input: encode keyboard events and send them to the shell

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I6ee2acd5f74575f4bcc2f41417207c626a6a6964

src/grid.rs

@@ -124,6 +124,8 @@ pub struct Grid {
     alt_saved: Option<Vec<Vec<Cell>>>,
     cursor_shape: CursorShape,
     cursor_visible: bool,
+    /// Application cursor-keys mode (DECCKM): arrows send SS3 instead of CSI.
+    app_cursor: bool,
     /// Cursor colour from OSC 12; `None` follows the cell under the cursor.
     cursor_color: Option<(u8, u8, u8)>,
 }
@@ -154,6 +156,7 @@ impl Grid {
             cursor_shape: CursorShape::default(),
             cursor_visible: true,
             cursor_color: None,
+            app_cursor: false,
         }
     }
 
@@ -250,6 +253,14 @@ impl Grid {
         self.cursor_color
     }
 
+    pub fn set_app_cursor(&mut self, on: bool) {
+        self.app_cursor = on;
+    }
+
+    pub fn app_cursor(&self) -> bool {
+        self.app_cursor
+    }
+
     // --- printing ---
 
     /// Place a printable character at the cursor, honouring width and autowrap.

src/input.rs

@@ -0,0 +1,186 @@
+//! Keyboard encoding: translate decoded key events into the byte sequences a
+//! terminal application expects (xterm/VT-style).
+
+use smithay_client_toolkit::seat::keyboard::{KeyEvent, Keysym, Modifiers};
+
+/// Encode a key press into bytes for the PTY, or `None` if it produces no input.
+pub fn encode(event: &KeyEvent, mods: Modifiers, app_cursor: bool) -> Option<Vec<u8>> {
+    let seq = match event.keysym {
+        Keysym::Return | Keysym::KP_Enter => prefix_alt(b"\r".to_vec(), mods),
+        Keysym::BackSpace => prefix_alt(b"\x7f".to_vec(), mods),
+        Keysym::Tab if mods.shift => b"\x1b[Z".to_vec(),
+        Keysym::Tab => b"\t".to_vec(),
+        Keysym::Escape => b"\x1b".to_vec(),
+
+        Keysym::Up => csi_letter(b'A', mods, app_cursor),
+        Keysym::Down => csi_letter(b'B', mods, app_cursor),
+        Keysym::Right => csi_letter(b'C', mods, app_cursor),
+        Keysym::Left => csi_letter(b'D', mods, app_cursor),
+        Keysym::Home => csi_letter(b'H', mods, app_cursor),
+        Keysym::End => csi_letter(b'F', mods, app_cursor),
+
+        Keysym::Insert => csi_tilde(2, mods),
+        Keysym::Delete => csi_tilde(3, mods),
+        Keysym::Page_Up => csi_tilde(5, mods),
+        Keysym::Page_Down => csi_tilde(6, mods),
+
+        // F1-F4 are SS3-introduced; F5+ use the CSI tilde forms.
+        Keysym::F1 => fkey(b'P', mods),
+        Keysym::F2 => fkey(b'Q', mods),
+        Keysym::F3 => fkey(b'R', mods),
+        Keysym::F4 => fkey(b'S', mods),
+        Keysym::F5 => csi_tilde(15, mods),
+        Keysym::F6 => csi_tilde(17, mods),
+        Keysym::F7 => csi_tilde(18, mods),
+        Keysym::F8 => csi_tilde(19, mods),
+        Keysym::F9 => csi_tilde(20, mods),
+        Keysym::F10 => csi_tilde(21, mods),
+        Keysym::F11 => csi_tilde(23, mods),
+        Keysym::F12 => csi_tilde(24, mods),
+
+        // Everything else: the xkb-composed text (which already folds in Ctrl),
+        // with Alt sending an ESC prefix (meta).
+        _ => {
+            let text = event.utf8.as_ref()?;
+            if text.is_empty() {
+                return None;
+            }
+            prefix_alt(text.as_bytes().to_vec(), mods)
+        }
+    };
+    Some(seq)
+}
+
+fn prefix_alt(bytes: Vec<u8>, mods: Modifiers) -> Vec<u8> {
+    if mods.alt {
+        let mut out = Vec::with_capacity(bytes.len() + 1);
+        out.push(0x1b);
+        out.extend_from_slice(&bytes);
+        out
+    } else {
+        bytes
+    }
+}
+
+/// xterm modifier parameter: 1 + a bitfield of the held modifiers.
+fn modifier_param(mods: Modifiers) -> u8 {
+    1 + u8::from(mods.shift)
+        + (u8::from(mods.alt) << 1)
+        + (u8::from(mods.ctrl) << 2)
+        + (u8::from(mods.logo) << 3)
+}
+
+/// Cursor/edit keys: `ESC [ X` (or `ESC O X` in application-cursor mode), and
+/// `ESC [ 1 ; m X` when modifiers are held.
+fn csi_letter(final_byte: u8, mods: Modifiers, app_cursor: bool) -> Vec<u8> {
+    let m = modifier_param(mods);
+    if m == 1 {
+        vec![0x1b, if app_cursor { b'O' } else { b'[' }, final_byte]
+    } else {
+        let mut v = format!("\x1b[1;{m}").into_bytes();
+        v.push(final_byte);
+        v
+    }
+}
+
+/// Keypad-style keys: `ESC [ n ~`, with `ESC [ n ; m ~` when modifiers are held.
+fn csi_tilde(n: u8, mods: Modifiers) -> Vec<u8> {
+    let m = modifier_param(mods);
+    if m == 1 {
+        format!("\x1b[{n}~").into_bytes()
+    } else {
+        format!("\x1b[{n};{m}~").into_bytes()
+    }
+}
+
+fn fkey(final_byte: u8, mods: Modifiers) -> Vec<u8> {
+    let m = modifier_param(mods);
+    if m == 1 {
+        vec![0x1b, b'O', final_byte]
+    } else {
+        let mut v = format!("\x1b[1;{m}").into_bytes();
+        v.push(final_byte);
+        v
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn key(keysym: Keysym, utf8: Option<&str>) -> KeyEvent {
+        KeyEvent {
+            time: 0,
+            raw_code: 0,
+            keysym,
+            utf8: utf8.map(str::to_owned),
+        }
+    }
+
+    const NONE: Modifiers = Modifiers {
+        ctrl: false,
+        alt: false,
+        shift: false,
+        caps_lock: false,
+        logo: false,
+        num_lock: false,
+    };
+
+    #[test]
+    fn plain_text_passes_through() {
+        assert_eq!(
+            encode(&key(Keysym::a, Some("a")), NONE, false),
+            Some(b"a".to_vec())
+        );
+    }
+
+    #[test]
+    fn alt_prefixes_escape() {
+        let mods = Modifiers { alt: true, ..NONE };
+        assert_eq!(
+            encode(&key(Keysym::a, Some("a")), mods, false),
+            Some(b"\x1ba".to_vec())
+        );
+    }
+
+    #[test]
+    fn arrows_respect_application_mode() {
+        assert_eq!(
+            encode(&key(Keysym::Up, None), NONE, false),
+            Some(b"\x1b[A".to_vec())
+        );
+        assert_eq!(
+            encode(&key(Keysym::Up, None), NONE, true),
+            Some(b"\x1bOA".to_vec())
+        );
+    }
+
+    #[test]
+    fn modified_arrow_uses_csi_param() {
+        let mods = Modifiers { ctrl: true, ..NONE };
+        assert_eq!(
+            encode(&key(Keysym::Right, None), mods, false),
+            Some(b"\x1b[1;5C".to_vec())
+        );
+    }
+
+    #[test]
+    fn special_keys() {
+        assert_eq!(
+            encode(&key(Keysym::Return, None), NONE, false),
+            Some(b"\r".to_vec())
+        );
+        assert_eq!(
+            encode(&key(Keysym::BackSpace, None), NONE, false),
+            Some(b"\x7f".to_vec())
+        );
+        assert_eq!(
+            encode(&key(Keysym::Delete, None), NONE, false),
+            Some(b"\x1b[3~".to_vec())
+        );
+        assert_eq!(
+            encode(&key(Keysym::F5, None), NONE, false),
+            Some(b"\x1b[15~".to_vec())
+        );
+    }
+}

