timebasedwidget: move center scroll functionality to base class so widgets like

Viewer can use it

app/widget/curvewidget/curvewidget.cpp

@@ -54,6 +54,7 @@ CurveWidget::CurveWidget(QWidget *parent) :
   ruler_view_layout->addWidget(ruler());
 
   view_ = new CurveView();
+  connect(view_, &CurveView::RequestCenterScrollOnPlayhead, this, &CurveWidget::CenterScrollOnPlayhead);
   ruler_view_layout->addWidget(view_);
 
   layout->addLayout(ruler_view_layout);
@@ -62,6 +63,9 @@ CurveWidget::CurveWidget(QWidget *parent) :
   connect(view_, &CurveView::TimeChanged, this, &CurveWidget::SetTimeAndSignal);
   connect(view_->scene(), &QGraphicsScene::selectionChanged, this, &CurveWidget::SelectionChanged);
   connect(view_, &CurveView::ScaleChanged, this, &CurveWidget::SetScale);
+
+  // TimeBasedWidget's scrollbar has extra functionality that we can take advantage of
+  view_->setHorizontalScrollBar(scrollbar());
   connect(view_->horizontalScrollBar(), &QScrollBar::valueChanged, ruler(), &TimeRuler::SetScroll);
 
   widget_bridge_layout_ = new QHBoxLayout();
@@ -158,7 +162,7 @@ void CurveWidget::ScaleChangedEvent(const double &scale)
 {
   TimeBasedWidget::ScaleChangedEvent(scale);
 
-  view_->SetScaleAndCenterOnPlayhead(scale);
+  view_->SetScale(scale);
 }
 
 void CurveWidget::UpdateInputLabel()

app/widget/nodeparamview/nodeparamview.cpp

@@ -69,6 +69,7 @@ NodeParamView::NodeParamView(QWidget *parent) :
   // Create keyframe view
   keyframe_view_ = new KeyframeView();
   keyframe_view_->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+  connect(keyframe_view_, &KeyframeView::RequestCenterScrollOnPlayhead, this, &NodeParamView::CenterScrollOnPlayhead);
   bottom_item_ = keyframe_view_->scene()->addRect(0, 0, 1, 1);
   keyframe_area_layout->addWidget(keyframe_view_);
 
@@ -104,6 +105,9 @@ NodeParamView::NodeParamView(QWidget *parent) :
   connect(vertical_scrollbar_, &QScrollBar::valueChanged, scroll_area->verticalScrollBar(), &QScrollBar::setValue);
   connect(vertical_scrollbar_, &QScrollBar::valueChanged, keyframe_view_->verticalScrollBar(), &QScrollBar::setValue);
 
+  // TimeBasedWidget's scrollbar has extra functionality that we can take advantage of
+  keyframe_view_->setHorizontalScrollBar(scrollbar());
+
   connect(keyframe_view_->horizontalScrollBar(), &QScrollBar::valueChanged, ruler(), &TimeRuler::SetScroll);
 
   // Set a default scale - FIXME: Hardcoded
@@ -173,7 +177,7 @@ void NodeParamView::ScaleChangedEvent(const double &scale)
 {
   TimeBasedWidget::ScaleChangedEvent(scale);
 
-  keyframe_view_->SetScaleAndCenterOnPlayhead(scale);
+  keyframe_view_->SetScale(scale);
 }
 
 void NodeParamView::TimebaseChangedEvent(const rational &timebase)

app/widget/timebased/timebased.cpp

@@ -13,6 +13,15 @@ TimeBasedWidget::TimeBasedWidget(bool ruler_text_visible, bool ruler_cache_statu
   scrollbar_ = new QScrollBar(Qt::Horizontal, this);
 }
 
+void TimeBasedWidget::SetScaleAndCenterOnPlayhead(const double &scale)
+{
+  SetScale(scale);
+
+  // Zoom towards the playhead
+  // (using a hacky singleShot so the scroll occurs after the scene and its scrollbars have updated)
+  QTimer::singleShot(0, this, &TimeBasedWidget::CenterScrollOnPlayhead);
+}
+
 rational TimeBasedWidget::GetTime() const
 {
   return Timecode::timestamp_to_time(ruler()->GetTime(), timebase());
@@ -118,12 +127,12 @@ void TimeBasedWidget::SetScale(const double &scale)
 
 void TimeBasedWidget::ZoomIn()
 {
-  SetScale(GetScale() * 2);
+  SetScaleAndCenterOnPlayhead(GetScale() * 2);
 }
 
 void TimeBasedWidget::ZoomOut()
 {
-  SetScale(GetScale() * 0.5);
+  SetScaleAndCenterOnPlayhead(GetScale() * 0.5);
 }
 
 void TimeBasedWidget::GoToPrevCut()
@@ -222,3 +231,8 @@ void TimeBasedWidget::SetTimeAndSignal(const int64_t &t)
   SetTime(t);
   emit TimeChanged(t);
 }
+
+void TimeBasedWidget::CenterScrollOnPlayhead()
+{
+  scrollbar_->setValue(qRound(TimeToScene(Timecode::timestamp_to_time(ruler_->GetTime(), timebase()))) - scrollbar_->width()/2);
+}

app/widget/timebased/timebased.h

@@ -26,6 +26,8 @@ public:
 
   void ConnectViewerNode(ViewerOutput *node);
 
