Mark the mask surface as dirty after touching all its pixels

Cairo is smart enough to assume it's still clean otherwise and then
skips masking with it.

1 files changed, 1 insertions, 0 deletions

diff --git a/gst/cairo/gstcairotestsrc.c b/gst/cairo/gstcairotestsrc.c
index 6284167..ed98b01 100644
--- a/gst/cairo/gstcairotestsrc.c
+++ b/gst/cairo/gstcairotestsrc.c
@@ -360,6 +360,7 @@ create_alpha_map (guint w, guint h)
     }
     data += stride;
   }
+  cairo_surface_mark_dirty (surface);
   return surface;
 }