fix gap after auto-route satin (#2907)

lib/elements/satin_column.py

@@ -795,7 +795,7 @@ class SatinColumn(EmbroideryElement):
 
         return self._csp_to_satin(self.csp)
 
-    def split(self, split_point):
+    def split(self, split_point, cut_points=None):
         """Split a satin into two satins at the specified point
 
         split_point is a point on or near one of the rails, not at one of the
@@ -813,13 +813,14 @@ class SatinColumn(EmbroideryElement):
         their transforms applied.
         """
 
-        cut_points = self._find_cut_points(split_point)
+        if cut_points is None:
+            cut_points = self.find_cut_points(split_point)
         path_lists = self._cut_rails(cut_points)
         self._assign_rungs_to_split_rails(path_lists)
         self._add_rungs_if_necessary(path_lists)
         return [self._path_list_to_satins(path_list) for path_list in path_lists]
 
-    def _find_cut_points(self, split_point):
+    def find_cut_points(self, split_point):
         """Find the points on each satin corresponding to the split point.
 
         split_point is a point that is near but not necessarily touching one

lib/stitches/auto_satin.py

@@ -70,12 +70,18 @@ class SatinSegment(object):
     def to_satin(self):
         satin = self.satin
 
+        # get cut points before actually cutting the satin to avoid
+        # rounding errors which may produce gaps in between the satins
         if self.start > 0.0:
-            before, satin = satin.split(self.start)
-
+            start = satin.find_cut_points(self.start)
         if self.end < 1.0:
-            satin, after = satin.split(
-                (self.end - self.start) / (1.0 - self.start))
+            end = satin.find_cut_points(self.end)
+
+        # cut satin
+        if self.start > 0.0:
+            before, satin = satin.split(None, cut_points=start)
+        if self.end < 1.0:
+            satin, after = satin.split(None, cut_points=end)
 
         if self.reverse:
             satin = satin.reverse()