Use objc2 for determining whether font smoothing is enabled

`objc2` / `objc2-foundation` is much more type-safe than `cocoa`, and
automatically ensures that memory management-rules are upheld.

See also alacritty/copypasta#74.

Author: madsmtm

CHANGELOG.md

@@ -6,6 +6,12 @@ The sections should follow the order `Added`, `Changed`, `Fixed`, and `Removed`.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Changed
+
+- On macOS, use `objc2` when determining whether font smoothing is enabled.
+
 ## 0.8.0
 
 ### Changed

Cargo.toml

@@ -25,13 +25,17 @@ freetype-rs = "0.36.0"
 pkg-config = "0.3"
 
 [target.'cfg(target_os = "macos")'.dependencies]
-cocoa = "0.25.0"
 core-foundation = "0.9.3"
 core-text = "20.1.0"
 core-graphics = "0.23.1"
 core-foundation-sys = "0.8.4"
-objc = "0.2.7"
 once_cell = "1.12"
+objc2 = "0.5.1"
+objc2-foundation = { version = "0.2.2", features = [
+    "NSString",
+    "NSUserDefaults",
+    "NSValue",
+] }
 
 [target.'cfg(windows)'.dependencies]
 dwrote = { version = "0.11" }

src/darwin/mod.rs

@@ -1,15 +1,11 @@
 //! Font rendering based on CoreText.
 
 use std::collections::HashMap;
-use std::ffi::c_char;
 use std::ffi::CStr;
 use std::iter;
 use std::path::PathBuf;
 use std::ptr;
 
-use cocoa::base::{id, nil};
-use cocoa::foundation::{NSInteger, NSString, NSUserDefaults};
-
 use core_foundation::array::{CFArray, CFIndex};
 use core_foundation::base::{CFType, ItemRef, TCFType};
 use core_foundation::number::{CFNumber, CFNumberRef};
@@ -28,10 +24,10 @@ use core_text::font_descriptor::{
     self, kCTFontColorGlyphsTrait, kCTFontDefaultOrientation, kCTFontEnabledAttribute,
     CTFontDescriptor, SymbolicTraitAccessors,
 };
+use objc2::rc::{autoreleasepool, Retained};
+use objc2_foundation::{ns_string, NSNumber, NSObject, NSObjectProtocol, NSString, NSUserDefaults};
 
 use log::{trace, warn};
-use objc::rc::autoreleasepool;
-use objc::{class, msg_send, sel, sel_impl};
 use once_cell::sync::Lazy;
 
 pub mod byte_order;
@@ -274,30 +270,40 @@ fn descriptors_for_family(family: &str) -> Vec<Descriptor> {
 // other integer, or a missing value (the default), or a value of any other type, as leaving it
 // enabled.
 static FONT_SMOOTHING_ENABLED: Lazy<bool> = Lazy::new(|| {
-    autoreleasepool(|| unsafe {
-        let key = NSString::alloc(nil).init_str("AppleFontSmoothing");
-        let value: id = msg_send![id::standardUserDefaults(), objectForKey: key];
+    autoreleasepool(|_| {
+        let value = unsafe {
+            NSUserDefaults::standardUserDefaults().objectForKey(ns_string!("AppleFontSmoothing"))
+        };
+        let Some(value) = value else {
+            return true;
+        };
 
-        if msg_send![value, isKindOfClass: class!(NSNumber)] {
-            let num_type: *const c_char = msg_send![value, objCType];
-            if num_type.is_null() {
-                return true;
-            }
+        // SAFETY: The values in `NSUserDefaults` are always subclasses of
+        // `NSObject`.
+        let value: Retained<NSObject> = unsafe { Retained::cast(value) };
+
+        if value.is_kind_of::<NSNumber>() {
+            // SAFETY: Just checked that the value is a NSNumber
+            let value: Retained<NSNumber> = unsafe { Retained::cast(value) };
 
             // NSNumber's objCType method returns one of these strings depending on the size:
             // q = quad (long long), l = long, i = int, s = short.
             // This is done to reject booleans, which are NSNumbers with an objCType of "c", but
             // macOS does not treat them the same as an integer 0 or 1 for this setting,
             // it just ignores it.
             let int_specifiers: [&[u8]; 4] = [b"q", b"l", b"i", b"s"];
-            if !int_specifiers.contains(&CStr::from_ptr(num_type).to_bytes()) {
+
+            let encoding = unsafe { CStr::from_ptr(value.objCType().as_ptr()).to_bytes() };
+            if !int_specifiers.contains(&encoding) {
                 return true;
             }
 
-            let smoothing: NSInteger = msg_send![value, integerValue];
+            let smoothing = value.integerValue();
             smoothing != 0
-        } else if msg_send![value, isKindOfClass: class!(NSString)] {
-            let smoothing: NSInteger = msg_send![value, integerValue];
+        } else if value.is_kind_of::<NSString>() {
+            // SAFETY: Just checked that the value is a NSString
+            let value: Retained<NSString> = unsafe { Retained::cast(value) };
+            let smoothing = unsafe { value.integerValue() };
             smoothing != 0
         } else {
             true