module Graphics.HsExif (
parseFileExif,
parseExif,
readExifDateTime,
getDateTimeOriginal,
getOrientation,
ImageOrientation(..),
RotationDirection(..),
getGpsLatitudeLongitude,
formatAsFloatingPoint,
ExifValue(..),
exposureTime,
fnumber,
isoSpeedRatings,
dateTimeOriginal,
shutterSpeedValue,
apertureValue,
brightnessValue,
exposureBiasValue,
maxApertureValue,
flash,
focalLength,
userComment,
orientation,
make,
model,
software,
copyright,
digitalZoomRatio,
focalLengthIn35mmFilm,
artist,
gpsVersionID,
gpsLatitudeRef,
gpsLatitude,
gpsLongitudeRef,
gpsLongitude,
gpsAltitudeRef,
gpsAltitude,
gpsTimeStamp,
gpsSatellites,
gpsStatus,
gpsMeasureMode,
gpsDop,
gpsSpeedRef,
gpsSpeed,
gpsTrackRef,
gpsTrack,
gpsImgDirectionRef,
gpsImgDirection,
gpsMapDatum,
gpsDestLatitudeRef,
gpsDestLatitude,
gpsDestLongitudeRef,
gpsDestLongitude,
gpsDestBearingRef,
gpsDestBearing,
gpsDestDistanceRef,
gpsDestDistance,
gpsProcessingMethod,
gpsAreaInformation,
gpsDateStamp,
gpsDifferential,
exifVersion,
sensingMethod,
fileSource,
sceneType,
makerNote,
subjectDistance,
meteringMode,
lightSource,
exifImageWidth,
exifImageHeight,
relatedSoundFile,
focalPlaneXResolution,
focalPlaneYResolution,
focalPlaneResolutionUnit,
dateTimeDigitized,
componentConfiguration,
compressedBitsPerPixel,
exposureProgram,
spectralSensitivity,
oecf,
subjectArea,
subSecTime,
subSecTimeOriginal,
subSecTimeDigitized,
flashPixVersion,
colorSpace,
flashEnergy,
spatialFrequencyResponse,
subjectLocation,
exposureIndex,
cfaPattern,
customRendered,
exposureMode,
whiteBalance,
sceneCaptureType,
gainControl,
contrast,
saturation,
sharpness,
deviceSettingDescription,
subjectDistanceRange,
imageUniqueId,
exifInteroperabilityOffset,
imageDescription,
xResolution,
yResolution,
resolutionUnit,
dateTime,
whitePoint,
primaryChromaticities,
yCbCrPositioning,
yCbCrCoefficients,
referenceBlackWhite,
exifIfdOffset,
printImageMatching,
gpsTagOffset,
ExifTag(..),
TagLocation(..),
) where
import Data.Binary.Get
import Data.Binary.Put
import qualified Data.ByteString.Lazy as B
import qualified Data.ByteString as BS
import Control.Monad (liftM, unless, replicateM)
import qualified Data.ByteString.Char8 as Char8
import Data.Word
import Data.Char (isDigit, ord, chr)
import Data.Int (Int32, Int16, Int8)
import Data.List
import Data.Maybe (fromMaybe, fromJust)
import qualified Data.Map as Map
import Data.Map (Map)
import Data.Time.LocalTime
import Data.Time.Calendar
import Numeric (showHex)
import Text.Printf
data ExifValue = ExifNumber !Int
| ExifText !String
| ExifRational !Int !Int
| ExifNumberList ![Int]
| ExifRationalList ![(Int,Int)]
| ExifUndefined !BS.ByteString
| ExifUnknown !Word16 !Int !Int
deriving Eq
instance Show ExifValue where
show (ExifNumber v) = show v
show (ExifText v) = v
show (ExifRational n d) = show n ++ "/" ++ show d
show (ExifUnknown t c v) = show "Unknown exif type. Type: " ++ show t
++ " count: " ++ show c ++ " value: " ++ show v
show (ExifNumberList l) = show l
show (ExifRationalList l) = show l
