Running stitch length sequence (#4034)

* allow running stitch length sequences
* contour fill: fix error message for long stitch length
* satin: fix center underlay stitch length

16 files changed, 121 insertions, 56 deletions

diff --git a/lib/elements/element.py b/lib/elements/element.py
index 8e66db58..9b438f56 100644
--- a/lib/elements/element.py
+++ b/lib/elements/element.py
@@ -161,7 +161,11 @@ class EmbroideryElement(object):
         try:
             params = [int(param) for param in params if param]
         except (TypeError, ValueError):
-            return [int(default)]
+            params = [int(default)]
+
+        if param.endswith('_mm'):
+            params = [value * PIXELS_PER_MM for value in params]
+
         return params
 
     # returns an array of multiple space separated float values
@@ -171,7 +175,11 @@ class EmbroideryElement(object):
         try:
             params = [float(param) for param in params if param]
         except (TypeError, ValueError):
-            return [float(default)]
+            params = [float(default)]
+
+        if param.endswith('_mm'):
+            params = [value * PIXELS_PER_MM for value in params]
+
         return params
 
     def get_json_param(self, param, default=None):
diff --git a/lib/elements/satin_column.py b/lib/elements/satin_column.py
index 6babc851..277c4f84 100644
--- a/lib/elements/satin_column.py
+++ b/lib/elements/satin_column.py
@@ -1117,14 +1117,16 @@ class SatinColumn(EmbroideryElement):
         linestring = shgeo.LineString(stitches)
         return linestring
 
-    def _get_center_line_stitches(self, position):
+    def _get_center_line_stitches(self, position, stitch_length=None):
         inset_prop = -np.array([position, 100-position]) / 100
+        if stitch_length is None:
+            stitch_length = self.running_stitch_length
 
         # Do it like contour underlay, but inset all the way to the center.
         pairs = self.plot_points_on_rails(self.running_stitch_tolerance, (0, 0), inset_prop)
 
         points = [points[0] for points in pairs]
-        stitches = running_stitch.even_running_stitch(points, self.running_stitch_length, self.running_stitch_tolerance)
+        stitches = running_stitch.even_running_stitch(points, [stitch_length], self.running_stitch_tolerance)
 
         if len(stitches) == 1:
             stitches.append(stitches[0])
@@ -1338,12 +1340,12 @@ class SatinColumn(EmbroideryElement):
 
         first_side = running_stitch.even_running_stitch(
             [points[0] for points in pairs],
-            self.contour_underlay_stitch_length,
+            [self.contour_underlay_stitch_length],
             self.contour_underlay_stitch_tolerance
         )
         second_side = running_stitch.even_running_stitch(
             [points[1] for points in pairs],
-            self.contour_underlay_stitch_length,
+            [self.contour_underlay_stitch_length],
             self.contour_underlay_stitch_tolerance
         )
 
@@ -1381,7 +1383,7 @@ class SatinColumn(EmbroideryElement):
         repeats = self.center_walk_underlay_repeats
 
         stitch_groups = []
-        stitches = self._get_center_line_stitches(self.center_walk_underlay_position)
+        stitches = self._get_center_line_stitches(self.center_walk_underlay_position, self.center_walk_underlay_stitch_length)
         if end_point:
             tags = ("satin_column", "satin_column_underlay", "satin_center_walk")
             stitches = shgeo.LineString(stitches)
diff --git a/lib/elements/stroke.py b/lib/elements/stroke.py
index 58cc5756..f0f44827 100644
--- a/lib/elements/stroke.py
+++ b/lib/elements/stroke.py
@@ -118,14 +118,15 @@ class Stroke(EmbroideryElement):
     @property
     @param('running_stitch_length_mm',
            _('Running stitch length'),
-           tooltip=_('Length of stitches. Stitches can be shorter according to the stitch tolerance setting.'),
+           tooltip=_('Length of stitches. Stitches can be shorter according to the stitch tolerance setting.\n'
+                     'It is possible to create stitch length patterns by adding multiple values separated by a space.'),
            unit='mm',
-           type='float',
+           type='string',
            select_items=[('stroke_method', 'running_stitch'), ('stroke_method', 'ripple_stitch')],
-           default=2.5,
+           default="2.5",
            sort_index=4)
     def running_stitch_length(self):
-        return max(self.get_float_param("running_stitch_length_mm", 2.5), 0.01)
+        return [max(value, 0.01) for value in self.get_multiple_float_param("running_stitch_length_mm", "2.5")]
 
