Move X11 backend to winit-x11 (#4253)

winit-x11/src/ime/callbacks.rs

@@ -0,0 +1,206 @@
+use std::collections::HashMap;
+use std::os::raw::c_char;
+use std::ptr;
+use std::sync::Arc;
+
+use super::context::{ImeContext, ImeContextCreationError};
+use super::ffi;
+use super::inner::{close_im, ImeInner};
+use super::input_method::PotentialInputMethods;
+use crate::xdisplay::{XConnection, XError};
+
+pub(crate) unsafe fn xim_set_callback(
+    xconn: &Arc<XConnection>,
+    xim: ffi::XIM,
+    field: *const c_char,
+    callback: *mut ffi::XIMCallback,
+) -> Result<(), XError> {
+    // It's advisable to wrap variadic FFI functions in our own functions, as we want to minimize
+    // access that isn't type-checked.
+    unsafe { (xconn.xlib.XSetIMValues)(xim, field, callback, ptr::null_mut::<()>()) };
+    xconn.check_errors()
+}
+
+// Set a callback for when an input method matching the current locale modifiers becomes
+// available. Note that this has nothing to do with what input methods are open or able to be
+// opened, and simply uses the modifiers that are set when the callback is set.
+// * This is called per locale modifier, not per input method opened with that locale modifier.
+// * Trying to set this for multiple locale modifiers causes problems, i.e. one of the rebuilt input
+//   contexts would always silently fail to use the input method.
+pub(crate) unsafe fn set_instantiate_callback(
+    xconn: &Arc<XConnection>,
+    client_data: ffi::XPointer,
+) -> Result<(), XError> {
+    unsafe {
+        (xconn.xlib.XRegisterIMInstantiateCallback)(
+            xconn.display,
+            ptr::null_mut(),
+            ptr::null_mut(),
+            ptr::null_mut(),
+            Some(xim_instantiate_callback),
+            client_data,
+        )
+    };
+    xconn.check_errors()
+}
+
+pub(crate) unsafe fn unset_instantiate_callback(
+    xconn: &Arc<XConnection>,
+    client_data: ffi::XPointer,
+) -> Result<(), XError> {
+    unsafe {
+        (xconn.xlib.XUnregisterIMInstantiateCallback)(
+            xconn.display,
+            ptr::null_mut(),
+            ptr::null_mut(),
+            ptr::null_mut(),
+            Some(xim_instantiate_callback),
+            client_data,
+        )
+    };
+    xconn.check_errors()
+}
+
+pub(crate) unsafe fn set_destroy_callback(
+    xconn: &Arc<XConnection>,
+    im: ffi::XIM,
+    inner: &ImeInner,
+) -> Result<(), XError> {
+    unsafe {
+        xim_set_callback(
+            xconn,
+            im,
+            ffi::XNDestroyCallback_0.as_ptr() as *const _,
+            &inner.destroy_callback as *const _ as *mut _,
+        )
+    }
+}
+
+#[derive(Debug)]
+#[allow(clippy::enum_variant_names)]
+enum ReplaceImError {
+    // Boxed to prevent large error type
+    MethodOpenFailed(#[allow(dead_code)] Box<PotentialInputMethods>),
+    ContextCreationFailed(#[allow(dead_code)] ImeContextCreationError),
+    SetDestroyCallbackFailed(#[allow(dead_code)] XError),
+}
+
+// Attempt to replace current IM (which may or may not be presently valid) with a new one. This
+// includes replacing all existing input contexts and free'ing resources as necessary. This only
+// modifies existing state if all operations succeed.
+unsafe fn replace_im(inner: *mut ImeInner) -> Result<(), ReplaceImError> {
+    let xconn = unsafe { &(*inner).xconn };
+
+    let (new_im, is_fallback) = {
+        let new_im = unsafe { (*inner).potential_input_methods.open_im(xconn, None) };
+        let is_fallback = new_im.is_fallback();
+        (
+            new_im.ok().ok_or_else(|| {
+                ReplaceImError::MethodOpenFailed(Box::new(unsafe {
+                    (*inner).potential_input_methods.clone()
+                }))
+            })?,
+            is_fallback,
+        )
+    };
+
+    // It's important to always set a destroy callback, since there's otherwise potential for us
+    // to try to use or free a resource that's already been destroyed on the server.
+    {
+        let result = unsafe { set_destroy_callback(xconn, new_im.im, &*inner) };
+        if result.is_err() {
+            let _ = unsafe { close_im(xconn, new_im.im) };
+        }
+        result
+    }
+    .map_err(ReplaceImError::SetDestroyCallbackFailed)?;
+
+    let mut new_contexts = HashMap::new();
+    for (window, old_context) in unsafe { (*inner).contexts.iter() } {
+        let area = old_context.as_ref().map(|old_context| old_context.ic_area);
+
+        // Check if the IME was allowed on that context.
+        let is_allowed =
+            old_context.as_ref().map(|old_context| old_context.is_allowed()).unwrap_or_default();
+
+        let new_context = {
+            let result = unsafe {
+                ImeContext::new(
+                    xconn,
+                    &new_im,
+                    *window,
+                    area,
+                    (*inner).event_sender.clone(),
+                    is_allowed,
+                )
+            };
+            if result.is_err() {
+                let _ = unsafe { close_im(xconn, new_im.im) };
+            }
+            result.map_err(ReplaceImError::ContextCreationFailed)?
+        };
+        new_contexts.insert(*window, Some(new_context));
+    }
+
+    // If we've made it this far, everything succeeded.
