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-<?xml version="1.0"?>
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
- "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
-]>
-<refentry id="gtk-other-software">
-<refmeta>
-<refentrytitle>Mixing GTK with other software</refentrytitle>
-<manvolnum>3</manvolnum>
-<refmiscinfo>Mixing GTK with other software</refmiscinfo>
-</refmeta>
-
-<refnamediv>
-<refname>Mixing GTK with other software</refname>
-<refpurpose>
-How to combine GTK with other code and event loops
-</refpurpose>
-</refnamediv>
-
-<refsect1>
-<title>Overview</title>
-
-<para>
-Often people want to use GTK in combination with another library or existing
-body of code that is not GTK-aware. The general problem people encounter
-is that the control flow of the other code does not return to GTK, so
-widgets do not repaint, mouse and keyboard events are ignored, and so forth.
-</para>
-
-<para>
-This section describes some approaches to solving this problem. The most
-suitable approach depends on the code that's involved, the platforms you're
-targetting, and your own familiarity with each approach.
-</para>
-
-</refsect1>
-
-<refsect1>
-<title>Periodically yield to GTK main loop</title>
-
-<para>
-This is the simplest method, but requires you to modify the non-GTK code.
-Say you have a function that does some kind of lengthy task:
-<informalexample>
-<programlisting>
- void
- do_lengthy_task (void)
- {
- int i;
- for (i = 0; i < BIG_NUMBER; ++i)
- {
- do_small_part_of_task ();
- }
- }
-</programlisting>
-</informalexample>
-You simply insert code into this function that processes pending main loop tasks, if any:
-<informalexample>
-<programlisting>
- void
- do_lengthy_task (void)
- {
- int i;
- for (i = 0; i < BIG_NUMBER; ++i)
- {
- do_small_part_of_task ();
-
- /* allow main loop to process pending events; NULL
- * means the default context.
- */
- while (g_main_context_pending (NULL))
- g_main_context_iteration (NULL, FALSE);
- }
- }
-</programlisting>
-</informalexample>
-</para>
-
-<para>
-The primary disadvantage of this approach is that you have to trade off UI
-responsiveness and the performance of the task. That is, if
-do_small_part_of_task() does very little of the task, you'll spend lots of CPU
-time on <link
-linkend="g-main-context-iteration">g_main_context_iteration()</link>. While if
-do_small_part_of_task() does a lot of work, the GUI will seem noticeably
-"chunky" to the user.
-</para>
-
-<para>
-Another disadvantage to this approach is that you can't have more than one
-lengthy task at the same time, unless you manually integrate them.
-</para>
-
-<para>
-The big advantage of this approach is that it's simple and straightforward, and
-works fine for simple applications such as tossing up a progress bar during the
-lengthy task.
-</para>
-
-</refsect1>
-
-<refsect1>
-<title>Run the other code as a slave of the GTK main loop</title>
-
-<para>
-As a slightly cleaner solution, you can ask the main loop to run a small part of your
-task whenever it isn't busy — that is, when it's <firstterm>idle</firstterm>.
-GLib provides a function <link linkend="g-idle-add">g_idle_add()</link> that's useful
-for this. An "idle handler" added with <link linkend="g-idle-add">g_idle_add()</link>
-will be run continuously as long as it returns <literal>TRUE</literal>. However,
-the main loop gives higher priority to GUI-related tasks, so will run those instead
-when appropriate.
-</para>
-
-<para>
-Here's a simple example:
-<informalexample>
-<programlisting>
- gboolean
- my_idle_handler (gpointer user_data)
- {
- do_small_part_of_task ();
-
- if (task_complete)
- return G_SOURCE_REMOVE; /* removes the idle handler */
- else
- return G_SOURCE_CONTINUE; /* runs the idle handler again */
- }
-
- g_idle_add (my_idle_handler, NULL);
-</programlisting>
-</informalexample>
-</para>
-
-<para>
-If your task involves reading data from the network, you should instead use
-<link linkend="g-input-add">g_input_add()</link>; this will allow the
-main loop to sleep until data is available on a file descriptor, then
-wake up to read that data.
-</para>
-
-<para>
-<link linkend="g-idle-add">g_idle_add()</link> returns a main loop source ID you can
-use to remove the idle handler with <link linkend="g-source-remove">g_source_remove()</link>.
-This is useful for cancelling a task, for example. Another approach is to keep a flag
-variable and have the idle handler itself return <literal>FALSE</literal> when appropriate.
-</para>
-
-</refsect1>
-
-<refsect1>
-<title>Use multiple processes</title>
-
-<para>
-If you can't break a task into small chunks — the
-"do_small_part_of_task()" function in the above examples — you'll have to
-separate your program into two parts, by spawning a child thread or process.
-A process does not share the same address space (variables and data) with its parent.
-A thread does share the same address space, so a change made to a variable in
-one thread will be visible to other threads as well.
-</para>
-
-<para>
-This manual can't go into full detail on processes, threads, and other UNIX
-programming topics. You may wish to get a book or two — two I'm familiar
-with are Beginning Linux Programming (WROX Press) and Advanced Programming in
-the UNIX Environment (by Richard Stevens.
-</para>
-
-<para>
-Those books also cover the central issue you'll need to address in order to have
-a multi-process application: how to communicate between the processes. The
-simplest solution is to use pipes; <link
-linkend="g-input-add">g_input_add()</link> in combination with <link
-linkend="g-spawn-async-with-pipes">g_spawn_async_with_pipes()</link> should make
-this reasonably convenient. There are other possibilities, of course, such as
-sockets, shared memory, and X Window System client message events, depending on
-your needs.
-</para>
-
-</refsect1>
-
-
-<refsect1>
-<title>Use multiple threads</title>
-
-<para>
-
-</para>
-
-</refsect1>
-
-<refsect1>
-<title>Integrate the GTK main loop with another main loop</title>
-
-<para>
-</para>
-
-</refsect1>
-
-
-<refsect1>
-<title>Things that won't work</title>
-
-<para>
-signals
-</para>
-
-</refsect1>
-
-
-</refentry>
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