Avoid assertion failure when rendering thumbnails of some pages

Change-Id: I5331ae27d8e492a8094e1904ba3af143c7c1a0e5

1 files changed, 9 insertions, 0 deletions

diff --git a/sw/source/core/layout/paintfrm.cxx b/sw/source/core/layout/paintfrm.cxx
index 0af0b447774f..b3efb8826a1d 100644
--- a/sw/source/core/layout/paintfrm.cxx
+++ b/sw/source/core/layout/paintfrm.cxx
@@ -4614,6 +4614,15 @@ lcl_MakeBorderLine(SwRect const& rRect,
         aEnd.setY(fStartY);
     }
 
+    // WHen rendering to very small (virtual) devices, like when producing
+    // page thumbnails in a mobile device app, the line geometry can end up
+    // bogus (negative width or height), so just ignore such border lines.
+    // Otherwise we will run into assertions later in lcl_TryMergeBorderLine()
+    // at least.
+    if (aEnd.getX() < aStart.getX() ||
+        aEnd.getY() < aStart.getY())
+        return;
+
     double const nExtentLeftStart = (isLeftOrTopBorder == isVertical)
         ?   lcl_GetExtent(pStartNeighbour, 0)
         :   lcl_GetExtent(0, pStartNeighbour);