mutter/doc/cookbook/examples/textures-crossfade.c

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#include <stdlib.h>
#include <glib.h>
#include <clutter/clutter.h>
static guint stage_side = 600;
static guint animation_duration_ms = 1500;
static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
typedef struct {
ClutterActor *front;
ClutterActor *back;
ClutterState *transitions;
GSList *image_paths;
guint next_image_index;
} State;
static gboolean
load_next_image (State *app)
{
/* don't do anything if already animating */
ClutterTimeline *timeline = clutter_state_get_timeline (app->transitions);
if (clutter_timeline_is_playing (timeline) == 1)
{
g_debug ("Animation is running already");
return FALSE;
}
if (!app->next_image_index)
app->next_image_index = 0;
gpointer next = g_slist_nth_data (app->image_paths, app->next_image_index);
if (next == NULL)
return FALSE;
gchar *image_path = (gchar *)next;
g_debug ("Loading %s", image_path);
CoglHandle *cogl_texture;
cogl_texture = clutter_texture_get_cogl_texture (CLUTTER_TEXTURE (app->front));
if (cogl_texture != NULL)
{
/* copy the current texture into the background */
clutter_texture_set_cogl_texture (CLUTTER_TEXTURE (app->back), cogl_texture);
/* make the back opaque and front transparent */
clutter_state_warp_to_state (app->transitions, "show-back");
}
/* load the next image into the front */
GError *error = NULL;
clutter_texture_set_from_file (CLUTTER_TEXTURE (app->front),
image_path,
&error);
if (error != NULL)
{
g_warning ("Error loading %s\n%s", image_path, error->message);
g_error_free (error);
return FALSE;
}
/* fade in the front texture and fade out the back texture */
clutter_state_set_state (app->transitions, "show-front");
app->next_image_index++;
return TRUE;
}
static gboolean
_key_pressed_cb (ClutterActor *actor,
ClutterEvent *event,
gpointer user_data)
{
State *app = (State *)user_data;
load_next_image (app);
return TRUE;
}
int
main (int argc, char *argv[])
{
if (argc < 2)
{
g_print ("Usage: %s <image paths to load>\n", argv[0]);
exit (EXIT_FAILURE);
}
State *app = g_new0 (State, 1);
app->image_paths = NULL;
/*
* NB if your shell globs arguments to this program so argv
* includes non-image files, they will fail to load and throw errors
*/
guint i;
for (i = 1; i < argc; i++)
app->image_paths = g_slist_append (app->image_paths, argv[i]);
GError *error = NULL;
/* UI */
ClutterActor *stage;
ClutterLayoutManager *layout;
ClutterActor *box;
clutter_init (&argc, &argv);
stage = clutter_stage_get_default ();
g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
clutter_stage_set_title (CLUTTER_STAGE (stage), "cross-fade");
clutter_actor_set_size (stage, stage_side, stage_side);
clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
layout = clutter_bin_layout_new (CLUTTER_BIN_ALIGNMENT_CENTER,
CLUTTER_BIN_ALIGNMENT_CENTER);
box = clutter_box_new (layout);
clutter_actor_set_size (box, stage_side, stage_side);
app->back = clutter_texture_new ();
clutter_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (app->back), TRUE);
app->front = clutter_texture_new ();
clutter_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (app->front), TRUE);
clutter_container_add_actor (CLUTTER_CONTAINER (box), app->back);
clutter_container_add_actor (CLUTTER_CONTAINER (box), app->front);
clutter_container_add_actor (CLUTTER_CONTAINER (stage), box);
/* animations */
app->transitions = clutter_state_new ();
clutter_state_set (app->transitions, NULL, "show-front",
app->front, "opacity", CLUTTER_EASE_IN_CUBIC, 255,
app->back, "opacity", CLUTTER_EASE_IN_CUBIC, 0,
NULL);
clutter_state_set (app->transitions, NULL, "show-back",
app->front, "opacity", CLUTTER_LINEAR, 0,
app->back, "opacity", CLUTTER_LINEAR, 255,
NULL);
clutter_state_set_duration (app->transitions,
NULL,
NULL,
animation_duration_ms);
/* display the next (first) image */
load_next_image (app);
/* key press displays the next image */
g_signal_connect (stage,
"key-press-event",
G_CALLBACK (_key_pressed_cb),
app);
clutter_actor_show (stage);
clutter_main ();
g_slist_free (app->image_paths);
g_object_unref (app->transitions);
g_free (app);
if (error != NULL)
g_error_free (error);
return EXIT_SUCCESS;
}