Provide a way to set cursor area for IME cursor

Rename `Window::set_ime_position` to `Window::set_ime_cursor_area`
adding a way to create cursor exclusive zone.

Fixes #2886.

CHANGELOG.md

@@ -8,6 +8,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 
 # Unreleased
 
+- **Breaking:** Rename `Window::set_ime_position` to `Window::set_ime_cursor_area` adding a way to set exclusize zone.
 - On Android, changed default behavior of Android to ignore volume keys letting the operating system handle them.
 - On Android, added `EventLoopBuilderExtAndroid::handle_volume_keys` to indicate that the application will handle the volume keys manually.
 - **Breaking:** Rename `DeviceEventFilter` to `DeviceEvents` reversing the behavior of variants.

examples/ime.rs

@@ -3,7 +3,7 @@
 use log::LevelFilter;
 use simple_logger::SimpleLogger;
 use winit::{
-    dpi::PhysicalPosition,
+    dpi::{PhysicalPosition, PhysicalSize},
     event::{ElementState, Event, Ime, WindowEvent},
     event_loop::{ControlFlow, EventLoop},
     keyboard::{Key, KeyCode},
@@ -66,7 +66,7 @@ fn main() {
                 );
                 ime_pos = cursor_position;
                 if may_show_ime {
-                    window.set_ime_position(ime_pos);
+                    window.set_ime_cursor_area(ime_pos, PhysicalSize::new(10, 10));
                 }
             }
             Event::WindowEvent {
@@ -76,7 +76,7 @@ fn main() {
                 println!("{event:?}");
                 may_show_ime = event != Ime::Disabled;
                 if may_show_ime {
-                    window.set_ime_position(ime_pos);
+                    window.set_ime_cursor_area(ime_pos, PhysicalSize::new(10, 10));
                 }
             }
             Event::WindowEvent {

src/event.rs

@@ -1034,7 +1034,7 @@ impl From<ModifiersState> for Modifiers {
 /// ```
 ///
 /// Additionally, certain input devices are configured to display a candidate box that allow the user to select the
-/// desired character interactively. (To properly position this box, you must use [`Window::set_ime_position`].)
+/// desired character interactively. (To properly position this box, you must use [`Window::set_ime_cursor_area`].)
 ///
 /// An example of a keyboard layout which uses candidate boxes is pinyin. On a latin keyboard the following event
 /// sequence could be obtained:
@@ -1058,7 +1058,7 @@ pub enum Ime {
     ///
     /// After getting this event you could receive [`Preedit`](Self::Preedit) and
     /// [`Commit`](Self::Commit) events. You should also start performing IME related requests
-    /// like [`Window::set_ime_position`].
+    /// like [`Window::set_ime_cursor_area`].
     Enabled,
 
     /// Notifies when a new composing text should be set at the cursor position.
@@ -1079,7 +1079,7 @@ pub enum Ime {
     ///
     /// After receiving this event you won't get any more [`Preedit`](Self::Preedit) or
     /// [`Commit`](Self::Commit) events until the next [`Enabled`](Self::Enabled) event. You should
-    /// also stop issuing IME related requests like [`Window::set_ime_position`] and clear pending
+    /// also stop issuing IME related requests like [`Window::set_ime_cursor_area`] and clear pending
     /// preedit text.
     Disabled,
 }

src/platform_impl/android/mod.rs

@@ -872,7 +872,7 @@ impl Window {
 
     pub fn set_window_icon(&self, _window_icon: Option<crate::icon::Icon>) {}
 
-    pub fn set_ime_position(&self, _position: Position) {}
+    pub fn set_ime_cursor_area(&self, _position: Position, _size: Size) {}
 
     pub fn set_ime_allowed(&self, _allowed: bool) {}
 

src/platform_impl/ios/window.rs

@@ -295,8 +295,8 @@ impl Inner {
         warn!("`Window::set_window_icon` is ignored on iOS")
     }
 
-    pub fn set_ime_position(&self, _position: Position) {
-        warn!("`Window::set_ime_position` 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")
     }
 
     pub fn set_ime_allowed(&self, _allowed: bool) {

src/platform_impl/linux/mod.rs

@@ -512,8 +512,8 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, position: Position) {
-        x11_or_wayland!(match self; Window(w) => w.set_ime_position(position))
+    pub fn set_ime_cursor_area(&self, position: Position, size: Size) {
+        x11_or_wayland!(match self; Window(w) => w.set_ime_cursor_area(position, size))
     }
 
