fix(macos): route keyboard through NSTextInputContext when a text input has focus

src/macos/view.rs

@@ -8,8 +8,8 @@ use objc::{
     class,
     declare::ClassDecl,
     msg_send,
-    runtime::{Class, Object, Sel},
-    sel, sel_impl,
+    runtime::{Class, Object, Protocol, Sel},
+    sel, sel_impl, Encode, Encoding,
 };
 use uuid::Uuid;
 
@@ -220,15 +220,280 @@ unsafe fn create_view_class() -> &'static Class {
     add_simple_mouse_class_method!(class, mouseEntered, MouseEvent::CursorEntered);
     add_simple_mouse_class_method!(class, mouseExited, MouseEvent::CursorLeft);
 
-    add_simple_keyboard_class_method!(class, keyDown);
+    // keyDown gets a custom impl that may route through NSTextInputContext
+    // when a text-input view has focus (see `key_down` below). keyUp and
+    // flagsChanged still go through the simple dispatch macro.
+    class.add_method(sel!(keyDown:), key_down as extern "C" fn(&Object, Sel, id));
+
+    // performKeyEquivalent: runs BEFORE keyDown: in AppKit's dispatch order.
+    // Hosts (REAPER on macOS) use this hook for their own accelerator
+    // tables — e.g. matching space against the transport shortcut. If none
+    // of the views in the responder chain claim the event via this path,
+    // AppKit then delivers it via keyDown:. Without our override, default
+    // NSView returns NO, the event bubbles up to the host window, REAPER
+    // fires its binding, and keyDown: is never called for space.
+    //
+    // Route through NSTextInputContext the same way we do in keyDown:,
+    // claiming the event when a text input has focus.
+    class.add_method(
+        sel!(performKeyEquivalent:),
+        perform_key_equivalent as extern "C" fn(&Object, Sel, id) -> BOOL,
+    );
+
     add_simple_keyboard_class_method!(class, keyUp);
     add_simple_keyboard_class_method!(class, flagsChanged);
 
+    // NSTextInputClient protocol stubs.
+    //
+    // Cocoa text hosts (including REAPER on macOS) use protocol conformance
+    // on the first-responder NSView as a signal that the view is a text
+    // editor — if present, the host's key-binding pre-check (e.g. REAPER's
+    // space-bar-is-transport) is bypassed and the key event is dispatched to
+    // the view's NSTextInputContext instead. The methods below are mostly
+    // inert sentinels; the real work still happens in the existing
+    // `keyDown:` handler via `process_native_key_event` + `trigger_event`.
+    if let Some(proto) = Protocol::get("NSTextInputClient") {
+        class.add_protocol(proto);
+    }
+
+    class.add_method(
+        sel!(hasMarkedText),
+        has_marked_text as extern "C" fn(&Object, Sel) -> BOOL,
+    );
+    class.add_method(
+        sel!(markedRange),
+        marked_range as extern "C" fn(&Object, Sel) -> NSRange,
+    );
+    class.add_method(
+        sel!(selectedRange),
+        selected_range as extern "C" fn(&Object, Sel) -> NSRange,
+    );
+    class.add_method(
+        sel!(setMarkedText:selectedRange:replacementRange:),
+        set_marked_text as extern "C" fn(&Object, Sel, id, NSRange, NSRange),
+    );
+    class.add_method(sel!(unmarkText), unmark_text as extern "C" fn(&Object, Sel));
+    class.add_method(
+        sel!(validAttributesForMarkedText),
+        valid_attributes_for_marked_text as extern "C" fn(&Object, Sel) -> id,
+    );
+    class.add_method(
+        sel!(attributedSubstringForProposedRange:actualRange:),
+        attributed_substring_for_proposed_range
+            as extern "C" fn(&Object, Sel, NSRange, *mut c_void) -> id,
+    );
+    class.add_method(
+        sel!(insertText:replacementRange:),
+        insert_text as extern "C" fn(&Object, Sel, id, NSRange),
+    );
+    class.add_method(
+        sel!(characterIndexForPoint:),
+        character_index_for_point as extern "C" fn(&Object, Sel, NSPoint) -> NSUInteger,
+    );
+    class.add_method(
+        sel!(firstRectForCharacterRange:actualRange:),
+        first_rect_for_character_range as extern "C" fn(&Object, Sel, NSRange, *mut c_void) -> NSRect,
+    );
+    class.add_method(
+        sel!(doCommandBySelector:),
+        do_command_by_selector as extern "C" fn(&Object, Sel, Sel),
+    );
+
     class.add_ivar::<*mut c_void>(BASEVIEW_STATE_IVAR);
 
