refactored so sequence is again a derivative of viewer

app/widget/timelinewidget/timelineundo.h

@@ -1395,9 +1395,9 @@ public:
       QString relevant_input;
 
       if (timeline_->type() == Track::kVideo) {
-        relevant_input = Sequence::kTextureInput;
+        relevant_input = ViewerOutput::kTextureInput;
       } else {
-        relevant_input = Sequence::kSamplesInput;
+        relevant_input = ViewerOutput::kSamplesInput;
       }
 
       if (!timeline_->parent()->IsInputConnected(relevant_input)) {

app/widget/timelinewidget/timelinewidget.cpp

@@ -218,10 +218,12 @@ void TimelineWidget::ScaleChangedEvent(const double &scale)
   }
 }
 
-void TimelineWidget::ConnectNodeInternal(Sequence *n)
+void TimelineWidget::ConnectNodeInternal(ViewerOutput *n)
 {
-  connect(n, &ViewerOutput::TrackAdded, this, &TimelineWidget::AddTrack);
-  connect(n, &ViewerOutput::TrackRemoved, this, &TimelineWidget::RemoveTrack);
+  Sequence* s = static_cast<Sequence*>(n);
+
+  connect(s, &Sequence::TrackAdded, this, &TimelineWidget::AddTrack);
+  connect(s, &Sequence::TrackRemoved, this, &TimelineWidget::RemoveTrack);
   connect(n, &ViewerOutput::TimebaseChanged, this, &TimelineWidget::SetTimebase);
 
   ruler()->SetPlaybackCache(n->video_frame_cache());
@@ -229,7 +231,6 @@ void TimelineWidget::ConnectNodeInternal(Sequence *n)
   SetTimebase(n->video_params().time_base());
 
   for (int i=0;i<views_.size();i++) {
-    Sequence* s = static_cast<Sequence*>(n);
     Track::Type track_type = static_cast<Track::Type>(i);
     TimelineView* view = views_.at(i)->view();
     TrackList* track_list = s->track_list(track_type);
@@ -246,15 +247,16 @@ void TimelineWidget::ConnectNodeInternal(Sequence *n)
   }
 }
 
-void TimelineWidget::DisconnectNodeInternal(Sequence *n)
+void TimelineWidget::DisconnectNodeInternal(ViewerOutput *n)
 {
-  disconnect(n, &ViewerOutput::TrackAdded, this, &TimelineWidget::AddTrack);
-  disconnect(n, &ViewerOutput::TrackRemoved, this, &TimelineWidget::RemoveTrack);
+  Sequence* s = static_cast<Sequence*>(n);
+
+  disconnect(s, &Sequence::TrackAdded, this, &TimelineWidget::AddTrack);
+  disconnect(s, &Sequence::TrackRemoved, this, &TimelineWidget::RemoveTrack);
   disconnect(n, &ViewerOutput::TimebaseChanged, this, &TimelineWidget::SetTimebase);
 
   DeselectAll();
 
-  Sequence* s = static_cast<Sequence*>(n);
   foreach (Track* track, s->GetTracks()) {
     RemoveTrack(track);
   }

app/widget/timelinewidget/timelinewidget.h

@@ -245,8 +245,8 @@ protected:
   virtual void TimeChangedEvent(const int64_t &) override;
   virtual void ScaleChangedEvent(const double &) override;
 
-  virtual void ConnectNodeInternal(Sequence* n) override;
-  virtual void DisconnectNodeInternal(Sequence* n) override;
+  virtual void ConnectNodeInternal(ViewerOutput* n) override;
+  virtual void DisconnectNodeInternal(ViewerOutput* n) override;
 
   virtual void CopyNodesToClipboardInternal(QXmlStreamWriter *writer, void* userdata) override;
   virtual void PasteNodesFromClipboardInternal(QXmlStreamReader *reader, XMLNodeData &xml_node_data, void* userdata) override;

app/widget/timelinewidget/tool/add.cpp

@@ -102,7 +102,7 @@ void AddTool::MouseRelease(TimelineViewMouseEvent *event)
       command->add_child(new NodeAddCommand(graph,
                                             clip));
 
-      command->add_child(new TrackPlaceBlockCommand(static_cast<Sequence*>(parent()->GetConnectedNode())->track_list(track.type()),
+      command->add_child(new TrackPlaceBlockCommand(sequence()->track_list(track.type()),
                                                     track.index(),
                                                     clip,
                                                     ghost_->GetAdjustedIn()));

app/widget/timelinewidget/tool/import.cpp

@@ -313,12 +313,11 @@ void ImportTool::DropGhosts(bool insert)
   MultiUndoCommand* command = new MultiUndoCommand();
 
   NodeGraph* dst_graph = nullptr;
-  Sequence* sequence = nullptr;
+  Sequence* sequence = this->sequence();
   bool open_sequence = false;
 
-  if (parent()->GetConnectedNode()) {
-    sequence = parent()->GetConnectedNode();
-    dst_graph = parent()->GetConnectedNode()->parent();
+  if (sequence) {
+    dst_graph = sequence->parent();
   } else {
     // There's no active timeline here, ask the user what to do