inkstitch/embroider.py

#!/usr/bin/python
#
# documentation: see included index.html
# LICENSE:
# Copyright 2010 by Jon Howell,
# Originally licensed under <a href="http://www.gnu.org/licenses/quick-guide-gplv3.html">GPLv3</a>.
# Copyright 2015 by Bas Wijnen <wijnen@debian.org>.
# New parts are licensed under AGPL3 or later.
# (Note that this means this work is licensed under the common part of those two: AGPL version 3.)
#
# Important resources:
# lxml interface for walking SVG tree:
# http://codespeak.net/lxml/tutorial.html#elementpath
# Inkscape library for extracting paths from SVG:
# http://wiki.inkscape.org/wiki/index.php/Python_modules_for_extensions#simplepath.py
# Shapely computational geometry library:
# http://gispython.org/shapely/manual.html#multipolygons
# Embroidery file format documentation:
# http://www.achatina.de/sewing/main/TECHNICL.HTM

import sys
sys.path.append("/usr/share/inkscape/extensions")
import os
import subprocess
from copy import deepcopy
import time
import inkex
import simplepath
import simplestyle
import simpletransform
from cspsubdiv import cspsubdiv
import cubicsuperpath
import PyEmb
import math
import random
import operator
import lxml.etree as etree
from lxml.builder import E
import shapely.geometry as shgeo
import shapely.affinity as affinity
from pprint import pformat

dbg = open("/tmp/embroider-debug.txt", "w")
PyEmb.dbg = dbg
#pixels_per_millimeter = 90.0 / 25.4

#this actually makes each pixel worth one tenth of a millimeter
pixels_per_millimeter = 10

# a 0.5pt stroke becomes a straight line.
STROKE_MIN = 0.5

def parse_boolean(s):
    if isinstance(s, bool):
        return s
    else:
        return s and s.lower in ('yes', 'y', 'true', 't', '1')

def get_param(node, param, default):
    value = node.get("embroider_" + param)

    if value is None or not value.strip():
        return default

    return value.strip()

def get_boolean_param(node, param, default=False):
    value = get_param(node, param, default)

    return parse_boolean(value)

def get_float_param(node, param, default=None):
    value = get_param(node, param, default)

    try:
        return float(value)
    except ValueError:
        return default

def get_int_param(node, param, default=None):
    value = get_param(node, param, default)

    try:
        return int(value)
    except ValueError:
        return default

def parse_path(node):
    path = cubicsuperpath.parsePath(node.get("d"))

#    print >> sys.stderr, pformat(path)

    # start with the identity transform
    transform = [[1.0, 0.0, 0.0], [0.0, 1.0, 0.0]]

    # combine this node's transform with all parent groups' transforms
    transform = simpletransform.composeParents(node, transform)

    # apply the combined transform to this node's path
    simpletransform.applyTransformToPath(transform, path)

    return path

def flatten(path, flatness):
    """approximate a path containing beziers with a series of points"""

    cspsubdiv(path, flatness)

    flattened = []

    for comp in path:
        vertices = []
        for ctl in comp:
            vertices.append((ctl[1][0], ctl[1][1]))
        flattened.append(vertices)

    return flattened

def bboxarea(poly):
	x0=None
	x1=None
	y0=None
	y1=None
	for pt in poly:
		if (x0==None or pt[0]<x0): x0 = pt[0]
		if (x1==None or pt[0]>x1): x1 = pt[0]
		if (y0==None or pt[1]<y0): y0 = pt[1]
		if (y1==None or pt[1]>y1): y1 = pt[1]
	return (x1-x0)*(y1-y0)

def area(poly):
	return bboxarea(poly)

def byarea(a,b):
	return -cmp(area(a), area(b))

def cspToShapelyPolygon(path):
	poly_ary = []
	for sub_path in path:
		point_ary = []
		last_pt = None
		for pt in sub_path:
			if (last_pt!=None):
				vp = (pt[0]-last_pt[0],pt[1]-last_pt[1])
				dp = math.sqrt(math.pow(vp[0],2.0)+math.pow(vp[1],2.0))
				#dbg.write("dp %s\n" % dp)
				if (dp > 0.01):
					# I think too-close points confuse shapely.
					point_ary.append(pt)
					last_pt = pt
			else:
				last_pt = pt
		poly_ary.append(point_ary)
	# shapely's idea of "holes" are to subtract everything in the second set
	# from the first. So let's at least make sure the "first" thing is the
	# biggest path.
	poly_ary.sort(byarea)

	polygon = shgeo.MultiPolygon([(poly_ary[0], poly_ary[1:])])
	return polygon

def shapelyCoordsToSvgD(geo):
	coords = list(geo.coords)
	new_path = []
	new_path.append(['M', coords[0]])
	for c in coords[1:]:
		new_path.append(['L', c])
	return simplepath.formatPath(new_path)

def shapelyLineSegmentToPyTuple(shline):
	tuple = ((shline.coords[0][0],shline.coords[0][1]),
			(shline.coords[1][0],shline.coords[1][1]))
	return tuple