     @property
     @param('running_stitch_tolerance_mm',
@@ -185,13 +186,13 @@ class Stroke(EmbroideryElement):
            _('Zig-zag spacing (peak-to-peak)'),
            tooltip=_('Length of stitches in zig-zag mode.'),
            unit='mm',
-           type='float',
-           default=0.4,
+           type='string',
+           default="0.4",
            select_items=[('stroke_method', 'zigzag_stitch')],
            sort_index=6)
     @cache
     def zigzag_spacing(self):
-        return max(self.get_float_param("zigzag_spacing_mm", 0.4), 0.01)
+        return [max(value, 0.01) for value in self.get_multiple_float_param("zigzag_spacing_mm", "0.4")]
 
     @property
     @param('stroke_pull_compensation_mm',
@@ -551,7 +552,8 @@ class Stroke(EmbroideryElement):
         # `self.zigzag_spacing` is the length for a zig and a zag
         # together (a V shape).  Start with running stitch at half
         # that length:
-        stitch_group = self.running_stitch(path, zigzag_spacing / 2.0, self.running_stitch_tolerance, False, 0, "")
+        spacing = [value / 2 for value in zigzag_spacing]
+        stitch_group = self.running_stitch(path, spacing, self.running_stitch_tolerance, False, 0, "")
         stitch_group.stitches = zigzag_stitch(stitch_group.stitches, zigzag_spacing, stroke_width, pull_compensation)
 
         return stitch_group
diff --git a/lib/extensions/fill_to_stroke.py b/lib/extensions/fill_to_stroke.py
index c1b5ce9d..f1d32cbe 100644
--- a/lib/extensions/fill_to_stroke.py
+++ b/lib/extensions/fill_to_stroke.py
@@ -110,11 +110,11 @@ class FillToStroke(InkstitchExtension):
 
     def _get_high_res_polygon(self, polygon):
         # use running stitch method
-        runs = [even_running_stitch(line_string_to_point_list(polygon.exterior), 1, 0.1)]
+        runs = [even_running_stitch(line_string_to_point_list(polygon.exterior), [1], 0.1)]
         if len(runs[0]) < 3:
             return
         for interior in polygon.interiors:
-            shape = even_running_stitch(line_string_to_point_list(interior), 1, 0.1)
+            shape = even_running_stitch(line_string_to_point_list(interior), [1], 0.1)
             if len(shape) >= 3:
                 runs.append(shape)
         return MultiPolygon([(runs[0], runs[1:])])
diff --git a/lib/stitches/auto_fill.py b/lib/stitches/auto_fill.py
index bcde63e7..2573bf88 100644
--- a/lib/stitches/auto_fill.py
+++ b/lib/stitches/auto_fill.py
@@ -391,7 +391,7 @@ def fallback(shape, running_stitch_length, running_stitch_tolerance):
     boundary = ensure_multi_line_string(shape.boundary)
     outline = boundary.geoms[0]
 
-    return even_running_stitch(line_string_to_point_list(outline), running_stitch_length, running_stitch_tolerance)
+    return even_running_stitch(line_string_to_point_list(outline), [running_stitch_length], running_stitch_tolerance)
 
 
 @debug.time
@@ -941,7 +941,7 @@ def path_to_stitches(shape, path, travel_graph, fill_stitch_graph, angle, row_sp
             if fill_stitch_graph.has_edge(edge[0], edge[1], key='segment'):
                 travel_graph.remove_edges_from(fill_stitch_graph[edge[0]][edge[1]]['segment'].get('underpath_edges', []))
         else:
-            stitches.extend(travel(shape, travel_graph, edge, running_stitch_length, running_stitch_tolerance, skip_last, underpath))
+            stitches.extend(travel(shape, travel_graph, edge, [running_stitch_length], running_stitch_tolerance, skip_last, underpath))
 
         check_stop_flag()
 
