diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/Text/Pandoc/ImageSize.hs | 63 |
1 files changed, 34 insertions, 29 deletions
diff --git a/src/Text/Pandoc/ImageSize.hs b/src/Text/Pandoc/ImageSize.hs index 2fbf509cc..b4e94da0f 100644 --- a/src/Text/Pandoc/ImageSize.hs +++ b/src/Text/Pandoc/ImageSize.hs @@ -68,14 +68,14 @@ imageType img = case B.take 4 img of "%!PS" | (B.take 4 $ B.drop 1 $ B.dropWhile (/=' ') img) == "EPSF" -> return Eps - _ -> (hush . Left) "Unknown image type" + _ -> mzero imageSize :: ByteString -> Either String ImageSize imageSize img = case imageType img of Just Png -> mbToEither "could not determine PNG size" $ pngSize img Just Gif -> mbToEither "could not determine GIF size" $ gifSize img - Just Jpeg -> mbToEither "could not determine JPEG size" $ jpegSize img + Just Jpeg -> jpegSize img Just Eps -> mbToEither "could not determine EPS size" $ epsSize img Just Pdf -> Left "could not determine PDF size" -- TODO Nothing -> Left "could not determine image type" @@ -151,47 +151,52 @@ gifSize img = do } _ -> (hush . Left) "GIF parse error" -jpegSize :: ByteString -> Maybe ImageSize -jpegSize img = do +jpegSize :: ByteString -> Either String ImageSize +jpegSize img = let (hdr, rest) = B.splitAt 4 img - guard $ B.length rest >= 14 - case hdr of - "\xff\xd8\xff\xe0" -> jfifSize rest - "\xff\xd8\xff\xe1" -> exifSize $ B.takeWhile (/= '\xff') rest - _ -> mzero + in if B.length rest < 14 + then Left "unable to determine JPEG size" + else case hdr of + "\xff\xd8\xff\xe0" -> jfifSize rest + "\xff\xd8\xff\xe1" -> exifSize $ B.takeWhile (/= '\xff') rest + _ -> Left "unable to determine JPEG size" -jfifSize :: ByteString -> Maybe ImageSize -jfifSize rest = do +jfifSize :: ByteString -> Either String ImageSize +jfifSize rest = let [dpiDensity,dpix1,dpix2,dpiy1,dpiy2] = map fromIntegral $ unpack $ B.take 5 $ B.drop 9 $ rest - let factor = case dpiDensity of + factor = case dpiDensity of 1 -> id 2 -> \x -> (x * 254 `div` 10) _ -> const 72 - let dpix = factor (shift dpix1 8 + dpix2) - let dpiy = factor (shift dpiy1 8 + dpiy2) - (w,h) <- findJfifSize rest - return $ ImageSize { pxX = w, pxY = h, dpiX = dpix, dpiY = dpiy } + dpix = factor (shift dpix1 8 + dpix2) + dpiy = factor (shift dpiy1 8 + dpiy2) + in case findJfifSize rest of + Left msg -> Left msg + Right (w,h) -> Right $ ImageSize { pxX = w + , pxY = h + , dpiX = dpix + , dpiY = dpiy } -findJfifSize :: ByteString -> Maybe (Integer,Integer) -findJfifSize bs = do +findJfifSize :: ByteString -> Either String (Integer,Integer) +findJfifSize bs = let bs' = B.dropWhile (=='\xff') $ B.dropWhile (/='\xff') bs - case B.uncons bs' of - Just (c,bs'') | c >= '\xc0' && c <= '\xc3' -> do + in case B.uncons bs' of + Just (c,bs'') | c >= '\xc0' && c <= '\xc3' -> case map fromIntegral $ unpack $ B.take 4 $ B.drop 3 bs'' of - [h1,h2,w1,w2] -> return (shift w1 8 + w2, shift h1 8 + h2) - _ -> (hush . Left) "JPEG parse error" - Just (_,bs'') -> do + [h1,h2,w1,w2] -> Right (shift w1 8 + w2, shift h1 8 + h2) + _ -> Left "JFIF parse error" + Just (_,bs'') -> case map fromIntegral $ unpack $ B.take 2 bs'' of - [c1,c2] -> do + [c1,c2] -> let len = shift c1 8 + c2 -- skip variables - findJfifSize $ B.drop len bs'' - _ -> (hush . Left) "JPEG parse error" - Nothing -> (hush . Left) "Did not find length record" + in findJfifSize $ B.drop len bs'' + _ -> Left "JFIF parse error" + Nothing -> Left "Did not find JFIF length record" -exifSize :: ByteString -> Maybe ImageSize -exifSize bs = hush . runGet header $ bl +exifSize :: ByteString -> Either String ImageSize +exifSize bs = runGet header $ bl where bl = BL.fromChunks [bs] header = runExceptT $ exifHeader bl -- NOTE: It would be nicer to do |