show (ExifUndefined bs) = show bs
parseFileExif :: FilePath -> IO (Either String (Map ExifTag ExifValue))
parseFileExif filename = liftM parseExif $ B.readFile filename
parseExif :: B.ByteString -> Either String (Map ExifTag ExifValue)
parseExif contents = case runGetOrFail getExif contents of
Left (_,_,errorMsg) -> Left errorMsg
Right (_,_,result) -> Right result
getExif :: Get (Map ExifTag ExifValue)
getExif = do
header <- getWord16be
unless (header == 0xffd8)
$ fail "Not a JPEG file"
findAndParseExifBlock
findAndParseExifBlock :: Get (Map ExifTag ExifValue)
findAndParseExifBlock = do
markerNumber <- getWord16be
dataSize <- liftM (fromIntegral . toInteger) getWord16be
case markerNumber of
0xffe1 -> parseExifBlock
0xffda -> fail "No EXIF in JPEG"
_ -> skip (dataSize2) >> findAndParseExifBlock
data ByteAlign = Intel | Motorola
getWord16 :: ByteAlign -> Get Word16
getWord16 Intel = getWord16le
getWord16 Motorola = getWord16be
getWord32 :: ByteAlign -> Get Word32
getWord32 Intel = getWord32le
getWord32 Motorola = getWord32be
putWord32 :: ByteAlign -> Word32 -> Put
putWord32 Intel = putWord32le
putWord32 Motorola = putWord32be
parseExifBlock :: Get (Map ExifTag ExifValue)
parseExifBlock = do
header <- getByteString 4
nul <- liftM toInteger getWord16be
unless (header == Char8.pack "Exif" && nul == 0)
$ fail "invalid EXIF header"
tiffHeaderStart <- liftM fromIntegral bytesRead
byteAlign <- parseTiffHeader
(exifSubIfdOffsetW, mGpsOffsetW, ifdEntries) <- parseIfd byteAlign tiffHeaderStart
let exifSubIfdOffset = fromIntegral $ toInteger exifSubIfdOffsetW
gpsData <- case mGpsOffsetW of
Nothing -> return []
Just gpsOffsetW -> lookAhead $ parseGps gpsOffsetW byteAlign tiffHeaderStart
bytesReadNow <- liftM fromIntegral bytesRead
skip $ (exifSubIfdOffset + tiffHeaderStart) bytesReadNow
exifSubEntries <- parseSubIfd byteAlign tiffHeaderStart ExifSubIFD
return $ Map.fromList $ ifdEntries ++ exifSubEntries ++ gpsData
parseGps :: Word32 -> ByteAlign -> Int -> Get [(ExifTag, ExifValue)]
parseGps gpsOffsetW byteAlign tiffHeaderStart = do
let gpsOffset = fromIntegral $ toInteger gpsOffsetW
bytesReadNow <- liftM fromIntegral bytesRead
skip $ (gpsOffset + tiffHeaderStart) bytesReadNow
parseSubIfd byteAlign tiffHeaderStart GpsSubIFD
parseTiffHeader :: Get ByteAlign
parseTiffHeader = do
byteAlignV <- getByteString 2
let byteAlign = case Char8.unpack byteAlignV of
"II" -> Intel
"MM" -> Motorola
_ -> error "Unknown byte alignment"
alignControl <- liftM toInteger (getWord16 byteAlign)
unless (alignControl == 0x2a)
$ fail "exif byte alignment mismatch"
ifdOffset <- liftM (fromIntegral . toInteger) (getWord32 byteAlign)
skip $ ifdOffset 8
return byteAlign
parseIfd :: ByteAlign -> Int -> Get (Word32, Maybe Word32, [(ExifTag, ExifValue)])
parseIfd byteAlign tiffHeaderStart = do
dirEntriesCount <- liftM toInteger (getWord16 byteAlign)
ifdEntries <- mapM (\_ -> parseIfEntry byteAlign) [1..dirEntriesCount]
let exifOffsetEntry = fromMaybe (error "Can't find the exif ifd offset")