+    unsafe {
+        let _ = (*inner).destroy_all_contexts_if_necessary();
+        let _ = (*inner).close_im_if_necessary();
+        (*inner).im = Some(new_im);
+        (*inner).contexts = new_contexts;
+        (*inner).is_destroyed = false;
+        (*inner).is_fallback = is_fallback;
+    }
+    Ok(())
+}
+
+pub unsafe extern "C" fn xim_instantiate_callback(
+    _display: *mut ffi::Display,
+    client_data: ffi::XPointer,
+    // This field is unsupplied.
+    _call_data: ffi::XPointer,
+) {
+    let inner: *mut ImeInner = client_data as _;
+    if !inner.is_null() {
+        let xconn = unsafe { &(*inner).xconn };
+        match unsafe { replace_im(inner) } {
+            Ok(()) => unsafe {
+                let _ = unset_instantiate_callback(xconn, client_data);
+                (*inner).is_fallback = false;
+            },
+            Err(err) => unsafe {
+                if (*inner).is_destroyed {
+                    // We have no usable input methods!
+                    panic!("Failed to reopen input method: {err:?}");
+                }
+            },
+        }
+    }
+}
+
+// This callback is triggered when the input method is closed on the server end. When this
+// happens, XCloseIM/XDestroyIC doesn't need to be called, as the resources have already been
+// free'd (attempting to do so causes our connection to freeze).
+pub unsafe extern "C" fn xim_destroy_callback(
+    _xim: ffi::XIM,
+    client_data: ffi::XPointer,
+    // This field is unsupplied.
+    _call_data: ffi::XPointer,
+) {
+    let inner: *mut ImeInner = client_data as _;
+    if !inner.is_null() {
+        unsafe { (*inner).is_destroyed = true };
+        let xconn = unsafe { &(*inner).xconn };
+        if unsafe { !(*inner).is_fallback } {
+            let _ = unsafe { set_instantiate_callback(xconn, client_data) };
+            // Attempt to open fallback input method.
+            match unsafe { replace_im(inner) } {
+                Ok(()) => unsafe { (*inner).is_fallback = true },
+                Err(err) => {
+                    // We have no usable input methods!
+                    panic!("Failed to open fallback input method: {err:?}");
+                },
+            }
+        }
+    }
+}

winit-x11/src/ime/context.rs

@@ -0,0 +1,405 @@
+use std::error::Error;
+use std::ffi::CStr;
+use std::sync::Arc;
+use std::{fmt, mem, ptr};
+
+use x11_dl::xlib::{XIMCallback, XIMPreeditCaretCallbackStruct, XIMPreeditDrawCallbackStruct};
+
+use super::input_method::{InputMethod, Style, XIMStyle};
+use super::{ffi, util, ImeEvent, ImeEventSender};
+use crate::xdisplay::{XConnection, XError};
+
+/// IME creation error.
+#[derive(Debug)]
+pub enum ImeContextCreationError {
+    /// Got the error from Xlib.
+    XError(XError),
+
+    /// Got null pointer from Xlib but without exact reason.
+    Null,
+}
+
+impl fmt::Display for ImeContextCreationError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            ImeContextCreationError::XError(err) => err.fmt(f),
+            ImeContextCreationError::Null => {
+                write!(f, "got null pointer from Xlib without exact reason")
+            },
+        }
+    }
+}
+
+impl Error for ImeContextCreationError {}
+
+/// The callback used by XIM preedit functions.
+type XIMProcNonnull = unsafe extern "C" fn(ffi::XIM, ffi::XPointer, ffi::XPointer);
+
+/// Wrapper for creating XIM callbacks.
+#[inline]
+fn create_xim_callback(client_data: ffi::XPointer, callback: XIMProcNonnull) -> ffi::XIMCallback {
+    XIMCallback { client_data, callback: Some(callback) }
+}
+
+/// The server started preedit.
+extern "C" fn preedit_start_callback(
+    _xim: ffi::XIM,
+    client_data: ffi::XPointer,
+    _call_data: ffi::XPointer,
+) -> i32 {
+    let client_data = unsafe { &mut *(client_data as *mut ImeContextClientData) };
+
+    client_data.text.clear();
+    client_data.cursor_pos = 0;
+    client_data
+        .event_sender
+        .send((client_data.window, ImeEvent::Start))
+        .expect("failed to send preedit start event");
+    -1
+}
+
+/// Done callback is used when the preedit should be hidden.
+extern "C" fn preedit_done_callback(
+    _xim: ffi::XIM,
+    client_data: ffi::XPointer,
+    _call_data: ffi::XPointer,
+) {
+    let client_data = unsafe { &mut *(client_data as *mut ImeContextClientData) };
+
+    // Drop text buffer and reset cursor position on done.
+    client_data.text = Vec::new();
+    client_data.cursor_pos = 0;
+
+    client_data
+        .event_sender
+        .send((client_data.window, ImeEvent::End))
+        .expect("failed to send preedit end event");
+}
+
+fn calc_byte_position(text: &[char], pos: usize) -> usize {
+    text.iter().take(pos).fold(0, |byte_pos, text| byte_pos + text.len_utf8())
+}
+
+/// Preedit text information to be drawn inline by the client.
