nodes/timeline: correctly detect when tracks are removed from the graph

Fixes several segfaults that could result from this occurring.

app/widget/timelinewidget/timelinewidget.cpp

@@ -241,7 +241,7 @@ void TimelineWidget::ConnectNodeInternal(ViewerOutput *n)
     view->ConnectTrackList(track_list);
 
     // Defer to the track to make all the block UI items necessary
-    foreach (TrackOutput* track, n->track_list(track_type)->Tracks()) {
+    foreach (TrackOutput* track, n->track_list(track_type)->GetTracks()) {
       AddTrack(track, track_type);
     }
   }
@@ -881,7 +881,7 @@ void TimelineWidget::InsertGapsAt(const rational &earliest_point, const rational
 
 TrackOutput *TimelineWidget::GetTrackFromReference(const TrackReference &ref)
 {
-  return GetConnectedNode()->track_list(ref.type())->TrackAt(ref.index());
+  return GetConnectedNode()->track_list(ref.type())->GetTrackAt(ref.index());
 }
 
 int TimelineWidget::GetTrackY(const TrackReference &ref)
@@ -1017,9 +1017,7 @@ void TimelineWidget::AddBlock(Block *block, TrackReference track)
 
 void TimelineWidget::RemoveBlock(Block *block)
 {
-  delete block_items_[block];
-
-  block_items_.remove(block);
+  delete block_items_.take(block);
 }
 
 void TimelineWidget::AddTrack(TrackOutput *track, Timeline::TrackType type)
@@ -1027,15 +1025,32 @@ void TimelineWidget::AddTrack(TrackOutput *track, Timeline::TrackType type)
   foreach (Block* b, track->Blocks()) {
     AddBlock(b, TrackReference(type, track->Index()));
   }
+
+  connect(track, &TrackOutput::IndexChanged, this, &TimelineWidget::TrackIndexChanged);
 }
 
 void TimelineWidget::RemoveTrack(TrackOutput *track)
 {
+  disconnect(track, &TrackOutput::IndexChanged, this, &TimelineWidget::TrackIndexChanged);
+
   foreach (Block* b, track->Blocks()) {
     RemoveBlock(b);
   }
 }
 
+void TimelineWidget::TrackIndexChanged()
+{
+  TrackOutput* track = static_cast<TrackOutput*>(sender());
+  TrackReference ref(track->track_type(), track->Index());
+
+  foreach (Block* b, track->Blocks()) {
+    TimelineViewBlockItem* item = block_items_.value(b);
+
+    item->SetYCoords(GetTrackY(ref), GetTrackHeight(ref));
+    item->SetTrack(ref);
+  }
+}
+
 void TimelineWidget::ViewSelectionChanged()
 {
   if (rubberband_.isVisible()) {

app/widget/timelinewidget/timelinewidget.h

@@ -486,6 +486,7 @@ private slots:
 
   void AddTrack(TrackOutput* track, Timeline::TrackType type);
   void RemoveTrack(TrackOutput* track);
+  void TrackIndexChanged();
 
   void ViewSelectionChanged();
 

app/widget/timelinewidget/trackview/trackview.cpp

@@ -81,7 +81,7 @@ void TrackView::ConnectTrackList(TrackList *list)
   list_ = list;
 
   if (list_ != nullptr) {
-    foreach (TrackOutput* track, list_->Tracks()) {
+    foreach (TrackOutput* track, list_->GetTracks()) {
       TrackViewItem* item = new TrackViewItem(track);
       items_.append(item);
       splitter_->Insert(track->Index(), track->GetTrackHeight(), item);
@@ -120,7 +120,7 @@ void TrackView::ScrollbarRangeChanged(int, int max)
 
 void TrackView::TrackHeightChanged(int index, int height)
 {
-  list_->TrackAt(index)->SetTrackHeight(height);
+  list_->GetTrackAt(index)->SetTrackHeight(height);
 }
 
