Allow user of API to decide whether keyboard events are canceled.

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

@@ -60,6 +60,9 @@ Guacamole.Keyboard = function(element) {
      * 
      * @event
      * @param {Number} keysym The keysym of the key being pressed.
+     * @returns {Boolean} true if the originating event of this keypress should
+     *                    be allowed through to the browser, false or undefined
+     *                    otherwise.
      */
     this.onkeydown = null;
 
@@ -69,6 +72,9 @@ Guacamole.Keyboard = function(element) {
      * 
      * @event
      * @param {Number} keysym The keysym of the key being released.
+     * @returns {Boolean} true if the originating event of this key release 
+     *                    should be allowed through to the browser, false or
+     *                    undefined otherwise.
      */
     this.onkeyup = null;
 
@@ -208,13 +214,15 @@ Guacamole.Keyboard = function(element) {
     // Sends a single keystroke over the network
     function sendKeyPressed(keysym) {
         if (keysym != null && guac_keyboard.onkeydown)
-			guac_keyboard.onkeydown(keysym);
+            return guac_keyboard.onkeydown(keysym) != false;
+        return true;
     }
 
     // Sends a single keystroke over the network
     function sendKeyReleased(keysym) {
         if (keysym != null && guac_keyboard.onkeyup)
-			guac_keyboard.onkeyup(keysym);
+            return guac_keyboard.onkeyup(keysym) != false;
+        return true;
     }
 
 
@@ -269,11 +277,13 @@ Guacamole.Keyboard = function(element) {
         // Send key event here
         if (keySymSource == KEYDOWN) {
 
+            var returnValue = true;
+
             if (keydownChar[keynum] != keysym) {
 
                 // Send event
                 keydownChar[keynum] = keysym;
-                sendKeyPressed(keysym);
+                returnValue = sendKeyPressed(keysym);
 
                 // Clear old key repeat, if any.
                 stopRepeat();
@@ -283,7 +293,7 @@ Guacamole.Keyboard = function(element) {
                     repeatKeyTimeoutId = setTimeout(function() { startRepeat(keysym); }, 500);
             }
 
-            return false;
+            return returnValue;
         }
 
         return true;
@@ -302,6 +312,7 @@ Guacamole.Keyboard = function(element) {
         if (window.event) keynum = window.event.keyCode;
         else if (e.which) keynum = e.which;
 
+        var returnValue = true;
         var keysym = getKeySymFromCharCode(keynum);
         if (keysym && keydownChar[keynum] != keysym) {
 
@@ -316,13 +327,14 @@ Guacamole.Keyboard = function(element) {
             stopRepeat();
 
             // Send key event
-            sendKeyPressed(keysym);
+            returnValue = sendKeyPressed(keysym);
 
             // Start repeating (if not a modifier key) after a short delay
             repeatKeyTimeoutId = setTimeout(function() { startRepeat(keysym); }, 500);
         }
 
-        return false;
+        return returnValue;
+
     };
 
     // When key released
@@ -352,9 +364,8 @@ Guacamole.Keyboard = function(element) {
         keydownChar[keynum] = null;
 
         // Send release event
-        sendKeyReleased(lastKeyDownChar);
+        return sendKeyReleased(lastKeyDownChar);
 
-		return false;
     };
 
     // When focus is lost, clear modifiers.