[gegl] crop: don't depend on the input node's bounding box ...

[N/A <ell src gnome org>]

commit 808501c60e4843357ac6d7c44e1472ab4ab6879e
Author: Ell <ell_se yahoo com>
Date:   Tue Dec 20 10:17:08 2016 -0500

    crop: don't depend on the input node's bounding box ...
    
    ... in process()
    
    At this point we already have the input buffer, and since what we
    really care about is making sure that the output buffer is a
    subset of it, we can use its extent directly.

 operations/core/crop.c |   21 +++++++++++++++++----
 1 files changed, 17 insertions(+), 4 deletions(-)
---
diff --git a/operations/core/crop.c b/operations/core/crop.c
index 3812fa3..1af88ff 100644
--- a/operations/core/crop.c
+++ b/operations/core/crop.c
@@ -143,15 +143,28 @@ gegl_crop_process (GeglOperation        *operation,
                    const GeglRectangle  *result,
                    gint                  level)
 {
-  GeglBuffer    *input;
-  gboolean       success = FALSE;
-  GeglRectangle  extent = gegl_crop_get_bounding_box (operation);
+  GeglProperties *o = GEGL_PROPERTIES (operation);
+  GeglBuffer     *input;
+  gboolean        success = FALSE;
 
   input = gegl_operation_context_get_source (context, "input");
 
   if (input)
     {
-      GeglBuffer *output = gegl_buffer_create_sub_buffer (input, &extent);
+      GeglRectangle  extent;
+      GeglBuffer    *output;
+
+      extent = *GEGL_RECTANGLE (o->x, o->y,  o->width, o->height);
+
+      /* The output buffer's extent must be a subset of the input buffer's
+       * extent; otherwise, if the output buffer is reused for in-place output,
+       * we might try to write to areas of the buffer that lie outside the
+       * input buffer, erroneously discarding the data.
+       */
+      gegl_rectangle_intersect (&extent,
+                                &extent, gegl_buffer_get_extent (input));
+
+      output = gegl_buffer_create_sub_buffer (input, &extent);
 
       if (gegl_object_get_has_forked (G_OBJECT (input)))
         gegl_object_set_has_forked (G_OBJECT (output));