Dynamic updates. The Javascript code estimates the time taken to

update the page, doubles it, and uses the average as the delay between
updates.  On high latency links this means that the delay between
updates will quickly increase so it won't prevent typing.

diff --git a/html/_js/editor.js b/html/_js/editor.js
index 84b930e..d4dc063 100644 (file)
--- a/html/_js/editor.js
+++ b/html/_js/editor.js
@@ -1,9 +1,17 @@
 /* Javascript for OCAMLWIKI.
  * Copyright (C) 2004 Merjis Ltd.
- * $Id: editor.js,v 1.4 2004/10/26 17:50:23 rich Exp $
+ * $Id: editor.js,v 1.5 2004/11/14 14:23:27 rich Exp $
  */
 
-var delay = 1000;              // Delay in milliseconds before updating.
+// Delay in milliseconds before updating.
+// We will adjust this during editing to take into account the actual
+// average round trip time measured during update_preview_now.
+var delay = 1000;
+
+// This is used to measure the average round trip time.
+var rtt_sum = 0;
+var rtt_n = 0;
+var rtt = 0;                   // Actual average RTT measured (ms).
 
 function update_preview (content_id, preview_id)
 {
@@ -25,6 +33,9 @@ function update_preview_now (content_id, preview_id)
   // Get the Wiki-markup content from the content textarea.
   var content = document.getElementById (content_id).value;
 
+  // Time how long it takes to send the document to the server.
+  var start_time = (new Date()).getTime();
+
   // Send the Wiki-markup to the server to be turned into XHTML.
   var http = document.all ?
     new ActiveXObject ('Microsoft.XMLHTTP') : new XMLHttpRequest ();
@@ -42,6 +53,15 @@ function update_preview_now (content_id, preview_id)
       // "Unknown runtime error"
       preview.innerHTML = xhtml;
     }
+
+  // Finish timer and recompute RTT.
+  var end_time = (new Date()).getTime();
+  rtt_sum += end_time - start_time;
+  rtt_n++;
+  rtt = rtt_sum / rtt_n;
+
+  // Recompute the next delay period.
+  delay = rtt * 2;
 }
 
 // Initialise the edit_buttons for a section.