Remove yeslogic-fontconfig dependency

We need only 9 different functions from fontconfig and one data
structure.  We can do that interaction with libloading by hand and avoid
causing issues like servo/font-kit#212

Cargo.toml

@@ -95,7 +95,6 @@ rust-version = "1.66"
 [workspace.dependencies]
 resvg = { version= "0.34.0", default-features = false, features = ["text"] }
 fontdb = { version = "0.14.1", default-features = false }
-yeslogic-fontconfig-sys = { version = "3.2.0", features = ["dlopen"] }
 send_wrapper = { version = "0.6.0" }
 
 [profile.release]

internal/common/Cargo.toml

@@ -16,7 +16,7 @@ homepage = "https://slint.dev"
 path = "lib.rs"
 
 [features]
-shared-fontdb = ["dep:fontdb", "dep:libc", "dep:yeslogic-fontconfig-sys", "derive_more", "cfg-if"]
+shared-fontdb = ["dep:fontdb", "dep:libloading", "derive_more", "cfg-if"]
 
 [dependencies]
 fontdb = { workspace = true, optional = true }
@@ -24,8 +24,7 @@ derive_more = { version = "0.99.5", optional = true }
 cfg-if = { version = "1", optional = true }
 
 [target.'cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios", target_arch = "wasm32")))'.dependencies]
-libc = { version = "0.2", optional = true }
+libloading = { version = "0.8.0", optional = true }
-yeslogic-fontconfig-sys = { workspace = true, optional = true }
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 fontdb = { workspace = true, optional = true, default-features = true, features = ["fontconfig", "memmap"] }

internal/common/sharedfontdb/fontconfig.rs

@@ -3,31 +3,86 @@
 
 #![allow(unsafe_code)]
 
-use fontconfig_sys as ffi;
+use core::ffi::{c_char, c_int, c_uchar, c_void};
 
-use ffi::statics::LIB;
+const FC_MATCH_PATTERN: c_int = 0;
+const FC_RESULT_MATCH: c_int = 0;
+
+#[repr(C)]
+struct FcFontSet {
+    nfont: c_int,
+    sfont: c_int,
+    fonts: *mut *mut c_void,
+}
 
 // This is duplicated in the slint-compiler's glyph embedding code
 pub fn find_families(requested_family: &str) -> Vec<String> {
     unsafe {
-        let config = (LIB.FcInitLoadConfigAndFonts)();
+        let fontconfig = libloading::Library::new("libfontconfig.so.1")
+            .expect("Unable to dlopen libfontconfig.so.1");
+        let fc_init_load_config_and_fonts: libloading::Symbol<
+            unsafe extern "C" fn() -> *mut c_void,
+        > = fontconfig
+            .get(b"FcInitLoadConfigAndFonts")
+            .expect("Unable to find FcInitLoadConfigAndFonts");
+        let fc_name_parse: libloading::Symbol<unsafe extern "C" fn(*const c_uchar) -> *mut c_void> =
+            fontconfig.get(b"FcNameParse").expect("Unable to find FcNameParse");
+        let fc_config_substitute: libloading::Symbol<
+            unsafe extern "C" fn(
+                *mut c_void, // FcConfig *
+                *mut c_void, // FcPattern *
+                c_int,       // FcMatchKind
+            ) -> c_int,
+        > = fontconfig.get(b"FcConfigSubstitute").expect("Unable to find FcConfigSubstitute");
+        let fc_default_substitute: libloading::Symbol<unsafe extern "C" fn(*mut c_void)> =
+            fontconfig.get(b"FcDefaultSubstitute").expect("Unable to find FcDefaultSubstitute");
+        let fc_font_sort: libloading::Symbol<
+            unsafe extern "C" fn(
+                *mut c_void,      // FcConfig *
+                *mut c_void,      // FcPattern *
+                c_int,            // FcBool trim
+                *mut *mut c_void, // FcCharSet **
+                *mut c_int,       // FcResult *
+            ) -> *mut FcFontSet,
+        > = fontconfig.get(b"FcFontSort").expect("Unable to find FcFontSort");
+        let fc_pattern_get_string: libloading::Symbol<
+            unsafe extern "C" fn(
+                *mut c_void,       // FcPattern *
+                *const c_char,     // const char *object
+                c_int,             // int n
+                *mut *mut c_uchar, // FcChar8 **s
+            ) -> c_int,
+        > = fontconfig.get(b"FcPatternGetString").expect("Unable to find FcPatternGetString");
+        let fc_font_set_destroy: libloading::Symbol<unsafe extern "C" fn(*mut FcFontSet)> =
+            fontconfig.get(b"FcFontSetDestroy").expect("Unable to find FcFontSetDestroy");
+        let fc_pattern_destroy: libloading::Symbol<
+            unsafe extern "C" fn(
+                *mut c_void, // FcPattern *
+            ),
+        > = fontconfig.get(b"FcPatternDestroy").expect("Unable to find FcPatternDestroy");
+        let fc_config_destroy: libloading::Symbol<
+            unsafe extern "C" fn(
+                *mut c_void, // FcConfig *
+            ),
+        > = fontconfig.get(b"FcConfigDestroy").expect("Unable to find FcConfigDestroy");
+
+        let config = fc_init_load_config_and_fonts();
         let family_cstr = std::ffi::CString::new(requested_family).unwrap();
-        let pattern = (LIB.FcNameParse)(family_cstr.as_ptr() as *mut libc::c_uchar);
+        let pattern = fc_name_parse(family_cstr.as_ptr() as *mut c_uchar);
-        (LIB.FcConfigSubstitute)(std::ptr::null_mut(), pattern, ffi::FcMatchPattern);
+        fc_config_substitute(std::ptr::null_mut(), pattern, FC_MATCH_PATTERN);
-        (LIB.FcDefaultSubstitute)(pattern);
+        fc_default_substitute(pattern);
-        let mut sort_result = ffi::FcResultMatch;
+        let mut sort_result = FC_RESULT_MATCH;
-        let result_set =
+        let result_set = fc_font_sort(config, pattern, 1, std::ptr::null_mut(), &mut sort_result);
-            (LIB.FcFontSort)(config, pattern, 1, std::ptr::null_mut(), &mut sort_result);
 
