pptx writer: Handle single column

Add an additional guard for a single column to be able to process it.

src/Text/Pandoc/Writers/Powerpoint/Presentation.hs

@@ -727,6 +727,7 @@ bodyBlocksToSlide _ (blk : blks) spkNotes
   , "columns" `elem` classes
   , Div (_, clsL, _) blksL : Div (_, clsR, _) blksR : remaining <- divBlks
   , "column" `elem` clsL, "column" `elem` clsR = do
+      -- At least 2 column elements
       mapM_ (addLogMessage . BlockNotRendered) (blks ++ remaining)
       let mkTwoColumn left right = do
             blksL' <- join . take 1 <$> splitBlocks left
@@ -755,6 +756,16 @@ bodyBlocksToSlide _ (blk : blks) spkNotes
       if (any null [blksL1, blksL2]) && (any null [blksR1, blksR2])
       then mkTwoColumn blksL blksR
       else mkComparison blksL1 blksL2 blksR1 blksR2
+  | Div (_, classes, _) divBlks <- blk
+  , "columns" `elem` classes
+  , Div (_, cls, _) columnBlks : remaining <- divBlks
+  , "column" `elem` cls = do
+      -- Only 1 column element.
+      mapM_ (addLogMessage . BlockNotRendered) (blks ++ remaining)
+      clBlks' <- join . take 1 <$> splitBlocks columnBlks
+      shapes <- blocksToShapes clBlks'
+      sldId <- asks envCurSlideId
+      return $ Slide sldId (ContentSlide [] shapes) spkNotes Nothing
 bodyBlocksToSlide _ (blk : blks) spkNotes = do
       sldId <- asks envCurSlideId
       inNoteSlide <- asks envInNoteSlide

test/Tests/Writers/Powerpoint.hs

@@ -102,6 +102,14 @@ tests = let
       def
       "pptx/two-column/text-and-image/input.native"
       "pptx/two-column/text-and-image/output.pptx"
+    , pptxTests "single column text"
+      def
+      "pptx/single-column/text/input.native"
+      "pptx/single-column/text/output.pptx"
+    , pptxTests "single column image"
+      def
+      "pptx/single-column/image/input.native"
+      "pptx/single-column/image/output.pptx"
     , pptxTests "speaker notes"
       def
       "pptx/speaker-notes/input.native"

test/pptx/single-column/image/input.native

@@ -0,0 +1,22 @@
+[ Header
+    1
+    ( "single-column" , [] , [] )
+    [ Str "Single" , Space , Str "column" ]
+, Div
+    ( "" , [ "columns" ] , [] )
+    [ Div
+        ( "" , [ "column" ] , [] )
+        [ Figure
+            ( "" , [] , [] )
+            (Caption
+               Nothing [ Plain [ Str "an" , Space , Str "image" ] ])
+            [ Plain
+                [ Image
+                    ( "" , [] , [] )
+                    [ Str "an" , Space , Str "image" ]
+                    ( "lalune.jpg" , "" )
+                ]
+            ]
+        ]
+    ]
+]

test/pptx/single-column/text/input.native

@@ -0,0 +1,13 @@
+[ Header
+    1
+    ( "single-column" , [] , [] )
+    [ Str "Single" , Space , Str "column" ]
+, Div
+    ( "" , [ "columns" ] , [] )
+    [ Div
+        ( "" , [ "column" ] , [] )
+        [ Para [ Str "One" , Space , Str "paragraph." ]
+        , Para [ Str "Another" , Space , Str "paragraph." ]
+        ]
+    ]
+]