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<refentry id="multihead" revision="1 May 2002">
<refmeta>
<refentrytitle>Multi-head Support Overview</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>GDK Library</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Multi-head Support Overview</refname>
<refpurpose>Overview of GdkDisplay and GdkScreen</refpurpose>
</refnamediv>
<refsect1>
<title>Overview</title>
<para>
Multihead support is based around two main object types:
<itemizedlist>
<listitem><para>GdkDisplay</para></listitem>
<listitem><para>GdkScreen</para></listitem>
</itemizedlist>
</para>
<para>
<link linkend="gdk-GdkDisplay">GdkDisplay</link> objects are the GDK
representation of the X Display which can be described as <emphasis>a
workstation consisting of a keyboard a pointing device (such as a
mouse) and one or more screens</emphasis>.
It is used to open and keep track of various <link
linkend="gdk-GdkScreen">GdkScreen</link> objects currently
instanciated by the application. It is also used to grab and release
the keyboard and the mouse pointer.
</para>
<para>
<link linkend="gdk-GdkScreen">GdkScreen</link> objects are the GDK
representation of a physical screen. It is used throughout GDK and GTK+
to specify which screen the top level windows are to be displayed on.
It is also used to query the screen specification and default settings such as
the default colormap (<link linkend="gdk-screen-get-default-colormap">gdk_screen_get_default_colormap</link>()),
the screen width (<link linkend="gdk-screen-get-width">gdk_screen_get_width</link>()), etc.
</para>
<para>
The following code samples demonstrate common usage of the objects described above.
</para>
<example>
<title>Testing the number of screen on the current display</title>
<programlisting><!--
-->gint num_screen = 0;
gchar *displayname = NULL;
GdkScreen **screen_list;
GdkDisplay *display;
gtk_init (&argc, &argv);
display = gdk_get_default_display ();
num_screen = gdk_display_get_n_screens (display);
displayname = gdk_display_get_name (display);
if (num_screen <= 1)
{
printf ("This Xserver (%s) manages only one screen. exiting...\n",
displayname);
exit (1);
}
else
{
printf ("This Xserver (%s) manages %d screens.\n", displayname,
num_screen);
}<!--
--> </programlisting>
</example>
<example>
<title>Opening a second display</title>
<programlisting><!--
-->gchar *second_screen_name;
GdkDisplay *second_display;
GdkScreen *second_screen;
GtkWidget *window;
gtk_init (&argc, &argv);
/* screen2_name needs to be initialized before calling
/* gdk_display_new() */
second_display = gdk_display_new (&argc, &argv, second_screen_name);
if (second_display)
second_screen = gdk_display_get_default_screen (second_display);
else
{
g_print ("Can't open display :\n\t%s\n\n",
second_screen_name);
exit (1);
}
/* now GdkScreen can be assigned to GtkWindows */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_screen (window, second_screen);<!--
--></programlisting>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<variablelist>
<varlistentry>
<term><link linkend="gdk-GdkDisplay">GdkDisplay</link></term>
<listitem><para>the GDK Object used to represent and manipulate display
related data</para></listitem>
</varlistentry>
<varlistentry>
<term><link linkend="gdk-GdkScreen">GdkScreen</link></term>
<listitem><para>the GDK Object used to represent and query screen related
data</para></listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
</refentry>
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sgml-parent-document: ("gdk-docs.sgml" "book" "refentry" "")
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