add outline extension (#2529)

1 files changed, 50 insertions, 0 deletions

diff --git a/lib/extensions/outline.py b/lib/extensions/outline.py
new file mode 100644
index 00000000..d6a16e99
--- /dev/null
+++ b/lib/extensions/outline.py
@@ -0,0 +1,50 @@
+# Authors: see git history
+#
+# Copyright (c) 2010 Authors
+# Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
+
+import inkex
+from shapely import concave_hull
+from shapely.geometry import LineString, MultiPolygon
+
+from ..i18n import _
+from ..svg.tags import SVG_PATH_TAG
+from .base import InkstitchExtension
+
+
+class Outline(InkstitchExtension):
+    def __init__(self, *args, **kwargs):
+        InkstitchExtension.__init__(self, *args, **kwargs)
+        self.arg_parser.add_argument("-r", "--ratio", type=float, default=0.0, dest="ratio")
+        self.arg_parser.add_argument("-a", "--allow-holes", type=inkex.Boolean, default=False, dest="allow_holes")
+
+    def effect(self):
+        if not self.svg.selection:
+            inkex.errormsg(_("Please select one or more shapes to convert to their outline."))
+            return
+
+        for element in self.svg.selection:
+            self.element_to_outline(element)
+
+    def element_to_outline(self, element):
+        if element.tag_name == 'g':
+            for element in element.iterdescendants(SVG_PATH_TAG):
+                self.element_to_outline(element)
+            return
+
+        path = element.get_path()
+        path = path.end_points
+        hull = concave_hull(LineString(path), ratio=self.options.ratio, allow_holes=self.options.allow_holes)
+        if isinstance(hull, LineString):
+            return
+
+        if not isinstance(hull, MultiPolygon):
+            hull = MultiPolygon([hull])
+        d = ''
+        for geom in hull.geoms:
+            d += 'M '
+            for x, y in geom.exterior.coords:
+                d += f'{x}, {y} '
+            d += "Z"
+
+        element.set('d', d)