[pango] [fc] Use FcWeightTo/FromOpenType() if available

[Behdad Esfahbod <behdad src gnome org>]

commit 40f5c151e911464cb9da569d8ceee88f52fcbfbf
Author: Behdad Esfahbod <behdad behdad org>
Date:   Sat Jul 26 16:27:59 2014 -0400

    [fc] Use FcWeightTo/FromOpenType() if available
    
    This makes the weight mapping a continuous, as ooposed to a step function.
    
    Last piece of Bug 733764 - Support more / free font weights

 configure.ac            |    6 ++++++
 pango/pangofc-fontmap.c |    8 ++++++++
 2 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 34e0eb9..77c6291 100644
--- a/configure.ac
+++ b/configure.ac
@@ -224,6 +224,12 @@ have_fontconfig=false
 if $have_harfbuzz ; then
   PKG_CHECK_MODULES(FONTCONFIG, fontconfig >= 2.10.91, have_fontconfig=true, AC_MSG_RESULT([no]))
 fi
+if $have_fontconfig ; then
+  pango_save_libs=$LIBS
+  LIBS="$LIBS $FONTCONFIG_LIBS"
+  AC_CHECK_FUNCS(FcWeightFromOpenType)
+  LIBS=$pango_save_libs
+fi
 
 #
 # Checks for FreeType
diff --git a/pango/pangofc-fontmap.c b/pango/pangofc-fontmap.c
index 6da934c..e703458 100644
--- a/pango/pangofc-fontmap.c
+++ b/pango/pangofc-fontmap.c
@@ -1375,6 +1375,9 @@ pango_fc_font_map_list_families (PangoFontMap      *fontmap,
 static int
 pango_fc_convert_weight_to_fc (PangoWeight pango_weight)
 {
+#ifdef HAVE_FCWEIGHTFROMOPENTYPE
+  return FcWeightFromOpenType (pango_weight);
+#else
   if (pango_weight <= (PANGO_WEIGHT_THIN + PANGO_WEIGHT_ULTRALIGHT) / 2)
     return FC_WEIGHT_THIN;
   else if (pango_weight <= (PANGO_WEIGHT_ULTRALIGHT + PANGO_WEIGHT_LIGHT) / 2)
@@ -1399,6 +1402,7 @@ pango_fc_convert_weight_to_fc (PangoWeight pango_weight)
     return FC_WEIGHT_BLACK;
   else
     return FC_WEIGHT_EXTRABLACK;
+#endif
 }
 
 static int
@@ -2061,6 +2065,9 @@ pango_fc_font_map_shutdown (PangoFcFontMap *fcfontmap)
 static PangoWeight
 pango_fc_convert_weight_to_pango (int fc_weight)
 {
+#ifdef HAVE_FCWEIGHTFROMOPENTYPE
+  return FcWeightToOpenType (fc_weight);
+#else
   if (fc_weight <= (FC_WEIGHT_THIN + FC_WEIGHT_EXTRALIGHT) / 2)
     return PANGO_WEIGHT_THIN;
   else if (fc_weight <= (FC_WEIGHT_EXTRALIGHT + FC_WEIGHT_LIGHT) / 2)
@@ -2085,6 +2092,7 @@ pango_fc_convert_weight_to_pango (int fc_weight)
     return PANGO_WEIGHT_HEAVY;
   else
     return PANGO_WEIGHT_ULTRAHEAVY;
+#endif
 }
 
 static PangoStyle