+extern "C" fn preedit_draw_callback(
+    _xim: ffi::XIM,
+    client_data: ffi::XPointer,
+    call_data: ffi::XPointer,
+) {
+    let client_data = unsafe { &mut *(client_data as *mut ImeContextClientData) };
+    let call_data = unsafe { &mut *(call_data as *mut XIMPreeditDrawCallbackStruct) };
+    client_data.cursor_pos = call_data.caret as usize;
+
+    let chg_range =
+        call_data.chg_first as usize..(call_data.chg_first + call_data.chg_length) as usize;
+    if chg_range.start > client_data.text.len() || chg_range.end > client_data.text.len() {
+        tracing::warn!(
+            "invalid chg range: buffer length={}, but chg_first={} chg_lengthg={}",
+            client_data.text.len(),
+            call_data.chg_first,
+            call_data.chg_length
+        );
+        return;
+    }
+
+    // NULL indicate text deletion
+    let mut new_chars = if call_data.text.is_null() {
+        Vec::new()
+    } else {
+        let xim_text = unsafe { &mut *(call_data.text) };
+        if xim_text.encoding_is_wchar > 0 {
+            return;
+        }
+
+        let new_text = unsafe { xim_text.string.multi_byte };
+
+        if new_text.is_null() {
+            return;
+        }
+
+        let new_text = unsafe { CStr::from_ptr(new_text) };
+
+        String::from(new_text.to_str().expect("Invalid UTF-8 String from IME")).chars().collect()
+    };
+    let mut old_text_tail = client_data.text.split_off(chg_range.end);
+    client_data.text.truncate(chg_range.start);
+    client_data.text.append(&mut new_chars);
+    client_data.text.append(&mut old_text_tail);
+    let cursor_byte_pos = calc_byte_position(&client_data.text, client_data.cursor_pos);
+
+    client_data
+        .event_sender
+        .send((
+            client_data.window,
+            ImeEvent::Update(client_data.text.iter().collect(), cursor_byte_pos),
+        ))
+        .expect("failed to send preedit update event");
+}
+
+/// Handling of cursor movements in preedit text.
+extern "C" fn preedit_caret_callback(
+    _xim: ffi::XIM,
+    client_data: ffi::XPointer,
+    call_data: ffi::XPointer,
+) {
+    let client_data = unsafe { &mut *(client_data as *mut ImeContextClientData) };
+    let call_data = unsafe { &mut *(call_data as *mut XIMPreeditCaretCallbackStruct) };
+
+    if call_data.direction == ffi::XIMCaretDirection::XIMAbsolutePosition {
+        client_data.cursor_pos = call_data.position as usize;
+        let cursor_byte_pos = calc_byte_position(&client_data.text, client_data.cursor_pos);
+
+        client_data
+            .event_sender
+            .send((
+                client_data.window,
+                ImeEvent::Update(client_data.text.iter().collect(), cursor_byte_pos),
+            ))
+            .expect("failed to send preedit update event");
+    }
+}
+
+/// Struct to simplify callback creation and latter passing into Xlib XIM.
+struct PreeditCallbacks {
+    start_callback: ffi::XIMCallback,
+    done_callback: ffi::XIMCallback,
+    draw_callback: ffi::XIMCallback,
+    caret_callback: ffi::XIMCallback,
+}
+
+impl PreeditCallbacks {
+    pub fn new(client_data: ffi::XPointer) -> PreeditCallbacks {
+        let start_callback = create_xim_callback(client_data, unsafe {
+            mem::transmute::<usize, unsafe extern "C" fn(ffi::XIM, ffi::XPointer, ffi::XPointer)>(
+                preedit_start_callback as usize,
+            )
+        });
+        let done_callback = create_xim_callback(client_data, preedit_done_callback);
+        let caret_callback = create_xim_callback(client_data, preedit_caret_callback);
+        let draw_callback = create_xim_callback(client_data, preedit_draw_callback);
+
+        PreeditCallbacks { start_callback, done_callback, caret_callback, draw_callback }
+    }
+}
+
+struct ImeContextClientData {
+    window: ffi::Window,
+    event_sender: ImeEventSender,
+    text: Vec<char>,
+    cursor_pos: usize,
+}
+
+// XXX: this struct doesn't destroy its XIC resource when dropped.
+// This is intentional, as it doesn't have enough information to know whether or not the context
+// still exists on the server. Since `ImeInner` has that awareness, destruction must be handled
+// through `ImeInner`.
+pub struct ImeContext {
+    pub(crate) ic: ffi::XIC,
+    pub(crate) ic_area: ffi::XRectangle,
+    pub(crate) allowed: bool,
+    // Since the data is passed shared between X11 XIM callbacks, but couldn't be directly free
+    // from there we keep the pointer to automatically deallocate it.
+    _client_data: Box<ImeContextClientData>,
+}
+
+impl ImeContext {
+    pub(crate) unsafe fn new(
+        xconn: &Arc<XConnection>,
+        im: &InputMethod,
+        window: ffi::Window,
+        ic_area: Option<ffi::XRectangle>,
+        event_sender: ImeEventSender,
+        allowed: bool,
+    ) -> Result<Self, ImeContextCreationError> {
+        let client_data = Box::into_raw(Box::new(ImeContextClientData {
+            window,
+            event_sender,
+            text: Vec::new(),
+            cursor_pos: 0,
+        }));
+
+        let style = if allowed { im.preedit_style } else { im.none_style };
+
+        let ic = match style as _ {
+            Style::Preedit(style) => unsafe {
+                ImeContext::create_preedit_ic(
+                    xconn,
+                    im.im,
+                    style,
+                    window,
+                    client_data as ffi::XPointer,
+                )
+            },
+            Style::Nothing(style) => unsafe {
+                ImeContext::create_nothing_ic(xconn, im.im, style, window)
+            },
+            Style::None(style) => unsafe {
+                ImeContext::create_none_ic(xconn, im.im, style, window)
+            },
+        }
+        .ok_or(ImeContextCreationError::Null)?;
+
+        xconn.check_errors().map_err(ImeContextCreationError::XError)?;
+
+        let mut context = ImeContext {
+            ic,
+            ic_area: ffi::XRectangle { x: 0, y: 0, width: 0, height: 0 },
+            allowed,
+            _client_data: unsafe { Box::from_raw(client_data) },
+        };
+
+        // Set the preedit cursor area, if it's present.
