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-- | Font compression and decompression.
module Graphics.Fountainhead.Compression
( compress
, hDecompress
) where
import qualified Data.ByteString.Lazy as ByteString.Lazy
import Data.ByteString (ByteString)
import qualified Data.ByteString as ByteString
import qualified Codec.Compression.Zlib as Zlib
import System.IO (Handle, SeekMode(..), hFileSize, hSeek)
-- | Reads the font from a file handle decompressing it if needed.
hDecompress :: Handle -> IO ByteString
hDecompress fontHandle = do
firstBytes <- ByteString.unpack <$> ByteString.hGet fontHandle 2
hSeek fontHandle AbsoluteSeek 0
fileSize <- fromIntegral <$> hFileSize fontHandle
case firstBytes of
0x78 : [secondByte]
| secondByte `elem` [0x01, 0x9c, 0x5e, 0xda] ->
ByteString.Lazy.toStrict . Zlib.decompress
<$> ByteString.Lazy.hGet fontHandle fileSize
_ -> ByteString.hGetContents fontHandle
compress :: ByteString -> ByteString
compress = ByteString.Lazy.toStrict . Zlib.compress . ByteString.Lazy.fromStrict
|
