feat: add pointer position to zoom event (#2377)

* add pointer position to zoom event
* Update docs with zoom api

docs/network/index.html

@@ -1400,8 +1400,14 @@ var options = {
                 <td>Fired if the option <code>interaction:{hover:true}</code> is enabled and the mouse moved away from an edge it was hovering over before.</td>
             </tr>
             <tr><td id="event_zoom">zoom</td>
-                <td><code>{direction:'+'/'-', scale: Number}</code></td>
-                <td>Fired when the user zooms in or out. The properties tell you which direction the zoom is in. The scale is a number greater than 0, which is the same that you get with network.getScale().</td>
+                <td>Object</td>
+                <td>Fired when the user zooms in or out. The properties tell you which direction the zoom is in. The scale is a number greater than 0, which is the same that you get with network.getScale(), Passes an object with properties structured as:
+<pre class="prettyprint lang-js">{
+  direction: '+'/'-',
+  scale: Number,
+  pointer: {x:pointer_x, y:pointer_y}
+}
+</pre></td>
             </tr>
             <tr><td id="event_showPopup">showPopup</td>
                 <td><code>id of item corresponding to popup</code></td>

lib/network/modules/InteractionHandler.js

@@ -472,10 +472,10 @@ class InteractionHandler {
       this.body.emitter.emit('_requestRedraw');
 
       if (scaleOld < scale) {
-        this.body.emitter.emit('zoom', {direction: '+', scale: this.body.view.scale});
+        this.body.emitter.emit('zoom', {direction: '+', scale: this.body.view.scale, pointer: pointer});
       }
       else {
-        this.body.emitter.emit('zoom', {direction: '-', scale: this.body.view.scale});
+        this.body.emitter.emit('zoom', {direction: '-', scale: this.body.view.scale, pointer: pointer});
       }
     }
   }

lib/network/modules/components/NavigationHandler.js

@@ -160,7 +160,7 @@ class NavigationHandler {
 
     this.body.view.scale = scale;
     this.body.view.translation = { x: tx, y: ty };
-    this.body.emitter.emit('zoom', { direction: '+', scale: this.body.view.scale });
+    this.body.emitter.emit('zoom', { direction: '+', scale: this.body.view.scale, pointer: pointer });
   }
   _zoomOut()  {
     var scaleOld = this.body.view.scale;
@@ -172,7 +172,7 @@ class NavigationHandler {
 
     this.body.view.scale = scale;
     this.body.view.translation = { x: tx, y: ty };
-    this.body.emitter.emit('zoom', { direction: '-', scale: this.body.view.scale });
+    this.body.emitter.emit('zoom', { direction: '-', scale: this.body.view.scale, pointer: pointer });
   }