add sxmo target

The SXMO (sway) environment expects that the on-screen keyboard does not
handle visibility by itself. Add a new target that ignores the program's
own show/hide requests and shows the keyboard on startup.

Cargo.toml

@@ -29,6 +29,10 @@ bindgen = "0.69.4"
 name = "ufkbd-gnome"
 path = "src/ufkbd_gnome.rs"
 
+[[bin]]
+name = "ufkbd-sxmo"
+path = "src/ufkbd_sxmo.rs"
+
 [[bin]]
 name = "ufkbd-wl"
 path = "src/ufkbd_wl.rs"

src/ufkbd_sxmo.rs

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ * Copyright (c) 2024, Richard Acayan. All rights reserved.
+ */
+
+mod core;
+mod wayland;
+
+use crate::core::Layout;
+use crate::wayland::Dispatcher;
+use polling::Event;
+use polling::Events;
+use polling::Poller;
+use std::mem;
+use std::path::Path;
+use std::time::Instant;
+use wayland_client::globals;
+
+pub struct VisibilityManager();
+
+impl VisibilityManager {
+    pub fn set_visible(&self, _visible: bool)
+    {
+        // SXMO manages visibility
+    }
+}
+
+fn main()
+{
+    let conn = wayland_client::Connection::connect_to_env().unwrap();
+
+    let (globals, mut queue) = globals::registry_queue_init::<Dispatcher>(&conn)
+                                            .expect("Registry required");
+
+    let layouts = Path::new("/usr/share/unfettered-keyboard/layouts");
+    let layout = Layout::load(layouts, "latn_qwerty_us.xml")
+                             .expect("Layout should be loadable");
+    let mut dispatcher = Dispatcher::new(layout, queue.handle(), &globals).unwrap();
+    dispatcher.set_osk(VisibilityManager());
+
+    let gfx = dispatcher.graphics();
+    let mut gfx = gfx.lock().unwrap();
+    gfx.display_mut().show();
+    mem::drop(gfx);
+
+    let wl_evt = Event::readable(0);
+
+    let mut events = Events::new();
+    let poller = Poller::new().unwrap();
+
+    loop {
+        conn.flush().unwrap();
+
+        let guard = queue.prepare_read().unwrap();
+        let fd = guard.connection_fd();
+        let timer = dispatcher.button().next_time().map(|t| t - Instant::now());
+
+        unsafe {
+            poller.add(&fd, wl_evt).unwrap();
+        }
+
+        events.clear();
+        poller.wait(&mut events, timer).unwrap();
+        poller.delete(fd).unwrap();
+
+        if !events.is_empty() {
+            // This may still emit EWOULDBLOCK errors.
+            let _ = guard.read();
+            queue.dispatch_pending(&mut dispatcher).unwrap();
+        }
+
+        dispatcher.dispatch_timers();
+    }
+}