ui/show manager: handle CTRL+mouse wheel to zoom in/out (fix #1629)

debian/changelog

@@ -4,6 +4,7 @@ qlcplus (4.13.2) stable; urgency=low
   * engine: add stopOnExit, waitFunctionStart and waitFunctionStop commands to Script - see documentation (thanks to ldebs)
   * UI/Fixture Manager: limit the number of RGB panel columns for RGBW to avoid crash
   * UI/Show Manager: show step notes on the timeline (thanks to anarchid)
+  * UI/Show Manager: handle CTRL+mouse wheel to zoom in/out
   * Plugins/OS2L: fix receiving multiple messages at once
   * Web Access: fix grand master stopping running functions
   * Web Access: fix simple desk not resetting the current universe

ui/src/showmanager/multitrackview.cpp

@@ -494,6 +494,23 @@ void MultiTrackView::mouseReleaseEvent(QMouseEvent * e)
     //qDebug() << Q_FUNC_INFO << "View clicked at pos: " << e->pos().x() << e->pos().y();
 }
 
+void MultiTrackView::wheelEvent(QWheelEvent *event)
+{
+    if (event->modifiers() & Qt::ControlModifier)
+    {
+        int zoomValue = m_timeSlider->value();
+        if (event->pixelDelta().y() > 0)
+            zoomValue++;
+        else
+            zoomValue--;
+
+        if (zoomValue >= m_timeSlider->minimum() && zoomValue <= m_timeSlider->maximum())
+            m_timeSlider->setValue(zoomValue);
+        return;
+    }
+    QGraphicsView::wheelEvent(event);
+}
+
 void MultiTrackView::slotHeaderClicked(QGraphicsSceneMouseEvent *event)
 {
     m_cursor->setPos(TRACK_WIDTH + event->pos().toPoint().x(), 0);

ui/src/showmanager/multitrackview.h

@@ -150,7 +150,8 @@ class MultiTrackView : public QGraphicsView
     bool m_snapToGrid;
 
 public slots:
-    void mouseReleaseEvent(QMouseEvent * e);
+    void mouseReleaseEvent(QMouseEvent *e);
+    void wheelEvent(QWheelEvent *event);
 
 protected slots:
     void slotHeaderClicked(QGraphicsSceneMouseEvent *event);