add bean stitch option

2 files changed, 45 insertions, 5 deletions

diff --git a/lib/elements/stroke.py b/lib/elements/stroke.py
index e8eb4783..e086ccd9 100644
--- a/lib/elements/stroke.py
+++ b/lib/elements/stroke.py
@@ -4,7 +4,7 @@ import shapely.geometry
 from .element import param, EmbroideryElement, Patch
 from ..i18n import _
 from ..utils import cache, Point
-from ..stitches import running_stitch
+from ..stitches import running_stitch, bean_stitch
 from ..svg import parse_length_with_units
 
 warned_about_legacy_running_stitch = False
@@ -27,18 +27,28 @@ class Stroke(EmbroideryElement):
         return self.get_style("stroke-dasharray") is not None
 
     @property
-    @param('running_stitch_length_mm', _('Running stitch length'), unit='mm', type='float', default=1.5)
+    @param('running_stitch_length_mm', _('Running stitch length'), unit='mm', type='float', default=1.5, sort_index=3)
     def running_stitch_length(self):
         return max(self.get_float_param("running_stitch_length_mm", 1.5), 0.01)
 
     @property
-    @param('zigzag_spacing_mm', _('Zig-zag spacing (peak-to-peak)'), unit='mm', type='float', default=0.4)
+    @param('bean_stitch_repeats',
+           _('Bean stitch number of repeats'),
+           tooltip=_('Backtrack each stitch this many times.  A value of 1 would triple each stitch (forward, back, forward).  A value of 2 would quintuple each stitch, etc.  Only applies to running stitch.'),
+           type='int',
+           default=0,
+           sort_index=2)
+    def bean_stitch_repeats(self):
+        return self.get_int_param("bean_stitch_repeats", 0)
+
+    @property
+    @param('zigzag_spacing_mm', _('Zig-zag spacing (peak-to-peak)'), unit='mm', type='float', default=0.4, sort_index=3)
     @cache
     def zigzag_spacing(self):
         return max(self.get_float_param("zigzag_spacing_mm", 0.4), 0.01)
 
     @property
-    @param('repeats', _('Repeats'), type='int', default="1")
+    @param('repeats', _('Repeats'), type='int', default="1", sort_index=1)
     def repeats(self):
         return self.get_int_param("repeats", 1)
 
@@ -58,7 +68,7 @@ class Stroke(EmbroideryElement):
         return shapely.geometry.MultiLineString(line_strings)
 
     @property
-    @param('manual_stitch', _('Manual stitch placement'), tooltip=_("Stitch every node in the path.  Stitch length and zig-zag spacing are ignored."), type='boolean', default=False)
+    @param('manual_stitch', _('Manual stitch placement'), tooltip=_("Stitch every node in the path.  Stitch length and zig-zag spacing are ignored."), type='boolean', default=False, sort_index=0)
     def manual_stitch_mode(self):
         return self.get_boolean_param('manual_stitch')
 
@@ -139,6 +149,7 @@ class Stroke(EmbroideryElement):
             repeated_path.extend(this_path)
 
         stitches = running_stitch(repeated_path, stitch_length)
+        stitches = bean_stitch(stitches, self.bean_stitch_repeats)
 
         return Patch(self.color, stitches)
 
diff --git a/lib/stitches/running_stitch.py b/lib/stitches/running_stitch.py
index 96075e7a..5f8ed21e 100644
--- a/lib/stitches/running_stitch.py
+++ b/lib/stitches/running_stitch.py
@@ -1,3 +1,6 @@
+from copy import copy
+
+
 """ Utility functions to produce running stitches. """
 
 
@@ -64,3 +67,29 @@ def running_stitch(points, stitch_length):
         output.append(segment_start)
 
     return output
+
+
+def bean_stitch(stitches, repeats):
+    """Generate bean stitch from a set of stitches.
+
+    "Bean" stitch is made by backtracking each stitch to make it heaver.  A
+    simple bean stitch would be two stitches forward, one stitch back, two
+    stitches forward, etc.  This would result in each stitch being tripled.
+
+    We'll say that the above counts as 1 repeat.  Backtracking each stitch
+    repeatedly will result in a heavier bean stitch.  There will always be
+    an odd number of threads piled up for each stitch.
+    """
+
+    if len(stitches) < 2:
+        return stitches
+
+    new_stitches = [stitches[0]]
+
+    for stitch in stitches:
+        new_stitches.append(stitch)
+
+        for i in xrange(repeats):
+            new_stitches.extend(copy(new_stitches[-2:]))
+
+    return new_stitches