(find (\ e -> entryTag e == tagKey exifIfdOffset) ifdEntries)
let exifOffset = entryContents exifOffsetEntry
let gpsOffsetEntry = find (\ e -> entryTag e == tagKey gpsTagOffset) ifdEntries
let gpsOffset = fmap entryContents gpsOffsetEntry
entries <- mapM (decodeEntry byteAlign tiffHeaderStart IFD0) ifdEntries
return (exifOffset, gpsOffset, entries)
parseSubIfd :: ByteAlign -> Int -> TagLocation -> Get [(ExifTag, ExifValue)]
parseSubIfd byteAlign tiffHeaderStart location = do
dirEntriesCount <- liftM toInteger (getWord16 byteAlign)
ifdEntries <- mapM (\_ -> parseIfEntry byteAlign) [1..dirEntriesCount]
mapM (decodeEntry byteAlign tiffHeaderStart location) ifdEntries
data IfEntry = IfEntry
{
entryTag :: !Word16,
entryFormat :: !Word16,
entryNoComponents :: !Int,
entryContents :: !Word32
} deriving Show
parseIfEntry :: ByteAlign -> Get IfEntry
parseIfEntry byteAlign = do
tagNumber <- getWord16 byteAlign
dataFormat <- getWord16 byteAlign
numComponents <- getWord32 byteAlign
value <- getWord32 byteAlign
return IfEntry
{
entryTag = tagNumber,
entryFormat = dataFormat,
entryNoComponents = fromIntegral $ toInteger numComponents,
entryContents = value
}
data TagLocation = ExifSubIFD | IFD0 | GpsSubIFD
deriving (Show, Eq, Ord)
data ExifTag = ExifTag
{
tagLocation :: TagLocation,
tagDesc :: Maybe String,
tagKey :: Word16
}
deriving (Eq, Ord)
instance Show ExifTag where
show (ExifTag _ (Just d) _) = d
show (ExifTag l _ v) = "Unknown tag, location: " ++ show l
++ ", value: 0x" ++ showHex v ""
exifSubIfdTag :: String -> Word16 -> ExifTag
exifSubIfdTag d = ExifTag ExifSubIFD (Just d)
exifIfd0Tag :: String -> Word16 -> ExifTag
exifIfd0Tag d = ExifTag IFD0 (Just d)
exifGpsTag :: String -> Word16 -> ExifTag
exifGpsTag d = ExifTag GpsSubIFD (Just d)
exposureTime = exifSubIfdTag "exposureTime" 0x829a
fnumber = exifSubIfdTag "fnumber" 0x829d
exposureProgram = exifSubIfdTag "exposureProgram" 0x8822
spectralSensitivity = exifSubIfdTag "spectralSensitivity" 0x8824
isoSpeedRatings = exifSubIfdTag "isoSpeedRatings" 0x8827
oecf = exifSubIfdTag "OECF" 0x8828
exifVersion = exifSubIfdTag "exifVersion" 0x9000
dateTimeOriginal = exifSubIfdTag "dateTimeOriginal" 0x9003
dateTimeDigitized = exifSubIfdTag "dateTimeDigitized" 0x9004
componentConfiguration = exifSubIfdTag "componentConfiguration" 0x9101
compressedBitsPerPixel = exifSubIfdTag "compressedBitsPerPixel" 0x9102
shutterSpeedValue = exifSubIfdTag "shutterSpeedValue" 0x9201
apertureValue = exifSubIfdTag "apertureValue" 0x9202
brightnessValue = exifSubIfdTag "brightnessValue" 0x9203
exposureBiasValue = exifSubIfdTag "exposureBiasValue" 0x9204
maxApertureValue = exifSubIfdTag "maxApertureValue" 0x9205
subjectDistance = exifSubIfdTag "subjectDistance" 0x9206
meteringMode = exifSubIfdTag "meteringMode" 0x9207
lightSource = exifSubIfdTag "lightSource" 0x9208
flash = exifSubIfdTag "flash" 0x9209
focalLength = exifSubIfdTag "focalLength" 0x920a
subjectArea = exifSubIfdTag "subjectArea" 0x9214
makerNote = exifSubIfdTag "makerNote" 0x927c
