From 2f4ca0cf10d9aa09711034c683e148b309822b86 Mon Sep 17 00:00:00 2001
From: Kaalleen <36401965+kaalleen@users.noreply.github.com>
Date: Sun, 19 Apr 2020 18:38:28 +0200
Subject: [PATCH] New Extension: Break Apart and Retain Holes (#653)

---
 lib/extensions/__init__.py    |  4 ++-
 lib/extensions/break_apart.py | 68 +++++++++++++++++++++++++++++++++++
 templates/break_apart.inx     | 17 +++++++++
 3 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 lib/extensions/break_apart.py
 create mode 100644 templates/break_apart.inx

diff --git a/lib/extensions/__init__.py b/lib/extensions/__init__.py
index cd8d79fbd..53a6638a0 100644
--- a/lib/extensions/__init__.py
+++ b/lib/extensions/__init__.py
@@ -1,4 +1,5 @@
 from auto_satin import AutoSatin
+from break_apart import BreakApart
 from convert_to_satin import ConvertToSatin
 from cut_satin import CutSatin
 from embroider import Embroider
@@ -36,4 +37,5 @@ __all__ = extensions = [Embroider,
                         AutoSatin,
                         Lettering,
                         Troubleshoot,
-                        RemoveEmbroiderySettings]
+                        RemoveEmbroiderySettings,
+                        BreakApart]
diff --git a/lib/extensions/break_apart.py b/lib/extensions/break_apart.py
new file mode 100644
index 000000000..625ace55a
--- /dev/null
+++ b/lib/extensions/break_apart.py
@@ -0,0 +1,68 @@
+from copy import deepcopy
+
+from shapely.geometry import Polygon
+
+import inkex
+
+from ..elements import AutoFill, Fill
+from ..i18n import _
+from ..svg import get_correction_transform
+from .base import InkstitchExtension
+
+
+class BreakApart(InkstitchExtension):
+    def effect(self):  # noqa: C901
+        if not self.get_elements():
+            return
+
+        if not self.selected:
+            inkex.errormsg(_("Please select one or more fill areas to break apart."))
+            return
+
+        for element in self.elements:
+            if not isinstance(element, AutoFill) and not isinstance(element, Fill):
+                continue
+            if len(element.paths) <= 1:
+                continue
+
+            polygons = []
+            multipolygons = []
+            holes = []
+
+            for path in element.paths:
+                polygons.append(Polygon(path))
+
+            # sort paths by size and convert to polygons
+            polygons.sort(key=lambda polygon: polygon.area, reverse=True)
+
+            for shape in polygons:
+                if shape in holes:
+                    continue
+                polygon_list = [shape]
+
+                for other in polygons:
+                    if shape != other and shape.contains(other) and other not in holes:
+                        # check if "other" is inside a hole, before we add it to the list
+                        if any(p.contains(other) for p in polygon_list[1:]):
+                            continue
+                        polygon_list.append(other)
+                        holes.append(other)
+                multipolygons.append(polygon_list)
+            self.element_to_nodes(multipolygons, element)
+
+    def element_to_nodes(self, multipolygons, element):
+        for polygons in multipolygons:
+            el = deepcopy(element)
+            d = ""
+            for polygon in polygons:
+                # copy element and replace path
+                el.node.set('id', self.uniqueId(element.node.get('id') + "_"))
+                d += "M"
+                for x, y in polygon.exterior.coords:
+                    d += "%s,%s " % (x, y)
+                    d += " "
+                d += "Z"
+            el.node.set('d', d)
+            el.node.set('transform', get_correction_transform(element.node))
+            element.node.getparent().insert(0, el.node)
+        element.node.getparent().remove(element.node)
diff --git a/templates/break_apart.inx b/templates/break_apart.inx
new file mode 100644
index 000000000..2580ddc30
--- /dev/null
+++ b/templates/break_apart.inx
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+    <name>{% trans %}Break Apart and Retain Holes{% endtrans %}</name>
+    <id>org.inkstitch.break_apart.{{ locale }}</id>
+    <param name="extension" type="string" gui-hidden="true">break_apart</param>
+    <effect>
+        <object-type>all</object-type>
+        <effects-menu>
+            <submenu name="Ink/Stitch">
+                <submenu name="{% trans %}Fill Tools{% endtrans %}" />
+            </submenu>
+        </effects-menu>
+    </effect>
+    <script>
+        {{ command_tag | safe }}
+    </script>
+</inkscape-extension>