[gegl] buffer: avoid clearing partially-damaged mipmapped tiles ...

[Ell <ell src gnome org>]

commit a460be2523321ffc0460b71bc8311c0626b6d111
Author: Ell <ell_se yahoo com>
Date:   Wed Nov 28 03:37:24 2018 -0500

    buffer: avoid clearing partially-damaged mipmapped tiles ...
    
    ... when the damaged region is empty
    
    When fetching a partially-damaged mipmapped tile, and the damaged
    region contains no lower-level tiles, avoid erroneously discarding
    the tile and returning NULL, since the non-damaged parts of the
    tile may contain non-zero data.

 gegl/buffer/gegl-tile-handler-zoom.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/gegl/buffer/gegl-tile-handler-zoom.c b/gegl/buffer/gegl-tile-handler-zoom.c
index 1b82a0716..0e8afc3d8 100644
--- a/gegl/buffer/gegl-tile-handler-zoom.c
+++ b/gegl/buffer/gegl-tile-handler-zoom.c
@@ -213,6 +213,10 @@ get_tile (GeglTileSource *gegl_tile_source,
                     }
                 }
             }
+          else
+            {
+              empty = FALSE;
+            }
         }
 
     if (empty)