userComment = exifSubIfdTag "userComment" 0x9286
subSecTime = exifSubIfdTag "subSecTime" 0x9290
subSecTimeOriginal = exifSubIfdTag "subSecTimeOriginal" 0x9291
subSecTimeDigitized = exifSubIfdTag "subSecTimeDigitized" 0x9292
flashPixVersion = exifSubIfdTag "flashPixVersion" 0xa000
colorSpace = exifSubIfdTag "colorSpace" 0xa001
exifImageWidth = exifSubIfdTag "exifImageWidth" 0xa002
exifImageHeight = exifSubIfdTag "exifImageHeight" 0xa003
relatedSoundFile = exifSubIfdTag "relatedSoundFile" 0xa004
flashEnergy = exifSubIfdTag "flashEnergy" 0xa20b
spatialFrequencyResponse= exifSubIfdTag "spatialFrequencyResponse" 0xa20c
focalPlaneXResolution = exifSubIfdTag "focalPlaneXResolution" 0xa20e
focalPlaneYResolution = exifSubIfdTag "focalPlaneYResolution" 0xa20f
focalPlaneResolutionUnit= exifSubIfdTag "focalPlaneResolutionUnit" 0xa210
subjectLocation = exifSubIfdTag "subjectLocation" 0xa214
exposureIndex = exifSubIfdTag "exposureIndex" 0xa215
sensingMethod = exifSubIfdTag "sensingMethod" 0xa217
fileSource = exifSubIfdTag "fileSource" 0xa300
sceneType = exifSubIfdTag "sceneType" 0xa301
cfaPattern = exifSubIfdTag "cfaPattern" 0xa302
customRendered = exifSubIfdTag "customRendered" 0xa401
exposureMode = exifSubIfdTag "exposureMode" 0xa402
whiteBalance = exifSubIfdTag "whiteBalance" 0xa403
digitalZoomRatio = exifSubIfdTag "digitalZoomRatio" 0xa404
focalLengthIn35mmFilm = exifSubIfdTag "focalLengthIn35mmFilm" 0xa405
sceneCaptureType = exifSubIfdTag "sceneCaptureType" 0xa406
gainControl = exifSubIfdTag "gainControl" 0xa407
contrast = exifSubIfdTag "contrast" 0xa408
saturation = exifSubIfdTag "saturation" 0xa409
sharpness = exifSubIfdTag "sharpness" 0xa40a
deviceSettingDescription= exifSubIfdTag "deviceSettingDescription" 0xa40b
subjectDistanceRange = exifSubIfdTag "subjectDistanceRange" 0xa40c
imageUniqueId = exifSubIfdTag "imageUniqueId" 0xa420
exifInteroperabilityOffset=exifSubIfdTag "exifInteroperabilityOffset" 0xa005
imageDescription = exifIfd0Tag "imageDescription" 0x010e
make = exifIfd0Tag "make" 0x010f
model = exifIfd0Tag "model" 0x0110
orientation = exifIfd0Tag "orientation" 0x0112
xResolution = exifIfd0Tag "xResolution" 0x011a
yResolution = exifIfd0Tag "xResolution" 0x011b
resolutionUnit = exifIfd0Tag "resolutionUnit" 0x0128
software = exifIfd0Tag "software" 0x0131
dateTime = exifIfd0Tag "dateTime" 0x0132
artist = exifIfd0Tag "artist" 0x013b
whitePoint = exifIfd0Tag "whitePoint" 0x013e
primaryChromaticities = exifIfd0Tag "primaryChromaticities" 0x013f
yCbCrCoefficients = exifIfd0Tag "yCbCrCoefficients" 0x0211
yCbCrPositioning = exifIfd0Tag "yCbCrPositioning" 0x0213
referenceBlackWhite = exifIfd0Tag "referenceBlackWhite" 0x0214
copyright = exifIfd0Tag "copyright" 0x8298
exifIfdOffset = exifIfd0Tag "exifIfdOffset" 0x8769
gpsTagOffset = exifIfd0Tag "gpsTagOffset" 0x8825
printImageMatching = exifIfd0Tag "printImageMatching" 0xc4a5
gpsVersionID = exifGpsTag "gpsVersionID" 0x0000
gpsLatitudeRef = exifGpsTag "gpsLatitudeRef" 0x0001
gpsLatitude = exifGpsTag "gpsLatitude" 0x0002
