From 5c8c380a7997156964a5402974f6f464233aab9b Mon Sep 17 00:00:00 2001 From: John MacFarlane Date: Thu, 9 Jan 2014 11:16:17 -0800 Subject: Better exif parsing, including image resolution. This introduces a dependency on binary >= 0.6, but we depend on binary >= 0.5 via zip-archive anyway. Closes #976. --- src/Text/Pandoc/ImageSize.hs | 225 ++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 210 insertions(+), 15 deletions(-) (limited to 'src/Text/Pandoc') diff --git a/src/Text/Pandoc/ImageSize.hs b/src/Text/Pandoc/ImageSize.hs index e2a8b8283..467205220 100644 --- a/src/Text/Pandoc/ImageSize.hs +++ b/src/Text/Pandoc/ImageSize.hs @@ -32,9 +32,14 @@ module Text.Pandoc.ImageSize ( ImageType(..), imageType, imageSize, sizeInPixels, sizeInPoints ) where import Data.ByteString (ByteString, unpack) import qualified Data.ByteString.Char8 as B +import qualified Data.ByteString.Lazy as BL +import Control.Applicative import Control.Monad import Data.Bits +import Data.Binary +import Data.Binary.Get import Text.Pandoc.Shared (safeRead) +import qualified Data.Map as M -- quick and dirty functions to get image sizes -- algorithms borrowed from wwwis.pl @@ -143,7 +148,7 @@ jpegSize img = do guard $ B.length rest >= 14 case hdr of "\xff\xd8\xff\xe0" -> jfifSize rest - "\xff\xd8\xff\xe1" -> exifSize rest + "\xff\xd8\xff\xe1" -> exifSize $ B.takeWhile (/= '\xff') rest _ -> mzero jfifSize :: ByteString -> Maybe ImageSize @@ -177,18 +182,208 @@ findJfifSize bs = do Nothing -> fail "Did not find length record" exifSize :: ByteString -> Maybe ImageSize -exifSize rest = do - let bs' = B.takeWhile (/='\xff') $ B.drop 8 rest -- exif data - let (_,bs'') = B.breakSubstring "\xa0\x02" bs' -- width - let rawWidth = B.take 2 $ B.drop 10 bs'' - let (_,bs''') = B.breakSubstring "\xa0\x03" bs' -- height - let rawHeight = B.take 2 $ B.drop 10 bs''' - let tonum bs = case map fromIntegral $ unpack bs of - [x,y] -> Just $ shift x 8 + y - _ -> Nothing - case (tonum rawWidth, tonum rawHeight) of - (Just w, Just h) -> - return $ ImageSize { pxX = w, pxY = h, dpiX = 72, dpiY = 72 } - _ -> fail "Could not determine exif image size" - -- some day, figure out how to parse dpi from exif +exifSize = -- runGet ((Just <$> exifHeader) `mplus` return Nothing) . + runGet (Just <$> exifHeader) . + BL.fromChunks . (:[]) +exifHeader :: Get ImageSize +exifHeader = do + _app1DataSize <- getWord16be + exifHdr <- getWord32be + unless (exifHdr == 0x45786966) $ fail "Did not find exif header" + zeros <- getWord16be + unless (zeros == 0) $ fail "Expected zeros after exif header" + -- beginning of tiff header -- we read whole thing to use + -- in getting data from offsets: + tiffHeader <- lookAhead getRemainingLazyByteString + byteAlign <- getWord16be + let bigEndian = byteAlign == 0x4d4d + let (getWord16, getWord32, getWord64) = + if bigEndian + then (getWord16be, getWord32be, getWord64be) + else (getWord16le, getWord32le, getWord64le) + let getRational = do + num <- getWord32 + den <- getWord32 + return $ fromIntegral num / fromIntegral den + tagmark <- getWord16 + unless (tagmark == 0x002a) $ fail "Failed alignment sanity check" + ifdOffset <- getWord32 + skip (fromIntegral ifdOffset - 8) -- skip to IDF + numentries <- getWord16 + let ifdEntry = do + tag <- getWord16 >>= \t -> + maybe (fail $ "Unknown tag type " ++ show t) return + (M.lookup t tagTypeTable) + dataFormat <- getWord16 + numComponents <- getWord32 + (fmt, bytesPerComponent) <- + case dataFormat of + 1 -> return (UnsignedByte . runGet getWord8, 1) + 2 -> return (AsciiString, 1) + 3 -> return (UnsignedShort . runGet getWord16, 2) + 4 -> return (UnsignedLong . runGet getWord32, 4) + 5 -> return (UnsignedRational . runGet getRational, 8) + 6 -> return (SignedByte . runGet getWord8, 1) + 7 -> return (Undefined . runGet getWord8, 1) + 8 -> return (SignedShort . runGet getWord16, 2) + 9 -> return (SignedLong . runGet getWord32, 4) + 10 -> return (SignedRational . runGet getRational, 8) + 11 -> return (SingleFloat . runGet getWord32 {- TODO -}, 4) + 12 -> return (DoubleFloat . runGet getWord64 {- TODO -}, 8) + _ -> fail $ "Unknown data format " ++ show dataFormat + let totalBytes = fromIntegral $ numComponents * bytesPerComponent + payload <- if totalBytes <= 4 -- data is right here + then (fmt . BL.fromChunks . (:[])) <$> + (getByteString totalBytes <* + skip (4 - totalBytes)) + else do -- get data from offset + offs <- getWord32 + return $ fmt $ BL.take (fromIntegral totalBytes) $ + BL.drop (fromIntegral offs) tiffHeader + return (tag, payload) + entries <- sequence $ replicate (fromIntegral numentries) ifdEntry + subentries <- case lookup ExifOffset entries of + Just (UnsignedLong offset) -> do + pos <- bytesRead + skip (fromIntegral offset - (fromIntegral pos - 8)) + numsubentries <- getWord16 + sequence $ + replicate (fromIntegral numsubentries) ifdEntry + _ -> return [] + let allentries = entries ++ subentries + (width, height) <- case (lookup ExifImageWidth allentries, + lookup ExifImageHeight allentries) of + (Just (UnsignedLong w), Just (UnsignedLong h)) -> + return (fromIntegral w, fromIntegral h) + _ -> fail "Could not determine image width, height" + let resfactor = case lookup ResolutionUnit allentries of + Just (UnsignedShort 1) -> (100 / 254) + _ -> 1 + let xres = maybe 72 (\(UnsignedRational x) -> floor $ x * resfactor) + $ lookup XResolution allentries + let yres = maybe 72 (\(UnsignedRational x) -> floor $ x * resfactor) + $ lookup YResolution allentries + return $ ImageSize{ + pxX = width + , pxY = height + , dpiX = xres + , dpiY = yres } + +data DataFormat = UnsignedByte Word8 + | AsciiString BL.ByteString + | UnsignedShort Word16 + | UnsignedLong Word32 + | UnsignedRational Rational + | SignedByte Word8 + | Undefined Word8 + | SignedShort Word16 + | SignedLong Word32 + | SignedRational Rational + | SingleFloat Word32 + | DoubleFloat Word64 + deriving (Show) + +data TagType = ImageDescription + | Make + | Model + | Orientation + | XResolution + | YResolution + | ResolutionUnit + | Software + | DateTime + | WhitePoint + | PrimaryChromaticities + | YCbCrCoefficients + | YCbCrPositioning + | ReferenceBlackWhite + | Copyright + | ExifOffset + | ExposureTime + | FNumber + | ExposureProgram + | ISOSpeedRatings + | ExifVersion + | DateTimeOriginal + | DateTimeDigitized + | ComponentConfiguration + | CompressedBitsPerPixel + | ShutterSpeedValue + | ApertureValue + | BrightnessValue + | ExposureBiasValue + | MaxApertureValue + | SubjectDistance + | MeteringMode + | LightSource + | Flash + | FocalLength + | MakerNote + | UserComment + | FlashPixVersion + | ColorSpace + | ExifImageWidth + | ExifImageHeight + | RelatedSoundFile + | ExifInteroperabilityOffset + | FocalPlaneXResolution + | FocalPlaneYResolution + | FocalPlaneResolutionUnit + | SensingMethod + | FileSource + | SceneType + deriving (Show, Eq, Ord) + +tagTypeTable :: M.Map Word16 TagType +tagTypeTable = M.fromList + [ (0x010e, ImageDescription) + , (0x010f, Make) + , (0x0110, Model) + , (0x0112, Orientation) + , (0x011a, XResolution) + , (0x011b, YResolution) + , (0x0128, ResolutionUnit) + , (0x0131, Software) + , (0x0132, DateTime) + , (0x013e, WhitePoint) + , (0x013f, PrimaryChromaticities) + , (0x0211, YCbCrCoefficients) + , (0x0213, YCbCrPositioning) + , (0x0214, ReferenceBlackWhite) + , (0x8298, Copyright) + , (0x8769, ExifOffset) + , (0x829a, ExposureTime) + , (0x829d, FNumber) + , (0x8822, ExposureProgram) + , (0x8827, ISOSpeedRatings) + , (0x9000, ExifVersion) + , (0x9003, DateTimeOriginal) + , (0x9004, DateTimeDigitized) + , (0x9101, ComponentConfiguration) + , (0x9102, CompressedBitsPerPixel) + , (0x9201, ShutterSpeedValue) + , (0x9202, ApertureValue) + , (0x9203, BrightnessValue) + , (0x9204, ExposureBiasValue) + , (0x9205, MaxApertureValue) + , (0x9206, SubjectDistance) + , (0x9207, MeteringMode) + , (0x9208, LightSource) + , (0x9209, Flash) + , (0x920a, FocalLength) + , (0x927c, MakerNote) + , (0x9286, UserComment) + , (0xa000, FlashPixVersion) + , (0xa001, ColorSpace) + , (0xa002, ExifImageWidth) + , (0xa003, ExifImageHeight) + , (0xa004, RelatedSoundFile) + , (0xa005, ExifInteroperabilityOffset) + , (0xa20e, FocalPlaneXResolution) + , (0xa20f, FocalPlaneYResolution) + , (0xa210, FocalPlaneResolutionUnit) + , (0xa217, SensingMethod) + , (0xa300, FileSource) + , (0xa301, SceneType) + ] -- cgit v1.2.3