squeekboard/src/keyboard.rs

/*! State of the emulated keyboard and keys.
 * Regards the keyboard as if it was composed of switches. */

use std::cell::RefCell;
use std::collections::HashMap;
use std::fmt;
use std::io;
use std::rc::Rc;
use std::string::FromUtf8Error;

use ::action::Action;

// Traits
use std::io::Write;
use std::iter::{ FromIterator, IntoIterator };

#[derive(Debug, Clone, Copy, PartialEq)]
pub enum PressType {
    Released = 0,
    Pressed = 1,
}

pub type KeyCode = u32;

bitflags!{
    /// Map to `virtual_keyboard.modifiers` modifiers values
    /// From https://www.x.org/releases/current/doc/kbproto/xkbproto.html#Keyboard_State
    pub struct Modifiers: u8 {
        const SHIFT = 0x1;
        const LOCK = 0x2;
        const CONTROL = 0x4;
        /// Alt
        const MOD1 = 0x8;
        const MOD2 = 0x10;
        const MOD3 = 0x20;
        /// Meta
        const MOD4 = 0x40;
        /// AltGr
        const MOD5 = 0x80;
    }
}

/// When the submitted actions of keys need to be tracked,
/// they need a stable, comparable ID
#[derive(Clone, PartialEq)]
pub struct KeyStateId(*const KeyState);

#[derive(Debug, Clone)]
pub struct KeyState {
    pub pressed: PressType,
    /// A cache of raw keycodes derived from Action::Submit given a keymap
    pub keycodes: Vec<KeyCode>,
    /// Static description of what the key does when pressed or released
    pub action: Action,
}

impl KeyState {
    #[must_use]
    pub fn into_released(self) -> KeyState {
        KeyState {
            pressed: PressType::Released,
            ..self
        }
    }

    #[must_use]
    pub fn into_pressed(self) -> KeyState {
        KeyState {
            pressed: PressType::Pressed,
            ..self
        }
    }

    /// KeyStates instances are the unique identifiers of pressed keys,
    /// and the actions submitted with them.
    pub fn get_id(keystate: &Rc<RefCell<KeyState>>) -> KeyStateId {
        KeyStateId(keystate.as_ptr() as *const KeyState)
    }
}

/// Sorts an iterator by converting it to a Vector and back
fn sorted<'a, I: Iterator<Item=String>>(
    iter: I
) -> impl Iterator<Item=String> {
    let mut v: Vec<String> = iter.collect();
    v.sort();
    v.into_iter()
}

/// Generates a mapping where each key gets a keycode, starting from ~~8~~
/// HACK: starting from 9, because 8 results in keycode 0,
/// which the compositor likes to discard
pub fn generate_keycodes<'a, C: IntoIterator<Item=String>>(
    key_names: C,
) -> HashMap<String, u32> {
    HashMap::from_iter(
        // Sort to remove a source of indeterminism in keycode assignment.
        sorted(key_names.into_iter())
            .map(|name| name)
            .zip(9..)
    )
}

#[derive(Debug)]
pub enum FormattingError {
    Utf(FromUtf8Error),
    Format(io::Error),
}

impl fmt::Display for FormattingError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            FormattingError::Utf(e) => write!(f, "UTF: {}", e),
            FormattingError::Format(e) => write!(f, "Format: {}", e),
        }
    }
}

impl From<io::Error> for FormattingError {
    fn from(e: io::Error) -> Self {
        FormattingError::Format(e)
    }
}

/// Generates a de-facto single level keymap.
/// Key codes must not repeat and must remain between 9 and 255.
pub fn generate_keymap(
    symbolmap: HashMap::<String, KeyCode>,
) -> Result<String, FormattingError> {
    let mut buf: Vec<u8> = Vec::new();
    writeln!(
        buf,
        "xkb_keymap {{

    xkb_keycodes \"squeekboard\" {{
        minimum = 8;
        maximum = 255;"
    )?;
    
    // 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() {
        write!(
            buf,
            "
        <I{}> = {0};",
            keycode,
        )?;
    }

    writeln!(
        buf,
        "
        indicator 1 = \"Caps Lock\"; // Xwayland won't accept without it.
    }};
    
    xkb_symbols \"squeekboard\" {{
"
    )?;
    
    for (name, keycode) in symbolmap.iter() {
        write!(
            buf,
            "
key <I{}> {{ [ {} ] }};",
            keycode,
            name,
        )?;
    }

    writeln!(
        buf,
        "
    }};

    xkb_types \"squeekboard\" {{
        virtual_modifiers Squeekboard; // No modifiers! Needed for Xorg for some reason.
    
        // Those names are needed for Xwayland.
        type \"ONE_LEVEL\" {{
            modifiers= none;
            level_name[Level1]= \"Any\";
        }};
        type \"TWO_LEVEL\" {{
            level_name[Level1]= \"Base\";
        }};
        type \"ALPHABETIC\" {{
            level_name[Level1]= \"Base\";
        }};
        type \"KEYPAD\" {{
            level_name[Level1]= \"Base\";
        }};
        type \"SHIFT+ALT\" {{
            level_name[Level1]= \"Base\";
        }};

    }};

    xkb_compatibility \"squeekboard\" {{
        // Needed for Xwayland again.
        interpret Any+AnyOf(all) {{
            action= SetMods(modifiers=modMapMods,clearLocks);
        }};
    }};
}};"
    )?;
    
    //println!("{}", String::from_utf8(buf.clone()).unwrap());
    String::from_utf8(buf).map_err(FormattingError::Utf)
}

#[cfg(test)]
mod tests {
    use super::*;
    
    use xkbcommon::xkb;

    #[test]
    fn test_keymap_multi() {
        let context = xkb::Context::new(xkb::CONTEXT_NO_FLAGS);

        let keymap_str = generate_keymap(hashmap!{
            "a".into() => 9,
            "c".into() => 10,
        }).unwrap();

        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);

        assert_eq!(state.key_get_one_sym(9), xkb::KEY_a);
        assert_eq!(state.key_get_one_sym(10), xkb::KEY_c);
    }
}