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Thread support updates from Owen. Various suggestions from Steve Chaplin.

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Tue Jun 24 20:00:45 BST 2003  Tony Gale <gale@gtk.org>

        * docs/faq/gtk-faq.sgml: Thread support updates
        from Owen. Various suggestions from Steve Chaplin.
This commit is contained in:
BST 2003 Tony Gale
2003-06-24 19:02:52 +00:00
committed by Tony Gale
parent 2baea29719
commit 7395e4dacd
6 changed files with 184 additions and 95 deletions
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5
ChangeLog
View File

@@ -1,3 +1,8 @@
Tue Jun 24 20:00:45 BST 2003 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Thread support updates
from Owen. Various suggestions from Steve Chaplin.
2003-03-24 Mohammad DAMT <mdamt@bisnisweb.com>
* po/id.po: Updated Indonesian translation

5
ChangeLog.pre-2-10
View File

@@ -1,3 +1,8 @@
Tue Jun 24 20:00:45 BST 2003 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Thread support updates
from Owen. Various suggestions from Steve Chaplin.
2003-03-24 Mohammad DAMT <mdamt@bisnisweb.com>
* po/id.po: Updated Indonesian translation

5
ChangeLog.pre-2-4
View File

@@ -1,3 +1,8 @@
Tue Jun 24 20:00:45 BST 2003 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Thread support updates
from Owen. Various suggestions from Steve Chaplin.
2003-03-24 Mohammad DAMT <mdamt@bisnisweb.com>
* po/id.po: Updated Indonesian translation

5
ChangeLog.pre-2-6
View File

@@ -1,3 +1,8 @@
Tue Jun 24 20:00:45 BST 2003 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Thread support updates
from Owen. Various suggestions from Steve Chaplin.
2003-03-24 Mohammad DAMT <mdamt@bisnisweb.com>
* po/id.po: Updated Indonesian translation

5
ChangeLog.pre-2-8
View File

@@ -1,3 +1,8 @@
Tue Jun 24 20:00:45 BST 2003 Tony Gale <gale@gtk.org>
* docs/faq/gtk-faq.sgml: Thread support updates
from Owen. Various suggestions from Steve Chaplin.
2003-03-24 Mohammad DAMT <mdamt@bisnisweb.com>
* po/id.po: Updated Indonesian translation

