.vim.xkb

// Vim like keys with CAPS as overlay switch.

// Using ISO_Level3_Shift or ISO_Level5_Shift would also make
// most applications work and would have been more flexible,
// however they don't work in Java Swing apps (e.g. IntelliJ IDEA)
// but using overlay works

// To enable, save this file as /usr/share/X11/xkb/symbols/emacs and run:
//
//   setxkbmap -option '' "emacs"
//
// However it may not persist and can get reset back to the default by other things.
// Alternatively, insert the following into /usr/share/X11/xkb/rules/evdev.xml
// ...
// <layoutList>
//   ...
//   <layout>
//     <configItem>
//       <name>emacs</name>
//       <shortDescription>en</shortDescription>
//       <description>English (US, Emacs)</description>
//       <languageList>
//         <iso639Id>eng</iso639Id>
//       </languageList>
//     </configItem>
//   </layout>
//   ...
// </layoutList>
// ...
// Then you should be able to choose 'English (US, Emacs)' in a keyboard preference
// GUI such as fcitx and have it persist.

default partial alphanumeric_keys
xkb_symbols "basic" {

    // Base keyboard functionality, using 'us' here
    // See definitions in /usr/share/X11/xkb/symbols
    // e.g. 'include "us(intl)"' where 'intl' is defined inside the 'us' file
    include "us"

    // Press Shift_L + Shift_R together as an alternative way to toggle Caps_Lock,
    // then turn CAPS key to enable overlay1 mode when and only when holding down.
    include "shift(both_capslock)"
    key <CAPS> {actions[Group1]=[SetControls(controls=overlay1)]};

    // VIM like navigation keys when holding down <CAPS>
    key <AC06> {overlay1=<LEFT>}; // h
    key <AC09> {overlay1=<RGHT>}; // l
    key <AC08> {overlay1=<UP>  }; // k
    key <AC07> {overlay1=<DOWN>}; // j

};