mutter/doc/cookbook/examples/events-pointer-motion-stacked.c

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/*
* Testing what happens with a stack of actors and pointer events
* red and green are reactive; blue is not
*
* when the pointer is over green (even if green is obscured by blue)
* signals are emitted by green (not by blue);
*
* but when the pointer is over the overlap between red and green,
* signals are emitted by green
*
* gcc -g -O0 -o stacked-actors-and-events stacked-actors-and-events.c `pkg-config --libs --cflags clutter-1.0 glib-2.0` -lm
*/
#include <clutter/clutter.h>
static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
static const ClutterColor red = { 0xff, 0x00, 0x00, 0xff };
static const ClutterColor green = { 0x00, 0xff, 0x00, 0xff };
static const ClutterColor blue = { 0x00, 0x00, 0xff, 0xff };
static gboolean
_pointer_motion_cb (ClutterActor *actor,
ClutterEvent *event,
gpointer user_data)
{
gfloat stage_x, stage_y;
gfloat actor_x, actor_y;
/* get the coordinates where the pointer crossed into the actor */
clutter_event_get_coords (event, &stage_x, &stage_y);
/*
* as the coordinates are relative to the stage, rather than
* the actor which emitted the signal, it can be useful to
* transform them to actor-relative coordinates
*/
clutter_actor_transform_stage_point (actor,
stage_x, stage_y,
&actor_x, &actor_y);
g_debug ("pointer on actor %s @ x %.0f, y %.0f",
clutter_actor_get_name (actor),
actor_x, actor_y);
return TRUE;
}
int
main (int argc, char *argv[])
{
ClutterActor *stage;
ClutterActor *r1, *r2, *r3;
if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
return 1;
stage = clutter_stage_new ();
clutter_actor_set_size (stage, 300, 300);
clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
r1 = clutter_rectangle_new_with_color (&red);
clutter_actor_set_size (r1, 150, 150);
clutter_actor_add_constraint (r1, clutter_align_constraint_new (stage, CLUTTER_ALIGN_X_AXIS, 0.25));
clutter_actor_add_constraint (r1, clutter_align_constraint_new (stage, CLUTTER_ALIGN_Y_AXIS, 0.25));
clutter_actor_set_reactive (r1, TRUE);
clutter_actor_set_name (r1, "red");
r2 = clutter_rectangle_new_with_color (&green);
clutter_actor_set_size (r2, 150, 150);
clutter_actor_add_constraint (r2, clutter_align_constraint_new (stage, CLUTTER_ALIGN_X_AXIS, 0.5));
clutter_actor_add_constraint (r2, clutter_align_constraint_new (stage, CLUTTER_ALIGN_Y_AXIS, 0.5));
clutter_actor_set_reactive (r2, TRUE);
clutter_actor_set_depth (r2, -100);
clutter_actor_set_name (r2, "green");
r3 = clutter_rectangle_new_with_color (&blue);
clutter_actor_set_size (r3, 150, 150);
clutter_actor_add_constraint (r3, clutter_align_constraint_new (stage, CLUTTER_ALIGN_X_AXIS, 0.75));
clutter_actor_add_constraint (r3, clutter_align_constraint_new (stage, CLUTTER_ALIGN_Y_AXIS, 0.75));
clutter_actor_set_opacity (r3, 125);
clutter_actor_set_name (r3, "blue");
clutter_container_add (CLUTTER_CONTAINER (stage), r1, r2, r3, NULL);
g_signal_connect (r1, "motion-event", G_CALLBACK (_pointer_motion_cb), NULL);
g_signal_connect (r2, "motion-event", G_CALLBACK (_pointer_motion_cb), NULL);
clutter_actor_show (stage);
clutter_main ();
return 0;
}