keymaps: Use multiple key maps, each within the limit of what Xorg can accept.

Key maps are switched on key press whenever needed.

eek/eek-keyboard.c

@@ -28,19 +28,12 @@
 #include <sys/random.h> // TODO: this is Linux-specific
 #include <xkbcommon/xkbcommon.h>
 
+
 #include "eek-keyboard.h"
 
-
+/// External linkage for Rust.
-static void eek_key_map_deinit(struct keymap *self) {
+/// The corresponding deinit is implemented in vkeyboard::KeyMap::drop
-    if (self->fd < 0) {
+struct keymap squeek_key_map_from_str(const char *keymap_str) {
-        g_error("Deinit called multiple times on KeyMap");
-    } else {
-        close(self->fd);
-    }
-    self->fd = -1;
-}
-
-static struct keymap eek_key_map_from_str(const char *keymap_str) {
     struct xkb_context *context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
     if (!context) {
         g_error("No context created");
@@ -91,7 +84,6 @@ static struct keymap eek_key_map_from_str(const char *keymap_str) {
 }
 
 void level_keyboard_free(LevelKeyboard *self) {
-    eek_key_map_deinit(&self->keymap);
     squeek_layout_free(self->layout);
     g_free(self);
 }
@@ -104,7 +96,5 @@ level_keyboard_new (struct squeek_layout *layout)
         g_error("Failed to create a keyboard");
     }
     keyboard->layout = layout;
-    const gchar *keymap_str = squeek_layout_get_keymap(keyboard->layout);
-    keyboard->keymap = eek_key_map_from_str(keymap_str);
     return keyboard;
 }

eek/eek-keyboard.h

@@ -41,7 +41,7 @@ struct keymap {
 /// Keyboard state holder
 struct _LevelKeyboard {
     struct squeek_layout *layout; // owned
-    struct keymap keymap; // owned
+// FIXME: This no longer needs to exist, keymap was folded into layout.
 };
 typedef struct _LevelKeyboard LevelKeyboard;
 

eekboard/eekboard-context-service.c

@@ -159,7 +159,7 @@ eekboard_context_service_use_layout(EekboardContextService *context, struct sque
     // Update the keymap if necessary.
     // TODO: Update submission on change event
     if (context->submission) {
-        submission_set_keyboard(context->submission, keyboard, timestamp);
+        submission_use_layout(context->submission, keyboard->layout, timestamp);
     }
 
     // Update UI
@@ -345,7 +345,7 @@ void eekboard_context_service_set_submission(EekboardContextService *context, st
     context->submission = submission;
     if (context->submission) {
         uint32_t time = gdk_event_get_time(NULL);
-        submission_set_keyboard(context->submission, context->keyboard, time);
+        submission_use_layout(context->submission, context->keyboard->layout, time);
     }
 }
 

src/data.rs

@@ -18,7 +18,7 @@ use xkbcommon::xkb;
 use ::action;
 use ::keyboard::{
     KeyState, PressType,
-    generate_keymap, generate_keycodes, FormattingError
+    generate_keymaps, generate_keycodes, KeyCode, FormattingError
 };
 use ::layout;
 use ::layout::ArrangementKind;
@@ -382,7 +382,7 @@ impl Layout {
                 )
             )}).collect();
 
-        let symbolmap: HashMap<String, u32> = generate_keycodes(
+        let symbolmap: HashMap<String, KeyCode> = generate_keycodes(
             extract_symbol_names(&button_actions)
         );
 
@@ -391,7 +391,7 @@ impl Layout {
                 let keycodes = match &action {
                     ::action::Action::Submit { text: _, keys } => {
                         keys.iter().map(|named_keysym| {
-                            *symbolmap.get(named_keysym.0.as_str())
+                            symbolmap.get(named_keysym.0.as_str())
                                 .expect(
                                     format!(
                                         "keysym {} in key {} missing from symbol map",
@@ -399,11 +399,13 @@ impl Layout {
                                         name
                                     ).as_str()
                                 )
+                                .clone()
                         }).collect()
                     },
                     action::Action::Erase => vec![
-                        *symbolmap.get("BackSpace")
+                        symbolmap.get("BackSpace")
-                            .expect(&format!("BackSpace missing from symbol map")),
+                            .expect(&format!("BackSpace missing from symbol map"))
+                            .clone(),
                     ],
                     _ => Vec::new(),
                 };
@@ -418,7 +420,7 @@ impl Layout {
             })
         );
 
