From 99838770abbd810caf63db7957d524537cb34290 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sun, 15 Jan 2023 10:54:01 -0700
Subject: [PATCH] [font] Add hb_font_get_var_named_instance()

Two new API:
+HB_FONT_NO_VAR_NAMED_INSTANCE
+hb_font_get_var_named_instance
---
 docs/harfbuzz-sections.txt |  2 ++
 src/hb-font.cc             | 28 ++++++++++++++++++++++------
 src/hb-font.h              | 15 ++++++++++++++-
 3 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/docs/harfbuzz-sections.txt b/docs/harfbuzz-sections.txt
index 78158dfa0..c782e7d5e 100644
--- a/docs/harfbuzz-sections.txt
+++ b/docs/harfbuzz-sections.txt
@@ -411,7 +411,9 @@ hb_font_get_scale
 hb_font_set_synthetic_slant
 hb_font_get_synthetic_slant
 hb_font_set_variations
+HB_FONT_NO_VAR_NAMED_INSTANCE
 hb_font_set_var_named_instance
+hb_font_get_var_named_instance
 hb_font_set_var_coords_design
 hb_font_get_var_coords_design
 hb_font_set_var_coords_normalized
diff --git a/src/hb-font.cc b/src/hb-font.cc
index 75271498a..29f69c8c1 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -1776,7 +1776,7 @@ DEFINE_NULL_INSTANCE (hb_font_t) =
   0, /* y_ppem */
   0, /* ptem */
 
-  (unsigned) -1, /* instance_index */
+  HB_FONT_NO_VAR_NAMED_INSTANCE, /* instance_index */
   0, /* num_coords */
   nullptr, /* coords */
   nullptr, /* design_coords */
@@ -1806,7 +1806,7 @@ _hb_font_create (hb_face_t *face)
   font->x_scale = font->y_scale = face->get_upem ();
   font->x_multf = font->y_multf = 1.f;
   font->x_mult = font->y_mult = 1 << 16;
-  font->instance_index = (unsigned) -1;
+  font->instance_index = HB_FONT_NO_VAR_NAMED_INSTANCE;
 
   return font;
 }
@@ -2515,7 +2515,7 @@ hb_font_set_variations (hb_font_t            *font,
 
   font->serial_coords = ++font->serial;
 
-  if (!variations_length && font->instance_index == (unsigned) -1)
+  if (!variations_length && font->instance_index == HB_FONT_NO_VAR_NAMED_INSTANCE)
   {
     hb_font_set_var_coords_normalized (font, nullptr, 0);
     return;
@@ -2536,7 +2536,7 @@ hb_font_set_variations (hb_font_t            *font,
   }
 
   /* Initialize design coords. */
-  if (font->instance_index == (unsigned) -1)
+  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
@@ -2608,13 +2608,13 @@ hb_font_set_var_coords_design (hb_font_t    *font,
  * @font: a font.
  * @instance_index: named instance index.
  *
- * Sets design coords of a font from a named instance index.
+ * Sets design coords of a font from a named-instance index.
  *
  * Since: 2.6.0
  */
 void
 hb_font_set_var_named_instance (hb_font_t *font,
-				unsigned instance_index)
+				unsigned int instance_index)
 {
   if (hb_object_is_immutable (font))
     return;
@@ -2628,6 +2628,22 @@ hb_font_set_var_named_instance (hb_font_t *font,
   hb_font_set_variations (font, nullptr, 0);
 }
 
+/**
+ * hb_font_get_var_named_instance:
+ * @font: a font.
+ *
+ * Returns the currently-set named-instance index of the font.
+ *
+ * Return value: Named-instance index or %HB_FONT_NO_VAR_NAMED_INSTANCE.
+ *
+ * Since: REPLACEME
+ **/
+unsigned int
+hb_font_get_var_named_instance (hb_font_t *font)
+{
+  return font->instance_index;
+}
+
 /**
  * hb_font_set_var_coords_normalized:
  * @font: #hb_font_t to work upon
diff --git a/src/hb-font.h b/src/hb-font.h
index 8f4fe0774..3659735ea 100644
--- a/src/hb-font.h
+++ b/src/hb-font.h
@@ -1160,10 +1160,23 @@ HB_EXTERN const int *
 hb_font_get_var_coords_normalized (hb_font_t *font,
 				   unsigned int *length);
 
+/**
+ * HB_FONT_NO_VAR_NAMED_INSTANCE:
+ *
+ * Constant signifying that a font does not have any
+ * named-instance index set.  This is the default of
+ * a font.
+ *
+ * Since: REPLACEME
+ */
+#define HB_FONT_NO_VAR_NAMED_INSTANCE 0xFFFFFFFF
+
 HB_EXTERN void
 hb_font_set_var_named_instance (hb_font_t *font,
-				unsigned instance_index);
+				unsigned int instance_index);
 
+HB_EXTERN unsigned int
+hb_font_get_var_named_instance (hb_font_t *font);
 
 HB_END_DECLS