examples: Add an example of layout manager

The MultiLayout shows how to write a layout manager with two policies,
and to use the easing state of a child to interpolate the allocation.
This commit is contained in:
Emmanuele Bassi 2012-05-04 17:43:30 +01:00
parent b7c76a45bc
commit 4d087f2c0a
2 changed files with 410 additions and 0 deletions

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@ -9,6 +9,7 @@ all_examples = \
drop-action \
easing-modes \
flow-layout \
layout-manager \
rounded-rectangle \
threads

409
examples/layout-manager.c Normal file
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@ -0,0 +1,409 @@
#include <math.h>
#include <stdlib.h>
#include <clutter/clutter.h>
typedef struct _MultiLayout MultiLayout;
typedef struct _MultiLayoutClass MultiLayoutClass;
typedef enum {
MULTI_LAYOUT_GRID,
MULTI_LAYOUT_CIRCLE
} MultiLayoutState;
struct _MultiLayout
{
ClutterLayoutManager parent_instance;
/* the state of the layout */
MultiLayoutState state;
/* spacing between children */
float spacing;
/* cell size */
float cell_width;
float cell_height;
};
struct _MultiLayoutClass
{
ClutterLayoutManagerClass parent_class;
};
GType multi_layout_get_type (void);
ClutterLayoutManager * multi_layout_new (void);
void multi_layout_set_state (MultiLayout *layout,
MultiLayoutState state);
void multi_layout_set_spacing (MultiLayout *layout,
float spacing);
G_DEFINE_TYPE (MultiLayout, multi_layout, CLUTTER_TYPE_LAYOUT_MANAGER)
static void
multi_layout_get_preferred_width (ClutterLayoutManager *manager,
ClutterContainer *container,
float for_height,
float *min_width_p,
float *nat_width_p)
{
MultiLayout *self = (MultiLayout *) manager;
float minimum, natural;
float max_natural_width;
ClutterActorIter iter;
ClutterActor *child;
int n_children;
minimum = natural = 0.f;
max_natural_width = 0.f;
n_children = 0;
clutter_actor_iter_init (&iter, CLUTTER_ACTOR (container));
while (clutter_actor_iter_next (&iter, &child))
{
float child_minimum, child_natural;
if (!CLUTTER_ACTOR_IS_VISIBLE (child))
continue;
clutter_actor_get_preferred_width (child, -1.f,
&child_minimum,
&child_natural);
max_natural_width = MAX (max_natural_width, child_natural);
if (self->state == MULTI_LAYOUT_GRID)
{
minimum += child_minimum;
natural += child_natural;
}
else if (self->state == MULTI_LAYOUT_CIRCLE)
{
minimum = MAX (minimum, child_minimum);
natural = MAX (natural, child_natural);
}
n_children += 1;
}
self->cell_width = max_natural_width;
minimum += (self->spacing * (n_children - 1));
natural += (self->spacing * (n_children - 1));
if (min_width_p != NULL)
*min_width_p = minimum;
if (nat_width_p != NULL)
*nat_width_p = natural;
}
static void
multi_layout_get_preferred_height (ClutterLayoutManager *manager,
ClutterContainer *container,
float for_width,
float *min_height_p,
float *nat_height_p)
{
MultiLayout *self = (MultiLayout *) manager;
float minimum, natural;
ClutterActorIter iter;
ClutterActor *child;
int n_children;
minimum = natural = self->spacing * 2.f;
n_children = 0;
clutter_actor_iter_init (&iter, CLUTTER_ACTOR (container));
while (clutter_actor_iter_next (&iter, &child))
{
float child_minimum, child_natural;
if (!CLUTTER_ACTOR_IS_VISIBLE (child))
continue;
clutter_actor_get_preferred_height (child, -1.f,
&child_minimum,
&child_natural);
minimum = MAX (minimum, child_minimum);
