winit-core/window: add Window::request_ime_update

Allow updating IME state atomically to make it easier for platforms
where it's atomic by its nature, like Wayland. The old API is marked
as deprecated and is routed to the new atomic API.

Co-authored-by: dcz <gilapfco.dcz@porcupinefactory.org>

winit-uikit/src/window.rs

@@ -1,7 +1,7 @@
 #![allow(clippy::unnecessary_cast)]
 
 use std::collections::VecDeque;
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 
 use dispatch2::MainThreadBound;
 use dpi::{
@@ -23,8 +23,9 @@ use winit_core::event::WindowEvent;
 use winit_core::icon::Icon;
 use winit_core::monitor::{Fullscreen, MonitorHandle as CoreMonitorHandle};
 use winit_core::window::{
-    CursorGrabMode, ImePurpose, ResizeDirection, Theme, UserAttentionType, Window as CoreWindow,
-    WindowAttributes, WindowButtons, WindowId, WindowLevel,
+    CursorGrabMode, ImeCapabilities, ImeRequest, ImeRequestError, ResizeDirection, Theme,
+    UserAttentionType, Window as CoreWindow, WindowAttributes, WindowButtons, WindowId,
+    WindowLevel,
 };
 
 use super::app_state::EventWrapper;
@@ -113,6 +114,7 @@ pub struct Inner {
     view_controller: Retained<WinitViewController>,
     view: Retained<WinitView>,
     gl_or_metal_backed: bool,
+    ime_capabilities: Mutex<Option<ImeCapabilities>>,
 }
 
 impl Inner {
@@ -377,28 +379,42 @@ impl Inner {
         warn!("`Window::set_window_icon` is ignored on iOS")
     }
 
-    pub fn set_ime_cursor_area(&self, _position: Position, _size: Size) {
-        warn!("`Window::set_ime_cursor_area` 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();
-            }
+    fn request_ime_update(&self, request: ImeRequest) -> Result<(), ImeRequestError> {
+        let mut current_caps = self.ime_capabilities.lock().unwrap();
+        match request {
+            ImeRequest::Enable(enable) => {
+                let (capabilities, _) = enable.into_raw();
+                if current_caps.is_some() {
+                    return Err(ImeRequestError::AlreadyEnabled);
+                }
+                *current_caps = Some(capabilities);
+
+                unsafe {
+                    self.view.becomeFirstResponder();
+                }
+            },
+            ImeRequest::Update(_) => {
+                if current_caps.is_none() {
+                    return Err(ImeRequestError::NotEnabled);
+                }
+            },
+            ImeRequest::Disable => {
+                *current_caps = None;
+                unsafe {
+                    self.view.resignFirstResponder();
+                }
+            },
         }
+
+        Ok(())
     }
 
-    pub fn set_ime_purpose(&self, _purpose: ImePurpose) {
-        warn!("`Window::set_ime_purpose` is ignored on iOS")
+    fn ime_capabilities(&self) -> Option<ImeCapabilities> {
+        *self.ime_capabilities.lock().unwrap()
     }
 
     pub fn focus_window(&self) {
@@ -529,7 +545,13 @@ impl Window {
         let window = WinitUIWindow::new(mtm, &window_attributes, frame, &view_controller);
         window.makeKeyAndVisible();
 
-        let inner = Inner { window, view_controller, view, gl_or_metal_backed };
+        let inner = Inner {
+            window,
+            view_controller,
+            view,
+            gl_or_metal_backed,
+            ime_capabilities: Default::default(),
+        };
         Ok(Window { inner: MainThreadBound::new(inner, mtm) })
     }
 
@@ -711,16 +733,12 @@ impl CoreWindow for Window {
         self.maybe_wait_on_main(|delegate| delegate.set_window_icon(window_icon));
     }
 
-    fn set_ime_cursor_area(&self, position: Position, size: Size) {
-        self.maybe_wait_on_main(|delegate| delegate.set_ime_cursor_area(position, size));
+    fn request_ime_update(&self, request: ImeRequest) -> Result<(), ImeRequestError> {
+        self.maybe_wait_on_main(|delegate| delegate.request_ime_update(request))
     }
 
-    fn set_ime_allowed(&self, allowed: bool) {
-        self.maybe_wait_on_main(|delegate| delegate.set_ime_allowed(allowed));
-    }
-
-    fn set_ime_purpose(&self, purpose: ImePurpose) {
-        self.maybe_wait_on_main(|delegate| delegate.set_ime_purpose(purpose));
+    fn ime_capabilities(&self) -> Option<ImeCapabilities> {
+        self.maybe_wait_on_main(|delegate| delegate.ime_capabilities())
     }
 
     fn focus_window(&self) {