Re: Problem running the GTK main loop in a separate thread (different from the main one).

[Jorge Opaso Pazos <jorge opaso gmail com>]

Hello,

This works for me:

#include <gtk/gtk.h>

static gpointer _gtkthread(gpointer a_data)
{
	GtkWidget *l_win;
	GtkWidget *l_but;
			
	gdk_threads_enter();
	l_win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
	l_but = gtk_button_new_with_label("My Button");
	gtk_container_add(GTK_CONTAINER(l_win),l_but);
	gtk_widget_show_all(l_win);
	gtk_main();
	gdk_threads_leave();
						
	return NULL;
}

int main(int a_argc,char **a_argv)
{
	GThread *l_th;

	g_thread_init(NULL);
	gdk_threads_init();
	gtk_init(&a_argc,&a_argv);
	l_th = g_thread_create(_gtkthread,NULL,TRUE,NULL);
	g_thread_join(l_th);

	return 0;
}


Atentamente,

Jorge Opaso Pazos
AUTOLogic LTDA




El 29-08-2009, a las 7:35, Cristi Cobzarenco escribió:

> Hi, I've been using GTK for a pretty long time but I've never used  
> threads with it and I'm not able to properly run the GTK main loop  
> in a separate thread.
> More to the point if I create a window, for example, in a thread  
> other than the GTK one, it becomes unresponsive. Other GTK calls  
> (that don't create widgets) seem to work fine, however.
> I've attached a sample program to show what I mean, the flag  
> "create_in_gt" sets whether to create the widgets in the GTK thread  
> or in the main one.
>
> Is this normal behaviour, am I not supposed to do this, or is it a  
> bug?
>
> (NOTE: The first time I've sent this message it was detected as spam  
> so I'll include the file instead of attaching it)
>
> threadtest1.cpp:
> #include <gtk/gtk.h>
>
> const int create_in_gt = FALSE; // Whether to create the widgets in  
> the GTK thread.
> GtkWidget *win, *but;
>
> // Creates a window with a button in it.
> // This function will be called in the GTK thread if "create_in_gt"  
> is TRUE
> // or in the main thread otherwise.
> int create_widgets(void*) {
>     win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
>     but = gtk_button_new_with_label("My Button");
>
>     gtk_container_add(GTK_CONTAINER(win),but);
>     gtk_widget_show_all(win);
>     return FALSE;
> }
>
> // The GTK thread function
> void* gtkthread(void *) {
>     gdk_threads_enter(); // GTK calls to follow - locking.
>
>     // Inits gtk in this thread (I have tried initing it in both  
> threads, the
>     // result is the same.)
>     gtk_init(NULL,NULL);
>
>     // Creates the widgets if neccesary and then enters the main loop.
>     if( create_in_gt ) create_widgets(NULL);
>     gtk_main();
>
>     gdk_threads_leave(); // GTK calls end here - unlocking
> }
>
> int main(int argc, char *argv[]) {
>     g_thread_init(NULL); // Init threads in main thread.
>     gdk_threads_init();
>
>     // Creates the GTK thread.
>     GThread *gt = g_thread_create(gtkthread, NULL, TRUE,NULL);
>
>     // Waits 1 second, creates widgets if neccesary then, waits 2  
> more seconds.
>     g_usleep( 1000000 );
>     if( !create_in_gt )
>         g_idle_add(create_widgets,NULL);
>     g_usleep( 2000000 );
>
>     gdk_threads_enter(); // Quits GTK safely.
>     gtk_main_quit();
>     gdk_threads_leave();
>
>     g_thread_join(gt); // Waits for GTK to quit.
>
>     return 0;
> }
>
> --
> Cristi Cobzarenco
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