add randomization options to linear gradient fill (#3311)

lib/elements/fill_stitch.py

@@ -496,7 +496,8 @@ class FillStitch(EmbroideryElement):
            select_items=[('fill_method', 'auto_fill'),
                          ('fill_method', 'contour_fill'),
                          ('fill_method', 'guided_fill'),
-                         ('fill_method', 'circular_fill')],
+                         ('fill_method', 'circular_fill'),
+                         ('fill_method', 'linear_gradient_fill'),],
            default=False,
            sort_index=44)
     def enable_random_stitch_length(self):
@@ -511,7 +512,8 @@ class FillStitch(EmbroideryElement):
            select_items=[('fill_method', 'auto_fill'),
                          ('fill_method', 'contour_fill'),
                          ('fill_method', 'guided_fill'),
-                         ('fill_method', 'circular_fill')],
+                         ('fill_method', 'circular_fill'),
+                         ('fill_method', 'linear_gradient_fill'),],
            default=10,
            sort_index=46)
     def random_stitch_length_jitter(self):
@@ -736,7 +738,8 @@ class FillStitch(EmbroideryElement):
                          ('fill_method', 'contour_fill'),
                          ('fill_method', 'guided_fill'),
                          ('fill_method', 'circular_fill'),
-                         ('fill_method', 'meander_fill')],
+                         ('fill_method', 'meander_fill'),
+                         ('fill_method', 'linear_gradient_fill')],
            type='random_seed',
            default='',
            sort_index=100)

lib/stitches/linear_gradient_fill.py

@@ -12,14 +12,18 @@ from shapely import segmentize
 from shapely.affinity import rotate
 from shapely.geometry import LineString, MultiLineString, Point, Polygon
 
+from lib.utils import prng
+
 from ..stitch_plan import StitchGroup
 from ..svg import get_node_transform
+from ..utils.geometry import Point as InkstitchPoint
 from ..utils.geometry import ensure_multi_line_string
 from ..utils.threading import check_stop_flag
 from .auto_fill import (build_fill_stitch_graph, build_travel_graph,
                         find_stitch_path, graph_make_valid)
 from .circular_fill import path_to_stitches
 from .guided_fill import apply_stitches
+from .running_stitch import random_running_stitch
 
 
 def linear_gradient_fill(fill, shape, starting_point, ending_point):
@@ -117,7 +121,12 @@ def _get_lines(fill, shape, bounding_box, angle):
     # stagger stitched lines according to user settings
     staggered_lines = []
     for i, line in enumerate(lines):
-        staggered_line = apply_stitches(LineString(line), fill.max_stitch_length, fill.staggers, fill.row_spacing, i)
+        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)))
+        else:
+            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