diff --git a/lib/stitches/circular_fill.py b/lib/stitches/circular_fill.py
index 26b48f24..fb6303ea 100644
--- a/lib/stitches/circular_fill.py
+++ b/lib/stitches/circular_fill.py
@@ -79,7 +79,7 @@ def circular_fill(shape,
         if isinstance(line, shgeo.LineString):
             # use running stitch here to adjust the stitch length
             coords = running_stitch([Point(*point) for point in line.coords],
-                                    running_stitch_length,
+                                    [running_stitch_length],
                                     running_stitch_tolerance,
                                     enable_random_stitch_length,
                                     running_stitch_length_jitter,
@@ -162,6 +162,6 @@ def path_to_stitches(shape, path, travel_graph, fill_stitch_graph, running_stitc
 
             travel_graph.remove_edges_from(fill_stitch_graph[edge[0]][edge[1]]['segment'].get('underpath_edges', []))
         else:
-            stitches.extend(travel(shape, travel_graph, edge, running_stitch_length, running_stitch_tolerance, skip_last, underpath))
+            stitches.extend(travel(shape, travel_graph, edge, [running_stitch_length], running_stitch_tolerance, skip_last, underpath))
 
     return stitches
diff --git a/lib/stitches/contour_fill.py b/lib/stitches/contour_fill.py
index 0665aacb..6a3ed4ff 100644
--- a/lib/stitches/contour_fill.py
+++ b/lib/stitches/contour_fill.py
@@ -422,7 +422,7 @@ def inner_to_outer(tree, polygon, offset,
         smoothed = smooth_path(points, smoothness)
         points = clamp_path_to_polygon(smoothed, polygon)
 
-    stitches = running_stitch(points, stitch_length, tolerance, enable_random_stitch_length, random_sigma, random_seed)
+    stitches = running_stitch(points, [stitch_length], tolerance, enable_random_stitch_length, random_sigma, random_seed)
 
     return stitches
 
@@ -460,6 +460,9 @@ def _interpolate_linear_rings(ring1, ring2, max_stitch_length, start=None):
     # orders of magnitude faster because we're not building and querying a KDTree.
 
     num_points = int(20 * ring1.length / max_stitch_length)
+    if num_points <= 1:
+        return LineString()
+
     ring1_resampled = trimesh.path.traversal.resample_path(np.array(ring1.coords), count=num_points)
     ring2_resampled = trimesh.path.traversal.resample_path(np.array(ring2.coords), count=num_points)
 
@@ -535,7 +538,7 @@ def _spiral_fill(tree, stitch_length, tolerance, close_point, enable_random_stit
     path = spiral_maker(rings, stitch_length, starting_point)
     path = [Stitch(*stitch) for stitch in path]
 
-    return running_stitch(path, stitch_length, tolerance, enable_random_stitch_length, random_sigma, random_seed)
+    return running_stitch(path, [stitch_length], tolerance, enable_random_stitch_length, random_sigma, random_seed)
 
 
 def _get_spiral_rings(tree):
diff --git a/lib/stitches/fill.py b/lib/stitches/fill.py
index ad082b2d..e50c4007 100644
--- a/lib/stitches/fill.py
+++ b/lib/stitches/fill.py
@@ -63,7 +63,8 @@ def stitch_row(stitches, beg, end, angle, row_spacing, max_stitch_length, stagge
     stitches.append(beg)
 
     if enable_random_stitch_length:
-        stitches += split_segment_random_phase(beg, end, max_stitch_length, random_sigma, random_seed)
+        stitched_line = split_segment_random_phase(beg, end, max_stitch_length, random_sigma, random_seed)
+        stitches.extend([Stitch(stitch, tags=('fill_row',)) for stitch in stitched_line])
     else:
         # We want our stitches to look like this:
         #
diff --git a/lib/stitches/guided_fill.py b/lib/stitches/guided_fill.py
index 16f0f2e8..84d7600e 100644
--- a/lib/stitches/guided_fill.py
+++ b/lib/stitches/guided_fill.py
@@ -102,7 +102,7 @@ def path_to_stitches(shape, path, travel_graph, fill_stitch_graph,
 
             travel_graph.remove_edges_from(fill_stitch_graph[edge[0]][edge[1]]['segment'].get('underpath_edges', []))
         else:
-            stitches.extend(travel(shape, travel_graph, edge, running_stitch_length, running_stitch_tolerance, skip_last, underpath))
+            stitches.extend(travel(shape, travel_graph, edge, [running_stitch_length], running_stitch_tolerance, skip_last, underpath))
 