-        let keymap_str = match generate_keymap(symbolmap) {
+        let keymaps = match generate_keymaps(symbolmap) {
             Err(e) => { return (Err(e), warning_handler) },
             Ok(v) => v,
         };
@@ -482,10 +484,10 @@ impl Layout {
         (
             Ok(::layout::LayoutData {
                 views: views,
-                keymap_str: {
+                keymaps: keymaps.into_iter().map(|keymap_str|
                     CString::new(keymap_str)
                         .expect("Invalid keymap string generated")
-                },
+                ).collect(),
                 // FIXME: use a dedicated field
                 margins: layout::Margins {
                     top: self.margins.top,
@@ -876,7 +878,7 @@ mod tests {
         assert_eq!(
             out.views["base"].1
                 .get_rows()[0].1
-                .buttons[0].1
+                .get_buttons()[0].1
                 .state.borrow()
                 .keycodes.len(),
             1

src/keyboard.rs

@@ -5,10 +5,13 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt;
 use std::io;
+use std::mem;
+use std::ptr;
 use std::rc::Rc;
 use std::string::FromUtf8Error;
 
 use ::action::Action;
+use ::util;
 
 // Traits
 use std::io::Write;
@@ -20,7 +23,12 @@ pub enum PressType {
     Pressed = 1,
 }
 
-pub type KeyCode = u32;
+/// The extended, unambiguous layout-keycode
+#[derive(Debug, Clone)]
+pub struct KeyCode {
+    pub code: u32,
+    pub keymap_idx: usize,
+}
 
 bitflags!{
     /// Map to `virtual_keyboard.modifiers` modifiers values
@@ -92,12 +100,15 @@ fn sorted<'a, I: Iterator<Item=String>>(
 /// which the compositor likes to discard
 pub fn generate_keycodes<'a, C: IntoIterator<Item=String>>(
     key_names: C,
-) -> HashMap<String, u32> {
+) -> HashMap<String, KeyCode> {
     HashMap::from_iter(
         // Sort to remove a source of indeterminism in keycode assignment.
         sorted(key_names.into_iter())
-            .map(|name| name)
+            .zip(util::cycle_count(9..255))
-            .zip(9..)
+            .map(|(name, (code, keymap_idx))| (
+                String::from(name),
+                KeyCode { code, keymap_idx },
+            ))
     )
 }
 
@@ -122,10 +133,50 @@ impl From<io::Error> for FormattingError {
     }
 }
 
+/// Index is the key code, String is the occupant.
+/// Starts all empty.
+/// https://gitlab.freedesktop.org/xorg/xserver/-/issues/260
+type SingleKeyMap = [Option<String>; 256];
+
+fn single_key_map_new() -> SingleKeyMap {
+    // Why can't we just initialize arrays without tricks -_- ?
+    unsafe {
+        // Inspired by
+        // https://www.reddit.com/r/rust/comments/5n7bh1/how_to_create_an_array_of_a_type_with_clone_but/
+        let mut array: SingleKeyMap = mem::MaybeUninit::uninit().assume_init();
+        for element in array.iter_mut() {
+            ptr::write(element, None);
+        }
+        array
+    }
+}
+
+pub fn generate_keymaps(symbolmap: HashMap::<String, KeyCode>)
+    -> Result<Vec<String>, FormattingError>
+{
+    let mut bins: Vec<SingleKeyMap> = Vec::new();
+    
+    for (name, KeyCode { code, keymap_idx }) in symbolmap.into_iter() {
+        if keymap_idx >= bins.len() {
+            bins.resize_with(
+                keymap_idx + 1,
+                || single_key_map_new(),
+            );
+        }
+        bins[keymap_idx][code as usize] = Some(name);
+    }
+
+    let mut out = Vec::new();
+    for bin in bins {
+        out.push(generate_keymap(&bin)?);
+    }
+    Ok(out)
+}
+
 /// Generates a de-facto single level keymap.
-/// Key codes must not repeat and should remain between 9 and 255.
+/// Key codes must not repeat and must remain between 9 and 255.
-pub fn generate_keymap(
+fn generate_keymap(
-    symbolmap: HashMap::<String, KeyCode>,
+    symbolmap: &SingleKeyMap,
 ) -> Result<String, FormattingError> {
     let mut buf: Vec<u8> = Vec::new();
     writeln!(
@@ -134,14 +185,21 @@ pub fn generate_keymap(
 
     xkb_keycodes \"squeekboard\" {{
         minimum = 8;
-        maximum = 999;"
+        maximum = 255;"
     )?;
 
