nodeview: added ctrl+scroll zooming

app/widget/nodeview/nodeview.cpp

@@ -41,6 +41,7 @@ NodeView::NodeView(QWidget *parent) :
   connect(this, &NodeView::customContextMenuRequested, this, &NodeView::ShowContextMenu);
 
   setMouseTracking(true);
+  setRenderHint(QPainter::Antialiasing);
 }
 
 NodeView::~NodeView()
@@ -273,6 +274,18 @@ void NodeView::mouseMoveEvent(QMouseEvent *event)
   }
 }
 
+void NodeView::wheelEvent(QWheelEvent *event)
+{
+  if (event->modifiers() & Qt::ControlModifier) {
+    // FIXME: Hardcoded divider (0.001)
+    qreal multiplier = 1.0 + (static_cast<qreal>(event->delta()) * 0.001);
+
+    scale(multiplier, multiplier);
+  } else {
+    QWidget::wheelEvent(event);
+  }
+}
+
 void NodeView::SceneSelectionChangedSlot()
 {
   emit SelectionChanged(scene_.GetSelectedNodes());

app/widget/nodeview/nodeview.h

@@ -73,6 +73,8 @@ protected:
 
   virtual void mouseMoveEvent(QMouseEvent *event) override;
 
+  virtual void wheelEvent(QWheelEvent* event) override;
+
 private:
   void PlaceNode(NodeViewItem* n, const QPointF& pos);