     return stitches
 
@@ -166,6 +166,7 @@ def take_only_line_strings(thing):
 def apply_stitches(line, max_stitch_length, num_staggers, row_spacing, row_num, threshold=None) -> shgeo.LineString:
     if num_staggers == 0:
         num_staggers = 1  # sanity check to avoid division by zero.
+    max_stitch_length = max_stitch_length[0]
     start = ((row_num / num_staggers) % 1) * max_stitch_length
     projections = np.arange(start, line.length, max_stitch_length)
     points = np.array([line.interpolate(projection).coords[0] for projection in projections])
@@ -275,9 +276,9 @@ def intersect_region_with_grating_guideline(shape, line, row_spacing, num_stagge
         if enable_random_stitch_length:
             points = [InkstitchPoint(*x) for x in offset_line.coords]
             stitched_line = shgeo.LineString(random_running_stitch(
-                points, max_stitch_length, tolerance, random_sigma, prng.join_args(random_seed, row)))
+                points, [max_stitch_length], tolerance, random_sigma, prng.join_args(random_seed, row)))
         else:
-            stitched_line = apply_stitches(offset_line, max_stitch_length, num_staggers, row_spacing, row)
+            stitched_line = apply_stitches(offset_line, [max_stitch_length], num_staggers, row_spacing, row)
         intersection = shape.intersection(stitched_line)
 
         if not intersection.is_empty and shape_envelope.intersects(stitched_line):
diff --git a/lib/stitches/linear_gradient_fill.py b/lib/stitches/linear_gradient_fill.py
index 589a1f23..4f2f3f74 100644
--- a/lib/stitches/linear_gradient_fill.py
+++ b/lib/stitches/linear_gradient_fill.py
@@ -127,9 +127,11 @@ def _get_lines(fill, shape, bounding_box, angle):
         if fill.enable_random_stitch_length:
             points = [InkstitchPoint(*x) for x in line]
             staggered_line = LineString(random_running_stitch(
-                points, fill.max_stitch_length, fill.running_stitch_tolerance, fill.random_stitch_length_jitter, prng.join_args(fill.random_seed, i)))
+                points,
+                [fill.max_stitch_length], fill.running_stitch_tolerance, fill.random_stitch_length_jitter, prng.join_args(fill.random_seed, i))
+            )
         else:
-            staggered_line = apply_stitches(LineString(line), fill.max_stitch_length, fill.staggers, fill.row_spacing, i)
+            staggered_line = apply_stitches(LineString(line), [fill.max_stitch_length], fill.staggers, fill.row_spacing, i)
         staggered_lines.append(staggered_line)
     return staggered_lines, bottom_line
 
diff --git a/lib/stitches/meander_fill.py b/lib/stitches/meander_fill.py
index 87c52e17..1883c97f 100644
--- a/lib/stitches/meander_fill.py
+++ b/lib/stitches/meander_fill.py
@@ -179,10 +179,10 @@ def post_process(points, shape, original_shape, fill):
     smoothed_points = [InkStitchPoint.from_tuple(point) for point in smoothed_points]
 
     if fill.zigzag_spacing > 0:
-        stitches = even_running_stitch(smoothed_points, fill.zigzag_spacing / 2, fill.running_stitch_tolerance)
+        stitches = even_running_stitch(smoothed_points, [fill.zigzag_spacing / 2], fill.running_stitch_tolerance)
         stitches = zigzag_stitch(stitches, fill.zigzag_spacing, fill.zigzag_width, (0, 0))
     else:
-        stitches = even_running_stitch(smoothed_points, fill.running_stitch_length, fill.running_stitch_tolerance)
+        stitches = even_running_stitch(smoothed_points, [fill.running_stitch_length], fill.running_stitch_tolerance)
 
     if fill.clip:
         # the stitch path may have self intersections
diff --git a/lib/stitches/ripple_stitch.py b/lib/stitches/ripple_stitch.py
index 804e5f15..2abb5963 100644
--- a/lib/stitches/ripple_stitch.py
+++ b/lib/stitches/ripple_stitch.py
@@ -4,6 +4,7 @@ from math import atan2, ceil
 import numpy as np
 from shapely.affinity import rotate, scale, translate
 from shapely.geometry import LineString, Point
+from shapely.ops import substring
 
