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-android/src/event_loop.rs

@@ -23,8 +23,9 @@ use winit_core::event_loop::{
 };
 use winit_core::monitor::{Fullscreen, MonitorHandle as CoreMonitorHandle};
 use winit_core::window::{
-    self, CursorGrabMode, ImePurpose, ResizeDirection, Theme, Window as CoreWindow,
-    WindowAttributes, WindowButtons, WindowId, WindowLevel,
+    self, CursorGrabMode, ImeCapabilities, ImePurpose, ImeRequest, ImeRequestError,
+    ResizeDirection, Theme, Window as CoreWindow, WindowAttributes, WindowButtons, WindowId,
+    WindowLevel,
 };
 
 use crate::keycodes;
@@ -758,6 +759,7 @@ pub struct PlatformSpecificWindowAttributes;
 #[derive(Debug)]
 pub struct Window {
     app: AndroidApp,
+    ime_capabilities: Mutex<Option<ImeCapabilities>>,
     redraw_requester: RedrawRequester,
 }
 
@@ -768,7 +770,11 @@ impl Window {
     ) -> Result<Self, RequestError> {
         // FIXME this ignores requested window attributes
 
-        Ok(Self { app: el.app.clone(), redraw_requester: el.redraw_requester.clone() })
+        Ok(Self {
+            app: el.app.clone(),
+            ime_capabilities: Default::default(),
+            redraw_requester: el.redraw_requester.clone(),
+        })
     }
 
     pub(crate) fn config(&self) -> ConfigurationRef {
@@ -936,12 +942,33 @@ impl CoreWindow for Window {
 
     fn set_ime_cursor_area(&self, _position: Position, _size: Size) {}
 
-    fn set_ime_allowed(&self, allowed: bool) {
-        if allowed {
-            self.app.show_soft_input(true);
-        } else {
-            self.app.hide_soft_input(true);
+    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);
+                self.app.show_soft_input(true);
+            },
+            ImeRequest::Update(_) => {
+                if current_caps.is_none() {
+                    return Err(ImeRequestError::NotEnabled);
+                }
+            },
+            ImeRequest::Disable => {
+                *current_caps = None;
+                self.app.hide_soft_input(true);
+            },
         }
+
+        Ok(())
+    }
+
+    fn ime_capabilities(&self) -> Option<ImeCapabilities> {
+        *self.ime_capabilities.lock().unwrap()
     }
 
     fn set_ime_purpose(&self, _purpose: ImePurpose) {}