     class.register()
 }
 
+const NSNOT_FOUND: NSUInteger = NSUInteger::MAX;
+
+/// Local NSRange that implements `objc::Encode`. `cocoa::foundation::NSRange`
+/// does not implement `Encode`, so we can't use it in `add_method` signatures
+/// on the objc 0.2 API.
+#[repr(C)]
+#[derive(Copy, Clone)]
+struct NSRange {
+    location: NSUInteger,
+    length: NSUInteger,
+}
+
+unsafe impl Encode for NSRange {
+    fn encode() -> Encoding {
+        let encoding = format!(
+            "{{_NSRange={}{}}}",
+            NSUInteger::encode().as_str(),
+            NSUInteger::encode().as_str()
+        );
+        unsafe { Encoding::from_str(&encoding) }
+    }
+}
+
+extern "C" fn has_marked_text(_this: &Object, _sel: Sel) -> BOOL {
+    NO
+}
+
+extern "C" fn marked_range(_this: &Object, _sel: Sel) -> NSRange {
+    NSRange { location: NSNOT_FOUND, length: 0 }
+}
+
+extern "C" fn selected_range(_this: &Object, _sel: Sel) -> NSRange {
+    NSRange { location: NSNOT_FOUND, length: 0 }
+}
+
+extern "C" fn set_marked_text(
+    _this: &Object,
+    _sel: Sel,
+    _text: id,
+    _selected: NSRange,
+    _replacement: NSRange,
+) {
+}
+
+extern "C" fn unmark_text(_this: &Object, _sel: Sel) {}
+
+extern "C" fn valid_attributes_for_marked_text(_this: &Object, _sel: Sel) -> id {
+    unsafe { NSArray::arrayWithObjects(nil, &[]) }
+}
+
+extern "C" fn attributed_substring_for_proposed_range(
+    _this: &Object,
+    _sel: Sel,
+    _range: NSRange,
+    _actual_range: *mut c_void,
+) -> id {
+    nil
+}
+
+extern "C" fn insert_text(this: &Object, _sel: Sel, _text: id, _replacement: NSRange) {
+    // When `keyDown:` routes the event through NSTextInputContext, AppKit
+    // decodes the NSEvent according to the keyboard layout + IME state and
+    // calls back here with the resulting text. The original NSEvent is still
+    // available via `WindowState::current_key_event`, so we can re-use the
+    // existing `process_native_key_event` path to produce a `KeyboardEvent`
+    // with both the physical `Code` and the decoded `Key::Character`.
+    let state = unsafe { WindowState::from_view(this) };
+    let event = state.current_key_event();
+    if event == nil {
+        return;
+    }
+    if let Some(key_event) = state.process_native_key_event(event) {
+        state.trigger_event(Event::Keyboard(key_event));
+    }
+}
+
+extern "C" fn character_index_for_point(_this: &Object, _sel: Sel, _point: NSPoint) -> NSUInteger {
+    NSNOT_FOUND
+}
+
+extern "C" fn first_rect_for_character_range(
+    _this: &Object,
+    _sel: Sel,
+    _range: NSRange,
+    _actual_range: *mut c_void,
+) -> NSRect {
+    NSRect::new(NSPoint::new(0.0, 0.0), NSSize::new(0.0, 0.0))
+}
+
+extern "C" fn do_command_by_selector(this: &Object, _sel: Sel, _selector: Sel) {
+    // For non-printable commands (arrow keys, backspace, enter, escape,
+    // etc.) AppKit calls this instead of `insertText:`. The stored NSEvent
+    // already carries a mac-native keyCode that `process_native_key_event`
+    // maps to the right `Code`, so we re-use the same dispatch path.
+    let state = unsafe { WindowState::from_view(this) };
+    let event = state.current_key_event();
+    if event == nil {
+        return;
+    }
+    if let Some(key_event) = state.process_native_key_event(event) {
+        state.trigger_event(Event::Keyboard(key_event));
+    }
+}
+
+/// Handler for `keyDown:`. When a text-input view has focus, route the
+/// event through AppKit's NSTextInputContext so that:
+///
+/// - the host's key-binding pre-check (e.g. REAPER's space-bar transport
+///   shortcut) is bypassed for text-input keys,
+/// - IME input (Japanese, Chinese, Korean) and the macOS accent menu
+///   work,
+/// - dead-key composition (option+e then 'e' → 'é') works.
+///
+/// Otherwise fall back to the same dispatch as the simple keyboard
+/// macro: translate the NSEvent into a `KeyboardEvent`, report it, and
+/// forward to the superclass if the app didn't consume it.
+extern "C" fn key_down(this: &Object, _sel: Sel, event: id) {
+    let state = unsafe { WindowState::from_view(this) };
+
+    // Route through the text-input pipeline only when the app reports a
+    // text field has focus. Otherwise preserve the old behaviour so host
+    // shortcuts still work (e.g. space toggles transport in REAPER when
+    // no text field is focused).
+    if state.has_text_focus() {
+        state.set_current_key_event(event);
+        let handled: BOOL = unsafe {
+            let input_context: id = msg_send![this, inputContext];
+            if input_context != nil {
+                msg_send![input_context, handleEvent: event]
+            } else {
+                NO
+            }
+        };
+        state.set_current_key_event(nil);
+
+        if handled == YES {
+            // NSTextInputContext dispatched via insertText: or
+            // doCommandBySelector:, which already called trigger_event.
+            // Do not call super — swallow the event so it does not bubble
+            // up to the host window.
+            return;
+        }
+        // Fall through. inputContext declined the event (e.g. a Cmd-modified
+        // key), let the usual path handle it.
+    }
+
+    if let Some(key_event) = state.process_native_key_event(event) {
+        let status = state.trigger_event(Event::Keyboard(key_event));
+
+        if let EventStatus::Ignored = status {
+            unsafe {
+                let superclass = msg_send![this, superclass];
+                let () = msg_send![super(this, superclass), keyDown: event];
+            }
+        }
+    }
+}
+
+/// Handler for `performKeyEquivalent:`. AppKit calls this before `keyDown:`
+/// so that host accelerator tables (REAPER's transport shortcut, Cmd-combos
+/// in menu bars, etc.) can claim an event first. If no view in the
+/// responder chain returns YES here, the event is then dispatched via
+/// `keyDown:`. Without this override, space is claimed by the host's
+/// transport binding via the default `NSWindow performKeyEquivalent:`
+/// before our view ever sees the event.
+///
+/// When a text input currently has focus we route the event through
+/// NSTextInputContext — same pipeline as `keyDown:` — and return YES so
+/// AppKit stops the dispatch there.
+extern "C" fn perform_key_equivalent(this: &Object, _sel: Sel, event: id) -> BOOL {
+    let state = unsafe { WindowState::from_view(this) };
+
+    if !state.has_text_focus() {
+        return NO;
+    }
+
+    state.set_current_key_event(event);
+    let handled: BOOL = unsafe {
+        let input_context: id = msg_send![this, inputContext];
+        if input_context != nil {
+            msg_send![input_context, handleEvent: event]
+        } else {
+            NO
+        }
+    };
+    state.set_current_key_event(nil);
+
+    handled
+}
+
 extern "C" fn property_yes(_this: &Object, _sel: Sel) -> BOOL {
     YES
 }
@@ -255,12 +520,34 @@ extern "C" fn become_first_responder(this: &Object, _sel: Sel) -> BOOL {
     if is_key_window {
         state.trigger_deferrable_event(Event::Window(WindowEvent::Focused));
     }
+
+    // Mark our NSTextInputContext as the globally-active input context. Hosts
+    // that inspect `[NSTextInputContext currentInputContext]` to decide
+    // whether to apply their own keyboard accelerators (REAPER on macOS
+    // appears to do this: its CGEventTap swallows space-bar keyDown events
+    // by default but bypasses the check when a text input is active) see a
+    // non-nil context and skip accelerator matching.
+    unsafe {
+        let input_context: id = msg_send![this, inputContext];
+        if input_context != nil {
+            let _: () = msg_send![input_context, activate];
+        }
+    }
+
     YES
 }
 