gpsLongitudeRef = exifGpsTag "gpsLongitudeRef" 0x0003
gpsLongitude = exifGpsTag "gpsLongitude" 0x0004
gpsAltitudeRef = exifGpsTag "gpsAltitudeRef" 0x0005
gpsAltitude = exifGpsTag "gpsAltitude" 0x0006
gpsTimeStamp = exifGpsTag "gpsTimeStamp" 0x0007
gpsSatellites = exifGpsTag "gpsSatellites" 0x0008
gpsStatus = exifGpsTag "gpsStatus" 0x0009
gpsMeasureMode = exifGpsTag "gpsMeasureMode" 0x000a
gpsDop = exifGpsTag "gpsDop" 0x000b
gpsSpeedRef = exifGpsTag "gpsSpeedRef" 0x000c
gpsSpeed = exifGpsTag "gpsSpeed" 0x000d
gpsTrackRef = exifGpsTag "gpsTrackRef" 0x000e
gpsTrack = exifGpsTag "gpsTrack" 0x000f
gpsImgDirectionRef = exifGpsTag "gpsImgDirectionRef" 0x0010
gpsImgDirection = exifGpsTag "gpsImgDirection" 0x0011
gpsMapDatum = exifGpsTag "gpsMapDatum" 0x0012
gpsDestLatitudeRef = exifGpsTag "gpsDestLatitudeRef" 0x0013
gpsDestLatitude = exifGpsTag "gpsDestLatitude" 0x0014
gpsDestLongitudeRef = exifGpsTag "gpsDestLongitudeRef" 0x0015
gpsDestLongitude = exifGpsTag "gpsDestLongitude" 0x0016
gpsDestBearingRef = exifGpsTag "gpsDestBearingRef" 0x0017
gpsDestBearing = exifGpsTag "gpsDestBearing" 0x0018
gpsDestDistanceRef = exifGpsTag "gpsDestDistanceRef" 0x0019
gpsDestDistance = exifGpsTag "gpsDestDistance" 0x001a
gpsProcessingMethod = exifGpsTag "gpsProcessingMethod" 0x001b
gpsAreaInformation = exifGpsTag "gpsAreaInformation" 0x001c
gpsDateStamp = exifGpsTag "gpsDateStamp" 0x001d
gpsDifferential = exifGpsTag "gpsDifferential" 0x001e
allExifTags :: [ExifTag]
allExifTags = [exposureTime, fnumber, exposureProgram, isoSpeedRatings,
exifVersion, dateTimeOriginal, dateTimeDigitized, componentConfiguration,
compressedBitsPerPixel, shutterSpeedValue, apertureValue, brightnessValue,
exposureBiasValue, maxApertureValue, subjectDistance, meteringMode,
lightSource, flash, focalLength, makerNote, userComment,
exifImageWidth, exifImageHeight, relatedSoundFile, focalPlaneXResolution,
focalPlaneYResolution, focalPlaneResolutionUnit, sensingMethod, fileSource,
sceneType, orientation, make, model, software, copyright,
spectralSensitivity, oecf, subjectArea, subSecTime, subSecTimeOriginal,
subSecTimeDigitized, flashPixVersion, colorSpace, flashEnergy,
spatialFrequencyResponse, subjectLocation, exposureIndex, cfaPattern,
customRendered, exposureMode, whiteBalance, digitalZoomRatio,
focalLengthIn35mmFilm, sceneCaptureType, gainControl, contrast,
saturation, sharpness, deviceSettingDescription, subjectDistanceRange,
imageUniqueId, exifInteroperabilityOffset, imageDescription,
xResolution, yResolution, resolutionUnit, dateTime, whitePoint,
primaryChromaticities, yCbCrPositioning, yCbCrCoefficients, referenceBlackWhite,
exifIfdOffset, printImageMatching, gpsTagOffset, artist,
gpsVersionID, gpsLatitudeRef, gpsLatitude, gpsLongitudeRef, gpsLongitude,
gpsAltitudeRef, gpsAltitude, gpsTimeStamp, gpsSatellites, gpsStatus,
gpsMeasureMode, gpsDop, gpsSpeedRef, gpsSpeed, gpsTrackRef, gpsTrack,
gpsImgDirectionRef, gpsImgDirection, gpsMapDatum, gpsDestLatitudeRef,
gpsDestLatitude, gpsDestLongitudeRef, gpsDestLongitude, gpsDestBearingRef,