     #[inline]

src/platform_impl/linux/wayland/window/mod.rs

@@ -534,12 +534,13 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, position: Position) {
+    pub fn set_ime_cursor_area(&self, position: Position, size: Size) {
         let window_state = self.window_state.lock().unwrap();
         if window_state.ime_allowed() {
             let scale_factor = window_state.scale_factor();
             let position = position.to_logical(scale_factor);
-            window_state.set_ime_position(position);
+            let size = size.to_logical(scale_factor);
+            window_state.set_ime_cursor_area(position, size);
         }
     }
 

src/platform_impl/linux/wayland/window/state.rs

@@ -741,13 +741,14 @@ impl WindowState {
     }
 
     /// Set the IME position.
-    pub fn set_ime_position(&self, position: LogicalPosition<u32>) {
+    pub fn set_ime_cursor_area(&self, position: LogicalPosition<u32>, size: LogicalSize<u32>) {
         // XXX This won't fly unless user will have a way to request IME window per seat, since
         // the ime windows will be overlapping, but winit doesn't expose API to specify for
         // which seat we're setting IME position.
         let (x, y) = (position.x as i32, position.y as i32);
+        let (width, height) = (size.width as i32, size.height as i32);
         for text_input in self.text_inputs.iter() {
-            text_input.set_cursor_rectangle(x, y, 0, 0);
+            text_input.set_cursor_rectangle(x, y, width, height);
             text_input.commit();
         }
     }

src/platform_impl/linux/x11/window.rs

@@ -1510,7 +1510,7 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, spot: Position) {
+    pub fn set_ime_cursor_area(&self, spot: Position, _size: Size) {
         let (x, y) = spot.to_physical::<i32>(self.scale_factor()).into();
         let _ = self
             .ime_sender

src/platform_impl/macos/util/async.rs

@@ -202,11 +202,15 @@ pub(crate) fn close_sync(window: &NSWindow) {
     });
 }
 
-pub(crate) fn set_ime_position_sync(window: &WinitWindow, logical_spot: LogicalPosition<f64>) {
+pub(crate) fn set_ime_cursor_area_sync(
+    window: &WinitWindow,
+    logical_spot: LogicalPosition<f64>,
+    size: LogicalSize<f64>,
+) {
     let window = MainThreadSafe(window);
     run_on_main(move || {
         // TODO(madsmtm): Remove the need for this
-        unsafe { Id::from_shared(window.view()) }.set_ime_position(logical_spot);
+        unsafe { Id::from_shared(window.view()) }.set_ime_cursor_area(logical_spot, size);
     });
 }
 

src/platform_impl/macos/view.rs

@@ -122,6 +122,7 @@ fn get_left_modifier_code(key: &Key) -> KeyCode {
 pub(super) struct ViewState {
     pub cursor_state: Mutex<CursorState>,
     ime_position: LogicalPosition<f64>,
+    ime_size: LogicalSize<f64>,
     pub(super) modifiers: Modifiers,
     phys_modifiers: HashMap<Key, ModLocationMask>,
     tracking_rect: Option<NSTrackingRectTag>,
@@ -167,6 +168,7 @@ declare_class!(
                 let state = ViewState {
                     cursor_state: Default::default(),
                     ime_position: LogicalPosition::new(0.0, 0.0),
+                    ime_size: Default::default(),
                     modifiers: Default::default(),
                     phys_modifiers: Default::default(),
                     tracking_rect: None,
@@ -416,11 +418,8 @@ declare_class!(
             let base_y = (content_rect.origin.y + content_rect.size.height) as f64;
             let x = base_x + self.state.ime_position.x;
             let y = base_y - self.state.ime_position.y;
-            // This is not ideal: We _should_ return a different position based on
-            // the currently selected character (which varies depending on the type
-            // and size of the character), but in the current `winit` API there is
-            // no way to express this. Same goes for the `NSSize`.
-            NSRect::new(NSPoint::new(x as _, y as _), NSSize::new(0.0, 0.0))
+            let LogicalSize { width, height } = self.state.ime_size;
+            NSRect::new(NSPoint::new(x as _, y as _), NSSize::new(width, height))
         }
 
         #[sel(insertText:replacementRange:)]
@@ -871,8 +870,13 @@ impl WinitView {
         }
     }
 
-    pub(super) fn set_ime_position(&mut self, position: LogicalPosition<f64>) {
+    pub(super) fn set_ime_cursor_area(
+        &mut self,
+        position: LogicalPosition<f64>,
+        size: LogicalSize<f64>,
+    ) {
         self.state.ime_position = position;
+        self.state.ime_size = size;
         let input_context = self.inputContext().expect("input context");
         input_context.invalidateCharacterCoordinates();
     }

src/platform_impl/macos/window.rs

@@ -1161,10 +1161,11 @@ impl WinitWindow {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, spot: Position) {
+    pub fn set_ime_cursor_area(&self, spot: Position, size: Size) {
         let scale_factor = self.scale_factor();
         let logical_spot = spot.to_logical(scale_factor);
-        util::set_ime_position_sync(self, logical_spot);
+        let size = size.to_logical(scale_factor);
+        util::set_ime_cursor_area_sync(self, logical_spot, size);
     }
 
     #[inline]

src/platform_impl/orbital/window.rs

@@ -324,7 +324,7 @@ impl Window {
     pub fn set_window_icon(&self, _window_icon: Option<crate::icon::Icon>) {}
 
     #[inline]
-    pub fn set_ime_position(&self, _position: Position) {}
+    pub fn set_ime_cursor_area(&self, _position: Position, _size: Size) {}
 
