Inv(#1020): control extension of the scrollable area

this uncovers some possible problem in GTK (#1037)

src/gui/panel/timeline-panel.cpp

@@ -113,7 +113,7 @@ namespace panel {
       scroller_.set_border_width(10);
       scroller_.add(canvas_);
       
-      canvas_.set_size(1000,500);
+      adjustToNecessaryCanvasSize();
       
       // show everything....
       this->add(twoParts_);
@@ -133,6 +133,28 @@ namespace panel {
   }
   
   
+  void
+  TimelinePanel::adjustToNecessaryCanvasSize()
+  {
+    uint sizeX = 10;
+    uint sizeY = 10;
+    for (Widget* chld : childz_)
+      {
+        uint x = canvas_.child_property_x(*chld);
+        uint y = canvas_.child_property_y(*chld);
+        x += chld->get_allocated_width();
+        y += chld->get_allocated_height();
+        sizeX = max (sizeX, x);
+        sizeY = max (sizeY, y);
+      }
+    // additional leeway for the scrollbars
+    sizeX += 10;
+    sizeY += 10;
+    
+    canvas_.set_size (sizeX, sizeY);
+  }
+  
+  
   void
   TimelinePanel::experiment_1()
   {
@@ -144,6 +166,7 @@ namespace panel {
     uint y = rand() % 500;
     canvas_.put(*chld, x, y);
     chld->show();
+    adjustToNecessaryCanvasSize();
   }
   
   
@@ -162,6 +185,7 @@ namespace panel {
         
         canvas_.move (*chld, x,y);
       }
+    adjustToNecessaryCanvasSize();
   }
   
   
@@ -178,6 +202,7 @@ namespace panel {
         int width = chld->get_allocated_width();
         pos += 0.6 * width;
       }
+    adjustToNecessaryCanvasSize();
   }
   
   

src/gui/panel/timeline-panel.hpp

@@ -118,6 +118,8 @@ namespace panel {
       using ChildV = std::vector<ChildEx*>;
       ChildV childz_;
       
+      void adjustToNecessaryCanvasSize();
+      
       void experiment_1();
       void experiment_2();
       void experiment_3();

wiki/renderengine.html

@@ -2635,7 +2635,7 @@ In the most general case, there can be per-track content and nested content at t
 → important question: how to [[organise the widgets|GuiTimelineWidgetStructure]]
 </pre>
 </div>
-<div title="GuiTimelineWidgetStructure" creator="Ichthyostega" modifier="Ichthyostega" created="201410250002" modified="201610291403" tags="GuiPattern discuss decision impl" changecount="45">
+<div title="GuiTimelineWidgetStructure" creator="Ichthyostega" modifier="Ichthyostega" created="201410250002" modified="201610291551" tags="GuiPattern discuss decision impl" changecount="48">
 <pre>The Timeline is probably the most prominent place in the GUI where we need to come up with a custom UI design.
 Instead of combining standard components in one of the well-known ways, here we need to come up with our own handling solution -- which also means to write one or several custom GTK widgets. Thus the question of layout and screen space division and organisation becomes a crucial design decision. The ~GTK-2 Gui, as implemented currently, did already take some steps along this route, yet this kind of decision should be cast and documented explicitly (be it after the fact).
 
@@ -2690,16 +2690,20 @@ In order to build a sensible plan for our timeline structure, we need to investi
 
 !!!Observations
 * children need to be made visible, otherwise they are added, but remain hidden
-* the size of the scrollable area is independent of the actual size extension of the canvas
-* the scrollable area determines when scrollbars are visible and what area can be reached through them
-* but children can well be placed beyond; they are fully functional then, just covered and out of sight
-* enlarging the enclosing window and thus enlarging the layout canvas will uncover such stray children.
 * when in sight, children receive events and are fully functional, even when placed out of the scrollable area.
 * the coordinate of children is their upper left corner, but they may extend beyond that and even beyond the scrollable area
-* children may be so close to the boundary, that it is not possible to click on them
-* when children close to the boundary receive an onClick event, the scrollable area might jumps back slightly..
 ;layering
 :children added later are always on top.
+;scrolling and size
+:the {{{Gtk::Layout}}} widget has a canvas size, which is defined implicitly, by placing child elements
+:* the size of the scrollable area is independent of the actual size extension of the canvas
+:* the scrollable area determines when scrollbars are visible and what area can be reached through them
+:* but children can well be placed beyond; they are fully functional then, just covered and out of sight
+:* enlarging the enclosing window and thus enlarging the layout canvas will uncover such stray children.
+:* //problematic//
+:** children may be so close to the boundary, that it is not possible to click on them
+:** when children close to the boundary receive an onClick event, the scrollable area might jump back slightly..
+:** the management of visible viewport within {{{Gtk::ScrolledWindow}}} is not correct (see [[ticket #1037|http://issues.lumiera.org/ticket/1037]])&lt;br/&gt;it does not account properly for the area covered by the scrollbars themselves
 ;moving child widgets
 :works as expected
 ;delete child widgets
@@ -2707,7 +2711,7 @@ In order to build a sensible plan for our timeline structure, we need to investi
 :removed child widgets will also removed from display (hidden)
 :but the widget object needs to be deleted manually, because detached widgets are no longer managed by GTK
 ;iteration over child widgets
-:problematic
+://problematic//
 :* the signal based {{{foreach}}} does not work -- there seems to be a problem with the slot's signature causing a wrong address to be passed in
 :* the interface {{{Gtk::Container}}} exposes a {{{get_children}}} function, but this returns a //copy// of the vector with pointers to all child widgets
 </pre>

wiki/thinkPad.ichthyo.mm

@@ -9386,9 +9386,10 @@
 <font ITALIC="true" NAME="SansSerif" SIZE="12"/>
 <icon BUILTIN="full-7"/>
 </node>
-<node CREATED="1477595418670" ID="ID_1516591439" MODIFIED="1477694985862" TEXT="# move and delete widgets">
+<node CREATED="1477595418670" ID="ID_1516591439" MODIFIED="1477754020121" TEXT="# move and delete widgets">
 <font ITALIC="true" NAME="SansSerif" SIZE="12"/>
 <icon BUILTIN="full-8"/>
+<icon BUILTIN="button_ok"/>
 <node CREATED="1477703725690" ID="ID_554135449" MODIFIED="1477703778772" TEXT="move">
 <icon BUILTIN="button_ok"/>
 <node CREATED="1477703730073" ID="ID_1070867956" MODIFIED="1477703771801" TEXT="foreach doesn&apos;t work">