+    let pairs: Vec<(&String, usize)> = symbolmap.iter()
+        // Attach a key code to each cell.
+        .enumerate()
+        // Get rid of empty keycodes.
+        .filter_map(|(code, name)| name.as_ref().map(|n| (n, code)))
+        .collect();
+    
     // Xorg can only consume up to 255 keys, so this may not work in Xwayland.
     // Two possible solutions:
     // - use levels to cram multiple characters into one key
     // - swap layouts on key presses
-    for keycode in symbolmap.values() {
+    for (_name, keycode) in &pairs {
         write!(
             buf,
             "
@@ -160,7 +218,7 @@ pub fn generate_keymap(
 "
     )?;
     
-    for (name, keycode) in symbolmap.iter() {
+    for (name, keycode) in pairs {
         write!(
             buf,
             "
@@ -218,13 +276,14 @@ mod tests {
     use xkbcommon::xkb;
 
     #[test]
-    fn test_keymap_multi() {
+    fn test_keymap_single_resolve() {
-        let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);
+        let mut key_map = single_key_map_new();
+        key_map[9] = Some("a".into());
+        key_map[10] = Some("c".into());
 
-        let keymap_str = generate_keymap(hashmap!{
+        let keymap_str = generate_keymap(&key_map).unwrap();
-            "a".into() => 9,
+
-            "c".into() => 10,
+        let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);
-        }).unwrap();
 
         let keymap = xkb::Keymap::new_from_string(
             &context,
@@ -238,4 +297,36 @@ mod tests {
         assert_eq!(state.key_get_one_sym(9), xkb::KEY_a);
         assert_eq!(state.key_get_one_sym(10), xkb::KEY_c);
     }
+
+    #[test]
+    fn test_keymap_second_resolve() {
+        let keymaps = generate_keymaps(hashmap!(
+            "a".into() => KeyCode { keymap_idx: 1, code: 9 },
+        )).unwrap();
+
+        let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);
+
+        let keymap = xkb::Keymap::new_from_string(
+            &context,
+            keymaps[1].clone(), // this index is part of the test
+            xkb::KEYMAP_FORMAT_TEXT_V1,
+            xkb::KEYMAP_COMPILE_NO_FLAGS,
+        ).expect("Failed to create keymap");
+
+        let state = xkb::State::new(&keymap);
+
+        assert_eq!(state.key_get_one_sym(9), xkb::KEY_a);
+    }
+
+    #[test]
+    fn test_symbolmap_overflow() {
+        // The 257th key (U1101) is interesting.
+        // Use Unicode encoding for being able to use in xkb keymaps.
+        let keynames = (0..258).map(|num| format!("U{:04X}", 0x1000 + num));
+        let keycodes = generate_keycodes(keynames);
+        
+        // test now
+        let code = keycodes.get("U1101").expect("Did not find the tested keysym");
+        assert_eq!(code.keymap_idx, 1);
+    }
 }

src/layout.h

@@ -39,7 +39,6 @@ struct transformation squeek_layout_calculate_transformation(
         double allocation_width, double allocation_size);
 
 struct squeek_layout *squeek_load_layout(const char *name, uint32_t type);
-const char *squeek_layout_get_keymap(const struct squeek_layout*);
 enum squeek_arrangement_kind squeek_layout_get_kind(const struct squeek_layout *);
 void squeek_layout_free(struct squeek_layout*);
 

src/layout.rs

@@ -237,13 +237,6 @@ pub mod c {
         })
     }
 
-    #[no_mangle]
-    pub extern "C"
-    fn squeek_layout_get_keymap(layout: *const Layout) -> *const c_char {
-        let layout = unsafe { &*layout };
-        layout.keymap_str.as_ptr()
-    }
-
     #[no_mangle]
     pub extern "C"
     fn squeek_layout_get_kind(layout: *const Layout) -> u32 {
@@ -686,8 +679,8 @@ pub struct Layout {
     pub views: HashMap<String, (c::Point, View)>,
 