natural = MAX (natural, child_natural);
n_children += 1;
}
self->cell_height = natural;
minimum += (self->spacing * (n_children - 1));
natural += (self->spacing * (n_children - 1));
if (min_height_p != NULL)
*min_height_p = minimum;
if (nat_height_p != NULL)
*nat_height_p = natural;
}
static int
get_items_per_row (MultiLayout *self,
float for_width)
{
int n_columns;
if (for_width < 0)
return 1;
if (self->cell_width <= 0)
return 1;
n_columns = (int) ((for_width + self->spacing) / (self->cell_width + self->spacing));
return MAX (n_columns, 1);
}
static int
get_visible_children (ClutterActor *actor)
{
ClutterActorIter iter;
ClutterActor *child;
int n_visible_children = 0;
clutter_actor_iter_init (&iter, actor);
while (clutter_actor_iter_next (&iter, &child))
{
if (CLUTTER_ACTOR_IS_VISIBLE (child))
n_visible_children += 1;
}
return n_visible_children;
}
static void
multi_layout_allocate (ClutterLayoutManager *manager,
ClutterContainer *container,
const ClutterActorBox *allocation,
ClutterAllocationFlags flags)
{
MultiLayout *self = (MultiLayout *) manager;
float avail_width, avail_height;
float x_offset, y_offset;
ClutterActorIter iter;
ClutterActor *child;
float item_x, item_y;
int n_items, n_items_per_row, item_index;
ClutterPoint center;
double radius, theta;
n_items = get_visible_children (CLUTTER_ACTOR (container));
if (n_items == 0)
return;
clutter_actor_box_get_origin (allocation, &x_offset, &y_offset);
clutter_actor_box_get_size (allocation, &avail_width, &avail_height);
/* ensure we have an updated value of cell_width and cell_height */
multi_layout_get_preferred_width (manager, container, avail_width, NULL, NULL);
multi_layout_get_preferred_height (manager, container, avail_height, NULL, NULL);
item_index = 0;
if (self->state == MULTI_LAYOUT_GRID)
{
n_items_per_row = get_items_per_row (self, avail_width);
item_x = x_offset;
item_y = y_offset;
}
else if (self->state == MULTI_LAYOUT_CIRCLE)
{
center.x = allocation->x2 / 2.f;
center.y = allocation->y2 / 2.f;
radius = MIN ((avail_width - self->cell_width) / 2.0,
(avail_height - self->cell_height) / 2.0);
}
clutter_actor_iter_init (&iter, CLUTTER_ACTOR (container));
while (clutter_actor_iter_next (&iter, &child))
{
ClutterActorBox child_allocation = CLUTTER_ACTOR_BOX_INIT (0, 0, 0, 0);
if (!CLUTTER_ACTOR_IS_VISIBLE (child))
continue;
if (self->state == MULTI_LAYOUT_GRID)
{
if (item_index == n_items_per_row)
{
item_index = 0;
item_x = x_offset;
item_y += self->cell_height + self->spacing;
}
child_allocation.x1 = item_x;
child_allocation.y1 = item_y;
child_allocation.x2 = child_allocation.x1 + self->cell_width;
child_allocation.y2 = child_allocation.y1 + self->cell_height;
item_x += self->cell_width + self->spacing;
}
else if (self->state == MULTI_LAYOUT_CIRCLE)
{
theta = 2.0 * G_PI / n_items * item_index;
child_allocation.x1 = center.x + radius * sinf (theta) - (self->cell_width / 2.f);
child_allocation.y1 = center.y + radius * -cosf (theta) - (self->cell_height / 2.f);
child_allocation.x2 = child_allocation.x1 + self->cell_width;
child_allocation.y2 = child_allocation.y1 + self->cell_height;
}
clutter_actor_save_easing_state (child);
clutter_actor_allocate (child, &child_allocation, flags);
clutter_actor_restore_easing_state (child);
item_index += 1;
}
}
static void
multi_layout_class_init (MultiLayoutClass *klass)
{
