Stroke to Fill: Ignore Small Artifacts (#2678)

* Ignore artifacts
* insert one centerline group per fill element
* prevent error on elements with fill and stroke

1 files changed, 119 insertions, 94 deletions

diff --git a/lib/extensions/fill_to_stroke.py b/lib/extensions/fill_to_stroke.py
index 28c1f651..c33ede3d 100644
--- a/lib/extensions/fill_to_stroke.py
+++ b/lib/extensions/fill_to_stroke.py
@@ -3,16 +3,16 @@
 # Copyright (c) 2022 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
-from inkex import Boolean, Group, PathElement, Transform, errormsg
+from inkex import Boolean, Group, Path, PathElement, Transform, errormsg
 from inkex.units import convert_unit
-from shapely.geometry import (LineString, MultiLineString, MultiPolygon, Point,
-                              Polygon)
+from shapely.geometry import LineString, MultiLineString, MultiPolygon, Point
 from shapely.ops import linemerge, nearest_points, split, voronoi_diagram
 
 from ..elements import FillStitch, Stroke
 from ..i18n import _
 from ..stitches.running_stitch import running_stitch
 from ..svg import get_correction_transform
+from ..utils import ensure_multi_line_string
 from ..utils.geometry import Point as InkstitchPoint
 from ..utils.geometry import line_string_to_point_list
 from .base import InkstitchExtension
@@ -33,10 +33,7 @@ class FillToStroke(InkstitchExtension):
             errormsg(_("Please select one or more fill objects to render the centerline."))
             return
 
-        cut_lines = []
-        fill_shapes = []
-
-        fill_shapes, cut_lines = self._get_shapes()
+        fill_shapes, cut_lines, cut_line_nodes = self._get_shapes()
 
         if not fill_shapes:
             errormsg(_("Please select one or more fill objects to render the centerline."))
@@ -45,67 +42,71 @@ class FillToStroke(InkstitchExtension):
         # convert user input from mm to px
         self.threshold = convert_unit(self.options.threshold_mm, 'px', 'mm')
 
-        # insert centerline group before the first selected element
-        first = fill_shapes[0].node
-        parent = first.getparent()
-        index = parent.index(first) + 1
-        centerline_group = Group.new("Centerline Group", id=self.uniqueId("centerline_group_"))
-        parent.insert(index, centerline_group)
-
+        # convert to center line elements and insert into svg
         for element in fill_shapes:
-            transform = Transform(get_correction_transform(parent, child=True))
-            stroke_width = convert_unit(self.options.line_width_mm, 'px', 'mm')
-            color = element.node.style('fill')
-            style = f"fill:none;stroke:{ color };stroke-width:{ stroke_width }"
-
-            multipolygon = element.shape
-            for cut_line in cut_lines:
-                split_polygon = split(multipolygon, cut_line)
-                poly = [polygon for polygon in split_polygon.geoms if isinstance(polygon, Polygon)]
-                multipolygon = MultiPolygon(poly)
-
-            lines = []
-
-            for polygon in multipolygon.geoms:
-                multilinestring = self._get_centerline(polygon)
-                if multilinestring is None:
-                    continue
-                lines.extend(multilinestring.geoms)
+            self._convert_to_centerline(element, cut_lines)
 
-            if self.options.close_gaps:
-                lines = self._close_gaps(lines, cut_lines)
-
-            # insert new elements
-            self._insert_elements(lines, centerline_group, index, transform, style)
-
-        # clean up
+        # remove cut lines
         if not self.options.keep_original:
-            self._remove_elements()
+            self._remove_cutlines(cut_line_nodes)
 
     def _get_shapes(self):
         fill_shapes = []
         cut_lines = []
+        cut_line_nodes = []
         for element in self.elements:
             if isinstance(element, FillStitch):
                 fill_shapes.append(element)
             elif isinstance(element, Stroke):
                 cut_lines.extend(list(element.as_multi_line_string().geoms))
-        return fill_shapes, cut_lines
+                cut_line_nodes.append(element.node)
+        return fill_shapes, cut_lines, cut_line_nodes
 
