minilight-lua

A binding library of minilight for Lua language.

NB: This package is in the very early stage.

What's this?

• minilight is a SDL2-based graphics library, equipped with component system.
• Lua is a lightweight interpreted language.

With this library, you can write a minilight component in Lua language.

Getting Started

See example directory. Main.hs is an entrypoint for minilight engine.

mainFile = "example/main.lua"

main :: IO ()
main = runLightT $ runMiniloop
  (defConfig { hotConfigReplacement = Just "example", appConfigFile = Just "" })
  initial
  (const mainloop)
 where
  initial = do
    comp <- registerComponent mainFile newLuaComponent
    reload mainFile

    return ()

  mainloop :: MiniLoop ()
  mainloop = do
    ref <- view _events
    evs <- liftIO $ tryReadMVar ref

    let notifys = case evs of
          Just evs -> mapMaybe asNotifyEvent evs
          _        -> []
    unless (null notifys) $ reload mainFile

Some notes here:

• When you pass hotConfigReplacement field, minilight will watch the given directory and emits file changed/created/delete events during the mainloop.
• For registerComponent you need to pass the filename like example/main.lua. The path is relative where you run cabal run.
• In mainloop, watches any events and reload the component. The reload function will load the lua file again and swap the component dynamically (code swapping).

local minilight = require("minilight")

function onDraw()
    print("[LUA OUTPUT] hello")

    return {
        minilight.translate(50, 50, minilight.picture("example/example.png")),
        minilight.translate(100, 100, minilight.text("こんにちは世界",
                                                     {0, 0, 0, 0})),
        minilight.translate(30, 50,
                            minilight.text("Hello, World!", {255, 0, 0, 0}))
    }
end

_G.onDraw = onDraw

For lua part:

• Require minilight library. This will be implicitly loaded by minilight-lua.
• You need to export onDraw : () -> Array<minilight.Figure> function globally. This function will be called from Haskell and the returned array will be rendered in the component.