Added footprint rule area anchors

Fixes #10461

(cherry picked from commit 47c0672f)

pcbnew/tools/pcb_grid_helper.cpp

@@ -2,7 +2,7 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2014 CERN
- * Copyright (C) 2018-2021 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2018-2022 KiCad Developers, see AUTHORS.txt for contributors.
  * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
  *
  * This program is free software; you can redistribute it and/or
@@ -683,6 +683,24 @@ void PCB_GRID_HELPER::computeAnchors( BOARD_ITEM* aItem, const VECTOR2I& aRefPos
             break;
         }
 
+        case PCB_FP_ZONE_T:
+        {
+            const SHAPE_POLY_SET* outline = static_cast<const FP_ZONE*>( aItem )->Outline();
+
+            SHAPE_LINE_CHAIN lc;
+            lc.SetClosed( true );
+
+            for( auto iter = outline->CIterateWithHoles(); iter; iter++ )
+            {
+                addAnchor( *iter, CORNER, aItem );
+                lc.Append( *iter );
+            }
+
+            addAnchor( lc.NearestPoint( aRefPos ), OUTLINE, aItem );
+
+            break;
+        }
+
         case PCB_DIM_ALIGNED_T:
         case PCB_DIM_ORTHOGONAL_T:
         {