On X11, don't require XIM to be present

In general, we may want to use xinput v2 for keyboard input in such
cases, so we have compose going, but for now just don't crash if
there's no XIM.

CHANGELOG.md

@@ -11,6 +11,7 @@ Unreleased` header.
 
 # Unreleased
 
+- On X11, don't require XIM to run.
 - Fix compatibility with 32-bit platforms without 64-bit atomics.
 - On X11, fix swapped instance and general class names.
 - **Breaking:** Removed unnecessary generic parameter `T` from `EventLoopWindowTarget`.

src/platform_impl/linux/x11/event_processor.rs

@@ -74,7 +74,11 @@ impl EventProcessor {
 
         // Handle IME requests.
         while let Ok(request) = self.ime_receiver.try_recv() {
-            let ime = window_target.ime.get_mut();
+            let ime = match window_target.ime.as_mut() {
+                Some(ime) => ime,
+                None => continue,
+            };
+            let ime = ime.get_mut();
             match request {
                 ImeRequest::Position(window_id, x, y) => {
                     ime.send_xim_spot(window_id, x, y);
@@ -792,10 +796,11 @@ impl EventProcessor {
 
         // Since all XIM stuff needs to happen from the same thread, we destroy the input
         // context here instead of when dropping the window.
-        wt.ime
-            .borrow_mut()
-            .remove_context(window as XWindow)
-            .expect("Failed to destroy input context");
+        if let Some(ime) = wt.ime.as_ref() {
+            ime.borrow_mut()
+                .remove_context(window as XWindow)
+                .expect("Failed to destroy input context");
+        }
 
         callback(
             &self.target,
@@ -922,7 +927,11 @@ impl EventProcessor {
                     },
                 },
             );
-        } else if let Some(ic) = wt.ime.borrow().get_context(window as XWindow) {
+        } else if let Some(ic) = wt
+            .ime
+            .as_ref()
+            .and_then(|ime| ime.borrow().get_context(window as XWindow))
+        {
             let written = wt.xconn.lookup_utf8(ic, xev);
             if !written.is_empty() {
                 let event = Event::WindowEvent {
@@ -1191,10 +1200,11 @@ impl EventProcessor {
         // Set the timestamp.
         wt.xconn.set_timestamp(xev.time as xproto::Timestamp);
 
-        wt.ime
-            .borrow_mut()
-            .focus(xev.event)
-            .expect("Failed to focus input context");
+        if let Some(ime) = wt.ime.as_ref() {
+            ime.borrow_mut()
+                .focus(xev.event)
+                .expect("Failed to focus input context");
+        }
 
         if self.active_window == Some(window) {
             return;
@@ -1262,10 +1272,11 @@ impl EventProcessor {
             return;
         }
 
-        wt.ime
-            .borrow_mut()
-            .unfocus(xev.event)
-            .expect("Failed to unfocus input context");
+        if let Some(ime) = wt.ime.as_ref() {
+            ime.borrow_mut()
+                .unfocus(xev.event)
+                .expect("Failed to unfocus input context");
+        }
 
         if self.active_window.take() == Some(window) {
             let window_id = mkwid(window);

src/platform_impl/linux/x11/mod.rs

@@ -133,7 +133,7 @@ pub struct EventLoopWindowTarget {
     control_flow: Cell<ControlFlow>,
     exit: Cell<Option<i32>>,
     root: xproto::Window,
-    ime: RefCell<Ime>,
+    ime: Option<RefCell<Ime>>,
     windows: RefCell<HashMap<WindowId, Weak<UnownedWindow>>>,
     redraw_sender: WakeSender<WindowId>,
     activation_sender: WakeSender<ActivationToken>,
@@ -209,13 +209,15 @@ impl<T: 'static> EventLoop<T> {
                 setlocale(LC_CTYPE, default_locale);
             }
         }
-        let ime = RefCell::new({
-            let result = Ime::new(Arc::clone(&xconn), ime_event_sender);
-            if let Err(ImeCreationError::OpenFailure(ref state)) = result {
-                panic!("Failed to open input method: {state:#?}");
-            }
-            result.expect("Failed to set input method destruction callback")
-        });
+
+        let ime = Ime::new(Arc::clone(&xconn), ime_event_sender);
+        if let Err(ImeCreationError::OpenFailure(state)) = ime.as_ref() {
+            warn!("Failed to open input method: {state:#?}");
+        } else if let Err(err) = ime.as_ref() {
+            warn!("Failed to set input method destruction callback: {err:?}");
+        }
+
+        let ime = ime.ok().map(RefCell::new);
 
         let randr_event_offset = xconn
             .select_xrandr_input(root)

src/platform_impl/linux/x11/window.rs

@@ -555,9 +555,9 @@ impl UnownedWindow {
             leap!(xconn.select_xinput_events(window.xwindow, super::ALL_MASTER_DEVICES, mask))
                 .ignore_error();
 
-            {
-                let result = event_loop
-                    .ime
+            // Try to create input context for the window.
+            if let Some(ime) = event_loop.ime.as_ref() {
+                let result = ime
                     .borrow_mut()
                     .create_context(window.xwindow as ffi::Window, false);
                 leap!(result);