WINGs: Add optional Pango text layout support

Currently WINGs renders text using Xft directly which does not support
any advanced text layout that is needed for scripts like Arabic or Indic
scripts (or even things like automatic ligature support for Latin
script).

With Pango we also get text fallback for free, so no more square boxes
for characters not supported in the current font (unless no font on the
system supports the specified character, of course).

This patch introduces support for using Pango to render the text (though
its Xft backed), to avoid forcing the additional dependency to everyone
it is made off by default.

Signed-off-by: Carlos R. Mafra <crmafra@gmail.com>

configure.ac

@@ -625,6 +625,26 @@ fi
 AC_SUBST(XFTFLAGS)
 AC_SUBST(XFTLIBS)
 
+dnl PANGO support
+dnl =============
+pango=no
+AC_ARG_ENABLE(pango, AS_HELP_STRING([--enable-pango], [enable Pango text layout support]),
+                pango=$enableval, pango=no)
+
+PANGOFLAGS=
+PANGOLIBS=
+if test "$pango" = yes; then
+	PANGOLIBS=`$PKGCONFIG pangoxft --libs`
+	PANGOFLAGS=`$PKGCONFIG pangoxft --cflags`
+	if test "x$PANGOLIBS" = "x" ; then
+	        AC_MSG_RESULT([not found])
+	else
+		AC_DEFINE(USE_PANGO, 1, [Define if Pango is to be used])
+		AC_MSG_RESULT([found])
+	fi
+fi
+inc_search_path="$inc_search_path $PANGOFLAGS"
+AC_SUBST(PANGOLIBS)
 
 dnl ==============================================
 dnl         Graphic Format Libraries
@@ -869,6 +889,7 @@ echo "Supported X extensions:             :$supported_xext"
 echo "Supported graphic format libraries  :$supported_gfx"
 echo "Unsupported features                :$unsupported"
 echo "Antialiased text support in WINGs   : $xft"
+echo "Pango text layout support in WINGs  : $pango"
 echo "Translated message files to install : $mof"
 dnl echo "Supported languages beside English  : $languages"
 if test "x$MOFILES" != "x"; then