# Spinner (C)

Monica Kochofar
monicakochofar@gmail.com 2012
A spinner animation
Rafael Fontenelle
rafaelff@gnome.org 2013, 2018

# Spinner

This Spinner is stopped and started by pressing the spacebar.

#include <gtk/gtk.h>

/*Global variable used to indicate active state of the spinner. TRUE = active, FALSE = not-active. This is because there isn't a current function for C that does this for us*/ gboolean active;

/*This is the callback function. It is a handler function which reacts to the signal. In this case, it will cause the spinner to start and stop according to how many times the user presses the spacebar.*/ static gboolean key_pressed_event (GtkWidget *widget, GdkEvent *event, gpointer user_data) { GtkWidget *spinner = user_data; guint keyval;

/*Extracts the keyval from an event. And stores it in the variable "keyval" (we give the function the address). In this case, the event is GdkEventKey, a key press event*/ gdk_event_get_keyval (event, &keyval);

/*Grabbing the boolean value from the spinner*/ g_object_get (GTK_SPINNER (spinner), "active", &active, NULL);

if (keyval == GDK_KEY_space) { if (active) { gtk_spinner_stop (GTK_SPINNER (spinner)); } else { gtk_spinner_start (GTK_SPINNER (spinner)); } }

return TRUE; }

static void activate (GtkApplication *app, gpointer user_data) { GtkWidget *window; GtkWidget *spinner;

/*Create a window with a title, border width and a default size*/ window = gtk_application_window_new (app);

gtk_window_set_title (GTK_WINDOW (window), "Spinner Example"); gtk_window_set_default_size (GTK_WINDOW (window), 200, 200); gtk_container_set_border_width (GTK_CONTAINER(window), 30);

/*Create a spinner, with extra horizontal and vertical space*/ spinner = gtk_spinner_new (); gtk_spinner_start (GTK_SPINNER (spinner));

gtk_container_add (GTK_CONTAINER (window), spinner);

/*Connecting the key-press-event signal to the callback*/ g_signal_connect (GTK_WINDOW (window), "key-press-event", G_CALLBACK (key_pressed_event), spinner);

gtk_widget_show_all (window); }

int main (int argc, char **argv) { GtkApplication *app; int status;

app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE); g_signal_connect (app, "activate", G_CALLBACK (activate), NULL); status = g_application_run (G_APPLICATION (app), argc, argv); g_object_unref (app);

return status; }

In this sample we used the following:

GtkApplication

GtkWindow

GObject

GtkSpinner