common canvas: ++ exception handling.

canvas update won't be performed if it's on drawing condition nor zero paints.

Change-Id: Ifb05ed0dc27e052d3d35c45c1a4a75cab3c31446

diff --git a/src/lib/tvgCanvasImpl.h b/src/lib/tvgCanvasImpl.h
index cce790e..11fe8b9 100644 (file)
--- a/src/lib/tvgCanvasImpl.h
+++ b/src/lib/tvgCanvasImpl.h
@@ -82,7 +82,7 @@ struct Canvas::Impl
 
     Result update(Paint* paint, bool force)
     {
-        if (!renderer) return Result::InsufficientCondition;
+        if (paints.count == 0 || drawing || !renderer) return Result::InsufficientCondition;
 
         Array<RenderData> clips;
         auto flag = RenderUpdateFlag::None;