Create ImageButton image on the fly in ASP.net

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Hello there,

Being new to ASP.Net but ok with winForm I rather naively thought I could create an image button on the fly and put an image on it (rather than an ImageURL).

The problem is this -

I want to create an imagebutton in my gridview. I am placing this in at design time and each row needs a custom image based on some values in the row. No problem with creating the image (using GDi+) but assigning it to the button seems impossible.

VB

Dim B As New ImageButton
B.CommandArgument = "RowNum"
B.CommandName = "AddMerit"
B.ImageUrl = THIS IS WHERE I NEED TO SET THE IMAGE
R.Cells(2).Controls.Add(B)

If ImageButton had an 'image' property then this would be trivial. However, it only has an ImageURL. I suppose that I could create the image, save it on the server and then reference it, but this would be difficult and messy to clean up. I have tried to understand how I might use a webmethod to serve the image, but this also seems expensive for a table of 30-40 rows - I would prefer to set the images before they are sent to the server....

Any help would be appreciated.

Posted 3-Jul-12 2:09am

Tim_1024

Updated 3-Jul-12 19:03pm

Sandeep Mewara

v2

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Tim_1024 · Answer 1 · 2012-07-03T03:18:00

I have found a solution but I cannot believe it is optimal! The solution is to build a complete page with the following code in the page load:

VB

Dim FinalBitmap As Bitmap
Dim NumMerits = Request.Params("Merits").ToString
Dim BarGraphPercent = Request.Params("BarGraph").ToString
Dim msStream As New MemoryStream

 'Code here to populate FinalBitmap with the image

FinalBitmap.Save(msStream, ImageFormat.Png)
Response.ContentType = "image/png"
msStream.WriteTo(Response.OutputStream)

If Not IsNothing(FinalBitmap) Then FinalBitmap.Dispose()

In the main page I then link each row to a "~/Pages/Register/GetGraph?Merits=3&BarGraph=80" (or whatever that student's figures are)

This then results in 30 calls to the server, one for each image. Surely there is a better way than this!

Tim_1024 · Answer 2 · 2012-07-13T00:14:00

Solution 2

I have not really found an acceptable solution - the sub optimal solution works, but the page takes ages to load each image. In the end I created images for each criteria - 400 images - and referenced these.

Posted 13-Jul-12 0:14am