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[fontations] Working get_glyph_advance()

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This commit is contained in:
Behdad Esfahbod 2025-03-04 04:45:07 -07:00 • committed by Khaled Hosny
parent 77b20cf7b9
commit 94a6cfba89
1 changed files with 25 additions and 14 deletions
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39
src/fontations/lib.rs
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@ -5,17 +5,14 @@ include!(concat!(env!("OUT_DIR"), "/hb.rs"));
use std::os::raw::{c_void};
use std::ptr::{null_mut};
// If you want to parse TTF/OTF with read-fonts, etc. import them:
//extern crate read_fonts;
//use read_fonts::FontRef;
// use skrifa::{...};
use skrifa::{MetadataProvider, GlyphId};
use skrifa::font::FontRef;
use skrifa::instance::{Location, Size};
// A struct for storing your “fontations” data
#[repr(C)]
struct FontationsData {
// e.g. storing an owned font buffer, or read-fonts handles:
// font_bytes: Vec<u8>,
// font_ref: Option<FontRef<'static>>,
font_ref: FontRef<'static>,
pub offset: i32,
}
@ -28,18 +25,25 @@ extern "C" fn _hb_fontations_data_destroy(ptr: *mut c_void) {
// Our callback: get glyph horizontal advance
extern "C" fn _hb_fontations_get_glyph_h_advance(
_font: *mut hb_font_t,
font_data: *mut c_void,
font: *mut hb_font_t,
font_data: *mut ::std::os::raw::c_void,
glyph: hb_codepoint_t,
_user_data: *mut c_void
_user_data: *mut ::std::os::raw::c_void,
) -> hb_position_t {
let data = unsafe {
assert!(!font_data.is_null());
&*(font_data as *const FontationsData)
};
// Just a dummy formula:
let advance = (glyph as i32) + data.offset;
advance
let mut x_scale : i32 = 0;
let mut y_scale : i32 = 0;
unsafe { hb_font_get_scale(font, &mut x_scale, &mut y_scale); };
let font_ref = &data.font_ref;
let size = Size::new(x_scale as f32);
let glyph_id = GlyphId::new(glyph);
let location = Location::default();
let glyph_metrics = font_ref.glyph_metrics(size, &location);
let advance = glyph_metrics.advance_width(glyph_id).unwrap_or_default();
advance as hb_position_t
}
fn _hb_fontations_font_funcs_create() -> *mut hb_font_funcs_t {
@ -64,8 +68,15 @@ pub extern "C" fn hb_fontations_font_set_funcs(
) {
let ffuncs = _hb_fontations_font_funcs_create ();
let face_index = unsafe { hb_face_get_index(hb_font_get_face(font)) };
let face_blob = unsafe { hb_face_reference_blob(hb_font_get_face(font)) };
let blob_length = unsafe { hb_blob_get_length(face_blob) };
let blob_data = unsafe { hb_blob_get_data(face_blob, null_mut()) };
let face_data = unsafe { std::slice::from_raw_parts(blob_data as *const u8, blob_length as usize) };
let font_ref = FontRef::from_index(face_data, face_index).unwrap();
// Set up some data for the callbacks to use:
let data = FontationsData { offset: 100 };
let data = FontationsData { font_ref, offset: 100 };
let data_ptr = Box::into_raw(Box::new(data)) as *mut c_void;
unsafe {