gpui: Introduce PlatformKeyboardLayout trait for human-friendly keyboard layout names (#29049)

This PR adds a new `PlatformKeyboardLayout` trait with two methods:
`id(&self) -> &str` and `name(&self) -> &str`. The `id()` method returns
a unique identifier for the keyboard layout, while `name()` provides a
human-readable name. This distinction is especially important on
Windows, where the `id` and `name` can be quite different. For example,
the French layout has an `id` of `0000040C`, which is not
human-readable, whereas the `name` would simply be `French`. Currently,
the existing `keyboard_layout()` method returns what's essentially the
same as `id()` in this new design.

This PR implements the `name()` method for both Windows and macOS. On
Linux, for now, `name()` still returns the same value as `id()`.

Release Notes:

- N/A

crates/gpui/src/platform/mac/platform.rs

@@ -7,9 +7,9 @@ use super::{
 use crate::{
     Action, AnyWindowHandle, BackgroundExecutor, ClipboardEntry, ClipboardItem, ClipboardString,
     CursorStyle, ForegroundExecutor, Image, ImageFormat, Keymap, MacDispatcher, MacDisplay,
-    MacWindow, Menu, MenuItem, PathPromptOptions, Platform, PlatformDisplay, PlatformTextSystem,
-    PlatformWindow, Result, ScreenCaptureSource, SemanticVersion, Task, WindowAppearance,
-    WindowParams, hash,
+    MacWindow, Menu, MenuItem, PathPromptOptions, Platform, PlatformDisplay,
+    PlatformKeyboardLayout, PlatformTextSystem, PlatformWindow, Result, ScreenCaptureSource,
+    SemanticVersion, Task, WindowAppearance, WindowParams, hash,
 };
 use anyhow::{Context as _, anyhow};
 use block::ConcreteBlock;
@@ -825,20 +825,8 @@ impl Platform for MacPlatform {
         self.0.lock().validate_menu_command = Some(callback);
     }
 
-    fn keyboard_layout(&self) -> String {
-        unsafe {
-            let current_keyboard = TISCopyCurrentKeyboardLayoutInputSource();
-
-            let input_source_id: *mut Object = TISGetInputSourceProperty(
-                current_keyboard,
-                kTISPropertyInputSourceID as *const c_void,
-            );
-            let input_source_id: *const std::os::raw::c_char =
-                msg_send![input_source_id, UTF8String];
-            let input_source_id = CStr::from_ptr(input_source_id).to_str().unwrap();
-
-            input_source_id.to_string()
-        }
+    fn keyboard_layout(&self) -> Box<dyn PlatformKeyboardLayout> {
+        Box::new(MacKeyboardLayout::new())
     }
 
     fn app_path(&self) -> Result<PathBuf> {
@@ -1501,6 +1489,7 @@ unsafe extern "C" {
     pub(super) fn LMGetKbdType() -> u16;
     pub(super) static kTISPropertyUnicodeKeyLayoutData: CFStringRef;
     pub(super) static kTISPropertyInputSourceID: CFStringRef;
+    pub(super) static kTISPropertyLocalizedName: CFStringRef;
 }
 
 mod security {
@@ -1590,6 +1579,45 @@ impl UTType {
     }
 }
 
+struct MacKeyboardLayout {
+    id: String,
+    name: String,
+}
+
+impl PlatformKeyboardLayout for MacKeyboardLayout {
+    fn id(&self) -> &str {
+        &self.id
+    }
+
+    fn name(&self) -> &str {
+        &self.name
+    }
+}
+
+impl MacKeyboardLayout {
+    fn new() -> Self {
+        unsafe {
+            let current_keyboard = TISCopyCurrentKeyboardLayoutInputSource();
+
+            let id: *mut Object = TISGetInputSourceProperty(
+                current_keyboard,
+                kTISPropertyInputSourceID as *const c_void,
+            );
+            let id: *const std::os::raw::c_char = msg_send![id, UTF8String];
+            let id = CStr::from_ptr(id).to_str().unwrap().to_string();
+
+            let name: *mut Object = TISGetInputSourceProperty(
+                current_keyboard,
+                kTISPropertyLocalizedName as *const c_void,
+            );
+            let name: *const std::os::raw::c_char = msg_send![name, UTF8String];
+            let name = CStr::from_ptr(name).to_str().unwrap().to_string();
+
+            Self { id, name }
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::ClipboardItem;