From d769e8ae7c125cf2ed0686f3c9e99e9525ecbbd4 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sun, 15 Jan 2023 10:58:15 -0700
Subject: [PATCH] [hb-shape/view] Add --named-instance

---
 src/hb-font.cc       | 11 ++++++-----
 util/font-options.hh |  3 +++
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/hb-font.cc b/src/hb-font.cc
index 29f69c8c1..b5c82a948 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -2536,15 +2536,16 @@ hb_font_set_variations (hb_font_t            *font,
   }
 
   /* Initialize design coords. */
-  if (font->instance_index == HB_FONT_NO_VAR_NAMED_INSTANCE)
-    for (unsigned int i = 0; i < coords_length; i++)
-      design_coords[i] = axes[i].get_default ();
-  else
+  for (unsigned int i = 0; i < coords_length; i++)
+    design_coords[i] = axes[i].get_default ();
+  if (font->instance_index != HB_FONT_NO_VAR_NAMED_INSTANCE)
   {
     unsigned count = coords_length;
+    /* This may fail if index is out-of-range;
+     * That's why we initialize design_coords from fvar above
+     * unconditionally. */
     hb_ot_var_named_instance_get_design_coords (font->face, font->instance_index,
 						&count, design_coords);
-    assert (count == coords_length);
   }
 
   for (unsigned int i = 0; i < variations_length; i++)
diff --git a/util/font-options.hh b/util/font-options.hh
index 9b0c2ab5d..64a462abe 100644
--- a/util/font-options.hh
+++ b/util/font-options.hh
@@ -71,6 +71,7 @@ struct font_options_t : face_options_t
   char *font_funcs = nullptr;
   int ft_load_flags = 2;
   unsigned int palette = 0;
+  unsigned int named_instance = 0;
 
   hb_font_t *font = nullptr;
 };
@@ -113,6 +114,7 @@ font_options_t::post_parse (GError **error)
   hb_font_set_scale (font, scale_x, scale_y);
 
 #ifndef HB_NO_VAR
+  hb_font_set_var_named_instance (font, named_instance);
   hb_font_set_variations (font, variations, num_variations);
 #endif
 
@@ -395,6 +397,7 @@ font_options_t::add_options (option_parser_t *parser)
   GOptionEntry entries2[] =
   {
     {"list-variations",	0, 0, G_OPTION_ARG_NONE,	&this->list_variations,		"List available font variations and quit",	nullptr},
+    {"named-instance",	0, 0, G_OPTION_ARG_INT,         &this->named_instance,		"Set named-instance index (default: none)",	"index"},
     {"variations",	0, 0, G_OPTION_ARG_CALLBACK,	(gpointer) &parse_variations,	variations_help,	"list"},
     {nullptr}
   };