gpsDestBearing, gpsDestDistanceRef, gpsDestDistance, gpsProcessingMethod,
gpsAreaInformation, gpsDateStamp, gpsDifferential]
getExifTag :: TagLocation -> Word16 -> ExifTag
getExifTag l v = fromMaybe (ExifTag l Nothing v) $ find (isSameTag l v) allExifTags
where isSameTag l1 v1 (ExifTag l2 _ v2) = l1 == l2 && v1 == v2
data ValueHandler = ValueHandler
{
dataTypeId :: Word16,
dataLength :: Int,
readSingle :: ByteAlign -> Get ExifValue,
readMany :: ByteAlign -> Int -> Get ExifValue
}
readNumberList :: Integral a => (ByteAlign -> Get a) -> ByteAlign -> Int -> Get ExifValue
readNumberList decoder byteAlign components = liftM (ExifNumberList . fmap fromIntegral)
$ count components (decoder byteAlign)
unsignedByteValueHandler = ValueHandler
{
dataTypeId = 1,
dataLength = 1,
readSingle = \_ -> liftM (ExifNumber . fromIntegral) getWord8,
readMany = readNumberList $ const getWord8
}
asciiStringValueHandler = ValueHandler
{
dataTypeId = 2,
dataLength = 1,
readSingle = \ba -> readMany asciiStringValueHandler ba 1,
readMany = \_ components -> liftM (ExifText . Char8.unpack) (getByteString (components1))
}
unsignedShortValueHandler = ValueHandler
{
dataTypeId = 3,
dataLength = 2,
readSingle = liftM (ExifNumber . fromIntegral) . getWord16,
readMany = readNumberList getWord16
}
unsignedLongValueHandler = ValueHandler
{
dataTypeId = 4,
dataLength = 4,
readSingle = liftM (ExifNumber . fromIntegral) . getWord32,
readMany = readNumberList getWord32
}
readRationalContents :: (Int -> Int -> a) -> ByteAlign -> Get a
readRationalContents c byteAlign = do
numerator <- liftM fromIntegral $ getWord32 byteAlign
denominator <- liftM fromIntegral $ getWord32 byteAlign
return $ c numerator denominator
unsignedRationalValueHandler = ValueHandler
{
dataTypeId = 5,
dataLength = 8,
readSingle = readRationalContents ExifRational,
readMany = \byteAlign components -> liftM ExifRationalList $ count components (readRationalContents (,) byteAlign)
}
signedByteValueHandler = ValueHandler
{
dataTypeId = 6,
dataLength = 1,
readSingle = \_ -> liftM (ExifNumber . signedInt8ToInt) getWord8,
readMany = readNumberList (liftM signedInt8ToInt . const getWord8)
}
undefinedValueHandler = ValueHandler
{
dataTypeId = 7,
dataLength = 1,
readSingle = \ba -> readMany undefinedValueHandler ba 1,
readMany = \_ components -> liftM ExifUndefined (getByteString (components1))
}
signedShortValueHandler = ValueHandler
{
dataTypeId = 8,
dataLength = 2,
readSingle = liftM (ExifNumber . signedInt16ToInt) . getWord16,
readMany = readNumberList (liftM signedInt16ToInt . getWord16)
}
signedLongValueHandler = ValueHandler
{
dataTypeId = 9,
dataLength = 4,
readSingle = liftM (ExifNumber . signedInt32ToInt) . getWord32,
readMany = readNumberList (liftM signedInt32ToInt . getWord32)
}
readSignedRationalContents :: (Int -> Int -> a) -> ByteAlign -> Get a
readSignedRationalContents c byteAlign = do
numerator <- liftM signedInt32ToInt $ getWord32 byteAlign
denominator <- liftM signedInt32ToInt $ getWord32 byteAlign
