GUACAMOLE-2175: Wait clipboard synchronization before pasting.

guacamole/src/main/frontend/src/app/client/directives/guacClient.js

@@ -132,6 +132,13 @@ angular.module('client').directive('guacClient', [function guacClient() {
          */
         const touch = new Guacamole.Touch(displayContainer);
 
+        /**
+         * Whether clipboard synchronization is currently in progress.
+         *
+         * @type boolean
+         */
+        let clipboardSyncInProgress = false;
+
         /**
          * Updates the scale of the attached Guacamole.Client based on current window
          * size and "auto-fit" setting.
@@ -239,15 +246,47 @@ angular.module('client').directive('guacClient', [function guacClient() {
             event.stopPropagation();
             event.preventDefault();
 
-            // Send mouse state, show cursor if necessary
-            display.showCursor(!localCursor);
-            client.sendMouseState(event.state, true);
+            // Wait for any in-progress clipboard synchronization to complete.
+            // This avoids the pasting of outdated clipboard content when guacamole
+            // window regains focus.
+            waitForClipboardSync().then(() => {
 
-            // Broadcast the mouse event
-            $rootScope.$broadcast(getMouseEventName(event), event, client);
+                // Send mouse state, show cursor if necessary
+                display.showCursor(!localCursor);
+                client.sendMouseState(event.state, true);
+
+                // Broadcast the mouse event
+                $rootScope.$broadcast(getMouseEventName(event), event, client);
+
+            });
 
         };
 
+        /**
+         * Returns a promise which resolves once any in-progress clipboard
+         * synchronization has completed.
+         *
+         * @returns {Promise}
+         *     A promise which resolves once any in-progress clipboard
+         *     synchronization has completed.
+         */
+        function waitForClipboardSync() {
+            return new Promise((resolve) => {
+                function checkClipboardSync() {
+                    if (!clipboardSyncInProgress) {
+                        resolve();
+                        return;
+                    }
+
+                    // Synchronization can take 8-10ms, so check again shortly
+                    // to not add slight latency in fast environments.
+                    setTimeout(checkClipboardSync, 10);
+                }
+
+                checkClipboardSync();
+            });
+        }
+
         /**
          * Handles a mouse event originating from one of Guacamole's mouse
          * emulation objects. This differs from handleMouseState() in that
@@ -601,6 +640,11 @@ angular.module('client').directive('guacClient', [function guacClient() {
                 client.sendKeyEvent(0, keysym);
         });
 
+        // Track clipboard synchronization status
+        $rootScope.$on('clipboardSyncInProgress', function clipboardSyncStatus(event, status) {
+            clipboardSyncInProgress = status;
+        });
+
         /**
          * Whether a drag/drop operation is currently in progress (the user has
          * dragged a file over the Guacamole connection but has not yet

guacamole/src/main/frontend/src/app/clipboard/services/clipboardService.js

@@ -603,6 +603,7 @@ angular.module('clipboard').factory('clipboardService', ['$injector',
             // updated contents
             storedClipboardData(data);
             $rootScope.$broadcast('guacClipboard', data);
+            $rootScope.$broadcast('clipboardSyncInProgress', false);
 
         });
     };
@@ -615,6 +616,7 @@ angular.module('clipboard').factory('clipboardService', ['$injector',
      * components like the "guacClient" directive.
      */
     service.resyncClipboard = function resyncClipboard() {
+        $rootScope.$broadcast('clipboardSyncInProgress', true);
         getLocalClipboard().then(function clipboardRead(data) {
             return service.setClipboard(data);
         }, angular.noop);