src/main.rs

@@ -2,6 +2,7 @@
 
 mod font;
 mod grid;
+mod input;
 mod pty;
 mod render;
 mod vt;

src/vt.rs

@@ -133,6 +133,7 @@ impl Term {
                     }
                 }
                 (false, 4) => self.grid.set_insert(on),
+                (true, 1) => self.grid.set_app_cursor(on),
                 (true, 25) => self.grid.set_cursor_visible(on),
                 // App-cursor/bracketed-paste/mouse/sync modes affect input and
                 // rendering, which arrive with the keyboard and renderer.

src/wayland.rs

@@ -19,12 +19,15 @@ use crate::render::Renderer;
 use crate::vt::Term;
 use smithay_client_toolkit::{
     compositor::{CompositorHandler, CompositorState},
-    delegate_compositor, delegate_output, delegate_registry, delegate_seat, delegate_shm,
-    delegate_xdg_shell, delegate_xdg_window,
+    delegate_compositor, delegate_keyboard, delegate_output, delegate_registry, delegate_seat,
+    delegate_shm, delegate_xdg_shell, delegate_xdg_window,
     output::{OutputHandler, OutputState},
     registry::{ProvidesRegistryState, RegistryState},
     registry_handlers,
-    seat::{Capability, SeatHandler, SeatState},
+    seat::{
+        Capability, SeatHandler, SeatState,
+        keyboard::{KeyEvent, KeyboardHandler, Keysym, Modifiers, RawModifiers, RepeatInfo},
+    },
     shell::{
         WaylandSurface,
         xdg::{
@@ -37,7 +40,7 @@ use smithay_client_toolkit::{
 use wayland_client::{
     Connection, QueueHandle,
     globals::registry_queue_init,
-    protocol::{wl_output, wl_seat, wl_shm, wl_surface},
+    protocol::{wl_keyboard, wl_output, wl_seat, wl_shm, wl_surface},
 };
 