+        if let Some(ic_area) = ic_area {
+            context.set_area(xconn, ic_area.x, ic_area.y, ic_area.width, ic_area.height);
+        }
+
+        Ok(context)
+    }
+
+    unsafe fn create_none_ic(
+        xconn: &Arc<XConnection>,
+        im: ffi::XIM,
+        style: XIMStyle,
+        window: ffi::Window,
+    ) -> Option<ffi::XIC> {
+        let ic = unsafe {
+            (xconn.xlib.XCreateIC)(
+                im,
+                ffi::XNInputStyle_0.as_ptr() as *const _,
+                style,
+                ffi::XNClientWindow_0.as_ptr() as *const _,
+                window,
+                ptr::null_mut::<()>(),
+            )
+        };
+
+        (!ic.is_null()).then_some(ic)
+    }
+
+    unsafe fn create_preedit_ic(
+        xconn: &Arc<XConnection>,
+        im: ffi::XIM,
+        style: XIMStyle,
+        window: ffi::Window,
+        client_data: ffi::XPointer,
+    ) -> Option<ffi::XIC> {
+        let preedit_callbacks = PreeditCallbacks::new(client_data);
+        let preedit_attr = util::memory::XSmartPointer::new(xconn, unsafe {
+            (xconn.xlib.XVaCreateNestedList)(
+                0,
+                ffi::XNPreeditStartCallback_0.as_ptr() as *const _,
+                &(preedit_callbacks.start_callback) as *const _,
+                ffi::XNPreeditDoneCallback_0.as_ptr() as *const _,
+                &(preedit_callbacks.done_callback) as *const _,
+                ffi::XNPreeditCaretCallback_0.as_ptr() as *const _,
+                &(preedit_callbacks.caret_callback) as *const _,
+                ffi::XNPreeditDrawCallback_0.as_ptr() as *const _,
+                &(preedit_callbacks.draw_callback) as *const _,
+                ptr::null_mut::<()>(),
+            )
+        })
+        .expect("XVaCreateNestedList returned NULL");
+
+        let ic = unsafe {
+            (xconn.xlib.XCreateIC)(
+                im,
+                ffi::XNInputStyle_0.as_ptr() as *const _,
+                style,
+                ffi::XNClientWindow_0.as_ptr() as *const _,
+                window,
+                ffi::XNPreeditAttributes_0.as_ptr() as *const _,
+                preedit_attr.ptr,
+                ptr::null_mut::<()>(),
+            )
+        };
+
+        (!ic.is_null()).then_some(ic)
+    }
+
+    unsafe fn create_nothing_ic(
+        xconn: &Arc<XConnection>,
+        im: ffi::XIM,
+        style: XIMStyle,
+        window: ffi::Window,
+    ) -> Option<ffi::XIC> {
+        let ic = unsafe {
+            (xconn.xlib.XCreateIC)(
+                im,
+                ffi::XNInputStyle_0.as_ptr() as *const _,
+                style,
+                ffi::XNClientWindow_0.as_ptr() as *const _,
+                window,
+                ptr::null_mut::<()>(),
+            )
+        };
+
+        (!ic.is_null()).then_some(ic)
+    }
+
+    pub(crate) fn focus(&self, xconn: &Arc<XConnection>) -> Result<(), XError> {
+        unsafe {
+            (xconn.xlib.XSetICFocus)(self.ic);
+        }
+        xconn.check_errors()
+    }
+
+    pub(crate) fn unfocus(&self, xconn: &Arc<XConnection>) -> Result<(), XError> {
+        unsafe {
+            (xconn.xlib.XUnsetICFocus)(self.ic);
+        }
+        xconn.check_errors()
+    }
+
+    pub fn is_allowed(&self) -> bool {
+        self.allowed
+    }
+
+    /// Set the spot and area for preedit text.
+    ///
+    /// This functionality depends on the libx11 version.
+    ///  - Until libx11 1.8.2, XNSpotLocation was blocked by libx11 in On-The-Spot mode.
+    ///  - Until libx11 1.8.11, XNArea was blocked by libx11 in On-The-Spot mode.
+    ///
+    /// Use of this information is discretionary by input method servers,
+    /// and some may not use it by default, even if they have support.
+    pub(crate) fn set_area(
+        &mut self,
+        xconn: &Arc<XConnection>,
+        x: i16,
+        y: i16,
+        width: u16,
+        height: u16,
+    ) {
+        let ic_area = ffi::XRectangle { x, y, width, height };
+
+        if !self.is_allowed() || self.ic_area == ic_area {
+            return;
+        }
+
+        self.ic_area = ic_area;
+        let ic_spot =
+            ffi::XPoint { x: x.saturating_add(width as i16), y: y.saturating_add(height as i16) };
+
+        unsafe {
+            let preedit_attr = util::memory::XSmartPointer::new(
+                xconn,
+                (xconn.xlib.XVaCreateNestedList)(
+                    0,
+                    ffi::XNSpotLocation_0.as_ptr(),
+                    &ic_spot,
+                    ffi::XNArea_0.as_ptr(),
+                    &self.ic_area,
+                    ptr::null_mut::<()>(),
+                ),
+            )
+            .expect("XVaCreateNestedList returned NULL");
+
+            (xconn.xlib.XSetICValues)(
+                self.ic,
+                ffi::XNPreeditAttributes_0.as_ptr() as *const _,
+                preedit_attr.ptr,
+                ptr::null_mut::<()>(),
+            );
+        }
+    }
+}

winit-x11/src/ime/inner.rs

@@ -0,0 +1,74 @@
+use std::collections::HashMap;
+use std::mem;
+use std::sync::Arc;
+
+use super::context::ImeContext;
+use super::input_method::{InputMethod, PotentialInputMethods};
+use super::{ffi, ImeEventSender};
+use crate::xdisplay::{XConnection, XError};
+
+pub(crate) unsafe fn close_im(xconn: &Arc<XConnection>, im: ffi::XIM) -> Result<(), XError> {
+    unsafe { (xconn.xlib.XCloseIM)(im) };
+    xconn.check_errors()
+}
+
+pub(crate) unsafe fn destroy_ic(xconn: &Arc<XConnection>, ic: ffi::XIC) -> Result<(), XError> {
+    unsafe { (xconn.xlib.XDestroyIC)(ic) };
+    xconn.check_errors()
+}
+
+pub(crate) struct ImeInner {
+    pub xconn: Arc<XConnection>,
+    pub im: Option<InputMethod>,
+    pub potential_input_methods: PotentialInputMethods,
+    pub contexts: HashMap<ffi::Window, Option<ImeContext>>,
+    // WARNING: this is initially zeroed!
