From 4100e98ebef835b6d61e484efdd85134c8f11136 Mon Sep 17 00:00:00 2001
From: Marius Stanciu <marius.adrian@gmail.com>
Date: Sun, 14 Apr 2019 01:03:42 +0300
Subject: [PATCH] - Gerber Editor: some more changes in processing LPC polygons

---
 camlib.py                          |  4 ++--
 flatcamEditors/FlatCAMGrbEditor.py | 34 ++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/camlib.py b/camlib.py
index c732b8a1..b3dffb83 100644
--- a/camlib.py
+++ b/camlib.py
@@ -3183,10 +3183,10 @@ class Gerber (Geometry):
             temp_geo = []
             for apid in self.apertures:
                 if 'clear_geometry' in self.apertures[apid]:
-                    clear_geo = cascaded_union(self.apertures[apid]['clear_geometry'])
+                    clear_geo = MultiPolygon(self.apertures[apid]['clear_geometry'])
                     for solid_geo in self.apertures[apid]['solid_geometry']:
                         if clear_geo.intersects(solid_geo):
-                            res_geo = clear_geo.symmetric_difference(solid_geo)
+                            res_geo = solid_geo.difference(clear_geo)
                             temp_geo.append(res_geo)
                         else:
                             temp_geo.append(solid_geo)
diff --git a/flatcamEditors/FlatCAMGrbEditor.py b/flatcamEditors/FlatCAMGrbEditor.py
index 6e384223..63dcc31d 100644
--- a/flatcamEditors/FlatCAMGrbEditor.py
+++ b/flatcamEditors/FlatCAMGrbEditor.py
@@ -1292,6 +1292,9 @@ class FlatCAMGrbEditor(QtCore.QObject):
         # this var will store the state of the toolbar before starting the editor
         self.toolbar_old_state = False
 
+        # holds flattened geometry
+        self.flat_geometry = []
+
         # Init GUI
         self.apdim_lbl.hide()
         self.apdim_entry.hide()
@@ -1927,6 +1930,37 @@ class FlatCAMGrbEditor(QtCore.QObject):
         self.shapes.clear(update=True)
         self.tool_shape.clear(update=True)
 
+    def flatten(self, geometry=None, reset=True, pathonly=False):
+        """
+        Creates a list of non-iterable linear geometry objects.
+        Polygons are expanded into its exterior pathonly param if specified.
+
+        Results are placed in flat_geometry
+
+        :param geometry: Shapely type or list or list of list of such.
+        :param reset: Clears the contents of self.flat_geometry.
+        :param pathonly: Expands polygons into linear elements from the exterior attribute.
+        """
+
+        if reset:
+            self.flat_geometry = []
+        ## If iterable, expand recursively.
+        try:
+            for geo in geometry:
+                if geo is not None:
+                    self.flatten(geometry=geo, reset=False, pathonly=pathonly)
+
+        ## Not iterable, do the actual indexing and add.
+        except TypeError:
+            if pathonly and type(geometry) == Polygon:
+                self.flat_geometry.append(geometry.exterior)
+                self.flatten(geometry=geometry.interiors,
+                             reset=False,
+                             pathonly=True)
+            else:
+                self.flat_geometry.append(geometry)
+        return self.flat_geometry
+
     def edit_fcgerber(self, orig_grb_obj):
         """
         Imports the geometry found in self.apertures from the given FlatCAM Gerber object