From: Alex <metallourlante@...>
Date: 2006-03-12T05:43:44+09:00
Subject: cgi script send a bad image to the browser

Hi everyone,
I'd like to use a ruby script to generate an image (directed graph) and
sand it to an ajax-like javascript script that display the image in the
browser.
I tryed to do it but what the browser display only a lot of strange
characters. I think it's a headers problem but I really don't know how
to solve it.
When I run the script in a shell and redirect the input to a file, the
generated image is good
What is the best way to send the image to the browser?
Any idea is welcome,
thanks in advance.

Alex

#this is the ruby script#

require "graphviz"
g = GraphViz::new( "G" )
main  = g.add_node( "main" )
parse = g.add_node( "parse" )
g.add_edge( main, parse )
puts "Content-Type: image/png"
puts
g.output( "output" => "png" )

 ############## This is the client-side javascript to display the
gener0ated image ##############

<script language="javascript" type="text/javascript">
var request = false;
try {
  request = new XMLHttpRequest();
} catch (trymicrosoft) {
  try {
    request = new ActiveXObject("Msxml2.XMLHTTP");
  } catch (othermicrosoft) {
    try {
      request = new ActiveXObject("Microsoft.XMLHTTP");
    } catch (failed) {
      request = false;
    }
  }
}

if (!request)
  alert("Error initializing XMLHttpRequest!");

/****************************************************/


function updatePage() {
     if (request.readyState == 4) {
       if (request.status == 200) {
         var response = request.responseText;
         document.getElementById("address").innerHTML ="<img
src="+response+" />";
       } else
         alert("status is " + request.status);
     }
   }

function getAnswer() {
     var url ="nph-script.rb";
		 request.open("GET", url, true);
		 request.onreadystatechange = updatePage;
     request.send(null);
   }

</script>
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