Eraser.hs

-----------------------------------------------------------------------------
-- |
-- Module      : Hoodle.ModelAction.Eraser 
-- Copyright   : (c) 2011, 2012 Ian-Woo Kim
--
-- License     : BSD3
-- Maintainer  : Ian-Woo Kim <ianwookim@gmail.com>
-- Stability   : experimental
-- Portability : GHC
--
-----------------------------------------------------------------------------

module Hoodle.ModelAction.Eraser where

import Control.Monad.State 
-- from hoodle-platform
import Data.Hoodle.BBox
import Graphics.Hoodle.Render.Type.HitTest
import Graphics.Hoodle.Render.Util.HitTest

-- |
eraseHitted :: (BBoxable a) => 
               AlterList (NotHitted a) (AlterList (NotHitted a) (Hitted a)) 
               -> State (Maybe BBox) [a]
eraseHitted Empty = error "something wrong in eraseHitted"
eraseHitted (n :-Empty) = return (unNotHitted n)
eraseHitted (n:-h:-rest) = do 
  mid <- elimHitted h 
  return . (unNotHitted n ++) . (mid ++) =<< eraseHitted rest