ptomato

/*
 * COMPILE ME WITH:
 * gcc -o eventloop eventloop.c `pkg-config --cflags --libs gtk+-2.0`
 */

#include <gtk/gtk.h>

typedef struct {
    GtkWidget *window, *pushbutton, *stopbutton, *indicator, *randnumentry,
        *indicatorlabel, *randnumlabel, *windowlabel, *vbox1, *hbox, *vbox2;
} Widgets;

/* Forward declarations */
static void on_push(GtkButton *pushbutton, Widgets *w);
static void on_stop(GtkButton *stopbutton, Widgets *w);
static gboolean on_quit(GtkWidget *window, GdkEvent *event, Widgets *w);
static gboolean on_timer(Widgets *w);
static gboolean on_user_event(Widgets *w);

int
main(int argc, char **argv)
{
    gtk_init(&argc, &argv);

    /* Construct the "controls" of our "front panel" */
    Widgets *w = g_new0(Widgets, 1);
    w->window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    w->pushbutton = gtk_button_new_with_label("Push!");
    w->stopbutton = gtk_button_new_with_label("STOP");
    w->indicator = gtk_image_new_from_stock(GTK_STOCK_NO, GTK_ICON_SIZE_BUTTON);
    w->randnumentry = gtk_entry_new();
    w->indicatorlabel = gtk_label_new("x > y?");
    w->randnumlabel = gtk_label_new("Randnum");
    w->windowlabel = gtk_label_new("Try to close this front panel\n"
        "while the VI is running.");

    /* Change the properties of some of the controls */
    gtk_container_set_border_width(GTK_CONTAINER(w->window), 12);
    gtk_entry_set_width_chars(GTK_ENTRY(w->randnumentry), 8);
    gtk_editable_set_editable(GTK_EDITABLE(w->randnumentry), FALSE);
    gtk_label_set_justify(GTK_LABEL(w->windowlabel), GTK_JUSTIFY_CENTER);

    /* Put the controls together */
    w->vbox1 = gtk_vbox_new(FALSE, 6);
    w->hbox = gtk_hbox_new(FALSE, 6);
    w->vbox2 = gtk_vbox_new(FALSE, 6);
    gtk_box_pack_start(GTK_BOX(w->vbox2), w->indicatorlabel, FALSE, FALSE, 0);
    gtk_box_pack_start(GTK_BOX(w->vbox2), w->indicator, FALSE, FALSE, 0);
    gtk_box_pack_start(GTK_BOX(w->vbox2), w->randnumlabel, FALSE, FALSE, 0);
    gtk_box_pack_start(GTK_BOX(w->vbox2), w->randnumentry, FALSE, FALSE, 0);
    gtk_box_pack_start(GTK_BOX(w->hbox), w->pushbutton, TRUE, TRUE, 0);
    gtk_box_pack_start(GTK_BOX(w->hbox), w->stopbutton, TRUE, TRUE, 0);
    gtk_box_pack_start(GTK_BOX(w->hbox), w->vbox2, TRUE, TRUE, 0);
    gtk_box_pack_start(GTK_BOX(w->vbox1), w->hbox, TRUE, TRUE, 0);
    gtk_box_pack_start(GTK_BOX(w->vbox1), w->windowlabel, TRUE, TRUE, 0);
    gtk_container_add(GTK_CONTAINER(w->window), w->vbox1);
    gtk_widget_show_all(w->window);

    /* Connect the signals. Here we define what functions get called when
    certain events happen. */
    g_signal_connect(w->pushbutton, "clicked", G_CALLBACK(on_push), w);
    g_signal_connect(w->stopbutton, "clicked", G_CALLBACK(on_stop), w);
    g_signal_connect(w->window, "delete-event", G_CALLBACK(on_quit), w);
    /* The function on_timer() takes the place of the LabVIEW code's while loop
    containing the 3000 ms wait. The main loop will call on_timer() every
    3000 milliseconds. */
    g_timeout_add(3000, (GSourceFunc)on_timer, w);

    /* This transfers control to GTK's main loop. From here on, the only parts
    of this code that are executed are those that respond to GUI events or the
    3000 millisecond timer. */
    gtk_main();

    g_free(w);
    return 0;
}

static void
on_push(GtkButton *pushbutton, Widgets *w)
{
    /* Show a dialog */
    GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(w->window), 0,
        GTK_MESSAGE_INFO, GTK_BUTTONS_OK, "You pressed Push!");
    gtk_dialog_run(GTK_DIALOG(dialog));
    gtk_widget_destroy(dialog);
}

static void
on_stop(GtkButton *stopbutton, Widgets *w)
{
    /* Tell the main loop to quit. The timeout function will be stopped
    automatically, so we don't need to do that here. */
    gtk_main_quit();
}

static gboolean
on_quit(GtkWidget *window, GdkEvent *event, Widgets *w)
{
    /* Show a dialog */
    GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(w->window), 0,
        GTK_MESSAGE_INFO, GTK_BUTTONS_OK, "A FilterEvent is not going to let "
        "you close this window!");
    gtk_dialog_run(GTK_DIALOG(dialog));
    gtk_widget_destroy(dialog);

    /* By returning TRUE from this callback, we filter this event, stopping it
    from closing our window. */
    return TRUE;
}

static gboolean
on_timer(Widgets *w)
{
    gdouble randnum = g_random_double();

    /* Put our number into the "randnum" indicator */
    gchar *text = g_strdup_printf("%0.6f", randnum);
    gtk_entry_set_text(GTK_ENTRY(w->randnumentry), text);
    g_free(text);

    if(randnum > 0.85)
    {
        /* This is our user-defined event. It's not implemented as a signal like
        the other events, but as an idle function, since only objects can have
        signals in GTK. */
        g_idle_add((GSourceFunc)on_user_event, w);
    }

    /* By returning TRUE from this event, we keep it repeating every 3 sec. */
    return TRUE;
}

static gboolean
on_user_event(Widgets *w)
{
    /* Change the "x > y?" indicator to light up */
    gtk_image_set_from_stock(GTK_IMAGE(w->indicator), GTK_STOCK_YES,
        GTK_ICON_SIZE_BUTTON);

    /* Show a dialog */
    GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(w->window), 0,
        GTK_MESSAGE_INFO, GTK_BUTTONS_OK, "Randnum > 0.85");
    gtk_dialog_run(GTK_DIALOG(dialog));
    gtk_widget_destroy(dialog);

    /* By returning FALSE from this event, we indicate that we only want it
    executed once. */
    return FALSE;
}