From 57a527b0c9313e3ffc7aa8b4eaa33fb6ffa0e9d5 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 9 Aug 2023 19:42:13 -0700
Subject: [PATCH] macos: detect keyboard layout change and reload the keymap

---
 include/ghostty.h                    |  1 +
 macos/Sources/Ghostty/AppState.swift | 20 ++++++++++++++++++++
 src/apprt/embedded.zig               | 20 ++++++++++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/include/ghostty.h b/include/ghostty.h
index 658d3a456..798957b50 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -283,6 +283,7 @@ ghostty_app_t ghostty_app_new(const ghostty_runtime_config_s *, ghostty_config_t
 void ghostty_app_free(ghostty_app_t);
 bool ghostty_app_tick(ghostty_app_t);
 void *ghostty_app_userdata(ghostty_app_t);
+void ghostty_app_keyboard_changed(ghostty_app_t);
 
 ghostty_surface_t ghostty_surface_new(ghostty_app_t, ghostty_surface_config_s*);
 void ghostty_surface_free(ghostty_surface_t);
diff --git a/macos/Sources/Ghostty/AppState.swift b/macos/Sources/Ghostty/AppState.swift
index 3bc180288..68076c224 100644
--- a/macos/Sources/Ghostty/AppState.swift
+++ b/macos/Sources/Ghostty/AppState.swift
@@ -74,6 +74,13 @@ extension Ghostty {
                 return
             }
             self.app = app
+            
+            // Subscribe to notifications for keyboard layout change so that we can update Ghostty.
+            NotificationCenter.default.addObserver(
+                self,
+                selector: #selector(self.keyboardSelectionDidChange(notification:)),
+                name: NSTextInputContext.keyboardSelectionDidChangeNotification,
+                object: nil)
 
             self.readiness = .ready
         }
@@ -82,6 +89,12 @@ extension Ghostty {
             // This will force the didSet callbacks to run which free.
             self.app = nil
             self.config = nil
+            
+            // Remove our observer
+            NotificationCenter.default.removeObserver(
+                self,
+                name: NSTextInputContext.keyboardSelectionDidChangeNotification,
+                object: nil)
         }
         
         /// Initializes a new configuration and loads all the values.
@@ -132,6 +145,13 @@ extension Ghostty {
             ghostty_surface_split_focus(surface, direction.toNative())
         }
         
+        // Called when the selected keyboard changes. We have to notify Ghostty so that
+        // it can reload the keyboard mapping for input.
+        @objc private func keyboardSelectionDidChange(notification: NSNotification) {
+            guard let app = self.app else { return }
+            ghostty_app_keyboard_changed(app)
+        }
+        
         // MARK: Ghostty Callbacks
         
         static func newSplit(_ userdata: UnsafeMutableRawPointer?, direction: ghostty_split_direction_e) {
diff --git a/src/apprt/embedded.zig b/src/apprt/embedded.zig
index 43bc7eb43..6d3dd7f43 100644
--- a/src/apprt/embedded.zig
+++ b/src/apprt/embedded.zig
@@ -92,6 +92,17 @@ pub const App = struct {
         self.keymap.deinit();
     }
 
+    /// This should be called whenever the keyboard layout was changed.
+    pub fn reloadKeymap(self: *App) !void {
+        // Reload the keymap
+        try self.keymap.reload();
+
+        // Clear the dead key state since we changed the keymap, any
+        // dead key state is just forgotten. i.e. if you type ' on us-intl
+        // and then switch to us and type a, you'll get a rather than á.
+        self.keymap_state = .{};
+    }
+
     pub fn reloadConfig(self: *App) !?*const Config {
         // Reload
         if (self.opts.reload_config(self.opts.userdata)) |new| {
@@ -475,6 +486,15 @@ pub const CAPI = struct {
         core_app.destroy();
     }
 
+    /// Notify the app that the keyboard was changed. This causes the
+    /// keyboard layout to be reloaded from the OS.
+    export fn ghostty_app_keyboard_changed(v: *App) void {
+        v.reloadKeymap() catch |err| {
+            log.err("error reloading keyboard map err={}", .{err});
+            return;
+        };
+    }
+
     /// Create a new surface as part of an app.
     export fn ghostty_surface_new(
         app: *App,