254
docs/faq/gtk-faq.sgml
View File

@@ -2,7 +2,7 @@
<book>
<bookinfo>
<date>April 30th 2003</date>
<date>June 24th 2003</date>
<title>GTK+ FAQ</title>
<authorgroup>
<author>
@@ -695,10 +695,10 @@ presents a list of GTK+ bindings.</para>
<listitem><simpara>There are several C++ wrappers for GTK+.</simpara>
<itemizedlist>
<listitem><simpara>the gtk-- package, which is a very small wrapper for
<listitem><simpara>the gtkmm package, which is a wrapper for
GTK+. You can find the home page at <ulink
url="http://www.cs.tut.fi/~p150650/gtk/gtk--.html">
http://www.cs.tut.fi/~p150650/gtk/gtk--.html</ulink>. The FTP site is
url="http://www.gtkmm.org">
http://www.gtkmm.org/</ulink>. The FTP site is
<ulink url="ftp://ftp.gtk.org/pub/gtk/gtk--">
ftp://ftp.gtk.org/pub/gtk/gtk--</ulink>.</simpara>
</listitem>
@@ -706,14 +706,14 @@ presents a list of GTK+ bindings.</para>
<listitem><simpara>the VDK package, which was built as
the base package of a GTK+ application Borland-like
builder. The home page can be found at <ulink
url="http://www.guest.net/homepages/mmotta/VDKHome">
http://www.guest.net/homepages/mmotta/VDKHome</ulink>.</simpara>
url="http://vdkbuilder.sourceforge.net/">
http://vdkbuilder.sourceforge.net/</ulink>.</simpara>
</listitem>
<listitem><simpara>The wxWindows/Gtk package, a free C++ library for
cross-platform GUI development. The home page of this package is
<ulink url="http://www.freiburg.linux.de/~wxxt/">
http://www.freiburg.linux.de/~wxxt/</ulink>.</simpara>
<ulink url="http://www.wxwindows.org/">
http://www.wxwindows.org/</ulink>.</simpara>
</listitem>
</itemizedlist>
@@ -831,6 +831,32 @@ grounding on what the widgets can do.</para>
<!-- ----------------------------------------------------------------- -->
<sect1>
<title>How do I use the Glade GUI builder with GTK+? <emphasis>[GTK 2.x]</emphasis></title>
<para>There are two ways to use Glade. The first way is to use
Glade's facilities for generating code; the second
way is to use the libglade library which directly loads
the XML user interface description files that Glade
generates into a running program.</para>
Experienced GTK+ programmers generally strongly recommend
using libglade; you don't have to worry about the interaction
between Glade generating the source and you editing it,
and its been shown to be a method that works better
for large projects, so there is a lot of example code
out there you can look at.</para>
<para>An introduction to using libglade can be found in the
libglade API docs
(<ulink url="http://developer.gnome.org/doc/API/2.0/libglade/libglade-notes.html#libglade-basics">
http://developer.gnome.org/doc/API/2.0/libglade/libglade-notes.html#libglade-basics</ulink>)
</para>
</sect1>
<!-- ----------------------------------------------------------------- -->
<sect1>
<title>How do I write security sensitive/SUID/SGID programs with GTK+?
Is GTK+ secure? What's this GTK_MODULES security hole I heard about?</title>
@@ -1140,7 +1166,7 @@ Netherlands, YMMV).</quote></para>
<sect1>
<title>Is GTK+ thread safe? How do I write multi-threaded GTK+
applications?</title>
applications? <emphasis>[GTK 2.x]</emphasis></title>
<para>The GLib library can be used in a thread-safe mode by
calling g_thread_init() before making any other GLib
@@ -1152,11 +1178,12 @@ simultaneously. If two different threads need to access the
same hash table, the application is responsible for locking
itself.</para>
<para>When GLib is intialized to be thread-safe, GTK+ is
<emphasis>thread aware</emphasis>. There is a single global
<para>In order to make GDK thread aware, you also need to
call gdk_threads_init() in conjunction with the above call.
There is a single global
lock that you must acquire with gdk_threads_enter() before
making any GDK calls, and release with gdk_threads_leave()
afterwards.</para>
afterwards throughout your code.</para>
<para>A minimal main program for a threaded GTK+ application
looks like:</para>
@@ -1194,36 +1221,30 @@ illustrate how to use threads within GTK+ programs.</para>
<programlisting role="C">
/*-------------------------------------------------------------------------
* Filename: gtk-thread.c
* Version: 0.99.1
* Version: 1.99.1
* Copyright: Copyright (C) 1999, Erik Mouw
* Author: Erik Mouw &lt;J.A.K.Mouw@its.tudelft.nl&gt;
* Description: GTK threads example.
* Description: GTK threads example.
* Created at: Sun Oct 17 21:27:09 1999
* Modified by: Erik Mouw &lt;J.A.K.Mouw@its.tudelft.nl&gt;
* Modified at: Sun Oct 24 17:21:41 1999
* Modified by: Owen Taylor &lt;otaylor@gtk.org&gt;
* Modified at: Wed May 28 10:43:00 2003
*-----------------------------------------------------------------------*/
/*
* Compile with:
*
* cc -o gtk-thread gtk-thread.c `pkg-config gtk+-2.0 --cflags --libs gthread`
* cc -o gtk-thread gtk-thread.c `pkg-config --cflags --libs gtk+-2.0 gthread`