 from ..elements import SatinColumn
 from ..utils import Point as InkstitchPoint
@@ -80,7 +81,7 @@ def _get_staggered_stitches(stroke, lines, skip_start):
     stitches = []
     stitch_length = stroke.running_stitch_length
     tolerance = stroke.running_stitch_tolerance
-    enable_random_stitch_length = stroke.enable_random_stitch_length
+    is_random = stroke.enable_random_stitch_length
     length_sigma = stroke.random_stitch_length_jitter
     random_seed = stroke.random_seed
     last_point = None
@@ -98,14 +99,18 @@ def _get_staggered_stitches(stroke, lines, skip_start):
         elif stroke.join_style == 1:
             should_reverse = (i + skip_start) % 2 == 1
 
-        if enable_random_stitch_length or stroke.staggers == 0:
+        if stroke.staggers == 0:
             if should_reverse and stroke.flip_copies:
                 line.reverse()
-            points = running_stitch(line, stitch_length, tolerance, enable_random_stitch_length, length_sigma, prng.join_args(random_seed, i))
-            stitched_line = connector + points
+            stitched_line = running_stitch(line, stitch_length, tolerance, is_random, length_sigma, prng.join_args(random_seed, i))
         else:
-            # uses the guided fill alforithm to stagger rows of stitches
-            points = list(apply_stitches(LineString(line), stitch_length, stroke.staggers, 0.5, i, tolerance).coords)
+            if len(stitch_length) > 1:
+                points = list(
+                    apply_stagger(line, stitch_length, stroke.staggers, i, tolerance, is_random, length_sigma, prng.join_args(random_seed, i)).coords
+                )
+            else:
+                # uses the guided fill alforithm to stagger rows of stitches
+                points = list(apply_stitches(LineString(line), stitch_length, stroke.staggers, 0.5, i, tolerance).coords)
 
             # simplifying the path in apply_stitches could have removed the start or end point
             # we can simply add it again, the minimum stitch length value will take care to remove possible duplicates
@@ -114,13 +119,33 @@ def _get_staggered_stitches(stroke, lines, skip_start):
             stitched_line = [InkstitchPoint(*point) for point in points]
             if should_reverse and stroke.flip_copies:
                 stitched_line.reverse()
-            stitched_line = connector + stitched_line
+
+        stitched_line = connector + stitched_line
 
         last_point = stitched_line[-1]
         stitches.extend(stitched_line)
     return stitches
 
 
+def apply_stagger(line, stitch_length, num_staggers, row_num, tolerance, is_random, stitch_length_sigma, random_seed):
+    if num_staggers == 0:
+        num_staggers = 1  # sanity check to avoid division by zero.
+    start = ((row_num / num_staggers) % 1) * sum(stitch_length)
+    first_segment = LineString(line[:2])
+    segment_length = max(first_segment.length, 0.1)
+    target_length = segment_length + 2 * start
+    scale_factor = target_length / segment_length
+    extended_line = scale(first_segment, scale_factor, scale_factor)
+
+    line = [InkstitchPoint(*extended_line.coords[0])] + line
+    stitched_row = running_stitch(line, stitch_length, tolerance, is_random, stitch_length_sigma, random_seed)
+    if len(stitched_row) <= 1:
+        return LineString()
+
+    stitched_line = LineString(stitched_row)
+    return substring(stitched_line, start, stitched_line.length)
+
+
 def _adjust_skip(stroke, num_lines, skip):
     if stroke.skip_start + stroke.skip_end >= num_lines:
         return 0
@@ -202,7 +227,7 @@ def _get_helper_lines(stroke):
 
 def _get_satin_ripple_helper_lines(stroke):
     # if grid_size has a number use this, otherwise use running_stitch_length
-    length = stroke.grid_size or stroke.running_stitch_length
+    length = stroke.grid_size or min(stroke.running_stitch_length)
 