+    pub destroy_callback: ffi::XIMCallback,
+    pub event_sender: ImeEventSender,
+    // Indicates whether or not the input method was destroyed on the server end
+    // (i.e. if ibus/fcitx/etc. was terminated/restarted)
+    pub is_destroyed: bool,
+    pub is_fallback: bool,
+}
+
+impl ImeInner {
+    pub(crate) fn new(
+        xconn: Arc<XConnection>,
+        potential_input_methods: PotentialInputMethods,
+        event_sender: ImeEventSender,
+    ) -> Self {
+        ImeInner {
+            xconn,
+            im: None,
+            potential_input_methods,
+            contexts: HashMap::new(),
+            destroy_callback: unsafe { mem::zeroed() },
+            event_sender,
+            is_destroyed: false,
+            is_fallback: false,
+        }
+    }
+
+    pub unsafe fn close_im_if_necessary(&self) -> Result<bool, XError> {
+        if !self.is_destroyed && self.im.is_some() {
+            unsafe { close_im(&self.xconn, self.im.as_ref().unwrap().im) }.map(|_| true)
+        } else {
+            Ok(false)
+        }
+    }
+
+    pub unsafe fn destroy_ic_if_necessary(&self, ic: ffi::XIC) -> Result<bool, XError> {
+        if !self.is_destroyed {
+            unsafe { destroy_ic(&self.xconn, ic) }.map(|_| true)
+        } else {
+            Ok(false)
+        }
+    }
+
+    pub unsafe fn destroy_all_contexts_if_necessary(&self) -> Result<bool, XError> {
+        for context in self.contexts.values().flatten() {
+            unsafe { self.destroy_ic_if_necessary(context.ic)? };
+        }
+        Ok(!self.is_destroyed)
+    }
+}

winit-x11/src/ime/input_method.rs

@@ -0,0 +1,347 @@
+use std::ffi::{CStr, CString, IntoStringError};
+use std::os::raw::{c_char, c_ulong, c_ushort};
+use std::sync::{Arc, Mutex};
+use std::{env, fmt, ptr};
+
+use x11rb::protocol::xproto;
+
+use super::super::atoms::*;
+use super::{ffi, util};
+use crate::xdisplay::{XConnection, XError};
+
+static GLOBAL_LOCK: Mutex<()> = Mutex::new(());
+
+unsafe fn open_im(xconn: &Arc<XConnection>, locale_modifiers: &CStr) -> Option<ffi::XIM> {
+    let _lock = GLOBAL_LOCK.lock();
+
+    // XSetLocaleModifiers returns...
+    // * The current locale modifiers if it's given a NULL pointer.
+    // * The new locale modifiers if we succeeded in setting them.
+    // * NULL if the locale modifiers string is malformed or if the current locale is not supported
+    //   by Xlib.
+    unsafe { (xconn.xlib.XSetLocaleModifiers)(locale_modifiers.as_ptr()) };
+
+    let im = unsafe {
+        (xconn.xlib.XOpenIM)(xconn.display, ptr::null_mut(), ptr::null_mut(), ptr::null_mut())
+    };
+
+    if im.is_null() {
+        None
+    } else {
+        Some(im)
+    }
+}
+
+#[derive(Debug)]
+pub struct InputMethod {
+    pub im: ffi::XIM,
+    pub preedit_style: Style,
+    pub none_style: Style,
+    _name: String,
+}
+
+impl InputMethod {
+    fn new(xconn: &Arc<XConnection>, im: ffi::XIM, name: String) -> Option<Self> {
+        let mut styles: *mut XIMStyles = std::ptr::null_mut();
+
+        // Query the styles supported by the XIM.
+        unsafe {
+            if !(xconn.xlib.XGetIMValues)(
+                im,
+                ffi::XNQueryInputStyle_0.as_ptr() as *const _,
+                (&mut styles) as *mut _,
+                std::ptr::null_mut::<()>(),
+            )
+            .is_null()
+            {
+                return None;
+            }
+        }
+
+        let mut preedit_style = None;
+        let mut none_style = None;
+
+        unsafe {
+            std::slice::from_raw_parts((*styles).supported_styles, (*styles).count_styles as _)
+                .iter()
+                .for_each(|style| match *style {
+                    XIM_PREEDIT_STYLE => {
+                        preedit_style = Some(Style::Preedit(*style));
+                    },
+                    XIM_NOTHING_STYLE if preedit_style.is_none() => {
+                        preedit_style = Some(Style::Nothing(*style))
+                    },
+                    XIM_NONE_STYLE => none_style = Some(Style::None(*style)),
+                    _ => (),
+                });
+
+            (xconn.xlib.XFree)(styles.cast());
+        };
+
+        if preedit_style.is_none() && none_style.is_none() {
+            return None;
+        }
+
+        let preedit_style = preedit_style.unwrap_or_else(|| none_style.unwrap());
+        let none_style = none_style.unwrap_or(preedit_style);
+
+        Some(InputMethod { im, _name: name, preedit_style, none_style })
+    }
+}
+
+const XIM_PREEDIT_STYLE: XIMStyle = (ffi::XIMPreeditCallbacks | ffi::XIMStatusNothing) as XIMStyle;
+const XIM_NOTHING_STYLE: XIMStyle = (ffi::XIMPreeditNothing | ffi::XIMStatusNothing) as XIMStyle;
+const XIM_NONE_STYLE: XIMStyle = (ffi::XIMPreeditNone | ffi::XIMStatusNone) as XIMStyle;
+
+/// Style of the IME context.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Style {
+    /// Preedit callbacks.