return $ c numerator denominator
signedRationalValueHandler = ValueHandler
{
dataTypeId = 10,
dataLength = 8,
readSingle = readSignedRationalContents ExifRational,
readMany = \byteAlign components -> liftM ExifRationalList $ count components (readSignedRationalContents (,) byteAlign)
}
valueHandlers :: [ValueHandler]
valueHandlers =
[
unsignedByteValueHandler,
asciiStringValueHandler,
unsignedShortValueHandler,
unsignedLongValueHandler,
unsignedRationalValueHandler,
signedByteValueHandler,
signedShortValueHandler,
signedLongValueHandler,
signedRationalValueHandler,
undefinedValueHandler
]
decodeEntry :: ByteAlign -> Int -> TagLocation -> IfEntry -> Get (ExifTag, ExifValue)
decodeEntry byteAlign tiffHeaderStart location entry = do
let exifTag = getExifTag location $ entryTag entry
let contentsInt = fromIntegral $ toInteger $ entryContents entry
tagValue <- case getHandler $ entryFormat entry of
Just handler -> decodeEntryWithHandler byteAlign tiffHeaderStart handler entry
Nothing -> return $ ExifUnknown (entryFormat entry) (entryNoComponents entry) contentsInt
return (exifTag, tagValue)
getHandler :: Word16 -> Maybe ValueHandler
getHandler typeId = find ((==typeId) . dataTypeId) valueHandlers
decodeEntryWithHandler :: ByteAlign -> Int -> ValueHandler -> IfEntry -> Get ExifValue
decodeEntryWithHandler byteAlign tiffHeaderStart handler entry =
if dataLength handler * entryNoComponents entry <= 4
then do
let inlineBs = runPut $ putWord32 byteAlign $ entryContents entry
return $ parseInline byteAlign handler entry inlineBs
else parseOffset byteAlign tiffHeaderStart handler entry
parseInline :: ByteAlign -> ValueHandler -> IfEntry -> B.ByteString -> ExifValue
parseInline byteAlign handler entry bytestring =
fromJust $ runMaybeGet getter bytestring
where
getter = case entryNoComponents entry of
1 -> readSingle handler byteAlign
_ -> readMany handler byteAlign $ entryNoComponents entry
parseOffset :: ByteAlign -> Int -> ValueHandler -> IfEntry -> Get ExifValue
parseOffset byteAlign tiffHeaderStart handler entry = do
let contentsInt = fromIntegral $ toInteger $ entryContents entry
curPos <- liftM fromIntegral bytesRead
skip $ contentsInt + tiffHeaderStart curPos
bytestring <- getLazyByteString (fromIntegral $ entryNoComponents entry * dataLength handler)
return $ parseInline byteAlign handler entry bytestring
signedInt32ToInt :: Word32 -> Int
signedInt32ToInt w = fromIntegral (fromIntegral w :: Int32)
signedInt16ToInt :: Word16 -> Int
signedInt16ToInt w = fromIntegral (fromIntegral w :: Int16)
signedInt8ToInt :: Word8 -> Int
signedInt8ToInt w = fromIntegral (fromIntegral w :: Int8)
runMaybeGet :: Get a -> B.ByteString -> Maybe a
runMaybeGet get bs = case runGetOrFail get bs of
Left _ -> Nothing
Right (_,_,x) -> Just x
readExifDateTime :: String -> Maybe LocalTime
readExifDateTime dateStr = runMaybeGet getExifDateTime $ B.pack $ map (fromIntegral . ord) dateStr
getExifDateTime :: Get LocalTime
getExifDateTime = do
year <- readDigit 4
