ImageSize: use viewBox for svg if no length, width.

This change allows pandoc to extract size information
from more SVGs.  Closes #7045.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/Text/Pandoc/ImageSize.hs b/src/Text/Pandoc/ImageSize.hs
index 098c16721..e19958f6a 100644
--- a/src/Text/Pandoc/ImageSize.hs
+++ b/src/Text/Pandoc/ImageSize.hs
@@ -328,12 +328,16 @@ getSize img =
 svgSize :: WriterOptions -> ByteString -> Maybe ImageSize
 svgSize opts img = do
   doc <- Xml.parseXMLDoc $ UTF8.toString img
+  let viewboxSize = do
+        vb <- Xml.findAttrBy (== Xml.QName "viewBox" Nothing Nothing) doc
+        [_,_,w,h] <- mapM safeRead (T.words (T.pack vb))
+        return (w,h)
   let dpi = fromIntegral $ writerDpi opts
   let dirToInt dir = do
         dim <- Xml.findAttrBy (== Xml.QName dir Nothing Nothing) doc >>= lengthToDim . T.pack
         return $ inPixel opts dim
-  w <- dirToInt "width"
-  h <- dirToInt "height"
+  w <- dirToInt "width" <|> (fst <$> viewboxSize)
+  h <- dirToInt "height" <|> (snd <$> viewboxSize)
   return ImageSize {
     pxX  = w
   , pxY  = h