+    Preedit(XIMStyle),
+
+    /// Nothing.
+    Nothing(XIMStyle),
+
+    /// No IME.
+    None(XIMStyle),
+}
+
+impl Default for Style {
+    fn default() -> Self {
+        Style::None(XIM_NONE_STYLE)
+    }
+}
+
+#[repr(C)]
+#[derive(Debug)]
+struct XIMStyles {
+    count_styles: c_ushort,
+    supported_styles: *const XIMStyle,
+}
+
+pub(crate) type XIMStyle = c_ulong;
+
+#[derive(Debug)]
+pub enum InputMethodResult {
+    /// Input method used locale modifier from `XMODIFIERS` environment variable.
+    XModifiers(InputMethod),
+    /// Input method used internal fallback locale modifier.
+    Fallback(InputMethod),
+    /// Input method could not be opened using any locale modifier tried.
+    Failure,
+}
+
+impl InputMethodResult {
+    pub fn is_fallback(&self) -> bool {
+        matches!(self, InputMethodResult::Fallback(_))
+    }
+
+    pub fn ok(self) -> Option<InputMethod> {
+        use self::InputMethodResult::*;
+        match self {
+            XModifiers(im) | Fallback(im) => Some(im),
+            Failure => None,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+enum GetXimServersError {
+    XError(#[allow(dead_code)] XError),
+    GetPropertyError(#[allow(dead_code)] util::GetPropertyError),
+    InvalidUtf8(#[allow(dead_code)] IntoStringError),
+}
+
+impl From<util::GetPropertyError> for GetXimServersError {
+    fn from(error: util::GetPropertyError) -> Self {
+        GetXimServersError::GetPropertyError(error)
+    }
+}
+
+// The root window has a property named XIM_SERVERS, which contains a list of atoms representing
+// the available XIM servers. For instance, if you're using ibus, it would contain an atom named
+// "@server=ibus". It's possible for this property to contain multiple atoms, though presumably
+// rare. Note that we replace "@server=" with "@im=" in order to match the format of locale
+// modifiers, since we don't want a user who's looking at logs to ask "am I supposed to set
+// XMODIFIERS to `@server=ibus`?!?"
+unsafe fn get_xim_servers(xconn: &Arc<XConnection>) -> Result<Vec<String>, GetXimServersError> {
+    let atoms = xconn.atoms();
+    let servers_atom = atoms[XIM_SERVERS];
+
+    let root = unsafe { (xconn.xlib.XDefaultRootWindow)(xconn.display) };
+
+    let mut atoms: Vec<ffi::Atom> = xconn
+        .get_property::<xproto::Atom>(
+            root as xproto::Window,
+            servers_atom,
+            xproto::Atom::from(xproto::AtomEnum::ATOM),
+        )
+        .map_err(GetXimServersError::GetPropertyError)?
+        .into_iter()
+        .map(|atom| atom as _)
+        .collect::<Vec<_>>();
+
+    let mut names: Vec<*const c_char> = Vec::with_capacity(atoms.len());
+    unsafe {
+        (xconn.xlib.XGetAtomNames)(
+            xconn.display,
+            atoms.as_mut_ptr(),
+            atoms.len() as _,
+            names.as_mut_ptr() as _,
+        )
+    };
+    unsafe { names.set_len(atoms.len()) };
+
+    let mut formatted_names = Vec::with_capacity(names.len());
+    for name in names {
+        let string = unsafe { CStr::from_ptr(name) }
+            .to_owned()
+            .into_string()
+            .map_err(GetXimServersError::InvalidUtf8)?;
+        unsafe { (xconn.xlib.XFree)(name as _) };
+        formatted_names.push(string.replace("@server=", "@im="));
+    }
+    xconn.check_errors().map_err(GetXimServersError::XError)?;
+    Ok(formatted_names)
+}
+
+#[derive(Clone)]
+struct InputMethodName {
+    c_string: CString,
+    string: String,
+}
+
+impl InputMethodName {
+    pub fn from_string(string: String) -> Self {
+        let c_string = CString::new(string.clone())
+            .expect("String used to construct CString contained null byte");
+        InputMethodName { c_string, string }
+    }
+
+    pub fn from_str(string: &str) -> Self {
+        let c_string =
+            CString::new(string).expect("String used to construct CString contained null byte");
+        InputMethodName { c_string, string: string.to_owned() }
+    }
+}
+
+impl fmt::Debug for InputMethodName {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.string.fmt(f)
+    }
+}
+
+#[derive(Debug, Clone)]
+struct PotentialInputMethod {
+    name: InputMethodName,
+    successful: Option<bool>,
+}
+
+impl PotentialInputMethod {
+    pub fn from_string(string: String) -> Self {
+        PotentialInputMethod { name: InputMethodName::from_string(string), successful: None }
+    }
+
+    pub fn from_str(string: &str) -> Self {
+        PotentialInputMethod { name: InputMethodName::from_str(string), successful: None }
+    }
+
+    pub fn reset(&mut self) {
+        self.successful = None;
+    }
+
+    pub fn open_im(&mut self, xconn: &Arc<XConnection>) -> Option<InputMethod> {
+        let im = unsafe { open_im(xconn, &self.name.c_string) };
+        self.successful = Some(im.is_some());
+        im.and_then(|im| InputMethod::new(xconn, im, self.name.string.clone()))
+    }
+}
+
+// By logging this struct, you get a sequential listing of every locale modifier tried, where it
+// came from, and if it succeeded.
