Possible fix for parallel offset in guided fill for macOS (#2321)

* fix parallel offset in guided fill for macOS

* ripple grid start position

* circular ripple grid

lib/stitches/guided_fill.py

@@ -247,7 +247,11 @@ def intersect_region_with_grating_guideline(shape, line, row_spacing, num_stagge
             translate_amount = translate_direction * row * row_spacing
             offset_line = translate(line, xoff=translate_amount.x, yoff=translate_amount.y)
         elif strategy == 1:
-            offset_line = line.parallel_offset(row * row_spacing, 'left', join_style=shgeo.JOIN_STYLE.round)
+            offset = row * row_spacing
+            if offset == 0:
+                # this is needed for macOS builds
+                offset = 0.0001
+            offset_line = line.parallel_offset(offset, 'left', join_style=shgeo.JOIN_STYLE.round)
 
         offset_line = clean_offset_line(offset_line)
 

lib/stitches/ripple_stitch.py

@@ -36,7 +36,7 @@ def ripple_stitch(stroke):
         stitches.reverse()
 
     if stroke.grid_size != 0:
-        stitches.extend(_do_grid(stroke, helper_lines, skip_start, skip_end))
+        stitches.extend(_do_grid(stroke, helper_lines, skip_start, skip_end, is_linear))
 
     return _repeat_coords(stitches, stroke.repeats)
 
@@ -229,7 +229,7 @@ def _target_point_helper_lines(stroke, outline):
     return helper_lines
 
 
-def _adjust_helper_lines_for_grid(stroke, helper_lines, skip_start, skip_end):
+def _adjust_helper_lines_for_grid(stroke, helper_lines, skip_start, skip_end, is_linear):
     num_lines = len(helper_lines[0])
     count = num_lines - skip_start - skip_end
 
@@ -239,19 +239,26 @@ def _adjust_helper_lines_for_grid(stroke, helper_lines, skip_start, skip_end):
                                       (not stroke.reverse and skip_start % 2 != 0))):
         count += 1
 
+    if not is_linear:
+        count = 1
+        if stroke.reverse:
+            count = 0
+
     if count % 2 != 0:
         helper_lines.reverse()
     return helper_lines
 
 
-def _do_grid(stroke, helper_lines, skip_start, skip_end):
+def _do_grid(stroke, helper_lines, skip_start, skip_end, is_linear):
-    helper_lines = _adjust_helper_lines_for_grid(stroke, helper_lines, skip_start, skip_end)
+    helper_lines = _adjust_helper_lines_for_grid(stroke, helper_lines, skip_start, skip_end, is_linear)
     grid = []
     for i, helper in enumerate(helper_lines):
         end = len(helper) - skip_end
         points = helper[skip_start:end]
         if stroke.reverse:
             points.reverse()
+        if len(helper_lines) - skip_start - skip_end % 2 != 0:
+            points.reverse()
         grid.append(points)
     grid = _get_staggered_stitches(stroke, grid, 0)
     return grid