     // Non-UI stuff
-    /// xkb keymap applicable to the contained keys. Unchangeable
+    /// xkb keymaps applicable to the contained keys. Unchangeable
-    pub keymap_str: CString,
+    pub keymaps: Vec<CString>,
     // Changeable state
     // a Vec would be enough, but who cares, this will be small & fast enough
     // TODO: turn those into per-input point *_buttons to track dragging.
@@ -703,7 +696,7 @@ pub struct Layout {
 pub struct LayoutData {
     /// Point is the offset within layout
     pub views: HashMap<String, (c::Point, View)>,
-    pub keymap_str: CString,
+    pub keymaps: Vec<CString>,
     pub margins: Margins,
 }
 
@@ -726,7 +719,7 @@ impl Layout {
             kind,
             current_view: "base".to_owned(),
             views: data.views,
-            keymap_str: data.keymap_str,
+            keymaps: data.keymaps,
             pressed_keys: HashSet::new(),
             margins: data.margins,
         }
@@ -1200,7 +1193,7 @@ mod test {
         ]);
         let layout = Layout {
             current_view: String::new(),
-            keymap_str: CString::new("").unwrap(),
+            keymaps: Vec::new(),
             kind: ArrangementKind::Base,
             pressed_keys: HashSet::new(),
             // Lots of bottom margin

src/submission.h

@@ -6,6 +6,7 @@
 #include "eek/eek-types.h"
 
 struct submission;
+struct squeek_layout;
 
 struct submission* get_submission(struct zwp_input_method_manager_v2 *immanager,
                                   struct zwp_virtual_keyboard_manager_v1 *vkmanager,
@@ -15,5 +16,5 @@ struct submission* get_submission(struct zwp_input_method_manager_v2 *immanager,
 // Defined in Rust
 struct submission* submission_new(struct zwp_input_method_v2 *im, struct zwp_virtual_keyboard_v1 *vk, EekboardContextService *state);
 void submission_set_ui(struct submission *self, ServerContextService *ui_context);
-void submission_set_keyboard(struct submission *self, LevelKeyboard *keyboard, uint32_t time);
+void submission_use_layout(struct submission *self, struct squeek_layout *layout, uint32_t time);
 #endif

src/submission.rs

@@ -23,8 +23,9 @@ use ::action::Modifier;
 use ::imservice;
 use ::imservice::IMService;
 use ::keyboard::{ KeyCode, KeyStateId, Modifiers, PressType };
-use ::layout::c::LevelKeyboard;
+use ::layout;
 use ::util::vec_remove;
+use ::vkeyboard;
 use ::vkeyboard::VirtualKeyboard;
 
 // traits
@@ -68,6 +69,8 @@ pub mod c {
                 modifiers_active: Vec::new(),
                 virtual_keyboard: VirtualKeyboard(vk),
                 pressed: Vec::new(),
+                keymap_fds: Vec::new(),
+                keymap_idx: None,
             }
         ))
     }
@@ -91,16 +94,17 @@ pub mod c {
 
     #[no_mangle]
     pub extern "C"
-    fn submission_set_keyboard(
+    fn submission_use_layout(
         submission: *mut Submission,
-        keyboard: LevelKeyboard,
+        layout: *const layout::Layout,
         time: u32,
     ) {
         if submission.is_null() {
             panic!("Null submission pointer");
         }
         let submission: &mut Submission = unsafe { &mut *submission };
-        submission.update_keymap(keyboard, Timestamp(time));
+        let layout = unsafe { &*layout };
+        submission.use_layout(layout, Timestamp(time));
     }
 }
 
@@ -119,6 +123,8 @@ pub struct Submission {
     virtual_keyboard: VirtualKeyboard,
     modifiers_active: Vec<(KeyStateId, Modifier)>,
     pressed: Vec<(KeyStateId, SubmittedAction)>,
+    keymap_fds: Vec<vkeyboard::c::KeyMap>,
+    keymap_idx: Option<usize>,
 }
 
