[fontations] Start building a libharfbuzz-fontations

meson.build

@@ -1,4 +1,4 @@
-project('harfbuzz', 'c', 'cpp',
+project('harfbuzz', ['c', 'cpp', 'rust'],
   meson_version: '>= 0.55.0',
   version: '10.4.0',
   default_options: [

meson_options.txt

@@ -15,6 +15,8 @@ option('graphite2', type: 'feature', value: 'disabled',
   description: 'Enable Graphite2 complementary shaper')
 option('freetype', type: 'feature', value: 'auto',
   description: 'Enable freetype interop helpers')
+option('fontations', type: 'feature', value: 'disabled',
+  description: 'Enabled fontations font functions')
 option('gdi', type: 'feature', value: 'disabled',
   description: 'Enable GDI helpers and Uniscribe shaper backend (Windows only)')
 option('directwrite', type: 'feature', value: 'disabled',

src/fontations/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "harfbuzz_fontations"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+name = "harfbuzz_fontations"
+crate-type = ["rlib"]
+
+[dependencies]
+read-fonts = "0.20"
+skrifa = "0.20"
+libc = "0.2"

src/fontations/lib.rs

@@ -0,0 +1,124 @@
+//
+// lib.rs — Rust code that sets up HarfBuzz font funcs
+//
+
+use std::os::raw::{c_void, c_char};
+use std::ptr::{null_mut};
+
+// If you want to parse TTF/OTF with read-fonts, etc. import them:
+// use read_fonts::FontRef;
+// use skrifa::{...};
+
+// Minimal HarfBuzz FFI
+// Typically you'd generate these with bindgen from <hb.h>, but we'll do a small subset:
+
+pub type hb_bool_t = i32;
+pub type hb_position_t = i32;
+pub type hb_codepoint_t = u32;
+pub type hb_destroy_func_t = Option<extern "C" fn(user_data: *mut c_void)>;
+
+#[repr(C)]
+pub struct hb_font_t { _unused: [u8; 0], }
+
+#[repr(C)]
+pub struct hb_font_funcs_t { _unused: [u8; 0], }
+
+extern "C" {
+    fn hb_font_funcs_create() -> *mut hb_font_funcs_t;
+
+    fn hb_font_funcs_set_glyph_h_advance_func(
+        ffuncs: *mut hb_font_funcs_t,
+        func: Option<hb_font_get_glyph_advance_func_t>,
+        user_data: *mut c_void,
+        destroy: hb_destroy_func_t
+    );
+
+    fn hb_font_set_funcs(
+        font: *mut hb_font_t,
+        klass: *mut hb_font_funcs_t,
+        font_data: *mut c_void,
+        destroy: hb_destroy_func_t
+    );
+
+    fn hb_font_funcs_destroy (
+        ffuncs: *mut hb_font_funcs_t
+    );
+
+    // If you need more sets or functions, declare them here
+}
+
+// Callback type: e.g. horizontal advance
+pub type hb_font_get_glyph_advance_func_t = extern "C" fn(
+    font: *mut hb_font_t,
+    font_data: *mut c_void,
+    glyph: hb_codepoint_t,
+    user_data: *mut c_void
+) -> hb_position_t;
+
+// A struct for storing your “fontations” data
+#[repr(C)]
+pub struct FontationsData {
+    // e.g. storing an owned font buffer, or read-fonts handles:
+    // font_bytes: Vec<u8>,
+    // font_ref: Option<FontRef<'static>>,
+    pub offset: i32,
+}
+
+// A destructor for the user_data
+#[no_mangle]
+pub extern "C" fn fontations_data_destroy(ptr: *mut c_void) {
+    if !ptr.is_null() {
+        unsafe { Box::from_raw(ptr as *mut FontationsData); }
+    }
+}
+
+// Our callback: get glyph horizontal advance
+#[no_mangle]
+pub extern "C" fn hb_fontations_get_glyph_h_advance(
+    _font: *mut hb_font_t,
+    font_data: *mut c_void,
+    glyph: hb_codepoint_t,
+    _user_data: *mut 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
+}
+
+#[no_mangle]
+pub extern "C" fn _hb_fontations_font_funcs_create() -> *mut hb_font_funcs_t {
+    let ffuncs = unsafe { hb_font_funcs_create() };
+
+    unsafe {
+        hb_font_funcs_set_glyph_h_advance_func(
+            ffuncs,
+            Some(hb_fontations_get_glyph_h_advance),
+            null_mut(),
+            None
+        );
+    }
+
+    ffuncs
+}
+
+// A helper to attach these funcs to a hb_font_t
+#[no_mangle]
+pub extern "C" fn hb_fontations_font_set_funcs(
+    font: *mut hb_font_t,
+) {
+    let ffuncs = _hb_fontations_font_funcs_create ();
+
+    // Set up some data for the callbacks to use:
+    let data = FontationsData { offset: 100 };
+    let data_ptr = Box::into_raw(Box::new(data)) as *mut c_void;
+
+    unsafe {
+        hb_font_set_funcs (font, ffuncs, data_ptr, Some(fontations_data_destroy));
+    }
+
+    unsafe { hb_font_funcs_destroy (ffuncs); }
+}

