[pango/simple-fontmap] Improve serialization for PangoHbFont

[Matthias Clasen <matthiasc src gnome org>]

commit 738c6b897031f8d49d63bc17ac4e153f15c8efb0
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Dec 26 12:42:30 2021 -0500

    Improve serialization for PangoHbFont
    
    Include index and instance_id in the output.

 pango/serializer.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
---
diff --git a/pango/serializer.c b/pango/serializer.c
index 2dab93b4..78fba783 100644
--- a/pango/serializer.c
+++ b/pango/serializer.c
@@ -26,6 +26,7 @@
 #include <pango/pango-context-private.h>
 #include <pango/pango-enum-types.h>
 #include <pango/pango-font-private.h>
+#include <pango/pango-hbface-private.h>
 
 #include <hb-ot.h>
 #include "pango/json/gtkjsonparserprivate.h"
@@ -549,6 +550,8 @@ add_font (GtkJsonPrinter *printer,
   const int *coords;
   hb_feature_t features[32];
   PangoMatrix matrix;
+  unsigned int index;
+  int instance_id;
 
   gtk_json_printer_start_object (printer, member);
 
@@ -567,6 +570,25 @@ add_font (GtkJsonPrinter *printer,
 
   gtk_json_printer_add_string (printer, "checksum", str);
 
+  if (PANGO_IS_HB_FACE (pango_font_get_face (font)))
+    {
+      PangoHbFace *hbface = PANGO_HB_FACE (pango_font_get_face (font));
+
+      index = hbface->index;
+      instance_id = hbface->instance_id;
+    }
+  else
+    {
+      index = hb_face_get_index (face);
+      instance_id = (index >> 16) - 1;
+      index = index & 0xffff;
+    }
+
+  if (index != 0)
+    gtk_json_printer_add_integer (printer, "index", index);
+  if (instance_id != -1)
+    gtk_json_printer_add_integer (printer, "instance-id", instance_id);
+
   g_free (str);
   hb_blob_destroy (blob);