32 lines
1.2 KiB
Haskell
32 lines
1.2 KiB
Haskell
{- This Source Code Form is subject to the terms of the Mozilla Public License,
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v. 2.0. If a copy of the MPL was not distributed with this file, You can
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obtain one at https://mozilla.org/MPL/2.0/. -}
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-- | Font compression and decompression.
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module Graphics.Fountainhead.Compression
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( compress
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, hDecompress
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) where
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import qualified Data.ByteString.Lazy as ByteString.Lazy
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import Data.ByteString (ByteString)
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import qualified Data.ByteString as ByteString
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import qualified Codec.Compression.Zlib as Zlib
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import System.IO (Handle, SeekMode(..), hFileSize, hSeek)
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-- | Reads the font from a file handle decompressing it if needed.
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hDecompress :: Handle -> IO ByteString
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hDecompress fontHandle = do
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firstBytes <- ByteString.unpack <$> ByteString.hGet fontHandle 2
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hSeek fontHandle AbsoluteSeek 0
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fileSize <- fromIntegral <$> hFileSize fontHandle
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case firstBytes of
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0x78 : [secondByte]
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| secondByte `elem` [0x01, 0x9c, 0x5e, 0xda] ->
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ByteString.Lazy.toStrict . Zlib.decompress
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<$> ByteString.Lazy.hGet fontHandle fileSize
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_ -> ByteString.hGetContents fontHandle
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compress :: ByteString -> ByteString
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compress = ByteString.Lazy.toStrict . Zlib.compress . ByteString.Lazy.fromStrict
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