*
* Thanks to Sebastian Wilhelmi and Owen Taylor for pointing out some
* bugs.
* Thanks to Sebastian Wilhelmi for pointing out some bugs in earlier versions.
*
*/
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;unistd.h&gt;
#include &lt;time.h&gt;
#include &lt;gtk/gtk.h&gt;
#include &lt;glib.h&gt;
#include &lt;pthread.h&gt;
#define YES_IT_IS (1)
#define NO_IT_IS_NOT (0)
typedef struct
typedef struct
{
GtkWidget *label;
int what;
@@ -1245,7 +1266,7 @@ void *argument_thread(void *args)
for(;;)
{
/* sleep a while */
sleep(rand() / (RAND_MAX / 3) + 1);
sleep(g_random_int_range (1, 4));
/* lock the yes_or_no_variable */
G_LOCK(yes_or_no);
@@ -1273,42 +1294,46 @@ void *argument_thread(void *args)
else
gtk_label_set_text(GTK_LABEL(data->label), "O no, it isn't!");
/* Make sure all X commands are sent to the X server; not strictly
* necessary here, but always a good idea when you do anything
* from a thread other than the one where the main loop is running.
*/
gdk_flush ();
/* release GTK thread lock */
gdk_threads_leave();
}
}
return(NULL);
return NULL;
}
int main(int argc, char *argv[])
{
GtkWidget *window;
GtkWidget *label;
GError *error = NULL;
yes_or_no_args yes_args, no_args;
pthread_t no_tid, yes_tid;
/* init threads */
g_thread_init(NULL);
gdk_threads_init();
/* 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);
g_signal_connect(window, "destroy",
G_CALLBACK(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);
@@ -1316,24 +1341,100 @@ int main(int argc, char *argv[])
/* create the threads */
yes_args.label = label;
yes_args.what = YES_IT_IS;
pthread_create(&amp;yes_tid, NULL, argument_thread, &amp;yes_args);
if (!g_thread_create(argument_thread, &amp;yes_args, FALSE, &amp;error))
{
g_printerr ("Failed to create YES thread: %s\n", error->message);
return 1;
}
no_args.label = label;
no_args.what = NO_IT_IS_NOT;
pthread_create(&amp;no_tid, NULL, argument_thread, &amp;no_args);
if (!g_thread_create(argument_thread, &amp;no_args, FALSE, &amp;error))
{
g_printerr ("Failed to create NO thread: %s\n", error->message);
return 1;
}
/* enter the GTK main loop */
gdk_threads_enter();
gtk_main();
gdk_threads_leave();
return(0);
return 0;
}
</programlisting>
</sect1>
<!-- ----------------------------------------------------------------- -->
<sect1>
<title>I'm doing some stuff with GTK+ in a separate thread, and
properly locking with gdk_threads_enter/gdk_threads_leave()
but the display doesn't update properly. <emphasis>[GTK 2.x]</emphasis>
</title>
<para>For efficiency, the X window system batches up commands
and sends them to the X server in batches instead of sending
out immediately.</para>
<para>In a non-multithreaded program, you don't have to worry about
this, since the first thing that happens when control returns
to the main loop is that any outstanding X requests are
sent to the X server.</para>
<para>However, if you are making GTK+ calls from a thread other
than the main loop, then GTK+ doesn't know when to send batched
commands out. For that reason, after making GTK+ calls
in a separate thread, it is usually a good idea to call
gdk_flush() before gdk_thread_leave().</para>
<para>Actually, gdk_flush() is more expensive than is necessary here,
since it waits for the X server to finish outstanding commands
as well; if performance is an issue, you may want to call
XFlush() directly:</para>
<programlisting role="C">
#include <gdk/gdkx.h>
void my_flush_commands (void)
{
GdkDisplay *display = gdk_display_get_default ();
XFlush (GDK_DISPLAY_XDISPLAY (display);
}
</programlisting>
</sect1>
<!-- ----------------------------------------------------------------- -->
<sect1>
<title>What's an easy way to run a function in the thread with
the main loop? <emphasis>[GTK 2.x]</emphasis></title>
<para>Sometimes the simplest way to set up a threaded program
is to make all the GTK+ calls in a single thread. In such
a program, you should still call g_threads_init(), but
don't need to call gdk_threads_init(), gkd_threads_enter(),
and gdk_threads_leave().</para>
<para>If you set your program up this way, how then do you get
the thread making GTK+ calls and running the main loop
to do something in response to another thread?</para>
<para>An easy way to do it is to take advantage of the fact that
the GLib main loop functions are all thread safe, and can
be called from any thread by adding an idle function
with g_idle_add(). The function provided will be called
at the next opportunity by the main thread. If you want
your function to take priority over event handling and
drawing, you can instead use g_idle_add_full() and pass
in a priority of G_PRIORITY_HIGH.</para>
</sect1>
<!-- ----------------------------------------------------------------- -->
<sect1>
<title>Why does this strange 'x io error' occur when I
