1 files changed, 104 insertions, 0 deletions
diff --git a/src/conn_info/keys.rs b/src/conn_info/keys.rs
new file mode 100644
index 0000000..1be3dfe
--- /dev/null
+++ b/src/conn_info/keys.rs
@@ -0,0 +1,104 @@
+use std::ops::RangeInclusive;
+
+use crate::Result;
+use xcb::{
+    x::{GetKeyboardMapping, GetKeyboardMappingReply, GetModifierMapping, ModMask},
+    Connection,
+};
+use xkeysym::{KeyCode, Keysym, RawKeyCode};
+
+/// Cached information about our keyboard layout.
+pub struct KeyboardInfo {
+    /// The range of keycodes used
+    keycodes: RangeInclusive<RawKeyCode>,
+
+    /// The `ModMask` corresponding to `NumLock`.
+    /// This varies sometimes, and we need to know to ignore it.
+    numlock_mask: ModMask,
+
+    /// The mapping from keycodes to (multiple) key symbols
+    mapping: GetKeyboardMappingReply,
+}
+
+impl KeyboardInfo {
+    /// Query information about the keyboard layout from the given connection.
+    pub fn new_with(conn: &Connection) -> Result<Self> {
+        let min_keycode = conn.get_setup().min_keycode();
+        let max_keycode = conn.get_setup().max_keycode();
+
+        let mapping = conn.wait_for_reply(conn.send_request(&GetKeyboardMapping {
+            first_keycode: min_keycode,
+            count: max_keycode - min_keycode + 1,
+        }))?;
+
+        let mut this = Self {
+            keycodes: RawKeyCode::from(min_keycode)..=RawKeyCode::from(max_keycode),
+            numlock_mask: ModMask::empty(),
+            mapping,
+        };
+
+        let Some(numlock_keycode) = this.keysym_to_keycode(Keysym::Num_Lock) else {
+            // No numlock button, so no modmask for numlock
+            return Ok(this);
+        };
+        let mod_map = conn.wait_for_reply(conn.send_request(&GetModifierMapping {}))?;
+        let keypermod = mod_map.keycodes().len() / 8;
+        for i in 0..8 {
+            for j in 0..keypermod {
+                if RawKeyCode::from(mod_map.keycodes()[i * keypermod + j]) == numlock_keycode.raw()
+                {
+                    this.numlock_mask =
+                        ModMask::from_bits(1 << i).expect("x11 returned unrecognised modifier");
+                }
+            }
+        }
+
+        Ok(this)
+    }
+
+    /// Get the modifier mask being used for numlock
+    pub const fn numlock_mask(&self) -> ModMask {
+        self.numlock_mask
+    }
+
+    /// Iterate over all keycodes and their bound keysyms.
+    /// This is likely to contain duplicate pairs.
+    pub fn iter_keycodes_keysyms(&self) -> impl Iterator<Item = (KeyCode, Keysym)> + '_ {
+        (0..self.mapping.keysyms_per_keycode())
+            .flat_map(|shift| self.keycodes.clone().map(move |keycode| (shift, keycode)))
+            .filter_map(|(shift, keycode)| -> Option<_> {
+                Some((
+                    keycode.into(),
+                    self.keycode_to_keysym(keycode.into(), shift)?,
+                ))
+            })
+    }
+
+    /// Lookup the first keycode which has the given keysym in any column
+    pub(crate) fn keysym_to_keycode(&self, keysym: Keysym) -> Option<KeyCode> {
+        for shift in 0..self.mapping.keysyms_per_keycode() {
+            for keycode in self.keycodes.clone() {
+                if self.mapping.keysyms()[(keycode as usize - *self.keycodes.start() as usize)
+                    * self.mapping.keysyms_per_keycode() as usize
+                    + shift as usize]
+                    == keysym.raw()
+                {
+                    return Some(keycode.into());
+                }
+            }
+        }
+
+        None
+    }
+
+    /// Lookup the keysym in the given column for the given keycode
+    pub fn keycode_to_keysym(&self, keycode: KeyCode, col: u8) -> Option<Keysym> {
+        xkeysym::keysym(
+            keycode,
+            col,
+            (*self.keycodes.start()).into(),
+            self.mapping.keysyms_per_keycode(),
+            self.mapping.keysyms(),
+        )
+    }
+}