Structure-Change: introduce a common accessor interface

...to solve the problem with interwoven nested ctor invocation.
This interface also promises to help with nested invcations,
without being overly generic.

src/stage/timeline/body-canvas-widget.cpp

@@ -537,6 +537,32 @@ namespace timeline {
   }
 /////////////////////////////////////////////////////////////////////////////////////////////////////////////TICKET #1201 : test/code... remove this
   
+  /* ==== Interface: ViewHook ===== */
+  
+  void
+  BodyCanvasWidget::hook (Gtk::Widget& head, int xPos, int yPos)
+  {
+    UNIMPLEMENTED ("find the relevant canvas and attach the widget at given pos");
+  }
+  
+  void
+  BodyCanvasWidget::remove (Gtk::Widget& head)
+  {
+    UNIMPLEMENTED ("find the relevant canvas and search and attach the widget");
+  }
+  
+  void
+  BodyCanvasWidget::rehook (model::ViewHooked<Gtk::Widget>&)  noexcept
+  {
+    UNIMPLEMENTED ("find the relevant canvas and attach the widget anew");
+  }
+  
+  void
+  BodyCanvasWidget::move (Gtk::Widget& head, int xPos, int yPos)
+  {
+    UNIMPLEMENTED ("find the relevant canvas and reposition the widget");
+  }
+  
   
   
   

src/stage/timeline/body-canvas-widget.hpp

@@ -59,6 +59,7 @@
 
 #include "stage/gtk-base.hpp"
 #include "stage/timeline/track-profile.hpp"
+#include "stage/model/view-hook.hpp"
 
 //#include "lib/util.hpp"
 
@@ -105,6 +106,7 @@ namespace timeline {
    */
   class BodyCanvasWidget
     : public Gtk::Box
+    , public model::ViewHook<Gtk::Widget>
     {
       DisplayManager& layout_;
       TrackProfile profile_;
@@ -136,6 +138,13 @@ namespace timeline {
       void DEBUG_injectTrackLabel(cuString const& trackName, int startLine);
 /////////////////////////////////////////////////////////////////////////////////////////////////////////////TICKET #1201 : test/code... remove this
       
+    protected: /* ==== Interface: ViewHook ===== */
+      
+      void hook (Gtk::Widget&, int xPos=0, int yPos=0) override;
+      void move (Gtk::Widget&, int xPos, int yPos)     override;
+      void remove (Gtk::Widget&)                       override;
+      void rehook (model::ViewHooked<Gtk::Widget>&)  noexcept override;
+      
     private:/* ===== Internals ===== */
       
       void slotStructureChange()  noexcept;

src/stage/timeline/display-manager.hpp

@@ -57,14 +57,11 @@
 
 #include "lib/error.hpp"
 #include "lib/nocopy.hpp"
-
+#include "stage/model/view-hook.hpp"
 #include "lib/util.hpp"
 
 #include <sigc++/signal.h>
 
-//#include <memory>
-//#include <vector>
-
 
 
 namespace stage  {
@@ -72,10 +69,35 @@ namespace timeline {
   
   using util::max;
   
-//  class TrackHeadWidget;
+  class TrackHeadWidget;
+  class TrackBody;
   
   
-  /** @todo quick-n-dirty hack. Should consider the Range TR (C++20) */
+  /**
+   * Interface: a compound of anchoring facilities.
+   * With the help of view-hooking, some detail presentation component
+   * or widget can attach itself into the overarching view context or canvas
+   * of the Timeline, while remaining agnostic about actual structure or implementation
+   * of this »display umbrella«. The local presentation component itself is then model::ViewHooked,
+   * thereby managing its attachment to the global context automatically. As it turns out, within
+   * the timeline display, we typically need a specific combination of such model::ViewHook, and
+   * we need them recursively: the actual timeline::DisplayFrame, while attaching below such
+   * DisplayViewHooks, is in turn itself again such a sub-anchor, allowing to attach
+   * child display frames recursively, which is required to display sub-tracks.
+   */
+  class DisplayViewHooks
+    {
+    public:
+      virtual ~DisplayViewHooks() { }    ///< this is an interface
+      
+      virtual model::ViewHook<TrackHeadWidget>& getHeadHook()  =0;
+      virtual model::ViewHook<TrackBody>&       getBodyHook()  =0;
+      virtual model::ViewHook<Gtk::Widget>&     getClipHook()  =0;
+    };
+  
+  
+  
+  /** @todo quick-n-dirty hack. Should consider the Range TS (C++20) */
   struct PixSpan
     {
       int b = 0;
@@ -100,11 +122,12 @@ namespace timeline {
     };
   
