Improved warnings when image size can't be determined.

Closes #1834.

data/templates

@@ -1 +1 @@
-Subproject commit 1b789219e50db1ac52d6fe6e471641a880cd7a33
+Subproject commit 1d55d847308dd681c80312e0d9549d5c765bf4cc

src/Text/Pandoc/Writers/Docx.hs

@@ -1122,8 +1122,11 @@ inlineToOpenXML opts (Image alt (src, tit)) = do
           ident <- ("rId"++) `fmap` getUniqueId
           (xpt,ypt) <- case imageSize img of
                              Right size  -> return $ sizeInPoints size
-                             Left msg    -> do liftIO (warn msg)
-                                               return (120,120)
+                             Left msg    -> do
+                               liftIO $ warn $
+                                 "Could not determine image size in `" ++
+                                 src ++ "': " ++ msg
+                               return (120,120)
           -- 12700 emu = 1 pt
           let (xemu,yemu) = fitToPage (xpt * 12700, ypt * 12700) (pageWidth * 12700)
           let cNvPicPr = mknode "pic:cNvPicPr" [] $

src/Text/Pandoc/Writers/ODT.hs

@@ -136,8 +136,10 @@ transformPicMath opts entriesRef (Image lab (src,t)) = do
      Right (img, mbMimeType) -> do
        (w,h) <- case imageSize img of
                      Right size -> return $ sizeInPoints size
-                     Left msg   -> do warn msg
-                                      return (0,0)
+                     Left msg   -> do
+                       warn $ "Could not determine image size in `" ++
+                         src ++ "': " ++ msg
+                       return (0,0)
        let tit' = show w ++ "x" ++ show h
        entries <- readIORef entriesRef
        let extension = fromMaybe (takeExtension $ takeWhile (/='?') src)

src/Text/Pandoc/Writers/RTF.hs

@@ -57,7 +57,10 @@ rtfEmbedImage opts x@(Image _ (src,_)) = do
                              "image/png"  -> "\\pngblip"
                              _            -> error "Unknown file type"
          sizeSpec <- case imageSize imgdata of
-                             Left msg -> warn msg >> return ""
+                             Left msg -> do
+                               warn $ "Could not determine image size in `" ++
+                                 src ++ "': " ++ msg
+                               return ""
                              Right sz -> return $ "\\picw" ++ show xpx ++
                                         "\\pich" ++ show ypx ++
                                         "\\picwgoal" ++ show (xpt * 20)