Timeline: inject sub-track into the header pane structure

src/stage/timeline/track-head-widget.cpp

@@ -66,6 +66,7 @@ namespace timeline {
     : Gtk::Grid{}
     , nameTODO_{"?"}
     , treeTODO_{"↳"}
+    , childCnt_{0}
     {
       this->attach (nameTODO_, 0,0, 2,1);
       this->attach (treeTODO_, 0,1, 1,1);
@@ -85,15 +86,29 @@ namespace timeline {
    * video editing software does -- rather, each sequence holds a _fork of nested scopes._
    * This recursively nested structure is reflected in the patchbay area corresponding to
    * each track in the _header pane_ of the timeline display, located to the left. The
-   * patchbay for each track is a grid with four quadrants, and the 4th quadrant is the
-   * _content area,_ which is recursively extended to hold nested PatchbayWidget elements,
-   * corresponding to the child tracks of this track. To _fund_ this recursively extensible
-   * structure, we need to set up the first four quadrants
+   * patchbay for each track is a grid with initially four quadrants, and the 4th quadrant
+   * holds the _content area,_ which is again a TrackHeadWidget. Additional sub-Tracks
+   * are added as additional lines to the grid, while nested sub-Tracks will be handled
+   * recursively by the corresponding nested TrackHeadWidget.
+   * @note Child tracks are always appended. When tracks are reordered or deleted,
+   *       the whole structure has to be re-built accordingly.
    */
   void
   TrackHeadWidget::injectSubFork (TrackHeadWidget& subForkHead)
   {
-    UNIMPLEMENTED ("how actually to represent the track in the patchbay");
+    ++childCnt_;
+    this->attach (subForkHead, 0, childCnt_, 1,1);
+  }
+  
+  
+  void
+  TrackHeadWidget::clearSubFork()
+  {
+    while (childCnt_ > 0)
+      {
+        this->remove_row (childCnt_);
+        --childCnt_;
+      }
   }
   
   

src/stage/timeline/track-head-widget.hpp

@@ -34,9 +34,9 @@
  **   + video overlay parameters (additive, opaque, transparent)
  **   + video or audio _level_ (=fader)
  ** - how to locate this content in time (e.g. relative to some marker)
- ** For each track, we show a patchbay in the timeline header pane, which serves to control
- ** such aspects relevant for all content contained within the scope of this track, including
- ** the sub-tracks nested therein.
+ ** For each track, we display a "patchbay"-like content control in the timeline header pane,
+ ** which serves to control such aspects relevant for all content contained within the scope
+ ** of this track, including the sub-tracks nested therein.
  ** 
  ** @todo WIP-WIP-WIP as of 10/2018
  ** 
@@ -74,6 +74,8 @@ namespace timeline {
       Gtk::Label nameTODO_;
       Gtk::Label treeTODO_;
       
+      uint childCnt_;
+      
     public:
       TrackHeadWidget();
      ~TrackHeadWidget();
@@ -82,6 +84,9 @@ namespace timeline {
       
       /** Integrate the control area for a nested sub track fork. */
       void injectSubFork (TrackHeadWidget& subForkHead);
+      
+      /** Discard all nested sub track display widgets. */
+      void clearSubFork();
 
     private:/* ===== Internals ===== */
      

src/stage/timeline/track-presenter.cpp

@@ -104,17 +104,17 @@ namespace timeline {
                   })
                .matchElement ([&](GenNode const& spec, PRuler const& elm) -> bool
                   {
-//                  return spec.idi == ID{*elm}; ////////////////////////////////////////////////////////////TICKET #1193 : shall RulerTrack be a Tangible?
+                    return spec.idi == ID{*elm};
                   })
                .constructFrom ([&](GenNode const& spec) -> PRuler
-                  {
-//                  return make_unique<RulerTrack> (spec.idi, this->uiBus_);  ///////////////////////////////TICKET #1193 : how to construct a RulerTrack?
+                  {                                            // »Constructor« : how to attach a new ruler track
+                    return make_unique<RulerTrack> (spec.idi, this->uiBus_, *this);
                   })
                .buildChildMutator ([&](PRuler& target, GenNode::ID const& subID, TreeMutator::Handle buff) -> bool
-                  {                                                           ///////////////////////////////TICKET #1193 : do we even want to "mutate" a ruler?
-//                  if (ID{*target} != subID) return false;
-//                  target->buildMutator (buff);
-//                  return true;
+                  {
+                    if (ID{*target} != subID) return false;
+                    target->buildMutator (buff);
+                    return true;
                   }))
         .attach (collection(markers_)
                .isApplicableIf ([&](GenNode const& spec) -> bool

src/stage/timeline/track-presenter.hpp

@@ -106,8 +106,8 @@ namespace timeline {
       void
       injectSubTrack (TrackHeadWidget& subHead, TrackBody& subBody)
         {
+          head.injectSubFork (subHead);
           body.attachSubTrack (&subBody);
-          UNIMPLEMENTED ("inject the widgets to represent a nested sub-track within this timeline track display frame");
         }
     };