def dupNodeAttrs(node):
	n2 = E.node()
	for k in node.attrib.keys():
		n2.attrib[k] = node.attrib[k]
	del n2.attrib["id"]
	del n2.attrib["d"]
	return n2

class Patch:
	def __init__(self, color, sortorder, stitches=None):
		self.color = color
		self.sortorder = sortorder
		if (stitches!=None):
			self.stitches = stitches
		else:
			self.stitches = []

	def addStitch(self, stitch):
		self.stitches.append(stitch)

	def reverse(self):
		return Patch(self.color, self.sortorder, self.stitches[::-1])

class DebugHole:
	pass

class PatchList:
	def __init__(self, patches):
		self.patches = patches

	def __len__(self):
		return len(self.patches)

	def sort_by_sortorder(self):
		def by_sort_order(a,b):
			return cmp(a.sortorder, b.sortorder)
		self.patches.sort(by_sort_order)

	def partition_by_color(self):
		self.sort_by_sortorder()
		#dbg.write("Sorted by sortorder:\n");
		#dbg.write("  %s\n" % ("\n".join(map(lambda p: str(p.sortorder), self.patches))))
		out = []
		lastPatch = None
		for patch in self.patches:
			if (lastPatch!=None and patch.sortorder==lastPatch.sortorder):
				out[-1].patches.append(patch)
			else:
				out.append(PatchList([patch]))
			lastPatch = patch
		#dbg.write("Emitted %s partitions\n" % len(out))
		return out
		
	def tsp_by_color(self):
		list_of_patchLists = self.partition_by_color()
		for patchList in list_of_patchLists:
			patchList.traveling_salesman()
		return PatchList(reduce(operator.add,
			map(lambda pl: pl.patches, list_of_patchLists)))

#	# TODO apparently dead code; replaced by partition_by_color above
#	def clump_like_colors_together(self):
#		out = PatchList([])
#		lastPatch = None
#		for patch in self.patches:
#			if (lastPatch!=None and patch.color==lastPatch.color):
#				out.patches[-1] = Patch(
#					out.patches[-1].color,
#					out.patches[-1].sortorder,
#					out.patches[-1].stitches+patch.stitches)
#			else:
#				out.patches.append(patch)
#			lastPatch = patch
#		return out

	def get(self, i):
		if (i<0 or i>=len(self.patches)):
			return None
		return self.patches[i]

	def cost(self, a, b):
		if (a==None or b==None):
			rc = 0.0
		else:
			rc = (a.stitches[-1] - b.stitches[0]).length()
		#dbg.write("cost(%s, %s) = %5.1f\n" % (a, b, rc))
		return rc

	def try_swap(self, i, j):
		# i,j are indices;
		#dbg.write("swap(%d, %d)\n" % (i,j))
		oldCost = (
			 self.cost(self.get(i-1), self.get(i))
			+self.cost(self.get(i), self.get(i+1))
			+self.cost(self.get(j-1), self.get(j))
			+self.cost(self.get(j), self.get(j+1)))
		npi = self.get(j)
		npj = self.get(i)
		rpi = npi.reverse()
		rpj = npj.reverse()
		options = [
			(npi,npj),
			(rpi,npj),
			(npi,rpj),
			(rpi,rpj),
		]
		def costOf(np):
			(npi,npj) = np
			return (
				 self.cost(self.get(i-1), npi)
				+self.cost(npi, self.get(i+1))
				+self.cost(self.get(j-1), npj)
				+self.cost(npj, self.get(j+1)))
		costs = map(lambda o: (costOf(o), o), options)
		costs.sort()
		(cost,option) = costs[0]
		savings = oldCost - cost
		if (savings > 0):
			self.patches[i] = option[0]
			self.patches[j] = option[1]
			success = "!"
		else:
			success = "."

		#dbg.write("old %5.1f new %5.1f savings: %5.1f\n" % (oldCost, cost, savings))
		return success

	def try_reverse(self, i):
		#dbg.write("reverse(%d)\n" % i)
		oldCost = (self.cost(self.get(i-1), self.get(i))
			+self.cost(self.get(i), self.get(i+1)))
		reversed = self.get(i).reverse()
		newCost = (self.cost(self.get(i-1), reversed)
			+self.cost(reversed, self.get(i+1)))
		savings = oldCost - newCost
		if (savings > 0.0):
			self.patches[i] = reversed
			success = "#"
		else:
			success = "_"
		return success

	def traveling_salesman(self):
		# shockingly, this is non-optimal and pretty much non-efficient. Sorry.
		self.centroid = PyEmb.Point(0.0,0.0)
		self.pointList = []
		for patch in self.patches:
			def visit(idx):
				ep = deepcopy(patch.stitches[idx])
				ep.patch = patch
				self.centroid+=ep
				self.pointList.append(ep)

			visit(0)
			visit(-1)

		self.centroid = self.centroid.mul(1.0/float(len(self.pointList)))

