[gimp] app: add "show all" support to the Perspective Clone tool

[Ell <ell src gnome org>]

commit 19c693a9372511d22b1e4887e7161feb82e256ee
Author: Ell <ell_se yahoo com>
Date:   Fri Sep 6 20:05:29 2019 +0300

    app: add "show all" support to the Perspective Clone tool
    
    ... by adapting GimpPerspectiveClone to handle buffers with
    arbitrary extents.  Note that the tool doesn't seem to work well in
    "sample merged" mode to begin with, but this is unrelated.

 app/paint/gimpperspectiveclone.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/app/paint/gimpperspectiveclone.c b/app/paint/gimpperspectiveclone.c
index a52d77a043..abb9fabb5a 100644
--- a/app/paint/gimpperspectiveclone.c
+++ b/app/paint/gimpperspectiveclone.c
@@ -407,7 +407,8 @@ gimp_perspective_clone_get_source (GimpSourceCore   *source_core,
     case GIMP_CLONE_IMAGE:
       if (! gimp_rectangle_intersect (xmin, ymin,
                                       xmax - xmin, ymax - ymin,
-                                      0, 0,
+                                      gegl_buffer_get_x      (src_buffer),
+                                      gegl_buffer_get_y      (src_buffer),
                                       gegl_buffer_get_width  (src_buffer),
                                       gegl_buffer_get_height (src_buffer),
                                       NULL, NULL, NULL, NULL))