write source files to output in custom asp.net server control - asp.net

Question

I am writing own server-side control.I need to use some images in this control.How can I write to output image file [or any other file] and then access it?
protected override void RenderContents(HtmlTextWriter output)
{
.......
output.Write("some file");
string endResult = "<img src= how to access this file? />"
output.Write(endResult);
}

Answer 1

Option 1: Embed It Directly
You can embed images (and other files) directly into webpages using a data URI. Something like:
protected override void RenderContents(HtmlTextWriter output)
{
............
byte[] rawImgData = []; //add your data here, maybe from a FileStream
String imgMimeType = "[img mime type, eg image/png]";
String encodedImgData = Convert.ToBase64String(rawImageData);
output.Write(String.Format("<img src=\"data:{0},{1}\" />", imageMimeType, encodedImageData))
}
As outlined in the link, this approach has lots of disadvantages. If you'll be serving the same images with every request to your control, you should really use static files.
Option 2: Save to the server and map it
Assuming your IIS worker account (normally called IUSR) has write access to some location on the server, you can save it with Server.MapPath and send the actual link out.
protected override void RenderContents(HtmlTextWriter output)
{
............
byte[] rawImgData = []; //add your data here, maybe from a FileStream
FileStream fileStream = System.IO.File.Create(Server.MapPath(virtualPath))
fileStream.Write(rawImgData, 0, rawImgData.Length)
fileStream.Close()
output.Write(String.Format("<img src=\"{0}\" />", virtualPath))
}
For repetitive requests, this definitely the best option.
Option 3: Store it in memory and serve via a second page
You can store the raw data in Session (or another temporary in-memory storage of your choice), send a link with an identifier, and server it from another page. Something like:
protected override void RenderContents(HtmlTextWriter output)
{
............
byte[] rawImgData = []; //add your data here, maybe from a FileStream
Session["MyImgTempStorage"] = rawImgData;
output.Write("<img src=\"ServeImgTempStorage.ashx?file=MyImgTempStorage\");
}
and make a generic handler called ServeImgTempStorage.ashx like this:
public class ServeImgTempStorage : System.Web.IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
string fileKey = context.Request.QueryString("file");
if (string.IsNullOrEmpty(fileKey)) {
return;
}
byte[] rawData = context.Session(fileKey);
context.Response.Write(rawData);
context.Response.ContentType = "[your mime type. you can force a download with attachment;]";
context.Response.End();
}
public bool IsReusable {
get { return false; }
}
}
You'll need to make sure you use session unique identifiers for every file served in this way, or you will overwrite data.
NOTE: My C# syntax may be off, I normally write in VB.