mutter/clutter/examples/rounded-rectangle.c

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C
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#include <stdlib.h>
#include <math.h>
#include <cairo.h>
#include <clutter/clutter.h>
static gboolean
draw_content (ClutterCanvas *canvas,
cairo_t *cr,
int surface_width,
int surface_height)
{
/* rounded rectangle taken from:
*
* http://cairographics.org/samples/rounded_rectangle/
*
* we leave 1 pixel around the edges to avoid jagged edges
* when rotating the actor
*/
double x = 1.0, /* parameters like cairo_rectangle */
y = 1.0,
width = surface_width - 2.0,
height = surface_height - 2.0,
aspect = 1.0, /* aspect ratio */
corner_radius = height / 20.0; /* and corner curvature radius */
double radius = corner_radius / aspect;
double degrees = M_PI / 180.0;
cairo_save (cr);
cairo_set_operator (cr, CAIRO_OPERATOR_CLEAR);
cairo_paint (cr);
cairo_restore (cr);
cairo_new_sub_path (cr);
cairo_arc (cr, x + width - radius, y + radius, radius, -90 * degrees, 0 * degrees);
cairo_arc (cr, x + width - radius, y + height - radius, radius, 0 * degrees, 90 * degrees);
cairo_arc (cr, x + radius, y + height - radius, radius, 90 * degrees, 180 * degrees);
cairo_arc (cr, x + radius, y + radius, radius, 180 * degrees, 270 * degrees);
cairo_close_path (cr);
cairo_set_source_rgba (cr, 0.5, 0.5, 1, 0.95);
cairo_fill (cr);
/* we're done drawing */
return TRUE;
}
int
main (int argc, char *argv[])
{
ClutterActor *stage, *actor;
ClutterContent *canvas;
ClutterTransition *transition;
/* initialize Clutter */
if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
return EXIT_FAILURE;
/* create a stage */
stage = clutter_stage_new ();
clutter_stage_set_title (CLUTTER_STAGE (stage), "Rectangle with rounded corners");
clutter_stage_set_use_alpha (CLUTTER_STAGE (stage), TRUE);
clutter_actor_set_background_color (stage, CLUTTER_COLOR_Black);
clutter_actor_set_size (stage, 500, 500);
clutter_actor_set_opacity (stage, 64);
clutter_actor_show (stage);
/* our 2D canvas, courtesy of Cairo */
canvas = clutter_canvas_new ();
clutter_canvas_set_size (CLUTTER_CANVAS (canvas), 300, 300);
/* the actor that will display the contents of the canvas */
actor = clutter_actor_new ();
clutter_actor_set_content (actor, canvas);
clutter_actor_set_content_gravity (actor, CLUTTER_CONTENT_GRAVITY_CENTER);
clutter_actor_set_content_scaling_filters (actor,
CLUTTER_SCALING_FILTER_TRILINEAR,
CLUTTER_SCALING_FILTER_LINEAR);
clutter_actor_set_pivot_point (actor, 0.5f, 0.5f);
clutter_actor_add_constraint (actor, clutter_align_constraint_new (stage, CLUTTER_ALIGN_BOTH, 0.5));
clutter_actor_set_request_mode (actor, CLUTTER_REQUEST_CONTENT_SIZE);
clutter_actor_add_child (stage, actor);
/* the actor now owns the canvas */
g_object_unref (canvas);
/* create the continuous animation of the actor spinning around its center */
transition = clutter_property_transition_new ("rotation-angle-y");
clutter_transition_set_from (transition, G_TYPE_DOUBLE, 0.0);
clutter_transition_set_to (transition, G_TYPE_DOUBLE, 360.0);
clutter_timeline_set_duration (CLUTTER_TIMELINE (transition), 2000);
clutter_timeline_set_repeat_count (CLUTTER_TIMELINE (transition), -1);
clutter_actor_add_transition (actor, "rotateActor", transition);
/* the actor now owns the transition */
g_object_unref (transition);
/* quit on destroy */
g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
/* connect our drawing code */
g_signal_connect (canvas, "draw", G_CALLBACK (draw_content), NULL);
/* invalidate the canvas, so that we can draw before the main loop starts */
clutter_content_invalidate (canvas);
clutter_main ();
return EXIT_SUCCESS;
}