Wiimote for controlling Rhythmbox

Last weekend I decided to write a small C program for controlling Rhythmbox with my Wiimote, using libcwiid en D-Bus. I implemented play, pause, previous, next and adjusting the volume. The Wiimote also rumbles when you press a working button and the LED's on the Wiimote show the current volume of Rhythmbox.

The only dependency is libcwiid, so build with the -lcwiid option. Here's the source code:

#include <cwiid.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

/*
 * This function reads Rhythmbox's volume and sets the LEDs of the Wiimote
 */
static void update_volume_leds(cwiid_wiimote_t *wiimote);

/*
 * Callback function for Wiimote messages
 */
static cwiid_mesg_callback_t callback;

int main(int argc, char **argv)
{
    cwiid_wiimote_t *wiimote;

    printf("Put Wiimote in discoverable mode now (press 1+2)...\n");

    if (!(wiimote = cwiid_open(BDADDR_ANY, 0)))
        fprintf(stderr, "Unable to connect to wiimote\n");
    if (cwiid_enable(wiimote, CWIID_FLAG_MESG_IFC))
        fprintf(stderr, "Error enabling messages\n");
    if (cwiid_set_rpt_mode(wiimote, CWIID_RPT_BTN))
        fprintf(stderr, "Error setting report mode\n");
    if (cwiid_set_mesg_callback(wiimote, callback))
        fprintf(stderr, "Unable to set message callback\n");

    printf("Connected to Wiimote...\n");

    update_volume_leds(wiimote);

    while (1) {}
}

static void update_volume_leds(cwiid_wiimote_t *wiimote)
{
    FILE *fp;
    char volume[128];
    unsigned char ledstate = 0;
    
    // Read Rhythmbox' volume
    fp = popen("qdbus org.gnome.Rhythmbox /org/gnome/Rhythmbox/Player org.gnome.Rhythmbox.Player.getVolume", "r");    
    while (fgets(volume, 128, fp) != NULL);
    pclose(fp);

    if (atof(volume) > 0)
        ledstate |= CWIID_LED1_ON;
    if (atof(volume) > 0.33)
        ledstate |= CWIID_LED2_ON;
    if (atof(volume) > 0.66)
        ledstate |= CWIID_LED3_ON;
    if (atof(volume) >= 1)
        ledstate |= CWIID_LED4_ON;

    cwiid_set_led(wiimote, ledstate);
}

static void callback(cwiid_wiimote_t *wiimote, int mesg_count, union cwiid_mesg mesg[], struct timespec *t)
{
    int i;

    for (i = 0; i < mesg_count; i++) {
        switch (mesg[i].type) {
        case CWIID_MESG_BTN:
            switch(mesg[i].btn_mesg.buttons) {
            case 0: // Ignore button releases
                break;
            case CWIID_BTN_A:
                printf("\"A\" button pressed; calling playPause()\n");
                // Give a rumble on each working button!
                cwiid_set_rumble(wiimote, 1);
                system("qdbus org.gnome.Rhythmbox /org/gnome/Rhythmbox/Player org.gnome.Rhythmbox.Player.playPause 0");
                break;
            case CWIID_BTN_LEFT:
                printf("\"Left\" button pressed; calling previous()\n");
                cwiid_set_rumble(wiimote, 1);
                system("qdbus org.gnome.Rhythmbox /org/gnome/Rhythmbox/Player org.gnome.Rhythmbox.Player.previous");
                break;
            case CWIID_BTN_RIGHT:
                printf("\"Right\" button pressed; calling next()\n");
                cwiid_set_rumble(wiimote, 1);
                system("qdbus org.gnome.Rhythmbox /org/gnome/Rhythmbox/Player org.gnome.Rhythmbox.Player.next");
                break;
            case CWIID_BTN_MINUS:
                printf("\"Minus\" button pressed; calling setVolumeRelative(-.1)\n");
                cwiid_set_rumble(wiimote, 1);
                system("qdbus org.gnome.Rhythmbox /org/gnome/Rhythmbox/Player org.gnome.Rhythmbox.Player.setVolumeRelative -.1");
                update_volume_leds(wiimote);
                break;
            case CWIID_BTN_PLUS:
                printf("\"Plus\" button pressed; calling setVolumeRelative(.1)\n");
                cwiid_set_rumble(wiimote, 1);
                system("qdbus org.gnome.Rhythmbox /org/gnome/Rhythmbox/Player org.gnome.Rhythmbox.Player.setVolumeRelative .1");
                update_volume_leds(wiimote);
                break;
            default:
                printf("Button \"%d\" not implemented...\n", mesg[i].btn_mesg.buttons);
                break;
            }
            usleep(10000);
            cwiid_set_rumble(wiimote, 0);

            break;
        default:
            printf("Uncaught report...\n");
            break;
        }
    }
}