Re: multithreading on win32

[todd <taf2 lehigh edu>]

Christophe Combelles wrote:
> >   It has never been impossible to control the GUI from a thread -- as 
> > a matter
> > of fact, the GUI is controlled by a thread itself :). Now, if you are 
> > talking
> > about having multiple threads accessing the GUI data structures, you 
> > will have
> > to provide the synchronization yourself.
> >
> >    gdk_threads_enter() and gdk_threads_leave() are your friends.
> >
> >    There are several apps that do that: Gaim and Urlget are 2 that 
> > comes to
> > mind.
> >
> > Hope this helps.
> > Harring Figueiredo
>
>
> I would like to something like that (see below):
> But it doesn't work. The window disappears immediatly when the thread 
> finishes,
> and if the thread is kept alive (uncomment "sleep"), the window is frozen.
> I just need to create a thread, and that thread must notify the user of 
> its activity. (at least when it starts and stop, or with a progress bar)
>
> -----------test.c--------------------
> #include <gtk/gtk.h>
>
> GtkWidget *window;
> GtkWidget *label;
> GThread *thread;
>
> gint function() {
>   gdk_threads_enter();
>   window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
>   label=gtk_label_new("my text");
>   gtk_container_add(GTK_CONTAINER(window), label);
>   gtk_widget_realize(window);
>   gtk_widget_show_all(window);
>   gdk_threads_leave();
>   //sleep(10000);
> }
> gint main(int argc, char *argv[]) {
>   g_thread_init (NULL);
>   gdk_threads_init();
>   gtk_init(&argc,&argv);
>   thread = g_thread_create((GThreadFunc)function, NULL, TRUE, NULL);
>   g_thread_join(thread);
>   gdk_threads_enter();
>   gtk_main();
>   gdk_threads_leave();
> }
> --------------------------------------------
> compiled on MinGW with:
> gcc -g -DDEBUG -mms-bitfields -mwindows `pkg-config --cflags gtk+-2.0` 
> -c test.c
> -o test.od
> gcc -static -mms-bitfields -mwindows -o test.exe test.od `pkg-config 
> --libs g
> tk+-2.0 --libs gthread-2.0` -L/lib
> --------------------------------------------

Hi,
        I think the program you posted above just needs to define a main loop
for the thread.  Like the following:

gint function()
{
    GMainLoop *main_loop;
>   gdk_threads_enter();
>   window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
>   label=gtk_label_new("my text");
>   gtk_container_add(GTK_CONTAINER(window), label);
>   gtk_widget_realize(window);
>   gtk_widget_show_all(window);
>   gdk_threads_leave();
>   //sleep(10000);
    main_loop = g_main_loop_new( NULL, TRUE );
    g_main_loop_run( main_loop );
}

this means this function will block. But then that's ok you can communicate
between threads using async queues, time out functions, or regular signal handlers.

hope this helps.

-todd