X-Git-Url: http://git.tdb.fi/?a=blobdiff_plain;f=source%2Flayout.h;h=cbd763e9e5337dc7a6395d7d0b3a860c6d9ad7e1;hb=9fdbf99cdb3c5620e665c3ecb34e83d778cb311a;hp=540c5ee4d90bacfe9b233e824ad181b81a21aeeb;hpb=01eaaef90f4c56cd4669d2f621e3061a938753eb;p=libs%2Fgltk.git

diff --git a/source/layout.h b/source/layout.h
index 540c5ee..cbd763e 100644
--- 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:
@@ -65,6 +101,7 @@ protected:
 		Layout &layout;
 		unsigned index;
 		Widget &widget;
+		Geometry autosize_geom;
 		Geometry geom;
 		std::list<Constraint> constraints;
 		Packing horiz_pack;
@@ -76,6 +113,12 @@ protected:
 		void autosize_changed();
 	};
 
+	enum SolveMode
+	{
+		UPDATE,
+		AUTOSIZE
+	};
+
 	class LinearProgram;
 	struct Pointers;
 
@@ -84,6 +127,7 @@ protected:
 	Sides margin;
 	unsigned row_spacing;
 	unsigned col_spacing;
+	Geometry autosize_geom;
 
 	static Pointers pointers[2];
 
@@ -109,11 +153,10 @@ public:
 	void set_expand(Widget &, bool, bool);
 
 	void update();
+	void autosize();
 
 protected:
-	void find_constraint_group(Slot &, ConstraintType, std::set<Slot *> &);
-	void sort_slots(std::list<Slot *> &, ConstraintType);
-	void solve_constraints(int);
+	void solve_constraints(int, SolveMode);
 };
 
 } // namespace GLtk