Basic iOS IME support (#3823)

This implements basic iOS IME support (typing, backspace, support for emojis
etc but no autocomplete or copy / paste menu).

Co-authored-by: Mads Marquart <mads@marquart.dk>

Cargo.toml

@@ -183,6 +183,8 @@ objc2-ui-kit = { version = "0.2.2", features = [
  "UIEvent",
  "UIGeometry",
  "UIGestureRecognizer",
+ "UITextInput",
+ "UITextInputTraits",
  "UIOrientation",
  "UIPanGestureRecognizer",
  "UIPinchGestureRecognizer",

src/changelog/unreleased.md

@@ -47,13 +47,13 @@ changelog entry.
  `DeviceEvent::MouseMotion` is returning raw data, not OS accelerated, when using
  `CursorGrabMode::Locked`.
 - On Web, implement `MonitorHandle` and `VideoModeHandle`.
- 
+
  Without prompting the user for permission, only the current monitor is returned. But when
  prompting and being granted permission through
  `ActiveEventLoop::request_detailed_monitor_permission()`, access to all monitors and their
  details is available. Handles created with "detailed monitor permissions" can be used in
  `Window::set_fullscreen()` as well.
- 
+
  Keep in mind that handles do not auto-upgrade after permissions are granted and have to be
  re-created to make full use of this feature.
 - Add `Touch::finger_id` with a new type `FingerId`.
@@ -62,6 +62,7 @@ changelog entry.
 - Implement `Clone`, `Copy`, `Debug`, `Deserialize`, `Eq`, `Hash`, `Ord`, `PartialEq`, `PartialOrd`
  and `Serialize` on many types.
 - Add `MonitorHandle::current_video_mode()`.
+- Add basic iOS IME support. The soft keyboard can now be shown using `Window::set_ime_allowed`.
 
 ### Changed
 

src/platform_impl/apple/uikit/view.rs

@@ -4,19 +4,23 @@ use std::cell::{Cell, RefCell};
 use objc2::rc::Retained;
 use objc2::runtime::{NSObjectProtocol, ProtocolObject};
 use objc2::{declare_class, msg_send, msg_send_id, mutability, sel, ClassType, DeclaredClass};
-use objc2_foundation::{CGFloat, CGPoint, CGRect, MainThreadMarker, NSObject, NSSet};
+use objc2_foundation::{CGFloat, CGPoint, CGRect, MainThreadMarker, NSObject, NSSet, NSString};
 use objc2_ui_kit::{
  UICoordinateSpace, UIEvent, UIForceTouchCapability, UIGestureRecognizer,
- UIGestureRecognizerDelegate, UIGestureRecognizerState, UIPanGestureRecognizer,
+ UIGestureRecognizerDelegate, UIGestureRecognizerState, UIKeyInput, UIPanGestureRecognizer,
  UIPinchGestureRecognizer, UIResponder, UIRotationGestureRecognizer, UITapGestureRecognizer,
- UITouch, UITouchPhase, UITouchType, UITraitEnvironment, UIView,
+ UITextInputTraits, UITouch, UITouchPhase, UITouchType, UITraitEnvironment, UIView,
 };
 
 use super::app_state::{self, EventWrapper};
 use super::window::WinitUIWindow;
 use super::{FingerId, DEVICE_ID};
 use crate::dpi::PhysicalPosition;
-use crate::event::{Event, FingerId as RootFingerId, Force, Touch, TouchPhase, WindowEvent};
+use crate::event::{
+ ElementState, Event, FingerId as RootFingerId, Force, KeyEvent, Touch, TouchPhase, WindowEvent,
+};
+use crate::keyboard::{Key, KeyCode, KeyLocation, NamedKey, NativeKeyCode, PhysicalKey};
+use crate::platform_impl::KeyEventExtra;
 use crate::window::{WindowAttributes, WindowId as RootWindowId};
 
 pub struct WinitViewState {
@@ -314,6 +318,11 @@ declare_class!(
  let mtm = MainThreadMarker::new().unwrap();
  app_state::handle_nonuser_event(mtm, gesture_event);
  }
+
+ #[method(canBecomeFirstResponder)]
+ fn can_become_first_responder(&self) -> bool {
+ true
+ }
  }
 
