Auto merge of #28308 - philip-lamb:phil-ime-textentry, r=jdm

Improve IME messaging to embedder with insertion point index and mult…

…iline flag.

<!-- Please describe your changes on the following line: -->
This improves handling of IME requests in the embedder by passing the location of the insertion point along with the current text, and a boolean flag 'multiline' (true for HTML textarea, false otherwise) which allows the embedder to be more clever about handling of the 'enter' or 'return' keys.

Tested and working in an embedding example.

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #___ (GitHub issue number if applicable)

<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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ports/libmlservo/src/lib.rs

@@ -416,7 +416,8 @@ impl HostTrait for HostCallbacks {
     fn on_ime_show(
         &self,
         _input_type: InputMethodType,
-        _text: Option<String>,
+        _text: Option<(String, i32)>,
+        _multiline: bool,
         _bounds: DeviceIntRect,
     ) {
         if let Some(keyboard) = self.keyboard.0 {

ports/libsimpleservo/api/src/lib.rs

@@ -141,7 +141,13 @@ pub trait HostTrait {
     /// Servo finished shutting down.
     fn on_shutdown_complete(&self);
     /// A text input is focused.
-    fn on_ime_show(&self, input_type: InputMethodType, text: Option<String>, bounds: DeviceIntRect);
+    fn on_ime_show(
+        &self,
+        input_type: InputMethodType,
+        text: Option<(String, i32)>,
+        multiline: bool,
+        bounds: DeviceIntRect,
+    );
     /// Input lost focus
     fn on_ime_hide(&self);
     /// Gets sytem clipboard contents.
@@ -742,10 +748,10 @@ impl ServoGlue {
 
                     let _ = sender.send(result);
                 },
-                EmbedderMsg::ShowIME(kind, text, bounds) => {
+                EmbedderMsg::ShowIME(kind, text, multiline, bounds) => {
                     self.callbacks
                         .host_callbacks
-                        .on_ime_show(kind, text, bounds);
+                        .on_ime_show(kind, text, multiline, bounds);
                 },
                 EmbedderMsg::HideIME => {
                     self.callbacks.host_callbacks.on_ime_hide();

ports/libsimpleservo/capi/src/lib.rs

@@ -205,7 +205,15 @@ pub struct CHostCallbacks {
     pub on_history_changed: extern "C" fn(can_go_back: bool, can_go_forward: bool),
     pub on_animating_changed: extern "C" fn(animating: bool),
     pub on_shutdown_complete: extern "C" fn(),
-    pub on_ime_show: extern "C" fn(text: *const c_char, x: i32, y: i32, width: i32, height: i32),
+    pub on_ime_show: extern "C" fn(
+        text: *const c_char,
+        text_index: i32,
+        multiline: bool,
+        x: i32,
+        y: i32,
+        width: i32,
+        height: i32,
+    ),
     pub on_ime_hide: extern "C" fn(),
     pub get_clipboard_contents: extern "C" fn() -> *const c_char,
     pub set_clipboard_contents: extern "C" fn(contents: *const c_char),
@@ -808,17 +816,21 @@ impl HostTrait for HostCallbacks {
     fn on_ime_show(
         &self,
         _input_type: InputMethodType,
-        text: Option<String>,
+        text: Option<(String, i32)>,
+        multiline: bool,
         bounds: DeviceIntRect,
     ) {
         debug!("on_ime_show");
-        let text = text.and_then(|s| CString::new(s).ok());
+        let text_index = text.as_ref().map_or(0, |(_, i)| *i);
+        let text = text.and_then(|(s, _)| CString::new(s).ok());
         let text_ptr = text
             .as_ref()
             .map(|cstr| cstr.as_ptr())
             .unwrap_or(std::ptr::null());
         (self.0.on_ime_show)(
             text_ptr,
+            text_index,
+            multiline,
             bounds.origin.x,
             bounds.origin.y,
             bounds.size.width,

ports/libsimpleservo/jniapi/src/lib.rs

@@ -530,7 +530,14 @@ impl HostTrait for HostCallbacks {
         .unwrap();
     }
 
-    fn on_ime_show(&self, _type: InputEncoding, _text: Option<String>, _rect: DeviceIntRect) {}
+    fn on_ime_show(
+        &self,
+        _type: InputEncoding,
+        _text: Option<(String, i32)>,
+        _multiline: bool,
+        _rect: DeviceIntRect,
+    ) {
+    }
     fn on_ime_hide(&self) {}
 
     fn get_clipboard_contents(&self) -> Option<String> {

ports/winit/browser.rs

@@ -487,7 +487,7 @@ where
                     let permission_state = prompt_user(prompt);
                     let _ = sender.send(permission_state);
                 },
-                EmbedderMsg::ShowIME(_kind, _text, _rect) => {
+                EmbedderMsg::ShowIME(_kind, _text, _multiline, _rect) => {
                     debug!("ShowIME received");
                 },
                 EmbedderMsg::HideIME => {