-    def _remove_elements(self):
-        parents = []
-        for element in self.elements:
-            # it is possible, that we get one element twice (if it has both, a fill and a stroke)
-            # just ignore the second time
-            try:
-                parents.append(element.node.getparent())
-                element.node.getparent().remove(element.node)
-            except AttributeError:
-                pass
-        # remove empty groups
-        for parent in set(parents):
-            if parent is not None and not parent.getchildren():
-                parent.getparent().remove(parent)
+    def _convert_to_centerline(self, element, cut_lines):
+        element_id = element.node.get_id()
+        element_label = element.node.label
+        group_name = element_label or element_id
+
+        centerline_group = Group.new(f'{ group_name } { _("center line") }', id=self.uniqueId("centerline_group_"))
+        parent = element.node.getparent()
+        index = parent.index(element.node) + 1
+        parent.insert(index, centerline_group)
+
+        transform = Transform(get_correction_transform(parent, child=True))
+        stroke_width = convert_unit(self.options.line_width_mm, 'px', 'mm')
+        color = element.node.style('fill')
+        style = f"fill:none;stroke:{ color };stroke-width:{ stroke_width }"
+
+        multipolygon = element.shape
+        multipolygon = self._apply_cut_lines(cut_lines, multipolygon)
+
+        lines = self._get_lines(multipolygon)
+
+        if self.options.close_gaps:
+            lines = self._close_gaps(lines, cut_lines)
+
+        # do not use a group in case there is only one line
+        if len(lines) <= 1:
+            parent.remove(centerline_group)
+            centerline_group = parent
+
+        # clean up
+        if not self.options.keep_original:
+            parent.remove(element.node)
+
+        # insert new elements
+        self._insert_elements(lines, centerline_group, index, element_id, element_label, transform, style)
+
+    def _get_lines(self, multipolygon):
+        lines = []
+        for polygon in multipolygon.geoms:
+            if polygon.area < 0.5:
+                continue
+            multilinestring = self._get_centerline(polygon)
+            if multilinestring is None:
+                continue
+            lines.extend(multilinestring.geoms)
+        return lines
 
     def _get_high_res_polygon(self, polygon):
         # use running stitch method
@@ -121,7 +122,7 @@ class FillToStroke(InkstitchExtension):
     def _get_centerline(self, polygon):
         # increase the resolution of the polygon
         polygon = self._get_high_res_polygon(polygon)
-        if polygon is isinstance(polygon, MultiPolygon):
+        if polygon is polygon.geom_type == 'MultiPolygon':
             return
 
         # generate voronoi centerline
@@ -139,14 +140,14 @@ class FillToStroke(InkstitchExtension):
         if multilinestring is None:
             return
         # simplify polygon
-        multilinestring = self._ensure_multilinestring(multilinestring.simplify(0.1))
+        multilinestring = ensure_multi_line_string(multilinestring.simplify(0.1))
         if multilinestring is None:
             return
         return multilinestring
 
     def _get_voronoi_centerline(self, polygon):
         lines = voronoi_diagram(polygon, edges=True).geoms[0]
-        if not isinstance(lines, MultiLineString):
+        if not lines.geom_type == 'MultiLineString':
             return
         multilinestring = []
         for line in lines.geoms:
@@ -155,7 +156,14 @@ class FillToStroke(InkstitchExtension):
         lines = linemerge(multilinestring)
         if lines.is_empty:
             return
-        return self._ensure_multilinestring(lines)
+        return ensure_multi_line_string(lines)
+
+    def _apply_cut_lines(self, cut_lines, multipolygon):
+        for cut_line in cut_lines:
+            split_polygon = split(multipolygon, cut_line)
+            poly = [polygon for polygon in split_polygon.geoms if polygon.geom_type == 'Polygon']
+            multipolygon = MultiPolygon(poly)
+        return multipolygon
 
     def _get_start_and_end_points(self, multilinestring):
         points = []
@@ -182,43 +190,49 @@ class FillToStroke(InkstitchExtension):
         if lines.is_empty:
             lines = None
         else:
-            lines = self._ensure_multilinestring(lines)
+            lines = ensure_multi_line_string(lines)
         return lines
 