 extern "C" fn resign_first_responder(this: &Object, _sel: Sel) -> BOOL {
     let state = unsafe { WindowState::from_view(this) };
     state.trigger_deferrable_event(Event::Window(WindowEvent::Unfocused));
+
+    unsafe {
+        let input_context: id = msg_send![this, inputContext];
+        if input_context != nil {
+            let _: () = msg_send![input_context, deactivate];
+        }
+    }
+
     YES
 }
 

src/macos/window.rs

@@ -268,6 +268,7 @@ impl<'a> Window<'a> {
             frame_timer: Cell::new(None),
             window_info: Cell::new(window_info),
             deferred_events: RefCell::default(),
+            current_key_event: Cell::new(nil),
         });
 
         let window_state_ptr = Rc::into_raw(Rc::clone(&window_state));
@@ -364,6 +365,11 @@ pub(super) struct WindowState {
 
     /// Events that will be triggered at the end of `window_handler`'s borrow.
     deferred_events: RefCell<VecDeque<Event>>,
+
+    /// The NSEvent currently being routed through NSTextInputContext, so
+    /// that `insertText:` / `doCommandBySelector:` callbacks from AppKit
+    /// can reach back to the original event's keyCode and modifiers.
+    current_key_event: Cell<id>,
 }
 
 impl WindowState {
@@ -420,6 +426,29 @@ impl WindowState {
         self.keyboard_state.process_native_event(event)
     }
 
+    /// Query the `WindowHandler` for whether a text-input view currently
+    /// has focus. Used to decide whether to route `keyDown:` through
+    /// NSTextInputContext on macOS. Returns `false` if the handler is
+    /// already mutably borrowed (re-entrant call) or the handler returns
+    /// `false`.
+    pub(super) fn has_text_focus(&self) -> bool {
+        match self.window_handler.try_borrow_mut() {
+            Ok(mut handler) => {
+                let mut window = crate::Window::new(Window { inner: &self.window_inner });
+                handler.has_text_focus(&mut window)
+            }
+            Err(_) => false,
+        }
+    }
+
+    pub(super) fn set_current_key_event(&self, event: id) {
+        self.current_key_event.set(event);
+    }
+
+    pub(super) fn current_key_event(&self) -> id {
+        self.current_key_event.get()
+    }
+
     unsafe fn setup_timer(window_state_ptr: *const WindowState) {
         extern "C" fn timer_callback(_: *mut __CFRunLoopTimer, window_state_ptr: *mut c_void) {
             unsafe {