timebasedwidget: added infrastructure of passing scroll wheel signals to the scrollbar

app/widget/timebased/timebased.cpp

@@ -45,6 +45,8 @@ TimeBasedWidget::TimeBasedWidget(bool ruler_text_visible, bool ruler_cache_statu
 
   scrollbar_ = new ResizableScrollBar(Qt::Horizontal, this);
   connect(scrollbar_, &ResizableScrollBar::RequestScale, this, &TimeBasedWidget::ScrollBarResized);
+
+  PassWheelEventsToScrollBar(ruler_);
 }
 
 void TimeBasedWidget::SetScaleAndCenterOnPlayhead(const double &scale)
@@ -237,6 +239,12 @@ void TimeBasedWidget::ConnectTimelineView(TimelineViewBase *base)
   timeline_views_.append(base);
 }
 
+void TimeBasedWidget::PassWheelEventsToScrollBar(QObject *object)
+{
+  wheel_passthrough_objects_.append(object);
+  object->installEventFilter(this);
+}
+
 void TimeBasedWidget::SetTimestamp(int64_t timestamp)
 {
   ruler_->SetTime(timestamp);
@@ -570,4 +578,13 @@ void TimeBasedWidget::MarkerAddCommand::undo_internal()
   marker_list_->RemoveMarker(added_marker_);
 }
 
+bool TimeBasedWidget::eventFilter(QObject *object, QEvent *event)
+{
+  if (wheel_passthrough_objects_.contains(object) && event->type() == QEvent::Wheel) {
+    QCoreApplication::sendEvent(scrollbar(), event);
+  }
+
+  return false;
+}
+
 }

app/widget/timebased/timebased.h

@@ -54,6 +54,8 @@ public:
 
   TimeRuler* ruler() const;
 
+  virtual bool eventFilter(QObject* object, QEvent* event) override;
+
 public slots:
   void SetTimestamp(int64_t timestamp);
 
@@ -121,6 +123,8 @@ protected:
 
   void ConnectTimelineView(TimelineViewBase* base);
 
+  void PassWheelEventsToScrollBar(QObject* object);
+
 protected slots:
   /**
    * @brief Slot to center the horizontal scroll bar on the playhead's current position
@@ -199,6 +203,8 @@ private:
 
   bool auto_set_timebase_;
 
+  QVector<QObject*> wheel_passthrough_objects_;
+
 private slots:
   void UpdateMaximumScroll();
 

app/widget/viewer/viewer.cpp

@@ -82,6 +82,7 @@ ViewerWidget::ViewerWidget(QWidget *parent) :
 
   // Create waveform view when audio is connected and video isn't
   waveform_view_ = new AudioWaveformView();
+  PassWheelEventsToScrollBar(waveform_view_);
   stack_->addWidget(waveform_view_);
 
   // Create time ruler