   /**
-   * Interface used by the widgets to translate themselves into screen layout.
-   * @todo WIP-WIP as of 11/2018
+   * Interface used by the widgets to attach and translate themselves into screen layout.
+   * @todo WIP-WIP as of 12/2019
    */
   class DisplayManager
     : util::NonCopyable
+    , public DisplayViewHooks
     {
       
 //    TimelineLayout();

src/stage/timeline/timeline-layout.hpp

@@ -140,6 +140,12 @@ namespace timeline {
       PixSpan getPixSpan()  override;
       void triggerDisplayEvaluation()  override;
       
+    protected: /* ==== Interface: DisplayViewHooks===== */
+      
+      model::ViewHook<TrackHeadWidget>& getHeadHook()  override { return *this;       };
+      model::ViewHook<TrackBody>&       getBodyHook()  override { return *this;       };
+      model::ViewHook<Gtk::Widget>&     getClipHook()  override { return bodyCanvas_; };
+      
     protected: /* ==== Interface: ViewHook ===== */
       
       void hook (TrackHeadWidget&, int xPos=0, int yPos=0) override;

wiki/thinkPad.ichthyo.mm

@@ -21895,6 +21895,28 @@
 <icon BUILTIN="smily_bad"/>
 </node>
 <node CREATED="1576760324713" ID="ID_1267786696" MODIFIED="1576760340354" TEXT="einziger Ausweg... Display-Manager wird zum Super-Hook"/>
+<node COLOR="#338800" CREATED="1576806720057" ID="ID_805988831" MODIFIED="1576855579888" TEXT="noch besser: das in ein Sammel-Interface packen">
+<icon BUILTIN="idea"/>
+<node CREATED="1576806744893" ID="ID_526365809" MODIFIED="1576855570801" TEXT="vielleicht sogar ein Accessor-Interface">
+<icon BUILTIN="idea"/>
+</node>
+<node CREATED="1576806754123" ID="ID_931227814" MODIFIED="1576806765651" TEXT="das was wir brauchen -- nicht generisch">
+<icon BUILTIN="yes"/>
+</node>
+<node CREATED="1576806780944" ID="ID_424677663" MODIFIED="1576806787371" TEXT="wo definieren?">
+<node CREATED="1576806800277" ID="ID_1586259922" MODIFIED="1576806811655" TEXT="Track-Presenter (zumindest) mu&#xdf; das sehen"/>
+<node CREATED="1576806815591" ID="ID_1412328590" MODIFIED="1576806824733" TEXT="ViewHook sollte reine Implementierung bleiben"/>
+<node COLOR="#435e98" CREATED="1576806845175" ID="ID_302576498" MODIFIED="1576855554242" TEXT="DisplayManager">
+<icon BUILTIN="yes"/>
+<node CREATED="1576806881586" ID="ID_1243796008" MODIFIED="1576806891357" TEXT="ja da geh&#xf6;rt&apos;s eigentlich hin"/>
+<node CREATED="1576806892609" ID="ID_981763412" MODIFIED="1576806908361" TEXT="versuch, m&#xf6;glichst mit forward-decl zu arbeiten"/>
+</node>
+</node>
+</node>
+<node COLOR="#435e98" CREATED="1576855633920" ID="ID_1642579599" MODIFIED="1576855726346" TEXT="damit ist auch die Basis zum relativen Positionieren gegeben">
+<arrowlink COLOR="#6780d3" DESTINATION="ID_1121301646" ENDARROW="Default" ENDINCLINATION="551;-498;" ID="Arrow_ID_229033893" STARTARROW="None" STARTINCLINATION="-477;21;"/>
+<icon BUILTIN="idea"/>
+</node>
 </node>
 </node>
 <node CREATED="1576710544415" ID="ID_88564726" MODIFIED="1576710556729" TEXT="zwei F&#xe4;lle zu unterscheiden">
@@ -22023,6 +22045,10 @@
 <node CREATED="1576705779910" ID="ID_968522268" MODIFIED="1576705792920" TEXT="damit ViewHook&lt;Clip&gt;"/>
 <node CREATED="1576705802515" ID="ID_674496871" MODIFIED="1576705809765" TEXT="und ViewHook&lt;Marker&gt;"/>
 </node>
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1576855620250" ID="ID_1121301646" MODIFIED="1576855705548" TEXT="relatives Positionieren erm&#xf6;glichen">
+<linktarget COLOR="#6780d3" DESTINATION="ID_1121301646" ENDARROW="Default" ENDINCLINATION="551;-498;" ID="Arrow_ID_229033893" SOURCE="ID_1642579599" STARTARROW="None" STARTINCLINATION="-477;21;"/>
+<icon BUILTIN="flag-yellow"/>
+</node>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1576705946751" ID="ID_478555928" MODIFIED="1576705956429" TEXT="re-Konstrkutions-Mechanismus realisieren">
 <icon BUILTIN="flag-yellow"/>