{-# LANGUAGE CPP #-}
module Codec.Picture.Jpg.Metadata ( extractMetadatas, encodeMetadatas ) where
#if !MIN_VERSION_base(4,8,0)
import Control.Applicative( pure )
import Data.Monoid( mempty )
import Data.Word( Word )
#endif
import Data.Word( Word16 )
import Data.Maybe( fromMaybe )
import qualified Codec.Picture.Metadata as Met
import Codec.Picture.Metadata( Metadatas )
import Codec.Picture.Jpg.Types
scalerOfUnit :: JFifUnit -> Met.Keys Word -> Word16 -> Metadatas -> Metadatas
scalerOfUnit unit k v = case unit of
JFifUnitUnknown -> id
JFifPixelsPerInch -> Met.insert k (fromIntegral v)
JFifPixelsPerCentimeter ->
Met.insert k (Met.dotsPerCentiMeterToDotPerInch $ fromIntegral v)
extractMetadatas :: JpgJFIFApp0 -> Metadatas
extractMetadatas jfif =
inserter Met.DpiX (_jfifDpiX jfif)
$ inserter Met.DpiY (_jfifDpiY jfif) mempty
where
inserter = scalerOfUnit $ _jfifUnit jfif
encodeMetadatas :: Metadatas -> [JpgFrame]
encodeMetadatas metas = fromMaybe [] $ do
dpiX <- Met.lookup Met.DpiX metas
dpiY <- Met.lookup Met.DpiY metas
pure . pure . JpgJFIF $ JpgJFIFApp0
{ _jfifUnit = JFifPixelsPerInch
, _jfifDpiX = fromIntegral dpiX
, _jfifDpiY = fromIntegral dpiY
, _jfifThumbnail = Nothing
}