     #[inline]
     pub fn set_ime_allowed(&self, _allowed: bool) {}

src/platform_impl/web/window.rs

@@ -327,7 +327,7 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, _position: Position) {
+    pub fn set_ime_cursor_area(&self, _position: Position, _size: Size) {
         // Currently a no-op as it does not seem there is good support for this on web
     }
 

src/platform_impl/windows/ime.rs

@@ -1,12 +1,11 @@
 use std::{
     ffi::{c_void, OsString},
-    mem::zeroed,
     os::windows::prelude::OsStringExt,
     ptr::null_mut,
 };
 
 use windows_sys::Win32::{
-    Foundation::POINT,
+    Foundation::{POINT, RECT},
     Globalization::HIMC,
     UI::{
         Input::Ime::{
@@ -19,7 +18,10 @@ use windows_sys::Win32::{
     },
 };
 
-use crate::{dpi::Position, platform::windows::HWND};
+use crate::{
+    dpi::{Position, Size},
+    platform::windows::HWND,
+};
 
 pub struct ImeContext {
     hwnd: HWND,
@@ -109,17 +111,24 @@ impl ImeContext {
         }
     }
 
-    pub unsafe fn set_ime_position(&self, spot: Position, scale_factor: f64) {
+    pub unsafe fn set_ime_cursor_area(&self, spot: Position, size: Size, scale_factor: f64) {
         if !ImeContext::system_has_ime() {
             return;
         }
 
         let (x, y) = spot.to_physical::<i32>(scale_factor).into();
+        let (width, height): (i32, i32) = size.to_physical::<i32>(scale_factor).into();
+        let rc_area = RECT {
+            left: x,
+            top: y,
+            right: x + width,
+            bottom: y - height,
+        };
         let candidate_form = CANDIDATEFORM {
             dwIndex: 0,
             dwStyle: CFS_EXCLUDE,
             ptCurrentPos: POINT { x, y },
-            rcArea: zeroed(),
+            rcArea: rc_area,
         };
 
         ImmSetCandidateWindow(self.himc, &candidate_form);

src/platform_impl/windows/window.rs

@@ -722,9 +722,9 @@ impl Window {
     }
 
     #[inline]
-    pub fn set_ime_position(&self, spot: Position) {
+    pub fn set_ime_cursor_area(&self, spot: Position, size: Size) {
         unsafe {
-            ImeContext::current(self.hwnd()).set_ime_position(spot, self.scale_factor());
+            ImeContext::current(self.hwnd()).set_ime_cursor_area(spot, size, self.scale_factor());
         }
     }
 

src/window.rs

@@ -1017,37 +1017,45 @@ impl Window {
         self.window.set_window_icon(window_icon)
     }
 
-    /// Sets location of IME candidate box in client area coordinates relative to the top left.
+    /// Set the IME cursor editing area, where the `position` is the top left corner of that area
+    /// and `size` is the size of this area starting from the position. An example of such area
+    /// could be a input field in the UI or line in the editor.
     ///
-    /// This is the window / popup / overlay that allows you to select the desired characters.
-    /// The look of this box may differ between input devices, even on the same platform.
+    /// The windowing system could place a candidate box close to that area, but try to not obscure
+    /// the specified area, so the user input to it stays visible.
+    ///
+    /// The candidate box is the window / popup / overlay that allows you to select the desired
+    /// characters. The look of this box may differ between input devices, even on the same
+    /// platform.
     ///
     /// (Apple's official term is "candidate window", see their [chinese] and [japanese] guides).
     ///
     /// ## Example
     ///
     /// ```no_run
-    /// # use winit::dpi::{LogicalPosition, PhysicalPosition};
+    /// # use winit::dpi::{LogicalPosition, PhysicalPosition, LogicalSize, PhysicalSize};
     /// # use winit::event_loop::EventLoop;
     /// # use winit::window::Window;
     /// # let mut event_loop = EventLoop::new();
     /// # let window = Window::new(&event_loop).unwrap();
     /// // Specify the position in logical dimensions like this:
-    /// window.set_ime_position(LogicalPosition::new(400.0, 200.0));
+    /// window.set_ime_cursor_area(LogicalPosition::new(400.0, 200.0), LogicalSize::new(100, 100));
     ///
     /// // Or specify the position in physical dimensions like this:
-    /// window.set_ime_position(PhysicalPosition::new(400, 200));
+    /// window.set_ime_cursor_area(PhysicalPosition::new(400, 200), PhysicalSize::new(100, 100));
     /// ```
     ///
     /// ## Platform-specific
     ///
+    /// - **X11:** - area is not supported, only position.
     /// - **iOS / Android / Web / Orbital:** Unsupported.
     ///
     /// [chinese]: https://support.apple.com/guide/chinese-input-method/use-the-candidate-window-cim12992/104/mac/12.0
     /// [japanese]: https://support.apple.com/guide/japanese-input-method/use-the-candidate-window-jpim10262/6.3/mac/12.0
     #[inline]
-    pub fn set_ime_position<P: Into<Position>>(&self, position: P) {
-        self.window.set_ime_position(position.into())
+    pub fn set_ime_cursor_area<P: Into<Position>, S: Into<Size>>(&self, position: P, size: S) {
+        self.window
+            .set_ime_cursor_area(position.into(), size.into())
     }
 
     /// Sets whether the window should get IME events