Handle XReadBitmapFile errors

2 files changed, 16 insertions, 6 deletions

diff --git a/src/Bitmap.hs b/src/Bitmap.hs
index c512ff2..9df2f67 100644
--- a/src/Bitmap.hs
+++ b/src/Bitmap.hs
@@ -46,9 +46,14 @@ loadBitmap d w p = do
     exist <- doesFileExist p
     if exist
        then do
-            (bw, bh, bp, _, _) <- readBitmapFile d w p
-            addFinalizer bp (freePixmap d bp)
-            return $ Just $ Bitmap bw bh bp
+            bmap <- readBitmapFile d w p
+            case bmap of
+                 Right (bw, bh, bp, _, _) -> do
+                     addFinalizer bp (freePixmap d bp)
+                     return $ Just $ Bitmap bw bh bp
+                 Left err -> do
+                     putStrLn err
+                     return Nothing
        else
            return Nothing
 
diff --git a/src/XGraphic.hs b/src/XGraphic.hs
index 9343580..416177f 100644
--- a/src/XGraphic.hs
+++ b/src/XGraphic.hs
@@ -22,7 +22,7 @@ import Foreign.C
 
 -- | interface to the X11 library function @XWriteBitmapFile@.
 readBitmapFile :: Display -> Drawable -> String
-                  -> IO (Dimension, Dimension, Pixmap, Maybe CInt, Maybe CInt)
+                  -> IO (Either String (Dimension, Dimension, Pixmap, Maybe CInt, Maybe CInt))
 readBitmapFile display d filename =
   withCString filename $ \ c_filename ->
   alloca $ \ width_return ->
@@ -30,7 +30,7 @@ readBitmapFile display d filename =
   alloca $ \ bitmap_return ->
   alloca $ \ x_hot_return ->
   alloca $ \ y_hot_return -> do
-    _ <- xReadBitmapFile display d c_filename width_return height_return
+    rv <- xReadBitmapFile display d c_filename width_return height_return
          bitmap_return x_hot_return y_hot_return
     width <- peek width_return
     height <- peek height_return
@@ -41,7 +41,12 @@ readBitmapFile display d filename =
                 | otherwise  = Just x_hot
         m_y_hot | y_hot == -1 = Nothing
                 | otherwise  = Just y_hot
-    return (fromIntegral width, fromIntegral height, bitmap, m_x_hot, m_y_hot)
+    case rv of
+        0 -> return $ Right (fromIntegral width, fromIntegral height, bitmap, m_x_hot, m_y_hot)
+        1 -> return $ Left "readBitmapFile: BitmapOpenFailed"
+        2 -> return $ Left "readBitmapFile: BitmapFileInvalid"
+        3 -> return $ Left "readBitmapFile: BitmapNoMemory"
+        _ -> return $ Left "readBitmapFile: BitmapUnknownError"
 foreign import ccall unsafe "X11/Xlib.h XReadBitmapFile"
   xReadBitmapFile :: Display -> Drawable -> CString -> Ptr CInt -> Ptr CInt
                      -> Ptr Pixmap -> Ptr CInt -> Ptr CInt -> IO CInt