{-# OPTIONS_HADDOCK hide #-}
{-# LANGUAGE RankNTypes #-}

module Graphics.Gloss.Internals.Interface.ViewState.KeyMouse
	(callback_viewState_keyMouse)
where
import Graphics.Gloss.Data.ViewState
import Graphics.Gloss.Internals.Interface.Backend
import Graphics.Gloss.Internals.Interface.Event
import Data.IORef


-- | Callback to handle keyboard and mouse button events
--	for controlling the 'ViewState'.
callback_viewState_keyMouse 
	:: IORef ViewState
	-> Callback

callback_viewState_keyMouse viewStateRef
 	= KeyMouse (viewState_keyMouse viewStateRef)


viewState_keyMouse :: IORef ViewState -> KeyboardMouseCallback
viewState_keyMouse viewStateRef stateRef key keyState keyMods pos
 = do	viewState <- readIORef viewStateRef
	ev	  <- keyMouseEvent stateRef key keyState keyMods pos
        case updateViewStateWithEventMaybe ev viewState of
		Nothing -> return ()
		Just viewState' 
                 -> do	viewStateRef `writeIORef` viewState'
			postRedisplay stateRef