diff options
Diffstat (limited to 'docs/gtkfaq.sgml')
| -rw-r--r-- | docs/gtkfaq.sgml | 160 |
1 files changed, 157 insertions, 3 deletions
diff --git a/docs/gtkfaq.sgml b/docs/gtkfaq.sgml index 3ed17164b6..6d8c35fa10 100644 --- a/docs/gtkfaq.sgml +++ b/docs/gtkfaq.sgml @@ -9,7 +9,7 @@ <!-- NOTE: Use only one author tag, otherwise sgml2txt barfs - TRG --> <author>Tony Gale, Shawn T. Amundson, Emmanuel Deloget, Nathan Froyd -<date>October 30th 1999 +<date>November 9th 1999 <abstract> This document is intended to answer questions that are likely to be frequently asked by programmers using GTK+ or people who are just looking at @@ -950,6 +950,149 @@ are made outside of the GTK+ lock. So, within a signal handler you do not need to call gdk_threads_enter(), but within the other types of callbacks, you do. +Erik Mouw contributed the following code example to illustrate how to +use threads within GTK+ programs. + +<tscreen><verb> +/*------------------------------------------------------------------------- + * Filename: gtk-thread.c + * Version: 0.99.1 + * Copyright: Copyright (C) 1999, Erik Mouw + * Author: Erik Mouw <J.A.K.Mouw@its.tudelft.nl> + * Description: GTK threads example. + * Created at: Sun Oct 17 21:27:09 1999 + * Modified by: Erik Mouw <J.A.K.Mouw@its.tudelft.nl> + * Modified at: Sun Oct 24 17:21:41 1999 + *-----------------------------------------------------------------------*/ +/* + * Compile with: + * + * cc -o gtk-thread gtk-thread.c `gtk-config --cflags --libs gthread` + * + * Thanks to Sebastian Wilhelmi and Owen Taylor for pointing out some + * bugs. + * + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <time.h> +#include <gtk/gtk.h> +#include <glib.h> +#include <pthread.h> + +#define YES_IT_IS (1) +#define NO_IT_IS_NOT (0) + +typedef struct +{ + GtkWidget *label; + int what; +} yes_or_no_args; + +G_LOCK_DEFINE_STATIC (yes_or_no); +static volatile int yes_or_no = YES_IT_IS; + +void destroy(GtkWidget *widget, gpointer data) +{ + gtk_main_quit(); +} + +void *argument_thread(void *args) +{ + yes_or_no_args *data = (yes_or_no_args *)args; + gboolean say_something; + + for(;;) + { + /* sleep a while */ + sleep(rand() / (RAND_MAX / 3) + 1); + + /* lock the yes_or_no_variable */ + G_LOCK(yes_or_no); + + /* do we have to say something? */ + say_something = (yes_or_no != data->what); + + if(say_something) + { + /* set the variable */ + yes_or_no = data->what; + } + + /* Unlock the yes_or_no variable */ + G_UNLOCK(yes_or_no); + + if(say_something) + { + /* get GTK thread lock */ + gdk_threads_enter(); + + /* set label text */ + if(data->what == YES_IT_IS) + gtk_label_set_text(GTK_LABEL(data->label), "O yes, it is!"); + else + gtk_label_set_text(GTK_LABEL(data->label), "O no, it isn't!"); + + /* release GTK thread lock */ + gdk_threads_leave(); + } + } + + return(NULL); +} + +int main(int argc, char *argv[]) +{ + GtkWidget *window; + GtkWidget *label; + yes_or_no_args yes_args, no_args; + pthread_t no_tid, yes_tid; + + /* init threads */ + g_thread_init(NULL); + + /* init gtk */ + gtk_init(&argc, &argv); + + /* init random number generator */ + srand((unsigned int)time(NULL)); + + /* create a window */ + window = gtk_window_new(GTK_WINDOW_TOPLEVEL); + + gtk_signal_connect(GTK_OBJECT (window), "destroy", + GTK_SIGNAL_FUNC(destroy), NULL); + + gtk_container_set_border_width(GTK_CONTAINER (window), 10); + + /* create a label */ + label = gtk_label_new("And now for something completely different ..."); + gtk_container_add(GTK_CONTAINER(window), label); + + /* show everything */ + gtk_widget_show(label); + gtk_widget_show (window); + + /* create the threads */ + yes_args.label = label; + yes_args.what = YES_IT_IS; + pthread_create(&yes_tid, NULL, argument_thread, &yes_args); + + no_args.label = label; + no_args.what = NO_IT_IS_NOT; + pthread_create(&no_tid, NULL, argument_thread, &no_args); + + /* enter the GTK main loop */ + gdk_threads_enter(); + gtk_main(); + gdk_threads_leave(); + + return(0); +} +</verb></tscreen> + <!-- This is the old answer - TRG @@ -1002,7 +1145,7 @@ carefully. Regardless, it's especially not a priority since relatively good workarounds exist. --> <!-- ----------------------------------------------------------------- --> -<sect1>Why do this strange 'x io error' occur when I <tt/fork()/ in my GTK+ app? +<sect1>Why does this strange 'x io error' occur when I <tt/fork()/ in my GTK+ app? <p> This is not really a GTK+ problem, and the problem is not related to <tt/fork()/ either. If the 'x io error' occurs then you probably use the <tt/exit()/ function @@ -1014,7 +1157,7 @@ and the underlying X library really doesn't like this. The right function to use here is <tt/_exit()/. -Erik Mouw gave the following code example to illustrate handling +Erik Mouw contributed the following code example to illustrate handling fork() and exit(). <tscreen><verb> @@ -1834,6 +1977,17 @@ gtk_misc_set_alignment(GTK_MISK(label), 1.0f, 1.0f); </verb></tscreen> <!-- ----------------------------------------------------------------- --> +<sect1>How do I set the background color of a GtkLabel widget? +<p> +The Gtklabel widget is one of a few GTK+ widgets that don't create +their own window to render themselves into. Instead, they draw +themselves directly onto their parents window. + +This means that in order to set the background color for a GtkLabel +widget, you need to change the background color of its parent, +i.e. the object that you pack it into. + +<!-- ----------------------------------------------------------------- --> <sect1>How do I set the color and font of a GtkLabel using a Resource File? <p> The widget name path constructed for a Label consists of the widget |