elm/libraries/Keyboard.elm

module Keyboard where

{-| Library for working with keyboard input.

# Representing Keys
@docs KeyCode

# Directions
@docs arrows, wasd, directions

# Specific Keys
@docs shift, enter, space, ctrl

# General Keypresses
@docs isDown, keysDown, lastPressed

-}

import Signal (Signal)
import Native.Keyboard

{-| Type alias to make it clearer what integers are supposed to represent
in this library. Use [`Char.toCode`](docs/Char.elm#toCode) and
[`Char.fromCode`](/docs/Char.elm#fromCode) to convert key codes to characters.
Use the uppercase character with `toCode`.
-}
type KeyCode = Int

{-| Custom key directions to support different locales. The order is up, down,
left, right.
-}
directions : KeyCode -> KeyCode -> KeyCode -> KeyCode -> Signal { x:Int, y:Int }
directions = Native.Keyboard.directions

{-| A signal of records indicating which arrow keys are pressed.

`{ x = 0, y = 0 }` when pressing no arrows.<br>
`{ x =-1, y = 0 }` when pressing the left arrow.<br>
`{ x = 1, y = 1 }` when pressing the up and right arrows.<br>
`{ x = 0, y =-1 }` when pressing the down, left, and right arrows.
-}
arrows : Signal { x:Int, y:Int }
arrows = directions 38 40 37 39

{-| Just like the arrows signal, but this uses keys w, a, s, and d,
which are common controls for many computer games.
-}
wasd : Signal { x:Int, y:Int }
wasd = directions 87 83 65 68

{-| Whether an arbitrary key is pressed. -}
isDown : KeyCode -> Signal Bool
isDown = Native.Keyboard.isDown

{-| Whether the shift key is pressed. -}
shift : Signal Bool
shift = isDown 16

{-| Whether the control key is pressed. -}
ctrl : Signal Bool
ctrl = isDown 17

{-| Whether the space key is pressed. -}
space : Signal Bool
space = isDown 32

{-| Whether the enter key is pressed. -}
enter : Signal Bool
enter = isDown 13

{-| List of keys that are currently down. -}
keysDown : Signal [KeyCode]
keysDown = Native.Keyboard.keysDown

{-| The latest key that has been pressed. -}
lastPressed : Signal KeyCode
lastPressed = Native.Keyboard.lastPressed