         let mut families = Vec::new();
         for idx in 0..(*result_set).nfont {
             let mut raw_family_name = std::ptr::null_mut();
-            if (LIB.FcPatternGetString)(
+            if fc_pattern_get_string(
                 *(*result_set).fonts.offset(idx as isize),
-                b"family\0".as_ptr() as *const libc::c_char,
+                b"family\0".as_ptr() as *const c_char,
                 0,
                 &mut raw_family_name,
-            ) != ffi::FcResultMatch
+            ) != FC_RESULT_MATCH
             {
                 continue;
             }
@@ -35,8 +90,7 @@ pub fn find_families(requested_family: &str) -> Vec<String> {
             if raw_family_name.is_null() {
                 continue;
             }
-            if let Some(family_name) =
+            if let Some(family_name) = std::ffi::CStr::from_ptr(raw_family_name as *const c_char)
-                std::ffi::CStr::from_ptr(raw_family_name as *const libc::c_char)
                 .to_str()
                 .ok()
                 .map(|raw_family_name| raw_family_name.to_owned())
@@ -45,9 +99,9 @@ pub fn find_families(requested_family: &str) -> Vec<String> {
             }
         }
 
-        (LIB.FcFontSetDestroy)(result_set);
+        fc_font_set_destroy(result_set);
-        (LIB.FcPatternDestroy)(pattern);
+        fc_pattern_destroy(pattern);
-        (LIB.FcConfigDestroy)(config);
+        fc_config_destroy(config);
         families
     }
 }

internal/core/Cargo.toml

@@ -96,10 +96,6 @@ fontdb = { workspace = true, optional = true, default-features = true, features
 rustybuzz = { version = "0.7.0", optional = true }
 fontdue = { version = "0.7.1", optional = true }
 
-[target.'cfg(not(any(target_family = "windows", target_os = "macos", target_os = "ios", target_arch = "wasm32")))'.dependencies]
-libc = { version = "0.2", optional = true }
-yeslogic-fontconfig-sys = { workspace = true, optional = true }
-
 [dev-dependencies]
 slint = { path = "../../api/rs/slint", default-features = false, features = ["std", "compat-1-0"] }
 i-slint-backend-testing = { path="../backends/testing" }