1 files changed, 23 insertions, 4 deletions

diff --git a/html/whiteboard.js b/html/whiteboard.js
index aef4391..58023fe 100644
--- a/html/whiteboard.js
+++ b/html/whiteboard.js
@@ -4,6 +4,8 @@ function init() {
 }
 
 var revision;
+var baseline = ""; // data contents relating to revision, acknowledged by server
+var baseline_candidate = ""; // will become baseline, after ack by server
 
 // helper for breaking feedback loop
 var caretpos = 0;
@@ -42,6 +44,7 @@ function on_getfile(data, rev, pos)
 		board.value = data;
 	}
 	revision = rev;
+        baseline = data;
 	textAreaSetPos("board", pos);
 }
 
@@ -72,6 +75,7 @@ function on_version(version)
 function on_modify_ack(rev)
 {
 	revision = rev;
+        baseline = baseline_candidate;
 }
 
 function on_message(e) {
@@ -158,9 +162,6 @@ function init_board() {
 	Module.onRuntimeInitialized = () => {
          connect_websocket();
         };
-	//Module.onRuntimeInitialized = () => { alert("DEBUG: " + Module._getnum(1) + " " + UTF8ToString(Module._getstring(allocateUTF8("abc"))));
-		//_free(allocateUTF8("abc"));
-	//};
 	
 	var board = document.getElementById("board");
 	board.addEventListener("input", function() {on_input(); });
@@ -219,7 +220,25 @@ function on_input()
 	dataElement.appendChild(document.createTextNode(document.getElementById("board").value));
 	requestElement.appendChild(dataElement);
 
-	var posElement = xmlDocument.createElement("pos");
+        baseline_candidate = document.getElementById("board").value;
+
+	var revisionElement = xmlDocument.createElement("baserev");
+	revisionElement.appendChild(document.createTextNode(revision));
+	requestElement.appendChild(revisionElement);
+	
+	//Module.onRuntimeInitialized = () => { alert("DEBUG: " + Module._getnum(1) + " " + UTF8ToString(Module._getstring(allocateUTF8("abc"))));
+		//_free(allocateUTF8("abc"));
+	//};
+        var old_version = allocateUTF8(baseline);
+        var new_version = allocateUTF8(baseline_candidate);
+        var diff = Module._diff_create(old_version, new_version);
+        var diffDocument = parser.parseFromString(UTF8ToString(diff), "text/xml");
+        _free(old_version);
+        _free(new_version);
+        _free(diff);
+	requestElement.appendChild(xmlDocument.importNode(diffDocument.getElementsByTagName("diff")[0], true));
+	
+        var posElement = xmlDocument.createElement("pos");
 	posElement.appendChild(document.createTextNode(document.getElementById("board").selectionStart));
 	requestElement.appendChild(posElement);