Stream dynamic image directly to web page? 2

[joelwenzel]

Hi,

I am creating an image via code during runtime. I need to display this image on my webpage. One way to do this would be to save the image to a file, and then have an image object reference the file. However, the page gets updated constantly and tons of images would be generated.

so, what I really need is a way to directly stream the image i create to an image object. How do I do this?

 

[Isadore]

joelwenzel - I use a third party package for creating chart images (ChartDirector -

http://www.advsofteng.com/index.html).

They have two mechanisms for handling the chart image which is referenced by the img tag (1) create the image and send to the rendered page (so 2 round trips to the server, the aspx page and then the page's reference to the bitstream which is credated within a dll, and (2) put the image in a Session and call the Session object. Just a couple of ideas - haven't worked directly in dot NET to create the image.

 

[Isadore]

joe: If it turns out that streaming the image object is what you are after here are a few links which discuss in some detail the process:

.NET Streams Explained

ShowImage - Output an image as a binary stream to the Response object

Creating Images on the Fly with ASP.NET - Drawing the graphics

Binary streaming of large images from Database

Using the OutputStream method

..thought perhaps you may gain some further insight here.

 

[ca8msm]

Yeah, as those links that Isadore posted will no doubt show, the overloaded Bitmap.Save method can save the image to a stream and therefore you can save it directly to the Response.OutputStream.

Here's the example from the help file:

http://msdn2.microsoft.com/en-us/library/system.web.httpresponse.outputstream.aspx

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[joelwenzel]

those resources were very good. I can now stream directly to a browser window. However, I would really like to be able to stream to an Webcontrol.Image object so that I can have other stuff on the page as well, besides images.

Is such a thing possible? From what i can tell, it isn't. It looks like I would have to same a temp copy of the file.

 

[ca8msm]

I don't believe you can do that. The Response.OutputStream will expect a certain type of stream (i.e. text, jpg, gif etc) and you won't be able to mix those.

I guess you'll have to save it as a temp file and have a clean up routine for those files.


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[Isadore]

ca8msm: There is the other option of putting the object into Session - just a thought (ChartDirector takes advantage of this).

 

[ca8msm]

How do you then load the session object into an image control as the ImageUrl property only accepts a file path string (not an image object)?


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[joelwenzel]

If I put it in a session, can I do something like

<img src=<%# Session("File") %> >

So that I can place the image and other controls?

 

[ca8msm]

No, you can't do that (which is why I also asked the question as, as far as I know, an Image control get's it's image from a physical file nto a stream).


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[joelwenzel]

ok..that's what I thought. Thanks for your help eveyone. Guess I better create a temp file afterall

 

[Isadore]

Thanks ca8msm - I posted that option as it was a technique used by ChartDirector as an alternative to creating a temporary file and saving it to a temporary directory. I also use ASPMap, which too has the option of either saving an image to a temporary directory or placing it in Session and then streaming it directly to the client form there (of course this occurs within their dll files - haven't had experience directly with dot NET on this).