Added busy handlers for layer, implemented ready instruction handling in client

guacamole-common-js/src/main/resources/layer.js

@@ -68,7 +68,9 @@ function Layer(width, height) {
 
     resize(width, height);
 
+    var busyHandler = null;
     var readyHandler = null;
+
     var updates = new Array();
     var autosize = 0;
 
@@ -131,6 +133,10 @@ function Layer(width, height) {
         readyHandler = handler;
     };
 
+    display.setBusyHandler = function(handler) {
+        busyHandler = handler;
+    };
+
 
     display.drawImage = function(x, y, image) {
         reserveJob(function() {
@@ -141,6 +147,11 @@ function Layer(width, height) {
 
 
     display.draw = function(x, y, url) {
+
+        // If about to become busy, call busy handler
+        if (display.isReady() && busyHandler != null)
+            busyHandler();
+
         var update = reserveJob(null);
 
         var image = new Image();