[gegl] png-save: correctly handle region of interest

[Øyvind Kolås <ok src gnome org>]

commit 3dce6741b0e7b135f7cfd07869812c0d1dc5845b
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu May 11 17:19:20 2017 +0200

    png-save: correctly handle region of interest

 operations/external/png-save.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/operations/external/png-save.c b/operations/external/png-save.c
index 5b82624..8ed0ec6 100644
--- a/operations/external/png-save.c
+++ b/operations/external/png-save.c
@@ -94,8 +94,8 @@ export_png (GeglOperation       *operation,
 
   src_x = result->x;
   src_y = result->y;
-  width = result->width - result->x;
-  height = result->height - result->y;
+  width = result->width;
+  height = result->height;
 
   {
     const Babl *babl = gegl_buffer_get_format (input);