some properties require non-empty layers

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/Util.hs b/lib/Util.hs
index 82d326f..5cf27e3 100644
--- a/lib/Util.hs
+++ b/lib/Util.hs
@@ -9,7 +9,7 @@ module Util where
 import           Data.Aeson as Aeson
 import           Data.Text  (Text)
 import qualified Data.Text  as T
-import Tiled2 (PropertyValue(..))
+import           Tiled2     (Layer (layerData), PropertyValue (..), mkTiledId)
 
 -- | haskell's many string types are FUN …
 showText :: Show a => a -> Text
@@ -32,7 +32,7 @@ instance PrettyPrint Aeson.Value where
 
 instance PrettyPrint PropertyValue where
   prettyprint = \case
-    StrProp str -> str
+    StrProp str   -> str
     BoolProp bool -> if bool then "true" else "false"
 
 -- | here since Unit is sometimes used as dummy type
@@ -41,3 +41,9 @@ instance PrettyPrint () where
 
 printPretty :: PrettyPrint a => a -> IO ()
 printPretty = putStr . T.unpack . prettyprint
+
+
+layerIsEmpty :: Layer -> Bool
+layerIsEmpty layer = case layerData layer of
+  Nothing -> True
+  Just d  -> all ((==) $ mkTiledId 0) d