1 #ifndef MSP_GLTK_LAYOUT_H_
2 #define MSP_GLTK_LAYOUT_H_
6 #include <sigc++/trackable.h>
16 Positions Widgets inside a Container.
18 A layout operates on constraints, which are used to form a linear program that
19 is then solved to obtain positions and dimensions that fulfill the constraints.
20 There are three kinds of constraints available: ordering, alignment and
23 Ordering constraints specify that the widgets should be placed next to other
24 along X or Y axis. These operate on one axis at a time, so a widget could be
25 "right of" another even if they are separated by hundreds of pixels vertically.
26 The widgets will be separated by a spacing value, which is settable on a per-
29 Alignment constraints make the corresponding edges of two widgets be on the
30 same line. These are incompatible with ordering constraints, so only one or
31 the other should be used between any pair of widgets for the same axis.
33 Dimension matching constraints force the two widgets to have the same dimension
34 along the relevant axis.
36 In addition to constraints, there are some other properties that can be set on
37 widgets to determine how they are laid out. Gravity affects which edge of the
38 container the widget should be placed at. This is a relatively weak hint and
39 will be overridden by many other things. Margins can also be specified to
40 prevent widgets from getting too close to the container's edges.
42 Usually widgets are made as small as their content allows. Setting the expand
43 flag for a widget causes it to use as much space as possible. If multiple co-
44 dependent widgets have the expand flag set, the results are currently
47 Since specifiyng constraints manually can be quite tedious, there are some
48 derived Layout classes that implement common positioning patterns. See
68 ABOVE = VERTICAL|SELF_POS|TARGET_POS|TARGET_DIM|SPACING,
69 BELOW = VERTICAL|SELF_POS|SELF_DIM|TARGET_POS|SPACING,
70 RIGHT_OF = HORIZONTAL|SELF_POS|TARGET_POS|TARGET_DIM|SPACING,
71 LEFT_OF = HORIZONTAL|SELF_POS|SELF_DIM|TARGET_POS|SPACING,
72 ALIGN_TOP = VERTICAL|SELF_POS|SELF_DIM|TARGET_POS|TARGET_DIM,
73 ALIGN_BOTTOM = VERTICAL|SELF_POS|TARGET_POS,
74 ALIGN_RIGHT = HORIZONTAL|SELF_POS|SELF_DIM|TARGET_POS|TARGET_DIM,
75 ALIGN_LEFT = HORIZONTAL|SELF_POS|TARGET_POS,
76 COPY_WIDTH = HORIZONTAL|SELF_DIM|TARGET_DIM,
77 COPY_HEIGHT = VERTICAL|SELF_DIM|TARGET_DIM
88 Constraint(ConstraintType, Slot &);
99 struct Slot: public sigc::trackable
105 std::list<Constraint> constraints;
109 Slot(Layout &, Widget &);
112 void autosize_changed();
118 Container *container;
119 std::list<Slot *> slots;
121 unsigned row_spacing;
122 unsigned col_spacing;
124 static Pointers pointers[2];
130 void set_container(Container &);
131 void set_margin(const Sides &);
132 void set_spacing(unsigned);
133 void set_row_spacing(unsigned);
134 void set_column_spacing(unsigned);
136 void add_widget(Widget &);
137 void remove_widget(Widget &);
139 virtual Slot *create_slot(Widget &);
140 Slot &get_slot_for_widget(Widget &);
141 static ConstraintType complement(ConstraintType);
143 void add_constraint(Widget &, ConstraintType, Widget &);
144 void set_gravity(Widget &, int, int);
145 void set_expand(Widget &, bool, bool);
150 void find_constraint_group(Slot &, ConstraintType, std::set<Slot *> &);
151 void sort_slots(std::list<Slot *> &, ConstraintType);
152 void solve_constraints(int);