Commit 32298832 authored by Emmanuele Bassi's avatar Emmanuele Bassi

Allow checking for GDK backends

Now that a single shared object can contain multiple backends we also
need to provide a simple way for third party code to verify that the
copy of GDK they are linking to supports their backend.

The simplest way to verify is an m4 macro, GTK_CHECK_BACKEND(), shipped
with the gtk+ m4 macros.

The usage is pretty basic:

  GTK_CHECK_BACKEND([x11], [gtk_has_x11=yes], [gtk_has_x11=no])
  AM_CONDITIONAL(BUILD_X11_CODE, test "x$gtk_has_x11" = "xno")

https://bugzilla.gnome.org/show_bug.cgi?id=642479
parent 68d176d8
......@@ -69,5 +69,33 @@ define the preprocessor symbol GDK_MULTIDEVICE_SAFE by using the command
line option <literal>-DGTK_MULTIDEVICE_SAFE=1</literal>.
</para>
<refsect2>
<title>Useful autotools macros</title>
<para>
GTK+ provides various macros for easily checking version and backends
supported. The macros are
<variablelist>
<varlistentry>
<term>AM_PATH_GTK_3_0([minimum-version], [if-found], [if-not-found], [modules])</term>
<listitem>This macro should be used to check that GTK+ is installed
and available for compilation. The four arguments are optional, and
they are: <emphasis>minimum-version</emphasis>, the minimum version
of GTK+ required for compilation; <emphasis>if-found</emphasis>, the
action to perform if a valid version of GTK+ has been found;
<emphasis>if-not-found</emphasis>, the action to perform if a valid
version of GTK+ has not been found; <emphasis>modules</emphasis>, a
list of modules to be checked along with GTK+.</listitem>
</varlistentry>
<varlistentry>
<term>GTK_CHECK_BACKEND([backend-name], [if-found], [if-not-found])</term>
<listitem>This macro should be used to check if a specific backend
is supported by GTK+. The <emphasis>if-found</emphasis> and the
<emphasis>if-not-found</emphasis> arguments are optional.</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
</refsect1>
</refentry>
......@@ -891,6 +891,19 @@ gdk_window_add_filter (NULL, message_filter, NULL);
}
</programlisting></informalexample>
</para>
<para>
If you used the pkg-config variable <varname>target</varname> to
conditionally build part of your project depending on the GDK backend,
for instance like this:
<informalexample><programlisting>
AM_CONDITIONAL(BUILD_X11, test `$PKG_CONFIG --variable=target gtk+-2.0` = "x11")
</programlisting></informalexample>
then you should now use the M4 macro provided by GTK+ itself:
<informalexample><programlisting>
GTK_CHECK_BACKEND([x11], [have_x11=yes], [have_x11=no])
AM_CONDITIONAL(BUILD_x11, [test "x$have_x11" = "xyes"])
</programlisting></informalexample>
</para>
</section>
<section>
......
......@@ -194,3 +194,35 @@ main ()
AC_SUBST(GTK_LIBS)
rm -f conf.gtktest
])
dnl GTK_CHECK_BACKEND(BACKEND-NAME [, ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]])
dnl Tests for BACKEND-NAME in the GTK targets list
dnl
AC_DEFUN([GTK_CHECK_BACKEND],
[
backend=$1
if test "x$backend" = "x"; then
AC_MSG_ERROR([A backend must be specified])
fi
PKG_PROG_PKG_CONFIG([0.16])
GDK_TARGETS=`$PKG_CONFIG --variable=targets gdk-3.0`
if test "x$GDK_TARGETS" = "x"; then
ifelse([$3],,[AC_MSG_ERROR([GDK targets not found.])],[$3])
else
ifelse([$2],,[:],[$2])
fi
target_found=no
for target in $GDK_TARGETS; do
if test "x$target" = "x$backend"; then
target_found=yes
fi
done
if test "x$target_found" = "xno"; then
ifelse([$3],,[AC_MSG_ERROR([Backend $backend not found.])],[$3])
else
ifelse([$2],,[:],[$2])
fi
])
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