[gnome-flashback] rectangle: add function to check if rectangle is adjacent to region

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 1463e4dee6cb4215f7eb78744a23dcea747fbd44
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Sep 13 14:56:40 2021 +0300

    rectangle: add function to check if rectangle is adjacent to region
    
    Based on mutter commit:
    https://gitlab.gnome.org/GNOME/mutter/-/commit/58c2f423f761

 backends/gf-rectangle-private.h | 11 +++++++----
 backends/gf-rectangle.c         | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)
---
diff --git a/backends/gf-rectangle-private.h b/backends/gf-rectangle-private.h
index acea48c..773f11a 100644
--- a/backends/gf-rectangle-private.h
+++ b/backends/gf-rectangle-private.h
@@ -26,11 +26,14 @@
 
 G_BEGIN_DECLS
 
-gboolean gf_rectangle_overlaps_with_region (const GList       *spanning_rects,
-                                            const GfRectangle *rect);
+gboolean gf_rectangle_overlaps_with_region         (const GList       *spanning_rects,
+                                                    const GfRectangle *rect);
 
-gboolean gf_rectangle_is_adjacent_to       (const GfRectangle *rect,
-                                            const GfRectangle *other);
+gboolean gf_rectangle_is_adjacent_to_any_in_region (const GList       *spanning_rects,
+                                                    GfRectangle       *rect);
+
+gboolean gf_rectangle_is_adjacent_to               (const GfRectangle *rect,
+                                                    const GfRectangle *other);
 
 G_END_DECLS
 
diff --git a/backends/gf-rectangle.c b/backends/gf-rectangle.c
index ca71d42..0571c4e 100644
--- a/backends/gf-rectangle.c
+++ b/backends/gf-rectangle.c
@@ -89,6 +89,26 @@ gf_rectangle_overlaps_with_region (const GList       *spanning_rects,
   return overlaps;
 }
 
+gboolean
+gf_rectangle_is_adjacent_to_any_in_region (const GList *spanning_rects,
+                                           GfRectangle *rect)
+{
+  const GList *l;
+
+  for (l = spanning_rects; l; l = l->next)
+    {
+      GfRectangle *other = (GfRectangle *) l->data;
+
+      if (rect == other || gf_rectangle_equal (rect, other))
+        continue;
+
+      if (gf_rectangle_is_adjacent_to (rect, other))
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
 gboolean
 gf_rectangle_is_adjacent_to (const GfRectangle *rect,
                              const GfRectangle *other)