month <- getCharValue ':' >> readDigit 2
day <- getCharValue ':' >> readDigit 2
hour <- getCharValue ' ' >> readDigit 2
minute <- getCharValue ':' >> readDigit 2
second <- getCharValue ':' >> readDigit 2
return $ LocalTime (fromGregorian year month day) (TimeOfDay hour minute second)
where
readDigit x = liftM read $ count x getDigit
count :: Int -> Get a -> Get [a]
count n p | n <= 0 = return []
| otherwise = replicateM n p
getDateTimeOriginal :: Map ExifTag ExifValue -> Maybe LocalTime
getDateTimeOriginal exifData = Map.lookup dateTimeOriginal exifData >>= readExifDateTime . show
getCharWhere :: (Char->Bool) -> Get Char
getCharWhere wher = do
char <- liftM (chr . fromIntegral) getWord8
if wher char
then return char
else fail "no parse"
getDigit :: Get Char
getDigit = getCharWhere isDigit
getCharValue :: Char -> Get Char
getCharValue char = getCharWhere (==char)
data RotationDirection = MinusNinety
| Ninety
| HundredAndEighty
deriving (Show, Eq)
data ImageOrientation = Normal
| Mirror
| Rotation RotationDirection
| MirrorRotation RotationDirection
deriving (Show, Eq)
getOrientation :: Map ExifTag ExifValue -> Maybe ImageOrientation
getOrientation exifData = do
rotationVal <- Map.lookup orientation exifData
case rotationVal of
ExifNumber 1 -> Just Normal
ExifNumber 2 -> Just Mirror
ExifNumber 3 -> Just $ Rotation HundredAndEighty
ExifNumber 4 -> Just $ MirrorRotation HundredAndEighty
ExifNumber 5 -> Just $ MirrorRotation MinusNinety
ExifNumber 6 -> Just $ Rotation MinusNinety
ExifNumber 7 -> Just $ MirrorRotation Ninety
ExifNumber 8 -> Just $ Rotation Ninety
_ -> Nothing
getGpsLatitudeLongitude :: Map ExifTag ExifValue -> Maybe (Double, Double)
getGpsLatitudeLongitude exifData = do
(ExifText latRef) <- Map.lookup gpsLatitudeRef exifData
latDec <- Map.lookup gpsLatitude exifData >>= gpsDecodeToDecimalDegrees
let signedLatDec = case latRef of
"S" -> latDec
_ -> latDec
(ExifText longRef) <- Map.lookup gpsLongitudeRef exifData
longDec <- Map.lookup gpsLongitude exifData >>= gpsDecodeToDecimalDegrees
let signedLongDec = case longRef of
"W" -> longDec
_ -> longDec
return (signedLatDec, signedLongDec)
gpsDecodeToDecimalDegrees :: ExifValue -> Maybe Double
gpsDecodeToDecimalDegrees (ExifRationalList intPairs) = case fmap intPairToFloating intPairs of
(degrees:minutes:seconds:[]) -> Just $ degrees + minutes / 60 + seconds / 3600
_ -> Nothing
where
intPairToFloating (n, d) = fromIntegral n / fromIntegral d
gpsDecodeToDecimalDegrees _ = Nothing
formatAsFloatingPoint :: Int -> ExifValue -> String
formatAsFloatingPoint n (ExifRational num den) = formatNumDenAsString n num den
formatAsFloatingPoint n (ExifRationalList values) = intercalate ", " $ foldl' step [] values
where step soFar (num,den) = soFar ++ [formatNumDenAsString n num den]
formatAsFloatingPoint _ v = show v
formatNumDenAsString :: Int -> Int -> Int -> String
formatNumDenAsString n num den = printf formatString (fromIntegral num / fromIntegral den :: Double)
where formatString = "%." ++ show n ++ "f"