[gimp] app: Use HarfBuzz directly instead of deprecated Pango functions

[Mukund Sivaraman <muks src gnome org>]

commit 33acc4b62b60107484ae5f6f9b00f939af6a6fa0
Author: Mukund Sivaraman <muks banu com>
Date:   Sat May 3 00:20:18 2014 +0530

    app: Use HarfBuzz directly instead of deprecated Pango functions
    
    I have verified manually that the previews ("Aa") shown for English and
    Tamil are correct (i.e., the modified function works).

 app/text/gimpfont.c |   37 ++++++++++++++++++++++++++++++++++---
 1 files changed, 34 insertions(+), 3 deletions(-)
---
diff --git a/app/text/gimpfont.c b/app/text/gimpfont.c
index 66c6e52..ea55a77 100644
--- a/app/text/gimpfont.c
+++ b/app/text/gimpfont.c
@@ -26,6 +26,10 @@
 
 #include <pango/pangocairo.h>
 
+#include <hb.h>
+#include <hb-ot.h>
+#include <hb-ft.h>
+
 #define PANGO_ENABLE_ENGINE  1   /* Argh */
 #include <pango/pango-ot.h>
 
@@ -350,13 +354,30 @@ gimp_font_covers_string (PangoFcFont *font,
   return TRUE;
 }
 
+/* This function was picked up from Pango's pango-ot-info.c. Until there
+ * is a better way to get the tag, we use this.
+ */
+static hb_tag_t
+get_hb_table_type (PangoOTTableType table_type)
+{
+  switch (table_type)
+    {
+    case PANGO_OT_TABLE_GSUB:
+      return HB_OT_TAG_GSUB;
+    case PANGO_OT_TABLE_GPOS:
+      return HB_OT_TAG_GPOS;
+    default:
+      return HB_TAG_NONE;
+    }
+}
+
 /* Guess a suitable short sample string for the font. */
 static const gchar *
 gimp_font_get_sample_string (PangoContext         *context,
                              PangoFontDescription *font_desc)
 {
   PangoFont        *font;
-  PangoOTInfo      *ot_info;
+  hb_face_t        *hb_face;
   FT_Face           face;
   TT_OS2           *os2;
   PangoOTTableType  tt;
@@ -642,7 +663,7 @@ gimp_font_get_sample_string (PangoContext         *context,
 
   face = pango_fc_font_lock_face (PANGO_FC_FONT (font));
   g_return_val_if_fail (face != NULL, "Aa");
-  ot_info = pango_ot_info_get (face);
+  hb_face = hb_ft_face_create (face, NULL);
 
   /* First check what script(s), if any, the font has GSUB or GPOS
    * OpenType layout tables for.
@@ -651,7 +672,15 @@ gimp_font_get_sample_string (PangoContext         *context,
        n_ot_alts < G_N_ELEMENTS (ot_alts) && tt <= PANGO_OT_TABLE_GPOS;
        tt++)
     {
-      PangoOTTag *slist = pango_ot_info_list_scripts (ot_info, tt);
+      hb_tag_t tag;
+      unsigned int count;
+      PangoOTTag *slist;
+
+      tag = get_hb_table_type(tt);
+      count = hb_ot_layout_table_get_script_tags (hb_face, tag, 0, NULL, NULL);
+      slist = g_new (PangoOTTag, count + 1);
+      hb_ot_layout_table_get_script_tags (hb_face, tag, 0, &count, slist);
+      slist[count] = 0;
 
       if (slist)
         {
@@ -687,6 +716,8 @@ gimp_font_get_sample_string (PangoContext         *context,
         }
     }
 
+  hb_face_destroy (hb_face);
+
   DEBUGPRINT (("; OS/2: "));
 
   /* Next check the OS/2 table for Unicode ranges the font claims