 /// Default window size in pixels before the compositor suggests one.
@@ -87,6 +90,8 @@ pub fn run() -> anyhow::Result<ExitCode> {
         window,
         renderer,
         loop_handle: event_loop.handle(),
+        keyboard: None,
+        modifiers: Modifiers::default(),
         // The PTY is spawned on the first configure, once the real window size
         // is known, so the shell starts at the final size and is not hit by a
         // startup SIGWINCH storm that makes it reprint its prompt.
@@ -151,6 +156,8 @@ struct App {
     window: Window,
     renderer: Renderer,
     loop_handle: LoopHandle<'static, App>,
+    keyboard: Option<wl_keyboard::WlKeyboard>,
+    modifiers: Modifiers,
     /// `None` until the first configure spawns the shell.
     session: Option<Session>,
     /// Last title applied to the toplevel, to avoid redundant requests.
@@ -225,6 +232,20 @@ impl App {
         });
     }
 
+    /// Encode a key event and write it to the shell.
+    fn send_key(&self, event: &KeyEvent) {
+        let app_cursor = self
+            .session
+            .as_ref()
+            .is_some_and(|s| s.term.grid().app_cursor());
+        if let Some(bytes) = crate::input::encode(event, self.modifiers, app_cursor)
+            && let Some(session) = self.session.as_ref()
+            && let Err(err) = write_all(session.pty.master(), &bytes)
+        {
+            tracing::warn!("write key to pty: {err}");
+        }
+    }
+
     /// After parsing child output: send any replies, sync the title, repaint.
     fn after_feed(&mut self) {
         let Some(session) = self.session.as_mut() else {
@@ -404,10 +425,16 @@ impl SeatHandler for App {
     fn new_capability(
         &mut self,
         _: &Connection,
-        _: &QueueHandle<Self>,
-        _: wl_seat::WlSeat,
-        _: Capability,
+        qh: &QueueHandle<Self>,
+        seat: wl_seat::WlSeat,
+        capability: Capability,
     ) {
+        if capability == Capability::Keyboard && self.keyboard.is_none() {
+            match self.seat_state.get_keyboard(qh, &seat, None) {
+                Ok(keyboard) => self.keyboard = Some(keyboard),
+                Err(err) => tracing::warn!("get keyboard: {err}"),
+            }
+        }
     }
 
     fn remove_capability(
@@ -415,13 +442,100 @@ impl SeatHandler for App {
         _: &Connection,
         _: &QueueHandle<Self>,
         _: wl_seat::WlSeat,
-        _: Capability,
+        capability: Capability,
     ) {
+        if capability == Capability::Keyboard
+            && let Some(keyboard) = self.keyboard.take()
+        {
+            keyboard.release();
+        }
     }
 
     fn remove_seat(&mut self, _: &Connection, _: &QueueHandle<Self>, _: wl_seat::WlSeat) {}
 }
 
+impl KeyboardHandler for App {
+    fn enter(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: &wl_surface::WlSurface,
+        _: u32,
+        _: &[u32],
+        _: &[Keysym],
+    ) {
+        self.focused = true;
+        self.dirty = true;
+    }
+
+    fn leave(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: &wl_surface::WlSurface,
+        _: u32,
+    ) {
+        self.focused = false;
+        self.dirty = true;
+    }
+
+    fn press_key(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: u32,
+        event: KeyEvent,
+    ) {
+        self.send_key(&event);
+    }
+
+    fn repeat_key(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: u32,
+        event: KeyEvent,
+    ) {
+        self.send_key(&event);
+    }
+
+    fn release_key(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: u32,
+        _: KeyEvent,
+    ) {
+    }
+
+    fn update_modifiers(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: u32,
+        modifiers: Modifiers,
+        _: RawModifiers,
+        _: u32,
+    ) {
+        self.modifiers = modifiers;
+    }
+
+    fn update_repeat_info(
+        &mut self,
+        _: &Connection,
+        _: &QueueHandle<Self>,
+        _: &wl_keyboard::WlKeyboard,
+        _: RepeatInfo,
+    ) {
+    }
+}
+
 impl OutputHandler for App {
     fn output_state(&mut self) -> &mut OutputState {
         &mut self.output_state
@@ -445,6 +559,7 @@ delegate_compositor!(App);
 delegate_output!(App);
 delegate_shm!(App);
 delegate_seat!(App);
+delegate_keyboard!(App);
 delegate_xdg_shell!(App);
 delegate_xdg_window!(App);
 delegate_registry!(App);