AFK

A library for modeling the internal state of a computer keyboard. It supports arbitrary layouts with any number of layers, and outputs a basic 6-key HID report byte string.

Its intended use is to model the state for keyboard firmware. A work-in-progress firmware using Nerves is being attempted over here.

Installation

AFK can be installed by adding afk to your list of dependencies in mix.exs:

def deps do
  [
    {:afk, "~> 0.1.0"}
  ]
end

Basic Usage

First, you define a keymap:

keymap = [
  # Layer 0 (default)
  %{
    k001: AFK.Keycode.Key.new(:a),
    k002: AFK.Keycode.Modifier.new(:left_control),
    k003: AFK.Keycode.Layer.new(:hold, 1),
    k004: AFK.Keycode.Key.new(:caps_lock)
  },
  # Layer 1
  %{
    k001: AFK.Keycode.Key.new(:z),
    k002: AFK.Keycode.Modifier.new(:right_super),
    k003: AFK.Keycode.None.new(),
    k004: AFK.Keycode.Transparent.new()
  }
]

You can now initialize an AFK.State struct and press and release keys. Using an implementation of the AFK.HIDReport behaviour and calling hid_report/1 returns a byte string for sending to a USB HID interface.

state = AFK.State.new(keymap)

state =
  state
  |> AFK.State.press_key(:k003)
  |> AFK.State.press_key(:k002)
  |> AFK.State.press_key(:k001)

AFK.HIDReport.SixKeyRollover.hid_report(state)
# => <<128, 0, 29, 0, 0, 0, 0, 0>>

state = AFK.State.release_key(state, :k002)

AFK.HIDReport.SixKeyRollover.hid_report(state)
# => <<0, 0, 29, 0, 0, 0, 0, 0>>

Future Features

AFK provides a behaviour for defining how to convert the state into a HID report. Currently only a 6-key rollover implementation is provided, but an N-key rollover implementation would be a great addition. (Pull requests welcome!)

It may eventually also support more complex interactions, such as sticky keys, macros, leader keys, etc. These features require a lot more thinking though, as they will require the state undergoing changes over time.

Docs

Documentation can be found at https://hexdocs.pm/afk.