 pub enum SubmitData<'a> {
@@ -177,11 +183,34 @@ impl Submission {
         let submit_action = match was_committed_as_text {
             true => SubmittedAction::IMService,
             false => {
-                self.virtual_keyboard.switch(
+                let keycodes_count = keycodes.len();
-                    keycodes,
+                for keycode in keycodes.iter() {
-                    PressType::Pressed,
+                    self.select_keymap(keycode.keymap_idx, time);
-                    time,
+                    let keycode = keycode.code;
-                );
+                    match keycodes_count {
+                        // Pressing a key made out of a single keycode is simple:
+                        // press on press, release on release.
+                        1 => self.virtual_keyboard.switch(
+                            keycode,
+                            PressType::Pressed,
+                            time,
+                        ),
+                        // A key made of multiple keycodes
+                        // has to submit them one after the other.
+                        _ => {
+                            self.virtual_keyboard.switch(
+                                keycode.clone(),
+                                PressType::Pressed,
+                                time,
+                            );
+                            self.virtual_keyboard.switch(
+                                keycode.clone(),
+                                PressType::Released,
+                                time,
+                            );
+                        },
+                    };
+                }
                 SubmittedAction::VirtualKeyboard(keycodes.clone())
             },
         };
@@ -199,11 +228,21 @@ impl Submission {
                 // no matter if the imservice got activated,
                 // keys must be released
                 SubmittedAction::VirtualKeyboard(keycodes) => {
-                    self.virtual_keyboard.switch(
+                    let keycodes_count = keycodes.len();
-                        &keycodes,
+                    match keycodes_count {
-                        PressType::Released,
+                        1 => {
-                        time,
+                            let keycode = &keycodes[0];
-                    )
+                            self.select_keymap(keycode.keymap_idx, time);
+                            self.virtual_keyboard.switch(
+                                keycode.code,
+                                PressType::Released,
+                                time,
+                            );
+                        },
+                        // Design choice here: submit multiple all at press time
+                        // and do nothing at release time.
+                        _ => {},
+                    };
                 },
             }
         };
@@ -274,6 +313,7 @@ impl Submission {
         }
     }
 
+
     /// Changes keymap and clears pressed keys and modifiers.
     ///
     /// It's not obvious if clearing is the right thing to do, 
@@ -283,9 +323,28 @@ impl Submission {
     /// Alternatively, modifiers could be restored on the new keymap.
     /// That approach might be difficult
     /// due to modifiers meaning different things in different keymaps.
-    pub fn update_keymap(&mut self, keyboard: LevelKeyboard, time: Timestamp) {
+    fn select_keymap(&mut self, idx: usize, time: Timestamp) {
-        self.clear_all_modifiers();
+        if self.keymap_idx != Some(idx) {
-        self.release_all_virtual_keys(time);
+            self.keymap_idx = Some(idx);
-        self.virtual_keyboard.update_keymap(keyboard);
+            self.clear_all_modifiers();
+            self.release_all_virtual_keys(time);
+            let keymap = &self.keymap_fds[idx];
+            self.virtual_keyboard.update_keymap(keymap);
+        }
+    }
+    
+    pub fn use_layout(&mut self, layout: &layout::Layout, time: Timestamp) {
+        self.keymap_fds = layout.keymaps.iter()
+            .map(|keymap_str| vkeyboard::c::KeyMap::from_cstr(
+                keymap_str.as_c_str()
+            ))
+            .collect();
+        self.keymap_idx = None;
+
+        // This can probably be eliminated,
+        // because key presses can trigger an update anyway.
+        // However, self.keymap_idx needs to become Option<>
+        // in order to force update on new layouts.
+        self.select_keymap(0, time);
     }
 }

src/tests.rs

@@ -40,21 +40,29 @@ pub fn check_layout_file(path: &str) {
     )
 }
 
-fn check_sym_presence(
+fn check_sym_in_keymap(state: &xkb::State, sym_name: &str) -> bool {
-    state: &xkb::State,
-    sym_name: &str,
-    handler: &mut dyn logging::Handler,
-) {
     let sym = xkb::keysym_from_name(sym_name, xkb::KEYSYM_NO_FLAGS);
     if sym == xkb::KEY_NoSymbol {
         panic!(format!("Entered invalid keysym: {}", sym_name));
     }
     let map = state.get_keymap();
     let range = map.min_keycode()..=map.max_keycode();
-    let found = range.flat_map(|code| state.key_get_syms(code))
+    range.flat_map(|code| state.key_get_syms(code))
         .find(|s| **s == sym)
-        .is_some();
+        .is_some()
-    if !found {
+}
+
+fn check_sym_presence(
+    states: &[xkb::State],
+    sym_name: &str,
+    handler: &mut dyn logging::Handler,
+) {
+    let found = states.iter()
+        .position(|state| {
+            check_sym_in_keymap(&state, sym_name)
+        });
+
+    if let None = found {
         handler.handle(
             logging::Level::Surprise,
             &format!("There's no way to input the keysym {} on this layout", sym_name),
@@ -72,25 +80,26 @@ fn check_layout(layout: Layout, allow_missing_return: bool) {
 
     let layout = layout.expect("layout broken");
     