src/fontations/meson.build

@@ -0,0 +1,9 @@
+harfbuzz_dep = dependency('harfbuzz', required: true)
+
+harfbuzz_fontations_rust = static_library(
+  'harfbuzz_fontations_rust',
+  'lib.rs',
+  dependencies: [harfbuzz_dep],
+  rust_abi: 'c',
+  install: true,
+)

src/hb-fontations.h

@@ -0,0 +1,37 @@
+/*
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_FONTATIONS_H
+#define HB_FONTATIONS_H
+
+#include "hb.h"
+
+HB_BEGIN_DECLS
+
+HB_EXTERN void
+hb_fontations_font_set_funcs (hb_font_t *font);
+
+HB_END_DECLS
+
+#endif /* HB_CAIRO_H */

src/meson.build

@@ -693,6 +693,57 @@ if conf.get('HAVE_CAIRO', 0) == 1
   )
 endif
 
+libharfbuzz_fontations_dep = null_dep
+if get_option('fontations').enabled()
+
+  subdir('fontations')
+
+  hb_fontations_sources = [
+  ]
+
+  hb_fontations_headers = [
+    'hb-fontations.h',
+  ]
+
+  harfbuzz_fontations_rust_dep = declare_dependency(
+    link_with: harfbuzz_fontations_rust,
+    dependencies: [harfbuzz_dep], # XXX
+  )
+
+  libharfbuzz_fontations = library('harfbuzz-fontations', hb_fontations_sources,
+    include_directories: incconfig,
+    dependencies: [harfbuzz_fontations_rust_dep],
+    link_with: [libharfbuzz],
+     cpp_args: cpp_args + extra_hb_cpp_args,
+    soversion: hb_so_version,
+    version: version,
+    install: true,
+    darwin_versions: darwin_versions,
+    link_language: chosen_linker,
+  )
+
+  install_headers(hb_fontations_headers, subdir: meson.project_name())
+
+  libharfbuzz_fontations_dep = declare_dependency(
+    link_with: libharfbuzz_fontations,
+    include_directories: incsrc,
+    dependencies: [])
+  meson.override_dependency('harfbuzz-fontations', libharfbuzz_fontations_dep)
+
+  harfbuzz_fontations_def = custom_target('harfbuzz-fontations.def',
+    command: gen_def_cmd,
+    input: hb_fontations_headers,
+    output: 'harfbuzz-fontations.def')
+  defs_list += [harfbuzz_fontations_def]
+
+  pkgmod.generate(libharfbuzz_fontations,
+    description: 'HarfBuzz fontations support',
+    requires: ['harfbuzz = @0@'.format(meson.project_version())],
+    subdirs: [meson.project_name()],
+    version: meson.project_version(),
+  )
+endif
+
 if get_option('tests').enabled()
   # TODO: Microsoft LINK gives the following because extern, non dllexport
   # symbols can only be used when linking against a static library