patch to improve uninstalled gtk+ handling

Hi,

Attached is a patch to improve configure's handling of
uninstalled Gtk+. The Gtk+ library itself is detected
by pkg-config, so uninstalled Gtk+ can be detected.
However, in later, configure lookup the command
"gdk-pixbuf-query-loaders" listing available gdk-pixbuf
backend for various image file format. configure lookups
it by normal AC_PATH_PROG() macro. Therefore, when Gtk+
is installed to system and the user is trying to build
librsvg with uninstalled Gtk+, gdk-pixbuf-query-loaders
from system is used.

At present, autoconf macro AM_PATH_GTK_2_0() does not
provide an abstract macro to use gdk-pixbuf-query-loaders
of uninstalled Gtk+. I have to detect it by myself.

Invoking gdk-pixbuf-query-loaders simply is insufficient.
This command has a builtin information of the directory
to lookup the loaders (e.g. /usr/local/lib/gtk-2.0/2.x.y/loaders).
Of course, it is different from the building directory.
So the list of uninstalled shared objects or GNU libtool
libraries of the loaders should be passed to uninstalled.
Attached patch generates ${top_builddir}/gdk-pixbuf.loaders
for this purpose.

Thus, when I use uninstalled Gtk+, QUERYLOADERS is not
a pathname of the command, it should be a combination
of the pathname of the command and the arguments.

When "make check" is executed, private gdk-pixbuf.loaders
should be used instead of the file searched by gdk-pixbuf
builtin rule. I introduced new macro SET_GDK_PIXBUF_LOADERS.
It include a sh command setting environmental variable
GDK_PIXBUF_MODULE_FILE point to private gdk-pixbuf.loaders.
It is executed as a part of "TESTS_ENVIRONMENT" while
"make check" is executed.

I'm not sure if this should be proposed to librsvg or Gtk+
developers. So, please give me comment.

Regards,
mpsuzuki


diff --git a/tests/Makefile.am b/tests/Makefile.am
index 4b07418..d2c8aab 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,6 +1,8 @@
 SUBDIRS=pdiff .
 
 TESTS = rsvg-test
+TESTS_ENVIRONMENT = \
+	$(SET_GDK_PIXBUF_LOADERS)
 
 LDADD = $(top_builddir)/librsvg-2.la		\
 	$(top_builddir)/tests/pdiff/libpdiff.la
diff --git a/configure.in b/configure.in
index 2d9517f..c144ddf 100644
--- a/configure.in
+++ b/configure.in
@@ -254,14 +254,45 @@ fi
 
 AM_CONDITIONAL(ENABLE_GTK_ENGINE, test "x$enable_gtk_theme" = "xyes")
 
-AC_PATH_PROG(QUERYLOADERS, gdk-pixbuf-query-loaders, true)
+m4_pattern_allow([PKG_CONFIG_DISABLE_UNINSTALLED])
+m4_pattern_allow([PKG_CONFIG_TOP_BUILD_DIR])
+
+
+SET_GDK_PIXBUF_LOADERS=
+gdk_installed=`env PKG_CONFIG_DISABLE_UNINSTALLED=yes $PKG_CONFIG --uninstalled gdk-pixbuf-2.0 && echo yes || echo no`
+if test "x${gdk_installed}" = "xno"; then
+  AC_MSG_WARN([check uninstalled gdk-pixbuf-query-loaders])
+  for gdk_pixbuf_libs_arg in `env PKG_CONFIG_TOP_BUILD_DIR=. $PKG_CONFIG gdk-pixbuf-2.0 --libs`
+  do
+    case ${gdk_pixbuf_libs_arg} in
+    -*) ;;
+    *la)
+      case `basename ${gdk_pixbuf_libs_arg}` in
+      libgdk_pixbuf*.la)
+        gdk_pixbuf_builddir=`dirname ${gdk_pixbuf_libs_arg}`
+        AC_MSG_WARN([generate gdk-pixbuf.loaders for libraries in ${gdk_pixbuf_builddir}])
+        QUERYLOADERS="${gdk_pixbuf_builddir}/gdk-pixbuf-query-loaders ${gdk_pixbuf_builddir}/libpixbufloader-*.la"
+        ${QUERYLOADERS} > gdk-pixbuf.loaders
+        SET_GDK_PIXBUF_LOADERS='GDK_PIXBUF_MODULE_FILE=${top_builddir}/gdk-pixbuf.loaders'
+        ;;
+      *) ;;
+      esac
+      ;;
+    *) ;;
+    esac
+  done
+else
+  AC_PATH_PROG(QUERYLOADERS, gdk-pixbuf-query-loaders, true)
+fi
+AC_SUBST(SET_GDK_PIXBUF_LOADERS)
+
 
 AC_ARG_ENABLE(pixbuf-loader,
     [  --enable-pixbuf-loader  Enable a RSVG based GdkPixbuf loader [default=auto]],
     enable_pixbuf_loader="$enableval", enable_pixbuf_loader=auto)
 
 if test "x$enable_pixbuf_loader" = xauto ; then
-    if test x$QUERYLOADERS != x ; then 
+    if test "x$QUERYLOADERS" != x ; then 
         enable_pixbuf_loader=yes
     else
         enable_pixbuf_loader=no

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