From afe1af8fa9de0c05cda5151059ecac37ecd16bda Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 4 Mar 2025 05:18:43 -0700
Subject: [PATCH] [fontations] Implement get_nominal_glyphs()

Shapes now.
---
 src/fontations/lib.rs | 49 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 9 deletions(-)

diff --git a/src/fontations/lib.rs b/src/fontations/lib.rs
index 1e01a3b78..470a9f414 100644
--- a/src/fontations/lib.rs
+++ b/src/fontations/lib.rs
@@ -5,13 +5,14 @@ include!(concat!(env!("OUT_DIR"), "/hb.rs"));
 use std::os::raw::{c_void};
 use std::ptr::{null_mut};
 
-use skrifa::{MetadataProvider, GlyphId};
+use skrifa::{charmap, GlyphId, MetadataProvider};
 use skrifa::font::FontRef;
 use skrifa::instance::{Location, Size};
 
 // A struct for storing your “fontations” data
 #[repr(C)]
-struct FontationsData {
+struct FontationsData
+{
     font_ref: FontRef<'static>,
 }
 
@@ -22,6 +23,32 @@ extern "C" fn _hb_fontations_data_destroy(ptr: *mut c_void) {
     // TODO
 }
 
+extern "C" fn _hb_fontations_get_nominal_glyphs(
+    _font: *mut hb_font_t,
+    font_data: *mut ::std::os::raw::c_void,
+    count: ::std::os::raw::c_uint,
+    first_unicode: *const hb_codepoint_t,
+    unicode_stride: ::std::os::raw::c_uint,
+    first_glyph: *mut hb_codepoint_t,
+    glyph_stride: ::std::os::raw::c_uint,
+    _user_data: *mut ::std::os::raw::c_void,
+) -> ::std::os::raw::c_uint
+{
+    let data = unsafe {
+        assert!(!font_data.is_null());
+        &*(font_data as *const FontationsData)
+    };
+    let font_ref = &data.font_ref;
+    let char_map = charmap::Charmap::new(font_ref);
+
+    for i in 0..count {
+        let unicode = unsafe { *(first_unicode as *const u8).offset((i * unicode_stride) as isize) as *const hb_codepoint_t };
+        let glyph = u32::from(char_map.map(unicode as u32).unwrap_or(GlyphId::new(0)));
+        unsafe { *((first_glyph as *mut u8).offset((i * glyph_stride) as isize) as *mut hb_codepoint_t) = glyph as hb_codepoint_t; }
+    }
+
+    count
+}
 extern "C" fn _hb_fontations_get_glyph_h_advances(
     font: *mut hb_font_t,
     font_data: *mut ::std::os::raw::c_void,
@@ -31,7 +58,8 @@ extern "C" fn _hb_fontations_get_glyph_h_advances(
     first_advance: *mut hb_position_t,
     advance_stride: ::std::os::raw::c_uint,
     _user_data: *mut ::std::os::raw::c_void,
-) {
+)
+{
     let data = unsafe {
         assert!(!font_data.is_null());
         &*(font_data as *const FontationsData)
@@ -45,17 +73,19 @@ extern "C" fn _hb_fontations_get_glyph_h_advances(
     let glyph_metrics = font_ref.glyph_metrics(size, &location);
 
     for i in 0..count {
-        let glyph = unsafe { *first_glyph.offset((i * glyph_stride) as isize) };
-        let glyph_id = GlyphId::new(glyph);
-        let advance = glyph_metrics.advance_width(glyph_id).unwrap_or_default();
-        unsafe { *first_advance.offset((i * advance_stride) as isize) = advance as hb_position_t; }
+        let glyph = unsafe { *(first_glyph as *const u8).offset((i * glyph_stride) as isize) as *const hb_codepoint_t };
+        let glyph_id = GlyphId::new(glyph as u32);
+        let advance = glyph_metrics.advance_width(glyph_id).unwrap_or_default().round() as i32;
+        unsafe { *((first_advance as *mut u8).offset((i * advance_stride) as isize) as *mut hb_position_t) = advance as hb_position_t; }
     }
 }
 
-fn _hb_fontations_font_funcs_create() -> *mut hb_font_funcs_t {
+fn _hb_fontations_font_funcs_create() -> *mut hb_font_funcs_t
+{
     let ffuncs = unsafe { hb_font_funcs_create() };
 
     unsafe {
+        hb_font_funcs_set_nominal_glyphs_func(ffuncs, Some(_hb_fontations_get_nominal_glyphs), null_mut(), None);
         hb_font_funcs_set_glyph_h_advances_func(ffuncs, Some(_hb_fontations_get_glyph_h_advances), null_mut(), None);
     }
 
@@ -66,7 +96,8 @@ fn _hb_fontations_font_funcs_create() -> *mut hb_font_funcs_t {
 #[no_mangle]
 pub extern "C" fn hb_fontations_font_set_funcs(
     font: *mut hb_font_t,
-) {
+)
+{
     let ffuncs = _hb_fontations_font_funcs_create ();
 
     let face_index = unsafe { hb_face_get_index(hb_font_get_face(font)) };