~alcinnz/fontconfig-pure

ref: f238fc9c1723e757f26f9ea0880923a71163f4f4 fontconfig-pure/Graphics/Text/Font/Choose/Range.hs -rw-r--r-- 1.1 KiB
f238fc9c — Adrian Cochrane Document FcObjectSet language bindings. 2 years ago
                                                                                
24a77a5f Adrian Cochrane
e21707cb Adrian Cochrane
24a77a5f Adrian Cochrane
5aedd01f Adrian Cochrane
24a77a5f Adrian Cochrane
e21707cb Adrian Cochrane
24a77a5f Adrian Cochrane
e21707cb Adrian Cochrane
5aedd01f Adrian Cochrane
e21707cb Adrian Cochrane
5aedd01f Adrian Cochrane
e21707cb Adrian Cochrane
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{-# LANGUAGE DeriveGeneric #-}
module Graphics.Text.Font.Choose.Range where

import Foreign.Ptr (Ptr)
import Control.Exception (bracket)
import Foreign.Marshal.Alloc (alloca)
import Foreign.Storable (peek)

import GHC.Generics (Generic)
import Data.Hashable (Hashable)
import Graphics.Text.Font.Choose.Result (throwNull, throwFalse)

data Range = Range Double Double deriving (Eq, Show, Ord, Generic)
iRange i j = toEnum i `Range` toEnum j

instance Hashable Range

------
--- Low-level
------
data Range'
type Range_ = Ptr Range'

withRange :: Range -> (Range_ -> IO a) -> IO a
withRange (Range i j) = bracket (throwNull <$> fcRangeCreateDouble i j) fcRangeDestroy
foreign import ccall "FcRangeCreateDouble" fcRangeCreateDouble ::
    Double -> Double -> IO Range_
foreign import ccall "FcRangeDestroy" fcRangeDestroy :: Range_ -> IO ()

thawRange :: Range_ -> IO Range
thawRange range' = alloca $ \i' -> alloca $ \j' -> do
    throwFalse <$> fcRangeGetDouble range' i' j'
    i <- peek i'
    j <- peek j'
    return $ Range i j
foreign import ccall "FcRangeGetDouble" fcRangeGetDouble ::
    Range_ -> Ptr Double -> Ptr Double -> IO Bool