+#[derive(Debug, Clone)]
+pub(crate) struct PotentialInputMethods {
+    // On correctly configured systems, the XMODIFIERS environment variable tells us everything we
+    // need to know.
+    xmodifiers: Option<PotentialInputMethod>,
+    // We have some standard options at our disposal that should ostensibly always work. For users
+    // who only need compose sequences, this ensures that the program launches without a hitch
+    // For users who need more sophisticated IME features, this is more or less a silent failure.
+    // Logging features should be added in the future to allow both audiences to be effectively
+    // served.
+    fallbacks: [PotentialInputMethod; 2],
+    // For diagnostic purposes, we include the list of XIM servers that the server reports as
+    // being available.
+    _xim_servers: Result<Vec<String>, GetXimServersError>,
+}
+
+impl PotentialInputMethods {
+    pub fn new(xconn: &Arc<XConnection>) -> Self {
+        let xmodifiers = env::var("XMODIFIERS").ok().map(PotentialInputMethod::from_string);
+        PotentialInputMethods {
+            // Since passing "" to XSetLocaleModifiers results in it defaulting to the value of
+            // XMODIFIERS, it's worth noting what happens if XMODIFIERS is also "". If simply
+            // running the program with `XMODIFIERS="" cargo run`, then assuming XMODIFIERS is
+            // defined in the profile (or parent environment) then that parent XMODIFIERS is used.
+            // If that XMODIFIERS value is also "" (i.e. if you ran `export XMODIFIERS=""`), then
+            // XSetLocaleModifiers uses the default local input method. Note that defining
+            // XMODIFIERS as "" is different from XMODIFIERS not being defined at all, since in
+            // that case, we get `None` and end up skipping ahead to the next method.
+            xmodifiers,
+            fallbacks: [
+                // This is a standard input method that supports compose sequences, which should
+                // always be available. `@im=none` appears to mean the same thing.
+                PotentialInputMethod::from_str("@im=local"),
+                // This explicitly specifies to use the implementation-dependent default, though
+                // that seems to be equivalent to just using the local input method.
+                PotentialInputMethod::from_str("@im="),
+            ],
+            // The XIM_SERVERS property can have surprising values. For instance, when I exited
+            // ibus to run fcitx, it retained the value denoting ibus. Even more surprising is
+            // that the fcitx input method could only be successfully opened using "@im=ibus".
+            // Presumably due to this quirk, it's actually possible to alternate between ibus and
+            // fcitx in a running application.
+            _xim_servers: unsafe { get_xim_servers(xconn) },
+        }
+    }
+
+    // This resets the `successful` field of every potential input method, ensuring we have
+    // accurate information when this struct is re-used by the destruction/instantiation callbacks.
+    fn reset(&mut self) {
+        if let Some(ref mut input_method) = self.xmodifiers {
+            input_method.reset();
+        }
+
+        for input_method in &mut self.fallbacks {
+            input_method.reset();
+        }
+    }
+
+    pub fn open_im(
+        &mut self,
+        xconn: &Arc<XConnection>,
+        callback: Option<&dyn Fn()>,
+    ) -> InputMethodResult {
+        use self::InputMethodResult::*;
+
+        self.reset();
+
+        if let Some(ref mut input_method) = self.xmodifiers {
+            let im = input_method.open_im(xconn);
+            if let Some(im) = im {
+                return XModifiers(im);
+            } else if let Some(ref callback) = callback {
+                callback();
+            }
+        }
+
+        for input_method in &mut self.fallbacks {
+            let im = input_method.open_im(xconn);
+            if let Some(im) = im {
+                return Fallback(im);
+            }
+        }
+
+        Failure
+    }
+}

winit-x11/src/ime/mod.rs

@@ -0,0 +1,241 @@
+// Important: all XIM calls need to happen from the same thread!
+
+mod callbacks;
+mod context;
+mod inner;
+mod input_method;
+
+use std::fmt;
+use std::sync::mpsc::{Receiver, Sender};
+use std::sync::Arc;
+
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use self::callbacks::*;
+use self::context::ImeContext;
+pub use self::context::ImeContextCreationError;
+use self::inner::{close_im, ImeInner};
+use self::input_method::PotentialInputMethods;
+use crate::xdisplay::{XConnection, XError};
+use crate::{ffi, util};
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum ImeEvent {
+    Enabled,
+    Start,
+    Update(String, usize),
+    End,
+    Disabled,
+}
+
+pub type ImeReceiver = Receiver<ImeRequest>;
+pub type ImeSender = Sender<ImeRequest>;
+pub type ImeEventReceiver = Receiver<(ffi::Window, ImeEvent)>;
+pub type ImeEventSender = Sender<(ffi::Window, ImeEvent)>;
+
+/// Request to control XIM handler from the window.
+pub enum ImeRequest {
+    /// Set IME preedit area for given `window_id`.
+    Area(ffi::Window, i16, i16, u16, u16),
+
+    /// Allow IME input for the given `window_id`.
+    Allow(ffi::Window, bool),
+}
+
+#[derive(Debug)]
+pub(crate) enum ImeCreationError {
+    // Boxed to prevent large error type
+    OpenFailure(Box<PotentialInputMethods>),
+    SetDestroyCallbackFailed(#[allow(dead_code)] XError),
+}
+
+pub(crate) struct Ime {
+    xconn: Arc<XConnection>,
+    // The actual meat of this struct is boxed away, since it needs to have a fixed location in
+    // memory so we can pass a pointer to it around.
