macos: hook up clipboards

include/ghostty.h

@@ -28,11 +28,15 @@ extern "C" {
 // for all of these types is available in the Zig source.
 typedef void (*ghostty_runtime_wakeup_cb)(void *);
 typedef void (*ghostty_runtime_set_title_cb)(void *, const char *);
+typedef const char* (*ghostty_runtime_read_clipboard_cb)(void *);
+typedef void (*ghostty_runtime_write_clipboard_cb)(void *, const char *);
 
 typedef struct {
     void *userdata;
     ghostty_runtime_wakeup_cb wakeup_cb;
     ghostty_runtime_set_title_cb set_title_cb;
+    ghostty_runtime_read_clipboard_cb read_clipboard_cb;
+    ghostty_runtime_write_clipboard_cb write_clipboard_cb;
 } ghostty_runtime_config_s;
 
 typedef struct {
@@ -221,9 +225,11 @@ void ghostty_config_finalize(ghostty_config_t);
 ghostty_app_t ghostty_app_new(const ghostty_runtime_config_s *, ghostty_config_t);
 void ghostty_app_free(ghostty_app_t);
 int ghostty_app_tick(ghostty_app_t);
+void *ghostty_app_userdata(ghostty_app_t);
 
 ghostty_surface_t ghostty_surface_new(ghostty_app_t, ghostty_surface_config_s*);
 void ghostty_surface_free(ghostty_surface_t);
+ghostty_app_t ghostty_surface_app(ghostty_surface_t);
 void ghostty_surface_refresh(ghostty_surface_t);
 void ghostty_surface_set_content_scale(ghostty_surface_t, double, double);
 void ghostty_surface_set_focus(ghostty_surface_t, bool);

macos/Sources/GhosttyApp.swift

@@ -55,6 +55,9 @@ class GhosttyState: ObservableObject {
     /// The ghostty app instance. We only have one of these for the entire app, although I guess
     /// in theory you can have multiple... I don't know why you would...
     var app: ghostty_app_t? = nil
+    
+    /// Cached clipboard string for `read_clipboard` callback.
+    private var cached_clipboard_string: String? = nil
 
     init() {
         // Initialize ghostty global state. This happens once per process.
@@ -84,7 +87,9 @@ class GhosttyState: ObservableObject {
         var runtime_cfg = ghostty_runtime_config_s(
             userdata: Unmanaged.passUnretained(self).toOpaque(),
             wakeup_cb: { userdata in GhosttyState.wakeup(userdata) },
-            set_title_cb: { userdata, title in GhosttyState.setTitle(userdata, title: title) })
+            set_title_cb: { userdata, title in GhosttyState.setTitle(userdata, title: title) },
+            read_clipboard_cb: { userdata in GhosttyState.readClipboard(userdata) },
+            write_clipboard_cb: { userdata, str in GhosttyState.writeClipboard(userdata, string: str) })
 
         // Create the ghostty app.
         guard let app = ghostty_app_new(&runtime_cfg, cfg) else {
@@ -97,11 +102,35 @@ class GhosttyState: ObservableObject {
         self.readiness = .ready
     }
     
+    deinit {
+        ghostty_app_free(app)
+        ghostty_config_free(config)
+    }
+    
     func appTick() {
         guard let app = self.app else { return }
         ghostty_app_tick(app)
     }
     
+    // MARK: Ghostty Callbacks
+    
+    static func readClipboard(_ userdata: UnsafeMutableRawPointer?) -> UnsafePointer<CChar>? {
+        guard let appState = self.appState(fromSurface: userdata) else { return nil }
+        guard let str = NSPasteboard.general.string(forType: .string) else { return nil }
+        
+        // Ghostty requires we cache the string because the pointer we return has to remain
+        // stable until the next call to readClipboard.
+        appState.cached_clipboard_string = str
+        return (str as NSString).utf8String
+    }
+    
+    static func writeClipboard(_ userdata: UnsafeMutableRawPointer?, string: UnsafePointer<CChar>?) {
+        guard let valueStr = String(cString: string!, encoding: .utf8) else { return }
+        let pb = NSPasteboard.general
+        pb.declareTypes([.string], owner: nil)
+        pb.setString(valueStr, forType: .string)
+    }
+    
     static func wakeup(_ userdata: UnsafeMutableRawPointer?) {
         let state = Unmanaged<GhosttyState>.fromOpaque(userdata!).takeUnretainedValue()
         
