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{-# LANGUAGE OverloadedStrings, ScopedTypeVariables, CPP #-}
{- |
Module : Text.Pandoc.Image
Copyright : Copyright (C) 2020-2021 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
Functions for converting images.
-}
module Text.Pandoc.Image ( svgToPng ) where
import Text.Pandoc.Process (pipeProcess)
import qualified Data.ByteString.Lazy as L
import System.Exit
import Data.Text (Text)
import Text.Pandoc.Shared (tshow)
import qualified Control.Exception as E
import Control.Monad.IO.Class (MonadIO(liftIO))
-- | Convert svg image to png. rsvg-convert
-- is used and must be available on the path.
svgToPng :: MonadIO m
=> Int -- ^ DPI
-> L.ByteString -- ^ Input image as bytestring
-> m (Either Text L.ByteString)
svgToPng dpi bs = do
let dpi' = show dpi
liftIO $ E.catch
(do (exit, out) <- pipeProcess Nothing "rsvg-convert"
["-f","png","-a","--dpi-x",dpi',"--dpi-y",dpi']
bs
return $ if exit == ExitSuccess
then Right out
else Left "conversion from SVG failed")
(\(e :: E.SomeException) -> return $ Left $
"check that rsvg-convert is in path.\n" <> tshow e)
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