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gtk/demos/gtk-demo/constraints.c
Matthias Clasen a9dfca04e4 constraint guide: Make strength tweakable 
The strength for the natural width can be used
as a tie-breaker to make instable systems behave
in a more predictable way. This can be seen
in the simple constraints demo in gtk-demo.
2019-07-01 00:10:11 +01:00

290 lines
10 KiB
C
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/* Constraints/Simple
*
* GtkConstraintLayout provides a layout manager that uses relations
* between widgets (also known as "constraints") to compute the position
* and size of each child.
*/
#include <glib/gi18n.h>
#include <gtk/gtk.h>
G_DECLARE_FINAL_TYPE (SimpleGrid, simple_grid, SIMPLE, GRID, GtkWidget)
struct _SimpleGrid
{
GtkWidget parent_instance;
GtkWidget *button1, *button2;
GtkWidget *button3;
};
G_DEFINE_TYPE (SimpleGrid, simple_grid, GTK_TYPE_WIDGET)
static void
simple_grid_destroy (GtkWidget *widget)
{
SimpleGrid *self = SIMPLE_GRID (widget);
g_clear_pointer (&self->button1, gtk_widget_destroy);
g_clear_pointer (&self->button2, gtk_widget_destroy);
g_clear_pointer (&self->button3, gtk_widget_destroy);
GTK_WIDGET_CLASS (simple_grid_parent_class)->destroy (widget);
}
static void
simple_grid_class_init (SimpleGridClass *klass)
{
GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
widget_class->destroy = simple_grid_destroy;
gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
}
/* Layout:
*
* +-------------------------------------+
* | +-----------++-------++-----------+ |
* | | Child 1 || Space || Child 2 | |
* | +-----------++-------++-----------+ |
* | +---------------------------------+ |
* | | Child 3 | |
* | +---------------------------------+ |
* +-------------------------------------+
*
* Constraints:
*
* super.start = child1.start - 8
* child1.width = child2.width
* child1.end = space.start
* space.end = child2.start
* child2.end = super.end - 8
* super.start = child3.start - 8
* child3.end = super.end - 8
* super.top = child1.top - 8
* super.top = child2.top - 8
* child1.bottom = child3.top - 12
* child2.bottom = child3.top - 12
* child3.height = child1.height
* child3.height = child2.height
* child3.bottom = super.bottom - 8
*
* To add some flexibility, we make the space
* stretchable:
*
* space.width >= 10
* space.width = 100
* space.width <= 200
*/
static void
build_constraints (SimpleGrid *self,
GtkConstraintLayout *manager)
{
GtkConstraintGuide *guide;
guide = gtk_constraint_guide_new ();
gtk_constraint_guide_set_name (guide, "space");
gtk_constraint_guide_set_min_size (guide, 10, 10);
gtk_constraint_guide_set_nat_size (guide, 100, 10);
gtk_constraint_guide_set_max_size (guide, 200, 20);
gtk_constraint_guide_set_strength (guide, GTK_CONSTRAINT_STRENGTH_STRONG);
gtk_constraint_layout_add_guide (manager, guide);
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new_constant (GTK_CONSTRAINT_TARGET (self->button1),
GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
GTK_CONSTRAINT_RELATION_LE,
200.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (NULL,
GTK_CONSTRAINT_ATTRIBUTE_START,
GTK_CONSTRAINT_RELATION_EQ,
self->button1,
GTK_CONSTRAINT_ATTRIBUTE_START,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button1,
GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
GTK_CONSTRAINT_RELATION_EQ,
self->button2,
GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
1.0,
0.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button1,
GTK_CONSTRAINT_ATTRIBUTE_END,
GTK_CONSTRAINT_RELATION_EQ,
guide,
GTK_CONSTRAINT_ATTRIBUTE_START,
1.0,
0.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (guide,
GTK_CONSTRAINT_ATTRIBUTE_END,
GTK_CONSTRAINT_RELATION_EQ,
self->button2,
GTK_CONSTRAINT_ATTRIBUTE_START,
1.0,
0.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button2,
