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

module Brillo.Internals.Interface.ViewState.Motion (callback_viewState_motion)
where

import Brillo.Data.ViewState
import Brillo.Internals.Interface.Backend
import Brillo.Internals.Interface.Event
import Data.IORef


{-| Callback to handle keyboard and mouse button events
     for controlling the viewport.
-}
callback_viewState_motion
  :: IORef ViewState
  -> Callback
callback_viewState_motion :: IORef ViewState -> Callback
callback_viewState_motion IORef ViewState
portRef =
  MotionCallback -> Callback
Motion (IORef ViewState -> MotionCallback
viewState_motion IORef ViewState
portRef)


viewState_motion :: IORef ViewState -> MotionCallback
viewState_motion :: IORef ViewState -> MotionCallback
viewState_motion IORef ViewState
viewStateRef IORef a
stateRef (Int, Int)
pos =
  do
    ViewState
viewState <- IORef ViewState -> IO ViewState
forall a. IORef a -> IO a
readIORef IORef ViewState
viewStateRef
    Event
ev <- IORef a -> (Int, Int) -> IO Event
forall a. Backend a => IORef a -> (Int, Int) -> IO Event
motionEvent IORef a
stateRef (Int, Int)
pos
    case Event -> ViewState -> Maybe ViewState
updateViewStateWithEventMaybe Event
ev ViewState
viewState of
      Maybe ViewState
Nothing -> () -> IO ()
forall a. a -> IO a
forall (m :: * -> *) a. Monad m => a -> m a
return ()
      Just ViewState
viewState' ->
        do
          IORef ViewState
viewStateRef IORef ViewState -> ViewState -> IO ()
forall a. IORef a -> a -> IO ()
`writeIORef` ViewState
viewState'
          IORef a -> IO ()
forall a. Backend a => IORef a -> IO ()
postRedisplay IORef a
stateRef