Rotar fondo de pantalla en Gnome cada cierto tiempo

En este manual se explica lo necesario para conseguir rotar los fondos de pantalla de Gnome.

Hay que compilar un pequeño programita:

Descargar

Quizás lo mejor sea descargar el .c de:
change-bg.c

El contenido es:

/* 

   Compile with:
   gcc -Wall -o change-bg `pkg-config --cflags --libs gnome-vfs-2.0 gconf-2.0` change-bg.c
   
   Copyright (C) 2005, Christian Kellner

   The Gnome Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The Gnome Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the Gnome Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.


*/

#include 
#include 
#include 
#include 
#include 

GConfClient  *gcc = NULL;
char         *text_uri = NULL;
GnomeVFSURI  *uri;
GList        *files = NULL;
GList        *iter = NULL;
static gboolean
change_picture (gpointer data)
{
        GnomeVFSURI *nuri;
        gboolean result;
        char *path;

        if (gcc == NULL) {
                gcc = gconf_client_get_default ();
        }
        path = (char *) iter->data;
        nuri = gnome_vfs_uri_append_string (uri, path);
        
        path = gnome_vfs_uri_to_string (nuri, GNOME_VFS_URI_HIDE_USER_NAME |
                                        GNOME_VFS_URI_HIDE_PASSWORD |
                                        GNOME_VFS_URI_HIDE_TOPLEVEL_METHOD |
                                        GNOME_VFS_URI_HIDE_FRAGMENT_IDENTIFIER |
                                        GNOME_VFS_URI_HIDE_HOST_PORT |
                                        GNOME_VFS_URI_HIDE_HOST_NAME);

        fprintf (stdout, "Setting bg to %s\n", path);
        
        result = gconf_client_set_string (gcc,
                                          "/desktop/gnome/background/picture_filename",
                                          path,
                                          NULL);

        g_free (path);

        if (result == FALSE) {
                fprintf (stderr, "Error setting %s as bg\n", path);
        }

        if (iter->next != NULL) {
                iter = iter->next;
        } else {
                iter = files;
        }
        
        return TRUE;
}

static gboolean
visit_files (const gchar *rel_path,
             GnomeVFSFileInfo *info,
             gboolean recursing_will_loop,
             gpointer data,
             gboolean *recurse)
{
        GList **files = (GList **) data;
        *recurse = TRUE;

        if (info->valid_fields & GNOME_VFS_FILE_INFO_FIELDS_MIME_TYPE &&
            (g_str_equal (info->mime_type, "image/png") ||
             g_str_equal (info->mime_type, "image/jpeg"))) {
                
                *files = g_list_prepend (*files, g_strdup (rel_path));
                fprintf (stdout, "Adding %s\n", rel_path);
        }
        
        return !recursing_will_loop;
}

int
main (int argc, char **argv)
{
        GnomeVFSResult  result;
        GMainLoop      *ml;
        int             mins;
                
        if (argc != 3) {
                fprintf (stderr, "Usage: %s  \n", argv[0]);
                return 1;
        }

        if (! gnome_vfs_init ()) {
                fprintf (stderr, "Cannot initialize gnome-vfs.\n");
                return 1;
        }

        text_uri = gnome_vfs_make_uri_from_shell_arg (argv[2]);

        mins = atoi (argv[1]);
        
        if (text_uri == NULL || mins == 0) {
                fprintf (stderr, "Usage: %s  0> \n", argv[0]);
                return 1;
        }
        
        fprintf (stdout, "Generating file list ...\n");
        files = NULL;
        result = gnome_vfs_directory_visit (text_uri,
                                            GNOME_VFS_FILE_INFO_GET_MIME_TYPE | 
                                            GNOME_VFS_FILE_INFO_FORCE_FAST_MIME_TYPE,
                                            GNOME_VFS_DIRECTORY_VISIT_LOOPCHECK |
                                            GNOME_VFS_DIRECTORY_VISIT_SAMEFS,
                                            visit_files,
                                            &files);

        if (result != GNOME_VFS_OK) {
                fprintf (stderr, "Error: %s\n",
                         gnome_vfs_result_to_string (result));
                return 1;
        }
        
        uri = gnome_vfs_uri_new (text_uri);
        
        iter = files;
        
        g_timeout_add (1000 * mins, change_picture, NULL);
        
        ml = g_main_loop_new (NULL, FALSE);

        fprintf (stdout, "Going into main loop (timeout: %d seconds)\n", mins);
        g_main_loop_run (ml);
        
        return 0;
}

Compilándolo

No hay más que ejecutar (es posible que tengáis que instalar los paquetes "-devel" de gconf y gnome-vfs en caso de que os falle al compilar):

gcc -Wall -o change-bg `pkg-config --cflags --libs gnome-vfs-2.0 gconf-2.0` change-bg.c

Uso

./change-bg  

Si no tuviese permisos de ejecución, bastaría con ejecutar:

chmod +x change-bg

Haciendo que se arranque al inicio de Gnome

Básicamente tenemos que escoger qué queremos que haga el comando, por ejemplo, yo quiero que rote las imágenes que tengo en /home/pacho/fondos cada 30 segundos, así que "mi" comando sería:

./change-bg 30 /home/pacho/fondos

Este es el comando a ejecutar al inicio, para ejecutar comandos al inicio de Gnome, no hay más que consultar este otro manual

Saludos

Gracias al original