How can I modify the entire ASP.NET page content right before it's output?

Question

I have a page that has a bunch of user controls on it. I want to be able to have "macros" or "placeholders" directly in the content that will get replaced in my code. It shouldn't really matter, but I'm using Ektron as my CMS.

Are there any page events that I can hook into to do a string replace on the entire rendered page content, right before it's sent to the client?

UPDATE

Here is the code that I am currently using to accomplish this:

protected override void Render(HtmlTextWriter writer)
{
    string content = string.Empty;

    using (var stringWriter = new StringWriter())
    using (var htmlWriter = new HtmlTextWriter(stringWriter))
    {
        // render the current page content to our temp writer
        base.Render(htmlWriter);
        htmlWriter.Close();

        // get the content
        content = stringWriter.ToString();
    }

    // replace our placeholders
    string newContent = content.Replace("$placeholder1$", "placeholder1 data").Replace("$placeholder2$", "placeholder2 data");

    // write the new html to the page
    writer.Write(newContent);
}

Answer 1

Have you tried overriding the render method?

protected override void Render(HtmlTextWriter writer)
{
   StringBuilder htmlString = new StringBuilder(); // this will hold the string
   StringWriter stringWriter = new StringWriter(htmlString);
   HtmlTextWriter tmpWriter = new HtmlTextWriter(stringWriter);
   Page.Render(tmpWriter);
   writer.Flush();

   writer.Write(DoReplaceLogic(htmlString.ToString()););
}