  unsafe impl NSObjectProtocol for WinitView {}
@@ -324,6 +333,26 @@ declare_class!(
  true
  }
  }
+
+ unsafe impl UITextInputTraits for WinitView {
+ }
+
+ unsafe impl UIKeyInput for WinitView {
+ #[method(hasText)]
+ fn has_text(&self) -> bool {
+ true
+ }
+
+ #[method(insertText:)]
+ fn insert_text(&self, text: &NSString) {
+ self.handle_insert_text(text)
+ }
+
+ #[method(deleteBackward)]
+ fn delete_backward(&self) {
+ self.handle_delete_backward()
+ }
+ }
 );
 
 impl WinitView {
@@ -512,4 +541,69 @@ impl WinitView {
  let mtm = MainThreadMarker::new().unwrap();
  app_state::handle_nonuser_events(mtm, touch_events);
  }
+
+ fn handle_insert_text(&self, text: &NSString) {
+ let window = self.window().unwrap();
+ let window_id = RootWindowId(window.id());
+ let mtm = MainThreadMarker::new().unwrap();
+ // send individual events for each character
+ app_state::handle_nonuser_events(
+ mtm,
+ text.to_string().chars().flat_map(|c| {
+ let text = smol_str::SmolStr::from_iter([c]);
+ // Emit both press and release events
+ [ElementState::Pressed, ElementState::Released].map(|state| {
+ EventWrapper::StaticEvent(Event::WindowEvent {
+ window_id,
+ event: WindowEvent::KeyboardInput {
+ event: KeyEvent {
+ text: if state == ElementState::Pressed {
+ Some(text.clone())
+ } else {
+ None
+ },
+ state,
+ location: KeyLocation::Standard,
+ repeat: false,
+ logical_key: Key::Character(text.clone()),
+ physical_key: PhysicalKey::Unidentified(
+ NativeKeyCode::Unidentified,
+ ),
+ platform_specific: KeyEventExtra {},
+ },
+ is_synthetic: false,
+ device_id: DEVICE_ID,
+ },
+ })
+ })
+ }),
+ );
+ }
+
+ fn handle_delete_backward(&self) {
+ let window = self.window().unwrap();
+ let window_id = RootWindowId(window.id());
+ let mtm = MainThreadMarker::new().unwrap();
+ app_state::handle_nonuser_events(
+ mtm,
+ [ElementState::Pressed, ElementState::Released].map(|state| {
+ EventWrapper::StaticEvent(Event::WindowEvent {
+ window_id,
+ event: WindowEvent::KeyboardInput {
+ device_id: DEVICE_ID,
+ event: KeyEvent {
+ state,
+ logical_key: Key::Named(NamedKey::Backspace),
+ physical_key: PhysicalKey::Code(KeyCode::Backspace),
+ platform_specific: KeyEventExtra {},
+ repeat: false,
+ location: KeyLocation::Standard,
+ text: None,
+ },
+ is_synthetic: false,
+ },
+ })
+ }),
+ );
+ }
 }

src/platform_impl/apple/uikit/window.rs

@@ -370,12 +370,24 @@ impl Inner {
  warn!("`Window::set_ime_cursor_area` is ignored on iOS")
  }
 
- pub fn set_ime_allowed(&self, _allowed: bool) {
- warn!("`Window::set_ime_allowed` is ignored on iOS")
+ /// Show / hide the keyboard. To show the keyboard, we call `becomeFirstResponder`,
+ /// requesting focus for the [WinitView]. Since [WinitView] implements
+ /// [objc2_ui_kit::UIKeyInput], the keyboard will be shown.
+ /// <https://developer.apple.com/documentation/uikit/uiresponder/1621113-becomefirstresponder>
+ pub fn set_ime_allowed(&self, allowed: bool) {
+ if allowed {
+ unsafe {
+ self.view.becomeFirstResponder();
+ }
+ } else {
+ unsafe {
+ self.view.resignFirstResponder();
+ }
+ }
  }
 
  pub fn set_ime_purpose(&self, _purpose: ImePurpose) {
- warn!("`Window::set_ime_allowed` is ignored on iOS")
+ warn!("`Window::set_ime_purpose` is ignored on iOS")
  }
 
  pub fn focus_window(&self) {

src/window.rs

@@ -1279,7 +1279,8 @@ impl Window {
  ///
  /// - **macOS:** IME must be enabled to receive text-input where dead-key sequences are
  /// combined.
- /// - **iOS / Android / Web / Orbital:** Unsupported.
+ /// - **iOS:** This will show / hide the soft keyboard.
+ /// - **Android / Web / Orbital:** Unsupported.
  /// - **X11**: Enabling IME will disable dead keys reporting during compose.
  ///
  /// [`Ime`]: crate::event::WindowEvent::Ime