add zigzag option to meander (#2699)

lib/elements/fill_stitch.py

@@ -422,6 +422,32 @@ class FillStitch(EmbroideryElement):
     def bean_stitch_repeats(self):
         return self.get_multiple_int_param("bean_stitch_repeats", "0")
 
+    @property
+    @param('zigzag_spacing_mm',
+           _('Zig-zag spacing (peak-to-peak)'),
+           tooltip=_('Length of stitches in zig-zag mode.'),
+           unit='mm',
+           type='float',
+           select_items=[('fill_method', 'meander_fill')],
+           default=0,
+           sort_index=35)
+    @cache
+    def zigzag_spacing(self):
+        return self.get_float_param("zigzag_spacing_mm", 0)
+
+    @property
+    @param('zigzag_width_mm',
+           _('Zigzag width'),
+           tooltip=_('Width of the zigzag line.'),
+           unit='mm',
+           type='float',
+           select_items=[('fill_method', 'meander_fill')],
+           default=3,
+           sort_index=36)
+    @cache
+    def zigzag_width(self):
+        return self.get_float_param("zigzag_width_mm", 0)
+
     @property
     def color(self):
         # SVG spec says the default fill is black

lib/elements/stroke.py

@@ -13,7 +13,8 @@ from ..i18n import _
 from ..marker import get_marker_elements
 from ..stitch_plan import StitchGroup
 from ..stitches.ripple_stitch import ripple_stitch
-from ..stitches.running_stitch import bean_stitch, running_stitch
+from ..stitches.running_stitch import (bean_stitch, running_stitch,
+                                       zigzag_stitch)
 from ..svg import get_node_transform, parse_length_with_units
 from ..svg.clip import get_clip_path
 from ..threads import ThreadColor
@@ -444,27 +445,7 @@ class Stroke(EmbroideryElement):
         # that length:
         patch = self.running_stitch(path, zigzag_spacing / 2.0, self.running_stitch_tolerance)
 
-        # Now move the points left and right.  Consider each pair
-        # of points in turn, and move perpendicular to them,
-        # alternating left and right.
-
-        stroke_width = stroke_width + pull_compensation
-        offset = stroke_width / 2.0
-
-        for i in range(len(patch) - 1):
-            start = patch.stitches[i]
-            end = patch.stitches[i + 1]
-            # sometimes the stitch results into zero length which cause a division by zero error
-            # ignoring this leads to a slightly bad result, but that is better than no output
-            if (end - start).length() == 0:
-                continue
-            segment_direction = (end - start).unit()
-            zigzag_direction = segment_direction.rotate_left()
-
-            if i % 2 == 1:
-                zigzag_direction *= -1
-
-            patch.stitches[i] += zigzag_direction * offset
+        patch.stitches = zigzag_stitch(patch.stitches, zigzag_spacing, stroke_width, pull_compensation)
 
         return patch
 

lib/stitches/meander_fill.py

@@ -14,7 +14,7 @@ from ..utils.list import poprandom
 from ..utils.prng import iter_uniform_floats
 from ..utils.smoothing import smooth_path
 from ..utils.threading import check_stop_flag
-from .running_stitch import bean_stitch, running_stitch
+from .running_stitch import bean_stitch, running_stitch, zigzag_stitch
 
 
 def meander_fill(fill, shape, original_shape, shape_index, starting_point, ending_point):
@@ -178,7 +178,11 @@ def post_process(points, shape, original_shape, fill):
     smoothed_points = smooth_path(points, fill.smoothness)
     smoothed_points = [InkStitchPoint.from_tuple(point) for point in smoothed_points]
 
-    stitches = running_stitch(smoothed_points, fill.running_stitch_length, fill.running_stitch_tolerance)
+    if fill.zigzag_spacing > 0:
+        stitches = running_stitch(smoothed_points, fill.zigzag_spacing / 2, fill.running_stitch_tolerance)
+        stitches = zigzag_stitch(stitches, fill.zigzag_spacing, fill.zigzag_width, 0)
+    else:
+        stitches = running_stitch(smoothed_points, fill.running_stitch_length, fill.running_stitch_tolerance)
 
     if fill.clip:
         stitches = clamp_path_to_polygon(stitches, original_shape)

lib/stitches/running_stitch.py

@@ -4,9 +4,9 @@
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
 import math
-from math import tau
 import typing
 from copy import copy
+from math import tau
 
 import numpy as np
 from shapely import geometry as shgeo
@@ -310,3 +310,29 @@ def bean_stitch(stitches, repeats, tags_to_ignore=None):
             new_stitches.extend(copy(new_stitches[-2:]))
 
     return new_stitches
+
+
+def zigzag_stitch(stitches, zigzag_spacing, stroke_width, pull_compensation):
+    # Move the points left and right.  Consider each pair
+    # of points in turn, and move perpendicular to them,
+    # alternating left and right.
+
+    stroke_width = stroke_width + pull_compensation
+    offset = stroke_width / 2.0
+
+    for i in range(len(stitches) - 1):
+        start = stitches[i]
+        end = stitches[i + 1]
+        # sometimes the stitch results into zero length which cause a division by zero error
+        # ignoring this leads to a slightly bad result, but that is better than no output
+        if (end - start).length() == 0:
+            continue
+        segment_direction = (end - start).unit()
+        zigzag_direction = segment_direction.rotate_left()
+
+        if i % 2 == 1:
+            zigzag_direction *= -1
+
+        stitches[i] += zigzag_direction * offset
+
+    return stitches

lib/svg/tags.py

@@ -107,6 +107,7 @@ inkstitch_attribs = [
     'running_stitch_length_mm',
     'running_stitch_tolerance_mm',
     'cutwork_needle',
+    'zigzag_width_mm',
     # ripples
     'line_count',
     'min_line_dist_mm',