<literal>fork()</literal> in my GTK+ app?</title>
@@ -1560,7 +1661,7 @@ ancestor?</title>
<para>There are a couple of ways to find the top level parent
of a widget. The easier way is to call the
<literal>gtk_widget_top_level()</literal> function that
<literal>gtk_widget_get_toplevel()</literal> function that
returns pointer to a GtkWidget that is the top level
window.</para>
@@ -1871,7 +1972,8 @@ and high priority idle functions, then return immediately
<!-- ----------------------------------------------------------------- -->
<sect1>
<title>How do I attach data to some GTK+ object/widget?</title>
<title>How do I attach data to some GTK+ object/widget?
<emphasis>[GTK 2.x]</emphasis></title>
<para>First of all, the attached data is stored in the
object_data field of a GtkObject. The type of this field is
@@ -1880,15 +1982,15 @@ gdataset.c file in your glib source directory very
carefully.</para>
<para>There are two (easy) ways to attach some data to a gtk
object. Using <literal>gtk_object_set_data()</literal> and
<literal>gtk_object_get_data()</literal> seems to be the most
object. Using <literal>g_object_set_data()</literal> and
<literal>g_object_get_data()</literal> seems to be the most
common way to do this, as it provides a powerful interface to
connect objects and data.</para>
<programlisting role="C">
void gtk_object_set_data(GtkObject *object, const gchar *key, gpointer data);
void g_object_set_data(GObject *object, const gchar *key, gpointer data);
gpointer gtk_object_get_data(GtkObject *object, const gchar *key);
gpointer g_object_get_data(GObject *object, const gchar *key);
</programlisting>
<para>Since a short example is better than any lengthy speech:</para>
@@ -1897,10 +1999,10 @@ gpointer gtk_object_get_data(GtkObject *object, const gchar *key);
struct my_struct p1,p2,*result;
GtkWidget *w;
gtk_object_set_data(GTK_OBJECT(w),"p1 data",(gpointer)&amp;p1);
gtk_object_set_data(GTK_OBJECT(w),"p2 data",(gpointer)&amp;p2);
g_object_set_data(G_OBJECT(w),"p1 data",(gpointer)&amp;p1);
g_object_set_data(G_OBJECT(w),"p2 data",(gpointer)&amp;p2);
result = gtk_object_get_data(GTK_OBJECT(w),"p1 data");
result = g_object_get_data(G_OBJECT(w),"p1 data");
</programlisting>
<para>The <literal>gtk_object_set_user_data()</literal> and
@@ -2023,62 +2125,24 @@ windows.</para>
<sect1>
<title>How do I set the size of a widget/window? How do I
prevent the user resizing my window?</title>
prevent the user resizing my window? <emphasis>[GTK 2.x]</emphasis></title>
<para>The <literal>gtk_widget_set_uposition()</literal>
function is used to set the position of any widget.</para>
<para>The <literal>gtk_widget_set_size_request()</literal> function
is used to set the size of a widget to a specific size.
<para>The <literal>gtk_widget_set_usize()</literal> function
is used to set the size of a widget. In order to use all the
features that are provided by this function when it acts on a
window, you may want to use the
<literal>gtk_window_set_policy</literal> function. The
The function
<literal>gtk_window_set_resizable()</literal> function sets whether
the user can resize a window, which they can by default. The
definition of these functions are:</para>
<programlisting role="C">
void gtk_widget_set_usize (GtkWidget *widget,
gint width,
gint height);
void gtk_widget_set_size_request (GtkWidget *widget,
gint width,
gint height);
void gtk_window_set_policy (GtkWindow *window,
gint allow_shrink,
gint allow_grow,
gint auto_shrink);
</programlisting>
void gtk_window_set_resizable (GtkWindow *window,
gboolean resizable);
<para><literal>auto_shrink</literal> will automatically shrink
the window when the requested size of the child widgets goes
below the current size of the
window. <literal>allow_shrink</literal> will give the user the
authorisation to make the window smaller that it should
normally be. <literal>allow_grow</literal> gives the user
the ability to make the window bigger. The default
values for these parameters are:</para>
<programlisting role="C">
allow_shrink = FALSE
allow_grow = TRUE
auto_shrink = FALSE
</programlisting>
<para>The <literal>gtk_widget_set_usize()</literal> functions
is not the easiest way to set a window size since you cannot
decrease this window size with another call to this function
unless you call it twice, as in:</para>
<programlisting role="C">
gtk_widget_set_usize(your_widget, -1, -1);
gtk_widget_set_usize(your_widget, new_x_size, new_y_size);
</programlisting>
<para>Another way to set the size of and/or move a window is to use
the <literal>gdk_window_move_resize()</literal> function which
uses to work fine both to grow or to shrink the window:</para>
<programlisting role="C">
gdk_window_move_resize(window->window,
x_pos, y_pos,
x_size, y_size);
</programlisting>
</sect1>