threads example from Erik Mouw. New question on GtkLabel background

Sat Nov 13 22:30:29 GMT 1999 Tony Gale  <gale@gtk.org>

        * docs/gtkfaq.sgml: threads example from Erik Mouw.
        New question on GtkLabel background colors.

        * docs/gtk_tut.sgml:
          - Correct the example code callback
            function definitions.
          - Update the gtkdial example code, from Frans van Schaik.
          - Update setselection.c to current API.

        * examples/Makefile examples/*/*.c: Update to code
        listed in tutorial.

1 files changed, 157 insertions, 3 deletions

diff --git a/docs/faq/gtkfaq.sgml b/docs/faq/gtkfaq.sgml
index 3ed17164b..6d8c35fa1 100644
--- a/docs/faq/gtkfaq.sgml
+++ b/docs/faq/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(&amp;argc, &amp;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(&amp;yes_tid, NULL, argument_thread, &amp;yes_args);
+
+  no_args.label = label;
+  no_args.what = NO_IT_IS_NOT;
+  pthread_create(&amp;no_tid, NULL, argument_thread, &amp;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