     # use satin column points for satin like build ripple stitches
     rail_pairs = SatinColumn(stroke.node).plot_points_on_rails(length)
diff --git a/lib/stitches/running_stitch.py b/lib/stitches/running_stitch.py
index 8b8add7e..058ee565 100644
--- a/lib/stitches/running_stitch.py
+++ b/lib/stitches/running_stitch.py
@@ -210,11 +210,12 @@ def take_stitch(start: Point, points: typing.Sequence[Point], idx: int, stitch_l
     return points[-1], None
 
 
-def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: float, tolerance: float) -> typing.List[Point]:
+def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: typing.List[float], tolerance: float, stitch_length_pos: int = 0) -> \
+        typing.Tuple[typing.List[Point], int]:
     # Will split a straight line into even-length stitches while still handling curves correctly.
     # Includes end point but not start point.
     if len(points) < 2:
-        return []
+        return [], stitch_length_pos
     distLeft = [0] * len(points)
     for j in reversed(range(0, len(points) - 1)):
         distLeft[j] = distLeft[j + 1] + points[j].distance(points[j+1])
@@ -225,26 +226,33 @@ def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: float, to
     while i is not None and i < len(points):
         d = last.distance(points[i]) + distLeft[i]
         if d == 0:
-            return stitches
-        stitch_len = d / math.ceil(d / stitch_length) + 0.000001  # correction for rounding error
+            return stitches, stitch_length_pos
+        stitch_len = d / math.ceil(d / stitch_length[stitch_length_pos]) + 0.000001  # correction for rounding error
 
         stitch, newidx = take_stitch(last, points, i, stitch_len, tolerance)
         i = newidx
         if stitch is not None:
             stitches.append(stitch)
             last = stitch
-    return stitches
+            stitch_length_pos += 1
+            if stitch_length_pos > len(stitch_length) - 1:
+                stitch_length_pos = 0
+    return stitches, stitch_length_pos
+
+
+def stitch_curve_randomly(
+      points: typing.Sequence[Point],
+      stitch_length: typing.List[float], tolerance: float, stitch_length_sigma: float,
+      random_seed: str, stitch_length_pos: int = 0) -> typing.Tuple[typing.List[Point], int]:
 
+    min_stitch_length = max(0, stitch_length[stitch_length_pos] * (1 - stitch_length_sigma))
+    max_stitch_length = stitch_length[stitch_length_pos] * (1 + stitch_length_sigma)
 
-def stitch_curve_randomly(points: typing.Sequence[Point], stitch_length: float, tolerance: float, stitch_length_sigma: float, random_seed: str) ->\
-      typing.List[Point]:
-    min_stitch_length = max(0, stitch_length * (1 - stitch_length_sigma))
-    max_stitch_length = stitch_length * (1 + stitch_length_sigma)
     # Will split a straight line into stitches of random length within the range.
     # Attempts to randomize phase so that the distribution of outputs does not depend on direction.
     # Includes end point but not start point.
     if len(points) < 2:
-        return []
+        return [], stitch_length_pos
 
     i: typing.Optional[int] = 1
     last = points[0]
@@ -252,6 +260,13 @@ def stitch_curve_randomly(points: typing.Sequence[Point], stitch_length: float,
     stitches = []
     rand_iter = iter(prng.iter_uniform_floats(random_seed))
     while i is not None and i < len(points):
+        if len(stitch_length) > 1:
+            min_stitch_length = max(0, stitch_length[stitch_length_pos] * (1 - stitch_length_sigma))
+            max_stitch_length = stitch_length[stitch_length_pos] * (1 + stitch_length_sigma)
+            stitch_length_pos += 1
+            if stitch_length_pos > len(stitch_length) - 1:
+                stitch_length_pos = 0
+
         r = next(rand_iter)
         # If the last stitch was shortened due to tolerance (or this is the first stitch),
         # reduce the lower length limit to randomize the phase. This prevents moiré and asymmetry.
@@ -263,7 +278,7 @@ def stitch_curve_randomly(points: typing.Sequence[Point], stitch_length: float,
             stitches.append(stitch)
             last_shortened = min(last.distance(stitch) / stitch_len, 1.0)
             last = stitch
-    return stitches
+    return stitches, stitch_length_pos
 
 
 def path_to_curves(points: typing.List[Point], min_len: float):
@@ -309,10 +324,12 @@ def even_running_stitch(points, stitch_length, tolerance):
     if not points:
         return
     stitches = [points[0]]
+    last_stitch_length_pos = 0
     for curve in path_to_curves(points, 2 * tolerance):
         # segments longer than twice the tolerance will usually be forced by it, so set that as the minimum for corner detection
         check_stop_flag()
-        stitches.extend(stitch_curve_evenly(curve, stitch_length, tolerance))
+        stitched_curve, last_stitch_length_pos = stitch_curve_evenly(curve, stitch_length, tolerance, last_stitch_length_pos)
+        stitches.extend(stitched_curve)
     return stitches
 
