GUAC-1480: Do not poll - just hook into events where the clipboard may have changed.

guacamole/src/main/webapp/app/client/services/clipboardService.js

@@ -104,6 +104,10 @@ angular.module('client').factory('clipboardService', ['$injector',
 
         var deferred = $q.defer();
 
+        // Wait for the next event queue run before attempting to read
+        // clipboard data (in case the copy/cut has not yet completed)
+        window.setTimeout(function deferredClipboardRead() {
+
             // Clear and select the clipboard DOM element
             clipboardContent.value = '';
             clipboardContent.select();
@@ -114,11 +118,16 @@ angular.module('client').factory('clipboardService', ['$injector',
             else
                 deferred.reject();
 
+        }, 10);
+
         return deferred.promise;
     };
 
-    // Periodically attempt to read the clipboard, firing an event if successful
+    /**
-    window.setInterval(function periodicallyReadClipboard() {
+     * Checks whether the clipboard data has changed, firing a new
+     * "guacClipboard" event if it has.
+     */
+    var checkClipboard = function checkClipboard() {
         service.getLocalClipboard().then(function clipboardRead(data) {
 
             // Fire clipboard event if the data has changed
@@ -128,7 +137,12 @@ angular.module('client').factory('clipboardService', ['$injector',
             }
 
         });
-    }, 100);
+    };
+
+    // Attempt to read the clipboard if it may have changed
+    window.addEventListener('copy',  checkClipboard, true);
+    window.addEventListener('cut',   checkClipboard, true);
+    window.addEventListener('focus', checkClipboard, true);
 
     return service;