frpsdl.hs

{-# LANGUAGE RankNTypes #-}
import Reactive.Banana
import Reactive.Banana.Frameworks
import qualified Graphics.UI.SDL as SDL 
import qualified Graphics.UI.SDL.Image as Image

main = do
  SDL.init [SDL.InitEverything]
  SDL.rawSetCaption (Just "foobar") Nothing
  SDL.setVideoMode 640 480 32 []
  img <- Image.load "foo.png"
  source <- newAddHandler
  network <- setupNetwork img source
  actuate network
  eventLoop source

eventLoop :: EventSource (Int, Int) -> IO ()
eventLoop esMouse = loop
  where
  loop = do
    (SDL.getMouseState >>= \(x, y, _) -> return (x, y)) >>= snd esMouse
    loop

type EventSource a = (AddHandler a, a -> IO ()) 

setupNetwork :: SDL.Surface -> EventSource (Int, Int) -> IO EventNetwork
setupNetwork img esMouse = compile $ do
  eMouse <- fromAddHandler $ fst esMouse
  reactimate $ fmap (render img) eMouse

render :: SDL.Surface -> (Int, Int) -> IO ()
render img (x, y) = do
  surf <- SDL.getVideoSurface
  SDL.blitSurface img (Just (SDL.Rect (x-25) (y-25) 50 50)) surf Nothing
  return ()