[gimp] app: fix #6961 Scaled image bug

[Jacob Boerema <jboerema src gnome org>]

commit ba841a98dacf3a99dc7446ca78a94e1600e32b72
Author: Jacob Boerema <jgboerema gmail com>
Date:   Sat May 28 12:13:44 2022 -0400

    app: fix #6961 Scaled image bug
    
    With large image sizes a 32-bit int is not enough for the intermediate
    computations, which byte per pixel, width and height are.
    
    So, just like the function below it does: gimp_gegl_pyramid_get_memsize,
    we will cast these to gint64.
    
    Thanks to Massimo Valentini for finding the cause.

 app/core/gimp-memsize.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/app/core/gimp-memsize.c b/app/core/gimp-memsize.c
index 2826bda6da..fc674d0842 100644
--- a/app/core/gimp-memsize.c
+++ b/app/core/gimp-memsize.c
@@ -285,9 +285,9 @@ gimp_gegl_buffer_get_memsize (GeglBuffer *buffer)
     {
       const Babl *format = gegl_buffer_get_format (buffer);
 
-      return (babl_format_get_bytes_per_pixel (format) *
-              gegl_buffer_get_width (buffer) *
-              gegl_buffer_get_height (buffer) +
+      return ((gint64) babl_format_get_bytes_per_pixel (format) *
+              (gint64) gegl_buffer_get_width (buffer) *
+              (gint64) gegl_buffer_get_height (buffer) +
               gimp_g_object_get_memsize (G_OBJECT (buffer)));
     }