diff --git a/CHANGELOG.md b/CHANGELOG.md --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,5 +1,10 @@ # Changelog +#### 1.1 + +* Add support for different exception methods with `MonadThrow` +* Add custom exception `ImageSizeException` + #### 1.0.0.4 * Change maintainer field diff --git a/Data/Conduit/ImageSize.hs b/Data/Conduit/ImageSize.hs --- a/Data/Conduit/ImageSize.hs +++ b/Data/Conduit/ImageSize.hs @@ -1,46 +1,56 @@ -{-# LANGUAGE OverloadedStrings #-} -{-# LANGUAGE RankNTypes #-} -{-# LANGUAGE DeriveDataTypeable #-} --- | Detect the image size without opening the image itself. +{-# LANGUAGE + OverloadedStrings + , RankNTypes + , DeriveDataTypeable + #-} +-- | Detect the image size without opening the image itself and retrieving the minimum amount of data. module Data.Conduit.ImageSize ( Size (..) , FileFormat (..) + , ImageSizeException (..) , sinkImageInfo , sinkImageSize ) where -import qualified Data.ByteString.Lazy as L -import Data.Conduit -import qualified Data.Conduit.Binary as CB -import qualified Data.ByteString as S +import Control.Applicative ((<$>), (<*>)) +import Control.Monad.Catch import Data.ByteString.Char8 () import Data.ByteString.Lazy.Char8 () -import qualified Data.Typeable as T -import Control.Applicative ((<$>), (<*>)) - +import Data.Conduit +import qualified Data.ByteString as S +import qualified Data.ByteString.Lazy as L +import qualified Data.Conduit.Binary as CB +import qualified Data.Typeable as T data Size = Size { width :: Int, height :: Int } deriving (Show, Eq, Ord, Read, T.Typeable) - data FileFormat = GIF | PNG | JPG deriving (Show, Eq, Ord, Read, Enum, T.Typeable) +data ImageSizeException + = EmptyImage + | UnknownImageFormat + | BadGIFHeader + | BadPNGHeader + | BadJPGHeader + deriving (Show, T.Typeable) +instance Exception ImageSizeException + -- | Specialized version of 'sinkImageInfo' that returns only the -- image size. -sinkImageSize :: Monad m => Consumer S.ByteString m (Maybe Size) +sinkImageSize :: (Monad m, MonadThrow n, Functor n) => Consumer S.ByteString m (n Size) sinkImageSize = fmap (fmap fst) sinkImageInfo - -- | Find out the size of an image. Also returns the file format -- that parsed correctly. Note that this function does not -- verify that the file is indeed in the format that it returns, -- since it looks only at a small part of the header. -sinkImageInfo :: Monad m => Consumer S.ByteString m (Maybe (Size, FileFormat)) +sinkImageInfo :: (Monad m, MonadThrow n) => Consumer S.ByteString m (n (Size, FileFormat)) sinkImageInfo = start id where - start front = await >>= maybe (return Nothing) (pushHeader front) + start front = await >>= maybe (return $ throwM EmptyImage) (pushHeader front) pushHeader front bs' | S.length bs >= 11 && S.take 3 bs == S.pack [0xFF, 0xD8, 0xFF] = @@ -50,7 +60,7 @@ | S.length bs >= 8 && S.take 8 bs == S.pack [137, 80, 78, 71, 13, 10, 26, 10] = leftover (S.drop 8 bs) >> png | S.length bs < 11 = start $ S.append bs - | otherwise = leftover bs >> return Nothing + | otherwise = leftover bs >> return (throwM UnknownImageFormat) where bs = front bs' @@ -59,8 +69,8 @@ b <- CB.take 4 let go x y = fromIntegral x + (fromIntegral y) * 256 return $ case L.unpack b of - [w1, w2, h1, h2] -> Just (Size (go w1 w2) (go h1 h2), GIF) - _ -> Nothing + [w1, w2, h1, h2] -> return (Size (go w1 w2) (go h1 h2), GIF) + _ -> throwM BadGIFHeader png = do CB.drop 4 @@ -69,14 +79,17 @@ then do mw <- getInt 4 0 mh <- getInt 4 0 - return $ (\w h -> (Size w h, PNG)) <$> mw <*> mh - else return Nothing + return $ maybe + (throwM BadPNGHeader) + (\(w, h) -> return (Size w h, PNG)) + ((,) <$> mw <*> mh) + else return $ throwM BadPNGHeader jpg = do mi <- getInt 2 0 case mi of - Nothing -> return (Just (Size 1 1, JPG)) - Just i -> do + Nothing -> return (return (Size 1 1, JPG)) + Just i -> do CB.drop $ i - 2 jpgFrame @@ -93,10 +106,13 @@ _ <- CB.take 3 mh <- getInt 2 0 mw <- getInt 2 0 - return $ (\w h -> (Size w h, JPG)) <$> mw <*> mh - Just _ -> jpg - Nothing -> return Nothing - _ -> return Nothing + return $ maybe + (throwM BadJPGHeader) + (\(w, h) -> return (Size w h, JPG)) + ((,) <$> mw <*> mh) + Just _ -> jpg + Nothing -> return $ throwM BadJPGHeader + _ -> return $ throwM BadJPGHeader getInt :: (Monad m, Integral i) => Int @@ -107,4 +123,4 @@ mx <- CB.head case mx of Nothing -> return Nothing - Just x -> getInt (len - 1) (i * 256 + fromIntegral x) + Just x -> getInt (len - 1) (i * 256 + fromIntegral x) diff --git a/imagesize-conduit.cabal b/imagesize-conduit.cabal --- a/imagesize-conduit.cabal +++ b/imagesize-conduit.cabal @@ -1,5 +1,5 @@ Name: imagesize-conduit -Version: 1.0.0.4 +Version: 1.1 Synopsis: Determine the size of some common image formats. Description: Currently supports PNG, GIF, and JPEG. This package provides a Sink that will consume the minimum number of bytes necessary to determine the image dimensions. License: BSD3 @@ -21,8 +21,9 @@ Library Exposed-modules: Data.Conduit.ImageSize Build-depends: base >= 4 && < 5 - , conduit >= 1.1 && < 1.2 + , conduit >= 1.1 && < 1.3 , conduit-extra >= 1.1 && < 1.2 + , exceptions >= 0.4 , bytestring >= 0.10 ghc-options: -Wall diff --git a/test/main.hs b/test/main.hs --- a/test/main.hs +++ b/test/main.hs @@ -1,10 +1,10 @@ {-# LANGUAGE OverloadedStrings #-} -import qualified Data.Conduit as C -import qualified Data.Conduit.Binary as CB import Control.Monad.Trans.Resource (runResourceT) -import Data.Conduit.ImageSize - import Test.Hspec +import qualified Data.Conduit as C +import qualified Data.Conduit.Binary as CB + +import Data.Conduit.ImageSize main :: IO () main = hspec $ do