 void TrackView::InsertTrack(TrackOutput *track)

app/widget/timelinewidget/trackview/trackviewsplitter.cpp

@@ -141,7 +141,7 @@ void TrackViewSplitter::Remove(int index)
   QList<int> sz = sizes();
 
   if (alignment_ == Qt::AlignBottom) {
-    index = count() - index;
+    index = count() - 1 - index;
   }
 
   sz.removeAt(index);

app/widget/timelinewidget/undo/undo.cpp

@@ -347,13 +347,13 @@ void TrackPlaceBlockCommand::redo_internal()
   added_track_count_ = 0;
 
   // Get track (or make it if necessary)
-  while (track_index_ >= timeline_->Tracks().size()) {
+  while (track_index_ >= timeline_->GetTracks().size()) {
     timeline_->AddTrack();
 
     added_track_count_++;
   }
 
-  track_ = timeline_->TrackAt(track_index_);
+  track_ = timeline_->GetTrackAt(track_index_);
 
   append_ = (in_ >= track_->track_length());
 
@@ -610,7 +610,7 @@ void TrackCleanGapsCommand::redo_internal()
   GapBlock* on_gap = nullptr;
   QList<GapBlock*> consecutive_gaps;
 
-  TrackOutput* track = track_list_->TrackAt(track_index_);
+  TrackOutput* track = track_list_->GetTrackAt(track_index_);
 
   foreach (Block* b, track->Blocks()) {
     if (b) {
@@ -657,7 +657,7 @@ void TrackCleanGapsCommand::redo_internal()
 
 void TrackCleanGapsCommand::undo_internal()
 {
-  TrackOutput* track = track_list_->TrackAt(track_index_);
+  TrackOutput* track = track_list_->GetTrackAt(track_index_);
 
   // Restored removed end gaps
   foreach (GapBlock* gap, removed_end_gaps_) {

app/widget/timelinewidget/view/timelineview.cpp

@@ -189,11 +189,7 @@ void TimelineView::drawBackground(QPainter *painter, const QRectF &rect)
 
   int line_y = 0;
 
-  foreach (TrackOutput* track, connected_track_list_->Tracks()) {
-    if (!track) {
-      continue;
-    }
-
+  foreach (TrackOutput* track, connected_track_list_->GetTracks()) {
     line_y += track->GetTrackHeight();
 
     // One px gap between tracks
@@ -294,9 +290,9 @@ int TimelineView::GetHeightOfAllTracks() const
 {
   if (connected_track_list_) {
     if (alignment() & Qt::AlignTop) {
-      return GetTrackY(connected_track_list_->TrackCount());
+      return GetTrackY(connected_track_list_->GetTrackCount());
     } else {
-      return GetTrackY(connected_track_list_->TrackCount() - 1);
+      return GetTrackY(connected_track_list_->GetTrackCount() - 1);
     }
   } else {
     return 0;
@@ -305,6 +301,10 @@ int TimelineView::GetHeightOfAllTracks() const
 
 int TimelineView::GetTrackY(int track_index) const
 {
+  if (!connected_track_list_ || !connected_track_list_->GetTrackCount()) {
+    return 0;
+  }
+
   int y = 0;
 
   if (alignment() & Qt::AlignBottom) {
@@ -327,11 +327,11 @@ int TimelineView::GetTrackY(int track_index) const
 
 int TimelineView::GetTrackHeight(int track_index) const
 {
-  if (!connected_track_list_ || track_index >= connected_track_list_->TrackCount()) {
+  if (!connected_track_list_ || track_index >= connected_track_list_->GetTrackCount()) {
     return TrackOutput::GetDefaultTrackHeight();
   }
 
-  return connected_track_list_->TrackAt(track_index)->GetTrackHeight();
+  return connected_track_list_->GetTrackAt(track_index)->GetTrackHeight();
 }
 
 QPoint TimelineView::GetScrollCoordinates() const