-- GENERATED by C->Haskell Compiler, version 0.16.0 Crystal Seed, 24 Jan 2009 (Haskell)
-- Edit the ORIGNAL .chs file instead!


{-# LINE 1 "./Algebra/Geometric/Polygon/File.chs" #-}{-# LANGUAGE ForeignFunctionInterface #-}

-- File.chs

-- hgeometric: A geometric library with bindings to GPC.
-- File.chs is part of hgeometric.

-- Copyright 2007, 2009 Marco Túlio Gontijo e Silva
-- Copyright 2007, 2009 Rafael Cunha de Almeida

-- See LICENSE

-- | Support for reading and writing a 'Polygon' in a file.
module Algebra.Geometric.Polygon.File (readPolygon, writePolygon) where


import Foreign
import Foreign.C

import Algebra.Geometric.Polygon


{-# LINE 24 "./Algebra/Geometric/Polygon/File.chs" #-}

type CPolygon = Ptr (Polygon)
{-# LINE 26 "./Algebra/Geometric/Polygon/File.chs" #-}

-- | Reads a file into a 'Polygon'. If the file isn't accessible, then
-- 'Nothing' is returned.
readPolygon :: FilePath -> Bool -> IO (Maybe Polygon)
readPolygon fileName hole =
    alloca $
    \cResult ->
    do
    cFileName <- newCString fileName
    mode <- newCString "r"

    file <- fopen cFileName mode

    let free_ = free cFileName >> free mode

    if file == nullPtr
        then free_ >> return Nothing
        else
        do
        gpc_read_polygon file (fromBool hole) cResult
        fclose file

        result <- peek cResult

        free_
        gpc_free_polygon cResult

        return $ Just result

-- | If the 'Polygon' was successfully written, then this function returns
-- 'True', and 'False' otherwise.
writePolygon :: String -> Bool -> Polygon -> IO Bool
writePolygon fileName hole polygon =
    alloca $
    \cPolygon ->
    do
    poke cPolygon polygon

    cFileName <- newCString fileName
    mode <- newCString "w"

    file <- fopen cFileName mode

    let free_ = free cFileName >> free mode

    if file == nullPtr
        then free_ >> return False
        else
        gpc_write_polygon file (fromBool hole) cPolygon >>
        fclose file >>

        free_ >> gpc_free_polygon cPolygon >>

        return True

foreign import ccall unsafe "Algebra/Geometric/Polygon/File.chs.h fopen"
  fopen :: ((Ptr CChar) -> ((Ptr CChar) -> (IO (Ptr ()))))

foreign import ccall unsafe "Algebra/Geometric/Polygon/File.chs.h gpc_read_polygon"
  gpc_read_polygon :: ((Ptr ()) -> (CInt -> ((CPolygon) -> (IO ()))))

foreign import ccall unsafe "Algebra/Geometric/Polygon/File.chs.h fclose"
  fclose :: ((Ptr ()) -> (IO CInt))

foreign import ccall unsafe "Algebra/Geometric/Polygon/File.chs.h gpc_free_polygon"
  gpc_free_polygon :: ((CPolygon) -> (IO ()))

foreign import ccall unsafe "Algebra/Geometric/Polygon/File.chs.h gpc_write_polygon"
  gpc_write_polygon :: ((Ptr ()) -> (CInt -> ((CPolygon) -> (IO ()))))