Data Item, "Descriptio n")
*NavigateURL = [DataBinder.Eval (Container.Data Item, "URL")
*ImageURL = ["ImageProcessor .aspx?filename= " &
DataBinder.Eval (Container.Data Item, "URL") & "&width=64&heig ht=64"]

***ImageProcess or.aspx Page_Load Code (Imports System.Drawing) ...
Dim imagePath As String = Request.Params( "filename")
Dim requestedWidth As Integer = Request.Params( "width")
Dim requestedHeight As Integer = Request.Params( "height")
Dim sourceImage As Image = Image.FromFile( imagePath)
Dim newImage As Bitmap = New Bitmap(requeste dWidth, requestedHeight ,
Imaging.PixelFo rmat.Format24bp pRgb)
newImage.SetRes olution(sourceI mage.Horizontal Resolution,
sourceImage.Ver ticalResolution )
Dim gr As Graphics = Graphics.FromIm age(newImage)
gr.Interpoloati onMode = Drawing2D.Inter polationMode.Hi ghQualityBicubi c
gr.DrawImage(so urceImage, _
New Rectangle(0, 0, requestedWidth, requestedHeight ), _
New Rectangle(0, 0, sourceImage.Wid th, sourceImage.Hei ght), _
GraphicsUnit.Pi xel)
gr.Dispose()
Response.Conten tType = "image/bmp"
newImage.Save(R esponse.OutputS tream, Imaging.ImageFo rmat.Bmp)

=============== =============== ====
When I run this code I get the hyperlink control with a 'X' in it because it could not load
an image, but the link itself IS active and correctly takes me to a view of the full size image.

I've tested the resizing code used in ImageProcessor. aspx on a Windows Form with a
couple of picture boxes and all seems to be fine, so I conclude that my
problem lies in
how I am writing the resized image to the Response OutputStream (new ground for me).

So, if anyone can spot my mistake I'd be very grateful.

Thanks,
Neil