+    inner: Box<ImeInner>,
+}
+
+impl fmt::Debug for Ime {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Ime").finish_non_exhaustive()
+    }
+}
+
+impl Ime {
+    pub fn new(
+        xconn: Arc<XConnection>,
+        event_sender: ImeEventSender,
+    ) -> Result<Self, ImeCreationError> {
+        let potential_input_methods = PotentialInputMethods::new(&xconn);
+
+        let (mut inner, client_data) = {
+            let mut inner = Box::new(ImeInner::new(xconn, potential_input_methods, event_sender));
+            let inner_ptr = Box::into_raw(inner);
+            let client_data = inner_ptr as _;
+            let destroy_callback =
+                ffi::XIMCallback { client_data, callback: Some(xim_destroy_callback) };
+            inner = unsafe { Box::from_raw(inner_ptr) };
+            inner.destroy_callback = destroy_callback;
+            (inner, client_data)
+        };
+
+        let xconn = Arc::clone(&inner.xconn);
+
+        let input_method = inner.potential_input_methods.open_im(
+            &xconn,
+            Some(&|| {
+                let _ = unsafe { set_instantiate_callback(&xconn, client_data) };
+            }),
+        );
+
+        let is_fallback = input_method.is_fallback();
+        if let Some(input_method) = input_method.ok() {
+            inner.is_fallback = is_fallback;
+            unsafe {
+                let result = set_destroy_callback(&xconn, input_method.im, &inner)
+                    .map_err(ImeCreationError::SetDestroyCallbackFailed);
+                if result.is_err() {
+                    let _ = close_im(&xconn, input_method.im);
+                }
+                result?;
+            }
+            inner.im = Some(input_method);
+            Ok(Ime { xconn, inner })
+        } else {
+            Err(ImeCreationError::OpenFailure(Box::new(inner.potential_input_methods)))
+        }
+    }
+
+    pub fn is_destroyed(&self) -> bool {
+        self.inner.is_destroyed
+    }
+
+    // This pattern is used for various methods here:
+    // Ok(_) indicates that nothing went wrong internally
+    // Ok(true) indicates that the action was actually performed
+    // Ok(false) indicates that the action is not presently applicable
+    pub fn create_context(
+        &mut self,
+        window: ffi::Window,
+        with_ime: bool,
+    ) -> Result<bool, ImeContextCreationError> {
+        let context = if self.is_destroyed() {
+            // Create empty entry in map, so that when IME is rebuilt, this window has a context.
+            None
+        } else {
+            let im = self.inner.im.as_ref().unwrap();
+
+            let context = unsafe {
+                ImeContext::new(
+                    &self.inner.xconn,
+                    im,
+                    window,
+                    None,
+                    self.inner.event_sender.clone(),
+                    with_ime,
+                )?
+            };
+
+            let event = if context.is_allowed() { ImeEvent::Enabled } else { ImeEvent::Disabled };
+            self.inner.event_sender.send((window, event)).expect("Failed to send enabled event");
+
+            Some(context)
+        };
+
+        self.inner.contexts.insert(window, context);
+        Ok(!self.is_destroyed())
+    }
+
+    pub fn get_context(&self, window: ffi::Window) -> Option<ffi::XIC> {
+        if self.is_destroyed() {
+            return None;
+        }
+        if let Some(Some(context)) = self.inner.contexts.get(&window) {
+            Some(context.ic)
+        } else {
+            None
+        }
+    }
+
+    pub fn remove_context(&mut self, window: ffi::Window) -> Result<bool, XError> {
+        if let Some(Some(context)) = self.inner.contexts.remove(&window) {
+            unsafe {
+                self.inner.destroy_ic_if_necessary(context.ic)?;
+            }
+            Ok(true)
+        } else {
+            Ok(false)
+        }
+    }
+
+    pub fn focus(&mut self, window: ffi::Window) -> Result<bool, XError> {
+        if self.is_destroyed() {
+            return Ok(false);
+        }
+        if let Some(&mut Some(ref mut context)) = self.inner.contexts.get_mut(&window) {
+            context.focus(&self.xconn).map(|_| true)
+        } else {
+            Ok(false)
+        }
+    }
+
+    pub fn unfocus(&mut self, window: ffi::Window) -> Result<bool, XError> {
+        if self.is_destroyed() {
+            return Ok(false);
+        }
+        if let Some(&mut Some(ref mut context)) = self.inner.contexts.get_mut(&window) {
+            context.unfocus(&self.xconn).map(|_| true)
+        } else {
+            Ok(false)
+        }
+    }
+
+    pub fn send_xim_area(&mut self, window: ffi::Window, x: i16, y: i16, w: u16, h: u16) {
+        if self.is_destroyed() {
+            return;
+        }
+        if let Some(&mut Some(ref mut context)) = self.inner.contexts.get_mut(&window) {
+            context.set_area(&self.xconn, x as _, y as _, w as _, h as _);
+        }
+    }
+
+    pub fn set_ime_allowed(&mut self, window: ffi::Window, allowed: bool) {
+        if self.is_destroyed() {
+            return;
+        }
+
+        if let Some(&mut Some(ref mut context)) = self.inner.contexts.get_mut(&window) {
+            if allowed == context.is_allowed() {
+                return;
+            }
+        }
+
+        // Remove context for that window.
+        let _ = self.remove_context(window);
+
+        // Create new context supporting IME input.
+        let _ = self.create_context(window, allowed);
+    }
+
+    pub fn is_ime_allowed(&self, window: ffi::Window) -> bool {
+        if self.is_destroyed() {
+            false
+        } else if let Some(Some(context)) = self.inner.contexts.get(&window) {
+            context.is_allowed()
+        } else {
+            false
+        }
+    }
+}
+
+impl Drop for Ime {
+    fn drop(&mut self) {
+        unsafe {
+            let _ = self.inner.destroy_all_contexts_if_necessary();
+            let _ = self.inner.close_im_if_necessary();
+        }
+    }
+}