Generalize the search for FlateDecode (there can be several filters in an array)

src/PDF/Object/Navigation.hs

@@ -61,7 +61,7 @@ getKey :: PDFContent m => String -> Object -> m DirectObject
 getKey key object = getDictionary object >>= catchMaybe . Map.lookup (Name key)
   where
     errorMessage =
-      printf "Key %s not found in dictionary %s" key (show object)
+      printf "Key %s not found in object %s" key (show object)
     catchMaybe = maybe (fail errorMessage) return
 
 objectById :: PDFContent m => ObjectId -> m Object
@@ -96,17 +96,27 @@ data Raw = Raw
 onLazy :: (Lazy.ByteString -> Lazy.ByteString) -> ByteString -> ByteString
 onLazy f = Lazy.toStrict . f . Lazy.fromStrict
 
+contains :: String -> DirectObject -> Bool
+contains needle (NameObject (Name n)) = needle == n
+contains needle (Array directObjects) = oneOf directObjects (contains needle)
+  where
+    oneOf [] _ = False
+    oneOf (x:xs) p = p x || oneOf xs p
+contains _ _ = False
+
 instance MonadFail m => Box m Clear Object ByteString where
   r Clear (Stream {header, streamContent}) = return $
     case Map.lookup (Name "Filter") header of
-      Just (NameObject (Name "FlateDecode")) -> onLazy decompress streamContent
+      Just directObject
+        | contains "FlateDecode" directObject -> onLazy decompress streamContent
       _ -> streamContent
   r _ obj = expected "stream" obj
 
   w Clear streamContent obj@(Stream {header}) = return $
     case Map.lookup (Name "Filter") header of
-      Just (NameObject (Name "FlateDecode")) ->
-        obj {streamContent = onLazy compress streamContent}
+      Just directObject
+        | contains "FlateDecode" directObject ->
+          obj {streamContent = onLazy compress streamContent}
       _ -> obj {streamContent}
   w _ _ obj = expected "stream" obj