added dragStart and dragEnd events

HISTORY.md

@@ -7,6 +7,7 @@ http://visjs.org
 ### Network
 
 - Fixed nodes not always being unfixed when using allowedToMove.
+- Added dragStart and dragEnd events.
 
 ### Graph2d
 

docs/network.html

@@ -2423,6 +2423,24 @@ network.off('select', onSelect);
       </ul>
     </td>
   </tr>
+    <tr>
+        <td>dragStart</td>
+        <td>Fired when a node is being dragged.</td>
+        <td>
+            <ul>
+                <li><code>nodeIds</code>: Array of ids of the nodes that are being dragged</li>
+            </ul>
+        </td>
+    </tr>
+    <tr>
+        <td>dragEnd</td>
+        <td>Fired when the dragging of a node(s) has ended.</td>
+        <td>
+            <ul>
+                <li><code>nodeIds</code>: Array of ids of the nodes that were being dragged</li>
+            </ul>
+        </td>
+    </tr>
   <tr>
     <td>stabilized</td>
     <td>Fired every time the network has been stabilized. This event can be used to trigger the .storePosition() function after stabilization. Fired with an object having the following properties:</td>

lib/network/Network.js

@@ -852,7 +852,7 @@ Network.prototype._handleDragStart = function() {
     if (!node.isSelected()) {
       this._selectObject(node,false);
     }
-
+    this.emit("dragStart",{nodeIds:this.getSelection().nodes});
     // create an array with the selected nodes and their original location and status
     for (var objectId in this.selectionObj.nodes) {
       if (this.selectionObj.nodes.hasOwnProperty(objectId)) {
@@ -952,6 +952,7 @@ Network.prototype._handleOnDrag = function(event) {
  * @private
  */
 Network.prototype._onDragEnd = function () {
+  this.emit("dragEnd",{nodeIds:this.getSelection().nodes});
   this.drag.dragging = false;
   var selection = this.drag.selection;
   if (selection && selection.length) {