feat: Have backend map mod-tap keycodes to/from strings

Author: ids1024

Cargo.lock

@@ -6,13 +6,15 @@ license = "GPL-3.0-or-later"
 edition = "2018"
 
 [dependencies]
+cascade = "1"
 futures = "0.3.13"
 futures-timer = "3.0.2"
 glib = { git = "https://github.com/pop-os/gtk-rs" }
 hidapi = { version = "1.2", default-features = false, features = ["linux-static-hidraw"] }
 once_cell = "1.4"
 ordered-float = { version = "2.0", features = ["serde"] }
 palette = "0.5"
+regex = "1"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 log = "0.4.0"

backend/Cargo.toml

@@ -147,7 +147,7 @@ impl Key {
         let board = self.board();
         let scancode = self.scancodes.get(layer)?.get();
         let scancode_name = match board.layout().scancode_to_name(scancode) {
-            Some(some) => some.to_string(),
+            Some(some) => some,
             None => String::new(),
         };
         Some((scancode, scancode_name))

backend/src/key.rs

@@ -20,6 +20,9 @@ pub struct Meta {
     pub has_brightness: bool,
     /// Has LED with color (i.e. not monochrome)
     pub has_color: bool,
+    /// Supports mod-tap bindings (assumes QMK mod-tap encoding)
+    #[serde(default)]
+    pub has_mod_tap: bool,
     /// Number or layers; e.g. 2 where layer 2 is used when `Fn` is held
     #[serde(default = "num_layers_default")]
     pub num_layers: u8,

backend/src/layout/meta.rs

@@ -1,12 +1,32 @@
+use cascade::cascade;
+use regex::Regex;
 use std::{collections::HashMap, fs, path::Path};
 
 mod meta;
+use once_cell::sync::Lazy;
 mod physical_layout;
 pub use self::meta::Meta;
 pub(crate) use physical_layout::{PhysicalLayout, PhysicalLayoutKey};
 
 use crate::KeyMap;
 
+const QK_MOD_TAP: u16 = 0x6000;
+const QK_MOD_TAP_MAX: u16 = 0x7FFF;
+
+pub static MOD_TAP_MODS: Lazy<HashMap<&str, u16>> = Lazy::new(|| {
+    cascade! {
+        HashMap::new();
+        ..insert("LEFT_CTRL", 0x01);
+        ..insert("LEFT_SHIFT", 0x02);
+        ..insert("LEFT_ALT", 0x04);
+        ..insert("LEFT_SUPER", 0x08);
+        ..insert("RIGHT_CTRL", 0x11);
+        ..insert("RIGHT_SHIFT", 0x12);
+        ..insert("RIGHT_ALT", 0x14);
+        ..insert("RIGHT_SUPER", 0x18);
+    }
+});
+
 pub struct Layout {
     /// Metadata for keyboard
     pub meta: Meta,
@@ -123,13 +143,29 @@ impl Layout {
     }
 
     /// Get the scancode number corresponding to a name
-    pub fn scancode_to_name(&self, scancode: u16) -> Option<&str> {
-        self.scancode_names.get(&scancode).map(String::as_str)
+    pub fn scancode_to_name(&self, scancode: u16) -> Option<String> {
+        if scancode >= QK_MOD_TAP && scancode <= QK_MOD_TAP_MAX {
+            let mod_ = (scancode >> 8) & 0x1f;
+            let kc = scancode & 0xff;
+            let mod_name = MOD_TAP_MODS.iter().find(|(_, v)| **v == mod_)?.0;
+            let kc_name = self.scancode_names.get(&kc)?;
+            Some(format!("MT({}, {})", mod_name, kc_name))
+        } else {
+            self.scancode_names.get(&scancode).cloned()
+        }
     }
 
     /// Get the name corresponding to a scancode number
     pub fn scancode_from_name(&self, name: &str) -> Option<u16> {
-        self.keymap.get(name).copied()
+        // Check if mod-tap
+        let mt_re = Regex::new("MT\\(([^()]+), ([^()]+)\\)").unwrap();
+        if let Some(captures) = mt_re.captures(name) {
+            let mod_ = *MOD_TAP_MODS.get(&captures.get(1).unwrap().as_str())?;
+            let kc = *self.keymap.get(captures.get(2).unwrap().as_str())?;
+            Some(QK_MOD_TAP | ((mod_ & 0x1f) << 8) | (kc & 0xff))
+        } else {
+            self.keymap.get(name).copied()
+        }
     }
 }
 

backend/src/layout/mod.rs

@@ -5,6 +5,7 @@
   "num_layers": 4,
   "has_brightness": true,
   "has_color": true,
+  "has_mod_tap": true,
   "pressed_color": "#202020",
   "keyboard": "system76/launch_1"
-}
+}