Add IME language selection to InputOptions for CJK support

crates/eframe/src/web/text_agent.rs

@@ -87,9 +87,17 @@ impl TextAgent {
         };
 
         let on_composition_update = {
+            let input = input.clone();
             move |event: web_sys::CompositionEvent, runner: &mut AppRunner| {
                 let Some(text) = event.data() else { return };
-                let event = egui::Event::Ime(egui::ImeEvent::Preedit(text));
+
+                let start = input.selection_start().ok().flatten().unwrap_or(0) as usize;
+                let end = input.selection_end().ok().flatten().unwrap_or(0) as usize;
+                let event = egui::Event::Ime(egui::ImeEvent::Preedit {
+                    text_mark: text,
+                    start,
+                    end,
+                });
                 runner.input.raw.events.push(event);
                 runner.needs_repaint.repaint_asap();
             }

crates/egui-winit/src/lib.rs

@@ -594,11 +594,15 @@ impl State {
                     self.ime_event_enable();
                 }
             }
-            winit::event::Ime::Preedit(text, Some(_cursor)) => {
+            winit::event::Ime::Preedit(text, Some(cursor)) => {
                 self.ime_event_enable();
                 self.egui_input
                     .events
-                    .push(egui::Event::Ime(egui::ImeEvent::Preedit(text.clone())));
+                    .push(egui::Event::Ime(egui::ImeEvent::Preedit {
+                        text_mark: text.clone(),
+                        start: cursor.0,
+                        end: cursor.1,
+                    }));
             }
             winit::event::Ime::Commit(text) => {
                 self.egui_input
@@ -618,8 +622,11 @@ impl State {
                 // TextEdit in such situation.
                 self.egui_input
                     .events
-                    .push(egui::Event::Ime(egui::ImeEvent::Preedit(String::new())));
-                self.ime_event_disable();
+                    .push(egui::Event::Ime(egui::ImeEvent::Preedit {
+                        text_mark: String::new(),
+                        start: 0,
+                        end: 0,
+                    }));
             }
         }
     }

crates/egui/src/data/input.rs

@@ -571,7 +571,11 @@ pub enum ImeEvent {
     Enabled,
 
     /// A new IME candidate is being suggested.
-    Preedit(String),
+    Preedit {
+        text_mark: String,
+        start: usize,
+        end: usize,
+    },
 
     /// IME composition ended with this final result.
     Commit(String),

crates/egui/src/input_state/mod.rs

@@ -53,10 +53,23 @@ impl SurrenderFocusOn {
     }
 }
 
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub enum ImeLanguage {
+    #[default]
+    None,
+    Korean,
+    Japanese,
+    Chinese,
+}
+
 /// Options for input state handling.
 #[derive(Clone, Copy, Debug, PartialEq)]
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct InputOptions {
+    /// The language used for specialized IME (Input Method Editor) processing.
+    pub ime_language: ImeLanguage,
+
     /// Multiplier for the scroll speed when reported in [`crate::MouseWheelUnit::Line`]s.
     pub line_scroll_speed: f32,
 
@@ -110,6 +123,7 @@ impl Default for InputOptions {
         };
 
         Self {
+            ime_language: ImeLanguage::default(),
             line_scroll_speed,
             scroll_zoom_speed: 1.0 / 200.0,
             max_click_dist: 6.0,
@@ -127,6 +141,7 @@ impl InputOptions {
     /// Show the options in the ui.
     pub fn ui(&mut self, ui: &mut crate::Ui) {
         let Self {
+            ime_language,
             line_scroll_speed,
             scroll_zoom_speed,
             max_click_dist,
@@ -141,6 +156,23 @@ impl InputOptions {
             .num_columns(2)
             .striped(true)
             .show(ui, |ui| {
+                ui.label("IME Language");
+                let inner_response = crate::ComboBox::from_id_salt("ime_language_combo")
+                    .selected_text(match ime_language {
+                        ImeLanguage::None => "None",
+                        ImeLanguage::Korean => "Korean",
+                        ImeLanguage::Japanese => "Japanese",
+                        ImeLanguage::Chinese => "Chinese",
+                    })
+                    .show_ui(ui, |ui| {
+                        ui.selectable_value(ime_language, ImeLanguage::None, "None");
+                        ui.selectable_value(ime_language, ImeLanguage::Korean, "Korean");
+                        ui.selectable_value(ime_language, ImeLanguage::Japanese, "Japanese");
+                        ui.selectable_value(ime_language, ImeLanguage::Chinese, "Chinese");
+                    });
+                inner_response.response.on_hover_text("Select the language for specialized IME processing (CJK)");
+                ui.end_row();
+
                 ui.label("Line scroll speed");
                 ui.add(crate::DragValue::new(line_scroll_speed).range(0.0..=f32::INFINITY))
                     .on_hover_text(
@@ -199,7 +231,6 @@ impl InputOptions {
                 ui.label("surrender_focus_on");
                 surrender_focus_on.ui(ui);
                 ui.end_row();
-
             });
     }
 }
@@ -330,7 +361,7 @@ pub struct InputState {
     /// Input state management configuration.
     ///
     /// This gets copied from `egui::Options` at the start of each frame for convenience.
-    options: InputOptions,
+    pub options: InputOptions,
 }
 
 impl Default for InputState {