@@ -120,8 +149,12 @@ class GhosttyState: ObservableObject {
         }
     }
     
-    deinit {
-        ghostty_app_free(app)
-        ghostty_config_free(config)
+    /// Returns the GhosttyState from the given userdata value.
+    static func appState(fromSurface userdata: UnsafeMutableRawPointer?) -> GhosttyState? {
+        let surfaceView = Unmanaged<TerminalSurfaceView_Real>.fromOpaque(userdata!).takeUnretainedValue()
+        guard let surface = surfaceView.surface else { return nil }
+        guard let app = ghostty_surface_app(surface) else { return nil }
+        guard let app_ud = ghostty_app_userdata(app) else { return nil }
+        return Unmanaged<GhosttyState>.fromOpaque(app_ud).takeUnretainedValue()
     }
 }

macos/Sources/TerminalSurfaceView.swift

@@ -76,8 +76,8 @@ class TerminalSurfaceView_Real: NSView, NSTextInputClient, ObservableObject {
         }
     }
 
-    private var surface: ghostty_surface_t? = nil
-    private var error: Error? = nil
+    var surface: ghostty_surface_t? = nil
+    var error: Error? = nil
     private var markedText: NSMutableAttributedString;
     
     // We need to support being a first responder so that we can get input events

src/App.zig

@@ -368,6 +368,11 @@ pub const CAPI = struct {
         };
     }
 
+    /// Return the userdata associated with the app.
+    export fn ghostty_app_userdata(v: *App) ?*anyopaque {
+        return v.runtime.opts.userdata;
+    }
+
     export fn ghostty_app_free(ptr: ?*App) void {
         if (ptr) |v| {
             v.destroy();
@@ -400,6 +405,11 @@ pub const CAPI = struct {
         if (ptr) |v| v.app.closeWindow(v);
     }
 
+    /// Returns the app associated with a surface.
+    export fn ghostty_surface_app(win: *Window) *App {
+        return win.app;
+    }
+
     /// Tell the surface that it needs to schedule a render
     export fn ghostty_surface_refresh(win: *Window) void {
         win.window.refresh();

src/apprt/embedded.zig

@@ -23,15 +23,27 @@ pub const App = struct {
     ///
     /// C type: ghostty_runtime_config_s
     pub const Options = extern struct {
+        /// These are just aliases to make the function signatures below
+        /// more obvious what values will be sent.
+        const AppUD = ?*anyopaque;
+        const SurfaceUD = ?*anyopaque;
+
         /// Userdata that is passed to all the callbacks.
-        userdata: ?*anyopaque = null,
+        userdata: AppUD = null,
 
         /// Callback called to wakeup the event loop. This should trigger
         /// a full tick of the app loop.
-        wakeup: *const fn (?*anyopaque) callconv(.C) void,
+        wakeup: *const fn (AppUD) callconv(.C) void,
 
         /// Called to set the title of the window.
-        set_title: *const fn (?*anyopaque, [*]const u8) callconv(.C) void,
+        set_title: *const fn (SurfaceUD, [*]const u8) callconv(.C) void,
+
+        /// Read the clipboard value. The return value must be preserved
+        /// by the host until the next call.
+        read_clipboard: *const fn (SurfaceUD) callconv(.C) [*:0]const u8,
+
+        /// Write the clipboard value.
+        write_clipboard: *const fn (SurfaceUD, [*:0]const u8) callconv(.C) void,
     };
 
     opts: Options,
@@ -114,13 +126,12 @@ pub const Window = struct {
     }
 
     pub fn getClipboardString(self: *const Window) ![:0]const u8 {
-        _ = self;
-        return "";
+        const ptr = self.core_win.app.runtime.opts.read_clipboard(self.opts.userdata);
+        return std.mem.sliceTo(ptr, 0);
     }
 
     pub fn setClipboardString(self: *const Window, val: [:0]const u8) !void {
-        _ = self;
-        _ = val;
+        self.core_win.app.runtime.opts.write_clipboard(self.opts.userdata, val.ptr);
     }
 
     pub fn setShouldClose(self: *Window) void {