Some cleanup in Layout

[libs/gltk.git] / source / layout.h

diff --git a/source/layout.h b/source/layout.h
index 540c5ee4d90bacfe9b233e824ad181b81a21aeeb..582bc1b0f685297b053ca73e38044aef592d777b 100644 (file)
--- a/source/layout.h
+++ b/source/layout.h
@@ -12,6 +12,42 @@ namespace GLtk {
 class Container;
 class Widget;
 
+/**
+Positions Widgets inside a Container.
+
+A layout operates on constraints, which are used to form a linear program that
+is then solved to obtain positions and dimensions that fulfill the constraints.
+There are three kinds of constraints available: ordering, alignment and
+dimension matching.
+
+Ordering constraints specify that the widgets should be placed next to each
+other along X or Y axis.  These operate on one axis at a time, so a widget
+could be "right of" another even if they are separated by hundreds of pixels
+vertically.  The widgets will be separated by a spacing value, which is
+settable on a per-layout basis.
+
+Alignment constraints make the corresponding edges of two widgets be on the
+same line.  These are incompatible with ordering constraints, so only one or
+the other should be used between any pair of widgets for the same axis.
+
+Dimension matching constraints force the two widgets to have the same dimension
+along the relevant axis.
+
+In addition to constraints, there are some other properties that can be set on
+widgets to determine how they are laid out.  Gravity affects which edge of the
+container the widget should be placed at.  This is a relatively weak hint and
+will be overridden by many other things.  Margins can also be specified to
+prevent widgets from getting too close to the container's edges.
+
+Usually widgets are made as small as their content allows.  Setting the expand
+flag for a widget causes it to use as much space as possible.  If multiple co-
+dependent widgets have the expand flag set, the results are currently
+undefined.
+
+Since specifiyng constraints manually can be quite tedious, there are some
+derived Layout classes that implement common positioning patterns.  See Row,
+Column, MixedRows and Grid.
+*/
 class Layout
 {
 private:
@@ -111,8 +147,6 @@ public:
        void update();
 
 protected:
-       void find_constraint_group(Slot &, ConstraintType, std::set<Slot *> &);
-       void sort_slots(std::list<Slot *> &, ConstraintType);
        void solve_constraints(int);
 };