     def _repair_splitted_ends(self, polygon, multilinestring, dead_ends):
         lines = list(multilinestring.geoms)
         for i, dead_end in enumerate(dead_ends):
-            coords = dead_end.coords
-            for j in range(i + 1, len(dead_ends)):
-                common_point = set([coords[0], coords[-1]]).intersection(dead_ends[j].coords)
-                if len(common_point) > 0:
-                    # prepare all lines to point to the common point
-                    dead_point1 = coords[0]
-                    if dead_point1 in common_point:
-                        dead_point1 = coords[-1]
-                    dead_point2 = dead_ends[j].coords[0]
-                    if dead_point2 in common_point:
-                        dead_point2 = dead_ends[j].coords[-1]
-                    end_line = LineString([dead_point1, dead_point2])
-                    if polygon.covers(end_line):
-                        dead_end_center_point = end_line.centroid
-                    else:
-                        continue
-                    lines.append(LineString([dead_end_center_point, list(common_point)[0]]))
-                    if dead_end in lines:
-                        lines.remove(dead_end)
-                    if dead_ends[j] in lines:
-                        lines.remove(dead_ends[j])
+            if dead_end.length > self.threshold:
+                continue
+            self._join_end(polygon, lines, dead_ends, dead_end, i)
+        return ensure_multi_line_string(linemerge(lines))
+
+    def _join_end(self, polygon, lines, dead_ends, dead_end, index):
+        coords = dead_end.coords
+        for j in range(index + 1, len(dead_ends)):
+            if dead_ends[j].length > self.threshold:
+                continue
+            common_point = set([coords[0], coords[-1]]).intersection(dead_ends[j].coords)
+            if len(common_point) > 0:
+                dead_point1 = coords[0]
+                if dead_point1 in common_point:
+                    dead_point1 = coords[-1]
+                dead_point2 = dead_ends[j].coords[0]
+                if dead_point2 in common_point:
+                    dead_point2 = dead_ends[j].coords[-1]
+                end_line = LineString([dead_point1, dead_point2])
+                if polygon.covers(end_line):
+                    dead_end_center_point = end_line.centroid
+                else:
                     continue
-        return self._ensure_multilinestring(linemerge(lines))
+                lines.append(LineString([dead_end_center_point, list(common_point)[0]]))
+                if dead_end in lines:
+                    lines.remove(dead_end)
+                if dead_ends[j] in lines:
+                    lines.remove(dead_ends[j])
+                continue
 
     def _close_gaps(self, lines, cut_lines):
         snaped_lines = []
         lines = MultiLineString(lines)
         for i, line in enumerate(lines.geoms):
-            # for each cutline check if a the line starts or ends close to it
+            # for each cutline check if a line starts or ends close to it
             # if so extend the line at the start/end for the distance of the nearest point and snap it to that other line
-            # we do not want to snap it to the rest of the lines directly, this could push the connection point into a unwanted direction
+            # we do not want to snap it to the rest of the lines directly, this could push the connection point into an unwanted direction
             coords = list(line.coords)
             start = Point(coords[0])
             end = Point(coords[-1])
@@ -243,15 +257,26 @@ class FillToStroke(InkstitchExtension):
         new_point = start_point - direction * distance
         return new_point
 
-    def _ensure_multilinestring(self, lines):
-        if not isinstance(lines, MultiLineString):
-            lines = MultiLineString([lines])
-        return lines
+    def _remove_cutlines(self, cut_line_nodes):
+        for cut_line in cut_line_nodes:
+            # it is possible, that we get one element twice (if it has both, a fill and a stroke)
+            # this means that we already removed it from the svg and we can ignore the error.
+            try:
+                cut_line.getparent().remove(cut_line)
+            except AttributeError:
+                pass
 
-    def _insert_elements(self, lines, parent, index, transform, style):
-        for line in lines:
-            d = "M "
-            for coord in line.coords:
-                d += "%s,%s " % (coord[0], coord[1])
-            centerline_element = PathElement(d=d, style=style, transform=str(transform))
+    def _insert_elements(self, lines, parent, index, element_id, element_label, transform, style):
+        replace = False if len(lines) > 1 or self.options.keep_original else True
+        for i, line in enumerate(lines):
+            line_id = element_id if replace else self.uniqueId(f"{ element_id }_")
+            centerline_element = PathElement(
+                id=line_id,
+                d=str(Path(line.coords)),
+                style=style,
+                transform=str(transform)
+            )
+            if element_label is not None:
+                label = element_label if replace else f"{ element_label }_{ i }"
+                centerline_element.label = label
             parent.insert(index, centerline_element)