+  void SetScaleAndCenterOnPlayhead(const double& scale);
+
 public slots:
   // FIXME: Rename this to SetTimestamp to reduce confusion
   void SetTime(int64_t timestamp);
@@ -70,6 +72,12 @@ protected:
 
   virtual void resizeEvent(QResizeEvent *event) override;
 
+protected slots:
+  /**
+   * @brief Slot to center the horizontal scroll bar on the playhead's current position
+   */
+  void CenterScrollOnPlayhead();
+
 signals:
   void TimeChanged(const int64_t&);
 

app/widget/timelinewidget/timelinewidget.cpp

@@ -88,6 +88,7 @@ TimelineWidget::TimelineWidget(QWidget *parent) :
     connect(view, &TimelineView::customContextMenuRequested, this, &TimelineWidget::ShowContextMenu);
     connect(scrollbar(), &QScrollBar::valueChanged, view->horizontalScrollBar(), &QScrollBar::setValue);
     connect(view->horizontalScrollBar(), &QScrollBar::valueChanged, scrollbar(), &QScrollBar::setValue);
+    connect(view, &TimelineView::RequestCenterScrollOnPlayhead, this, &TimelineWidget::CenterScrollOnPlayhead);
 
     connect(view, &TimelineView::MousePressed, this, &TimelineWidget::ViewMousePressed);
     connect(view, &TimelineView::MouseMoved, this, &TimelineWidget::ViewMouseMoved);

app/widget/timelinewidget/view/timelineviewbase.cpp

@@ -27,7 +27,7 @@ TimelineViewBase::TimelineViewBase(QWidget *parent) :
   scene_.addItem(end_item_);
 
   // Set default scale
-  SetScaleAndCenterOnPlayhead(1.0);
+  SetScale(1.0);
 
   SetDefaultDragMode(NoDrag);
 
@@ -57,7 +57,7 @@ void TimelineViewBase::SetTime(const int64_t time)
     PageScrollToPlayhead();
     break;
   case AutoScroll::kSmooth:
-    CenterScrollOnPlayhead();
+    emit RequestCenterScrollOnPlayhead();
     break;
   }
 
@@ -198,7 +198,7 @@ void TimelineViewBase::ToolChangedEvent(Tool::Item)
 
 qreal TimelineViewBase::GetPlayheadX()
 {
-  return TimeToScene(rational(playhead_ * timebase().numerator(), timebase().denominator()));
+  return TimeToScene(Timecode::timestamp_to_time(playhead_, timebase()));
 }
 
 void TimelineViewBase::SetEndTime(const rational &length)
@@ -253,11 +253,6 @@ void TimelineViewBase::UpdateSceneRect()
   scene_.setSceneRect(bounding_rect);
 }
 
-void TimelineViewBase::CenterScrollOnPlayhead()
-{
-  horizontalScrollBar()->setValue(qRound(GetPlayheadX()) - viewport()->width()/2);
-}
-
 void TimelineViewBase::PageScrollToPlayhead()
 {
   int playhead_pos = qRound(GetPlayheadX());
@@ -290,15 +285,6 @@ void TimelineViewBase::ScaleChangedEvent(const double &scale)
   viewport()->update();
 }
 
-void TimelineViewBase::SetScaleAndCenterOnPlayhead(const double &scale)
-{
-  SetScale(scale);
-
-  // Zoom towards the playhead
-  // (using a hacky singleShot so the scroll occurs after the scene and its scrollbars have updated)
-  QTimer::singleShot(0, this, &TimelineViewBase::CenterScrollOnPlayhead);
-}
-
 bool TimelineViewBase::HandleZoomFromScroll(QWheelEvent *event)
 {
   if (WheelEventIsAZoomEvent(event)) {

app/widget/timelinewidget/view/timelineviewbase.h

@@ -16,8 +16,6 @@ public:
 
   void SetEndTime(const rational& length);
 
-  void SetScaleAndCenterOnPlayhead(const double& scale);
-
   static const double kMaximumScale;
 
 public slots:
@@ -28,6 +26,8 @@ signals:
 
   void ScaleChanged(double scale);
 
+  void RequestCenterScrollOnPlayhead();
+
 protected:
   virtual void drawForeground(QPainter *painter, const QRectF &rect) override;
 
@@ -87,11 +87,6 @@ private slots:
    */
   void UpdateSceneRect();
 
-  /**
-   * @brief Slot to center the horizontal scroll bar on the playhead's current position
-   */
-  void CenterScrollOnPlayhead();
-
   /**
    * @brief Slot to handle page scrolling of the playhead
    *