-    let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);
+    let xkb_states: Vec<xkb::State> = layout.keymaps.iter()
+        .map(|keymap_str| {
+            let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);
+            let keymap_str = keymap_str
+                .clone()
+                .into_string().expect("Failed to decode keymap string");
+            let keymap = xkb::Keymap::new_from_string(
+                &context,
+                keymap_str.clone(),
+                xkb::KEYMAP_FORMAT_TEXT_V1,
+                xkb::KEYMAP_COMPILE_NO_FLAGS,
+            ).expect("Failed to create keymap");
+            xkb::State::new(&keymap)
+        })
+        .collect();
 
-    let keymap_str = layout.keymap_str
+    check_sym_presence(&xkb_states, "BackSpace", &mut handler);
-        .clone()
-        .into_string().expect("Failed to decode keymap string");
-    
-    let keymap = xkb::Keymap::new_from_string(
-        &context,
-        keymap_str.clone(),
-        xkb::KEYMAP_FORMAT_TEXT_V1,
-        xkb::KEYMAP_COMPILE_NO_FLAGS,
-    ).expect("Failed to create keymap");
-
-    let state = xkb::State::new(&keymap);
-
-    check_sym_presence(&state, "BackSpace", &mut handler);
     let mut printer = logging::Print;
     check_sym_presence(
-        &state,
+        &xkb_states,
         "Return",
         if allow_missing_return { &mut printer }
         else { &mut handler },
@@ -102,10 +111,19 @@ fn check_layout(layout: Layout, allow_missing_return: bool) {
             for (_x, button) in row.get_buttons() {
                 let keystate = button.state.borrow();
                 for keycode in &keystate.keycodes {
-                    match state.key_get_one_sym(*keycode) {
+                    match xkb_states[keycode.keymap_idx].key_get_one_sym(keycode.code) {
                         xkb::KEY_NoSymbol => {
-                            eprintln!("{}", keymap_str);
+                            eprintln!(
-                            panic!("Keysym {} on key {:?} can't be resolved", keycode, button.name);
+                                "keymap {}: {}",
+                                keycode.keymap_idx,
+                                layout.keymaps[keycode.keymap_idx].to_str().unwrap(),
+                            );
+                            panic!(
+                                "Keysym for code {:?} on key {} ({:?}) can't be resolved",
+                                keycode,
+                                button.name.to_string_lossy(),
+                                button.name,
+                            );
                         },
                         _ => {},
                     }

src/util.rs

@@ -203,6 +203,23 @@ pub fn vec_remove<T, F: FnMut(&T) -> bool>(v: &mut Vec<T>, pred: F) -> Option<T>
     idx.map(|idx| v.remove(idx))
 }
 
+/// Repeats all the items of the iterator forever,
+/// but returns the cycle number alongside.
+/// Inefficient due to all the vectors, but doesn't have to be fast.
+pub fn cycle_count<T, I: Clone + Iterator<Item=T>>(iter: I)
+    -> impl Iterator<Item=(T, usize)>
+{
+    let numbered_copies = vec![iter].into_iter()
+        .cycle()
+        .enumerate();
+    numbered_copies.flat_map(|(idx, cycle)|
+        // Pair each element from the cycle with a copy of the index.
+        cycle.zip(
+            vec![idx].into_iter().cycle() // Repeat the index forever.
+        )
+    )
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -217,4 +234,12 @@ mod tests {
         assert_eq!(s.insert(Pointer(Rc::new(2u32))), true);
         assert_eq!(s.remove(&Pointer(first)), true);
     }
+
+    #[test]
+    fn check_count() {
+        assert_eq!(
+            cycle_count(5..8).take(7).collect::<Vec<_>>(),
+            vec![(5, 0), (6, 0), (7, 0), (5, 1), (6, 1), (7, 1), (5, 2)]
+        );
+    }
 }

src/vkeyboard.rs

@@ -1,20 +1,47 @@
 /*! Managing the events belonging to virtual-keyboard interface. */
 
-use ::keyboard::{ KeyCode, Modifiers, PressType };
+use ::keyboard::{ Modifiers, PressType };
-use ::layout::c::LevelKeyboard;
 use ::submission::Timestamp;
 
+/// Standard xkb keycode
+type KeyCode = u32;
+
 /// Gathers stuff defined in C or called by C
 pub mod c {
-    use super::*;
+    use std::ffi::CStr;
-    use std::os::raw::c_void;
+    use std::os::raw::{ c_char, c_void };
 