 
@@ -323,10 +340,14 @@ def random_running_stitch(points, stitch_length, tolerance, stitch_length_sigma,
     if not points:
         return
     stitches = [points[0]]
+    last_stitch_length_pos = 0
     for i, curve in enumerate(path_to_curves(points, 2 * tolerance)):
         # segments longer than twice the tolerance will usually be forced by it, so set that as the minimum for corner detection
         check_stop_flag()
-        stitches.extend(stitch_curve_randomly(curve, stitch_length, tolerance, stitch_length_sigma, prng.join_args(random_seed, i)))
+        stitched_curve, last_stitch_length_pos = stitch_curve_randomly(
+            curve, stitch_length, tolerance, stitch_length_sigma, prng.join_args(random_seed, i), last_stitch_length_pos
+        )
+        stitches.extend(stitched_curve)
     return stitches
 
 
diff --git a/lib/stitches/tartan_fill.py b/lib/stitches/tartan_fill.py
index c25bb435..521919a0 100644
--- a/lib/stitches/tartan_fill.py
+++ b/lib/stitches/tartan_fill.py
@@ -155,7 +155,7 @@ def _generate_herringbone_lines(
         staggered_lines = []
         for i, line in enumerate(lines):
             linestring = LineString(line)
-            staggered_line = apply_stitches(linestring, fill.max_stitch_length, fill.staggers, fill.row_spacing, i)
+            staggered_line = apply_stitches(linestring, [fill.max_stitch_length], fill.staggers, fill.row_spacing, i)
             # make sure we do not ommit the very first or very last point (it would confuse our sorting algorithm)
             staggered_line = LineString([linestring.coords[0]] + list(staggered_line.coords) + [linestring.coords[-1]])
             staggered_lines.append(staggered_line)
@@ -205,7 +205,7 @@ def _generate_tartan_lines(
     staggered_lines = []
     for i, line in enumerate(lines):
         linestring = LineString(line)
-        staggered_line = apply_stitches(linestring, fill.max_stitch_length, fill.staggers, fill.row_spacing, i)
+        staggered_line = apply_stitches(linestring, [fill.max_stitch_length], fill.staggers, fill.row_spacing, i)
         # make sure we do not ommit the very first or very last point (it would confuse our sorting algorithm)
         staggered_line = LineString([linestring.coords[0]] + list(staggered_line.coords) + [linestring.coords[-1]])
         staggered_lines.append(staggered_line)
diff --git a/lib/utils/settings.py b/lib/utils/settings.py
index b2220ef9..82d8938a 100644
--- a/lib/utils/settings.py
+++ b/lib/utils/settings.py
@@ -49,7 +49,7 @@ class GlobalSettings(MutableMapping):
         # We set create=False here because this code is executed on module load
         # and via imports also runs on generate-inx-files, which with the Nix
         # package manager is executed with a non-writable home directory.
-        user_dir = get_user_dir(create=False)
+        user_dir = get_user_dir(create=True)
         self._settings_file = os.path.join(user_dir, "settings.json")
         self._settings = {}
 
diff --git a/lib/utils/smoothing.py b/lib/utils/smoothing.py
index 1511b0a3..c451140c 100644
--- a/lib/utils/smoothing.py
+++ b/lib/utils/smoothing.py
@@ -44,7 +44,7 @@ def smooth_path(path, smoothness=1.0, iterations=5):
     #
     # Fortunately, we can convert the path to segments that are mostly the same
     # length by using the running stitch algorithm.
-    points = stitch_curve_evenly(points, smoothness * 5, smoothness * 2)
+    points, _ = stitch_curve_evenly(points, [smoothness * 5], smoothness * 2)
     points = np.array(points)
     for _ in range(iterations):
         ll = points.repeat(2, axis=0)