GTK_CONSTRAINT_ATTRIBUTE_END,
GTK_CONSTRAINT_RELATION_EQ,
NULL,
GTK_CONSTRAINT_ATTRIBUTE_END,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (NULL,
GTK_CONSTRAINT_ATTRIBUTE_START,
GTK_CONSTRAINT_RELATION_EQ,
self->button3,
GTK_CONSTRAINT_ATTRIBUTE_START,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button3,
GTK_CONSTRAINT_ATTRIBUTE_END,
GTK_CONSTRAINT_RELATION_EQ,
NULL,
GTK_CONSTRAINT_ATTRIBUTE_END,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (NULL,
GTK_CONSTRAINT_ATTRIBUTE_TOP,
GTK_CONSTRAINT_RELATION_EQ,
self->button1,
GTK_CONSTRAINT_ATTRIBUTE_TOP,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (NULL,
GTK_CONSTRAINT_ATTRIBUTE_TOP,
GTK_CONSTRAINT_RELATION_EQ,
self->button2,
GTK_CONSTRAINT_ATTRIBUTE_TOP,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button1,
GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
GTK_CONSTRAINT_RELATION_EQ,
self->button3,
GTK_CONSTRAINT_ATTRIBUTE_TOP,
1.0,
-12.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button2,
GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
GTK_CONSTRAINT_RELATION_EQ,
self->button3,
GTK_CONSTRAINT_ATTRIBUTE_TOP,
1.0,
-12.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button3,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
GTK_CONSTRAINT_RELATION_EQ,
self->button1,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
1.0,
0.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button3,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
GTK_CONSTRAINT_RELATION_EQ,
self->button2,
GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
1.0,
0.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
gtk_constraint_layout_add_constraint (manager,
gtk_constraint_new (self->button3,
GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
GTK_CONSTRAINT_RELATION_EQ,
NULL,
GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
1.0,
-8.0,
GTK_CONSTRAINT_STRENGTH_REQUIRED));
}
static void
simple_grid_init (SimpleGrid *self)
{
GtkWidget *widget = GTK_WIDGET (self);
self->button1 = gtk_button_new_with_label ("Child 1");
gtk_widget_set_parent (self->button1, widget);
gtk_widget_set_name (self->button1, "button1");
self->button2 = gtk_button_new_with_label ("Child 2");
gtk_widget_set_parent (self->button2, widget);
gtk_widget_set_name (self->button2, "button2");
self->button3 = gtk_button_new_with_label ("Child 3");
gtk_widget_set_parent (self->button3, widget);
gtk_widget_set_name (self->button3, "button3");
GtkLayoutManager *manager = gtk_widget_get_layout_manager (GTK_WIDGET (self));
build_constraints (self, GTK_CONSTRAINT_LAYOUT (manager));
}
GtkWidget *
do_constraints (GtkWidget *do_widget)
{
static GtkWidget *window;
if (!window)
{
GtkWidget *header, *box, *grid, *button;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_display (GTK_WINDOW (window), gtk_widget_get_display (do_widget));
header = gtk_header_bar_new ();
gtk_header_bar_set_title (GTK_HEADER_BAR (header), "Constraints");
gtk_header_bar_set_show_title_buttons (GTK_HEADER_BAR (header), FALSE);
gtk_window_set_titlebar (GTK_WINDOW (window), header);
g_signal_connect (window, "destroy",
G_CALLBACK (gtk_widget_destroyed), &window);
box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
gtk_container_add (GTK_CONTAINER (window), box);
grid = g_object_new (simple_grid_get_type (), NULL);
gtk_widget_set_hexpand (grid, TRUE);
gtk_widget_set_vexpand (grid, TRUE);
gtk_container_add (GTK_CONTAINER (box), grid);
button = gtk_button_new_with_label ("Close");
gtk_container_add (GTK_CONTAINER (box), button);
gtk_widget_set_hexpand (grid, TRUE);
g_signal_connect_swapped (button, "clicked",
G_CALLBACK (gtk_widget_destroy), window);
}
if (!gtk_widget_get_visible (window))
gtk_widget_show (window);
else
gtk_widget_destroy (window);
return window;
}
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