     #[repr(transparent)]
     #[derive(Clone, Copy)]
     pub struct ZwpVirtualKeyboardV1(*const c_void);
 
+    #[repr(C)]
+    pub struct KeyMap {
+        fd: u32,
+        fd_len: usize,
+    }
+    
+    impl KeyMap {
+        pub fn from_cstr(s: &CStr) -> KeyMap {
+            unsafe {
+                squeek_key_map_from_str(s.as_ptr())
+            }
+        }
+    }
+
+    impl Drop for KeyMap {
+        fn drop(&mut self) {
+            unsafe {
+                close(self.fd as u32);
+            }
+        }
+    }
+
     #[no_mangle]
     extern "C" {
+        // From libc, to let KeyMap get deallocated.
+        fn close(fd: u32);
+
         pub fn eek_virtual_keyboard_v1_key(
             virtual_keyboard: ZwpVirtualKeyboardV1,
             timestamp: u32,
@@ -24,13 +51,15 @@ pub mod c {
 
         pub fn eek_virtual_keyboard_update_keymap(
             virtual_keyboard: ZwpVirtualKeyboardV1,
-            keyboard: LevelKeyboard,
+            keymap: *const KeyMap,
         );
         
         pub fn eek_virtual_keyboard_set_modifiers(
             virtual_keyboard: ZwpVirtualKeyboardV1,
             modifiers: u32,
         );
+        
+        pub fn squeek_key_map_from_str(keymap_str: *const c_char) -> KeyMap;
     }
 }
 
@@ -41,35 +70,15 @@ impl VirtualKeyboard {
     // TODO: error out if keymap not set
     pub fn switch(
         &self,
-        keycodes: &[KeyCode],
+        keycode: KeyCode,
         action: PressType,
         timestamp: Timestamp,
     ) {
-        let keycodes_count = keycodes.len();
+        let keycode = keycode - 8;
-        for keycode in keycodes.iter() {
+        unsafe {
-            let keycode = keycode - 8;
+            c::eek_virtual_keyboard_v1_key(
-            match (action, keycodes_count) {
+                self.0, timestamp.0, keycode, action.clone() as u32
-                // Pressing a key made out of a single keycode is simple:
+            );
-                // press on press, release on release.
-                (_, 1) => unsafe {
-                    c::eek_virtual_keyboard_v1_key(
-                        self.0, timestamp.0, keycode, action.clone() as u32
-                    );
-                },
-                // A key made of multiple keycodes
-                // has to submit them one after the other
-                (PressType::Pressed, _) => unsafe {
-                    c::eek_virtual_keyboard_v1_key(
-                        self.0, timestamp.0, keycode, PressType::Pressed as u32
-                    );
-                    c::eek_virtual_keyboard_v1_key(
-                        self.0, timestamp.0, keycode, PressType::Released as u32
-                    );
-                },
-                // Design choice here: submit multiple all at press time
-                // and do nothing at release time
-                (PressType::Released, _) => {},
-            }
         }
     }
     
@@ -80,9 +89,12 @@ impl VirtualKeyboard {
         }
     }
     
-    pub fn update_keymap(&self, keyboard: LevelKeyboard) {
+    pub fn update_keymap(&self, keymap: &c::KeyMap) {
         unsafe {
-            c::eek_virtual_keyboard_update_keymap(self.0, keyboard);
+            c::eek_virtual_keyboard_update_keymap(
+                self.0,
+                keymap as *const c::KeyMap,
+            );
         }
     }
 }

src/wayland.c

@@ -14,10 +14,10 @@ eek_virtual_keyboard_v1_key(struct zwp_virtual_keyboard_v1 *zwp_virtual_keyboard
 }
 
 
-void eek_virtual_keyboard_update_keymap(struct zwp_virtual_keyboard_v1 *zwp_virtual_keyboard_v1, const LevelKeyboard *keyboard) {
+void eek_virtual_keyboard_update_keymap(struct zwp_virtual_keyboard_v1 *zwp_virtual_keyboard_v1, struct keymap *keymap) {
     zwp_virtual_keyboard_v1_keymap(zwp_virtual_keyboard_v1,
         WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1,
-        keyboard->keymap.fd, keyboard->keymap.fd_len);
+        keymap->fd, keymap->fd_len);
 }
 
 void