ClutterLayoutManagerClass *manager_class = CLUTTER_LAYOUT_MANAGER_CLASS (klass);
manager_class->get_preferred_width = multi_layout_get_preferred_width;
manager_class->get_preferred_height = multi_layout_get_preferred_height;
manager_class->allocate = multi_layout_allocate;
}
static void
multi_layout_init (MultiLayout *self)
{
self->state = MULTI_LAYOUT_GRID;
self->cell_width = -1.f;
self->cell_height = -1.f;
self->spacing = 0.f;
}
ClutterLayoutManager *
multi_layout_new (void)
{
return g_object_new (multi_layout_get_type (), NULL);
}
void
multi_layout_set_state (MultiLayout *self,
MultiLayoutState state)
{
if (self->state == state)
return;
self->state = state;
clutter_layout_manager_layout_changed (CLUTTER_LAYOUT_MANAGER (self));
}
void
multi_layout_set_spacing (MultiLayout *self,
float spacing)
{
self->spacing = spacing;
clutter_layout_manager_layout_changed (CLUTTER_LAYOUT_MANAGER (self));
}
#define N_RECTS 16
#define RECT_SIZE 64.0
#define N_ROWS 4
#define PADDING 12.0
#define BOX_SIZE (RECT_SIZE * (N_RECTS / N_ROWS) + PADDING * (N_RECTS / N_ROWS - 1))
static gboolean
on_key_press (ClutterActor *stage,
ClutterEvent *event,
ClutterActor *box)
{
guint keysym = clutter_event_get_key_symbol (event);
MultiLayout *layout = (MultiLayout *) clutter_actor_get_layout_manager (box);
if (keysym == CLUTTER_KEY_q)
{
clutter_main_quit ();
return CLUTTER_EVENT_STOP;
}
switch (keysym)
{
case CLUTTER_KEY_g:
multi_layout_set_state (layout, MULTI_LAYOUT_GRID);
break;
case CLUTTER_KEY_c:
multi_layout_set_state (layout, MULTI_LAYOUT_CIRCLE);
break;
default:
break;
}
return CLUTTER_EVENT_STOP;
}
int
main (int argc, char *argv[])
{
ClutterActor *stage, *box, *label;
ClutterLayoutManager *manager;
ClutterMargin margin;
int i;
if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
return EXIT_FAILURE;
stage = clutter_stage_new ();
clutter_stage_set_title (CLUTTER_STAGE (stage), "Multi-layout");
g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
clutter_actor_show (stage);
manager = multi_layout_new ();
multi_layout_set_spacing ((MultiLayout *) manager, PADDING);
margin.top = margin.bottom = margin.left = margin.right = PADDING;
box = clutter_actor_new ();
clutter_actor_set_margin (box, &margin);
clutter_actor_set_layout_manager (box, manager);
clutter_actor_set_size (box, BOX_SIZE, BOX_SIZE);
clutter_actor_add_constraint (box, clutter_align_constraint_new (stage, CLUTTER_ALIGN_BOTH, 0.5));
clutter_actor_add_child (stage, box);
for (i = 0; i < N_RECTS; i++)
{
ClutterActor *rect = clutter_actor_new ();
ClutterColor color;
clutter_color_from_hls (&color,
360.0 / N_RECTS * i,
0.5,
0.8);
color.alpha = 128 + 128 / N_RECTS * i;
clutter_actor_set_size (rect, RECT_SIZE, RECT_SIZE);
clutter_actor_set_background_color (rect, &color);
clutter_actor_add_child (box, rect);
}
label = clutter_text_new ();
clutter_text_set_text (CLUTTER_TEXT (label),
"Press g\t\342\236\236\tGrid layout\n"
"Press c\t\342\236\236\tCircular layout\n"
"Press q\t\342\236\236\tQuit");
clutter_actor_add_constraint (label, clutter_align_constraint_new (stage, CLUTTER_ALIGN_X_AXIS, 0.5));
clutter_actor_add_constraint (label, clutter_align_constraint_new (stage, CLUTTER_ALIGN_Y_AXIS, 0.95));
clutter_actor_add_child (stage, label);
g_signal_connect (stage, "key-press-event", G_CALLBACK (on_key_press), box);
clutter_main ();
return EXIT_SUCCESS;
}