How to use g_timeout_add? - c

Question

I am making a program in C with GTK and Glade for a serial communication. I am having problem using g_timeout_add. For example I have a function serial_data() which contain my serial data and I have a button handler on_update_button_clicked(). So till now I have done that if update button is clicked, gtk_timeout should run. But it running just for one time.
on_update_button_clicked(GtkButton *Update_Button)
{
//2nd argument is serial_data function which contain actual data
g_timeout_add(250,serial_data,NULL);
}
where I am missing the point?
I have another button stop button. So i want that timeout should stop when stop button handler is clicked. How to do that.??
One more question to ask, I want to count the number of times timeout is running like a counter. So that I can display the numbers of counter. How is this possible.?
Please help thanks.

Answer 1

From the documentation, The function is called repeatedly until it returns FALSE. You can call on_update_button with a boolean argument to toggle the timeout call from being continually called, set it running when argument evaluates to TRUE, and delete the thread with g_source_remove(threadID) if argument is FALSE. Here's a demonstration:
// compiling with: gcc test.c `pkg-config --cflags gtk+-3.0` `pkg-config --libs gtk+-3.0` -o test
#include <stdio.h>
#include <gtk/gtk.h>
#include <glib/gi18n.h>
guint threadID = 0;
guint serial_counter = 0;
static gboolean
serial_data (gpointer user_data)
{
// do something
printf("counter: %d\n", serial_counter);
serial_counter++;
return user_data;
}
static void
on_update_button_clicked (GtkButton* button, gpointer user_data)
{
if (user_data == 1)
{
threadID = g_timeout_add(250, serial_data, user_data);
}
else if (user_data == 0)
{
g_source_remove(threadID);
threadID = 0;
}
}
int
main (int argc, char *argv[])
{
GtkWidget *window;
gtk_init (&argc, &argv);
GtkWidget *update_button;
GtkWidget *stop_button;
GtkWidget *box;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "test.c");
box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 5);
update_button = gtk_button_new_with_label (_("Update"));
stop_button = gtk_button_new_with_label (_("Stop"));
gtk_box_pack_start (GTK_BOX (box), update_button, FALSE, FALSE, 0);
gtk_box_pack_start (GTK_BOX (box), stop_button, FALSE, FALSE, 0);
gtk_container_add (GTK_CONTAINER (window), box);
g_signal_connect (update_button, "clicked", G_CALLBACK (on_update_button_clicked), 1);
g_signal_connect (stop_button, "clicked", G_CALLBACK (on_update_button_clicked), 0);
g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
gtk_widget_show_all (window);
gtk_main ();
return 0;
}

Answer 2

g_timeout_add() returns an event source id that you should store. You can use g_source_remove() with that id in your stop button handler to stop the timeout.

Answer 3

check the developer site
https://developer.gnome.org/glib/stable/glib-The-Main-Event-Loop.html#g-timeout-add
its quite explicit.
you can have a gpointer to a gboolean STOP, finish the serial_data func in return STOP, and make your stop button change that STOP = FALSE and it will stop calling on that function. Or something like that.