		def linear_min(list, func):
			min_item = None
			min_value = None
			for item in list:
				value = func(item)
				#dbg.write('linear_min %s: value %s => %s (%s)\n' % (func, item, value, value<min_value))
				if (min_value==None or value<min_value):
					min_item = item
					min_value = value
			#dbg.write('linear_min final item %s value %s\n' % (min_item, min_value))
			return min_item

		sortedPatchList = PatchList([])
		def takePatchStartingAtPoint(point):
			patch = point.patch
			#dbg.write("takePatchStartingAtPoint angling for patch %s--%s\n" % (patch.stitches[0],patch.stitches[-1]))
			self.pointList = filter(lambda pt: pt.patch!=patch, self.pointList)
			reversed = ""
			if (point!=patch.stitches[0]):
				reversed = " (reversed)"
				#dbg.write('patch.stitches[0] %s point %s match %s\n' % (patch.stitches[0], point, point==patch.stitches[0]))
				patch = patch.reverse()
			sortedPatchList.patches.append(patch)
			#dbg.write('took patch %s--%s %s\n' % (patch.stitches[0], patch.stitches[-1], reversed))

		# Take the patch farthest from the centroid first
		# O(n)
		#dbg.write('centroid: %s\n' % self.centroid)
		def neg_distance_from_centroid(p):
			return -(p-self.centroid).length()
		farthestPoint = linear_min(self.pointList, neg_distance_from_centroid)
		takePatchStartingAtPoint(farthestPoint)
		#sortedPatchList.patches[0].color = "#000000"

		# Then greedily take closer-and-closer patches
		# O(n^2)
		while (len(self.pointList)>0):
			#dbg.write('pass %s\n' % len(self.pointList));
			last_point = sortedPatchList.patches[-1].stitches[-1]
			#dbg.write('last_point now %s\n' % last_point)
			def distance_from_last_point(p):
				return (p-last_point).length()
			nearestPoint = linear_min(self.pointList, distance_from_last_point)
			takePatchStartingAtPoint(nearestPoint)

		# install the initial result
		self.patches = sortedPatchList.patches

		if (1):
			# Then hill-climb.
			#dbg.write("len(self.patches) = %d\n" % len(self.patches))
			count = 0
			successStr = ""
			while (count < 100):
				i = random.randint(0, len(self.patches)-1)
				j = random.randint(0, len(self.patches)-1)
				successStr += self.try_swap(i,j)

				count += 1
			# tidy up at end as best we can
			for i in range(len(self.patches)):
				successStr += self.try_reverse(i)

			#dbg.write("success: %s\n" % successStr)

class EmbroideryObject:
	def __init__(self, patchList, row_spacing_px):
		self.patchList = patchList
		self.row_spacing_px = row_spacing_px


	def make_preamble_stitch(self, lastp, nextp):
		def fromPolar(r, phi):
			x = r * math.cos(phi)
			y = r * math.sin(phi)
			return (x, y)

		def toPolar(x, y):
			r = math.sqrt(x ** 2 + y ** 2)
			if r == 0:
				phi = 0
			elif y == 0:
				phi = 0 if x > 0 else math.pi
			else:
				phi = cmp(y, 0) * math.acos(x / r)
			return (r, phi)

		v = nextp - lastp
		(r, phi) = toPolar(v.x, v.y)

		PREAMBLE_MAX_DIST = 0.5 * pixels_per_millimeter  # 1/2mm
		if r < PREAMBLE_MAX_DIST:
			# nextp is close enough to lastp, so we don't generate
			# extra points in between, but just use nextp
			return nextp
		r = PREAMBLE_MAX_DIST
		(x, y) = fromPolar(r, phi)
		return PyEmb.Point(x, y) + lastp

	def emit_file(self, filename, output_format, collapse_len_px, add_preamble):
		emb = PyEmb.Embroidery()
		lastStitch = None
		lastColor = None
		for patch in self.patchList.patches:
			jumpStitch = True
			for stitch in patch.stitches:
                                if lastStitch and lastColor == patch.color:
                                        c = math.sqrt((stitch.x - lastStitch.x) ** 2 + (stitch.y - lastStitch.y) ** 2)
					#dbg.write("stitch length: %f (%d/%d -> %d/%d)\n" % (c, lastStitch.x, lastStitch.y, stitch.x, stitch.y))

                                        if c == 0:
                                                # filter out duplicate successive stitches
                                                jumpStitch = False
                                                continue

                                        if jumpStitch:
                                                # consider collapsing jump stich, if it is pretty short
                                                if c < collapse_len_px:
							#dbg.write("... collapsed\n")
                                                        jumpStitch = False

				#dbg.write("stitch color %s\n" % patch.color)

				newStitch = PyEmb.Point(stitch.x, -stitch.y)
				newStitch.color = patch.color
				newStitch.jumpStitch = jumpStitch
				emb.addStitch(newStitch)

				if jumpStitch and add_preamble != "0":
					locs = [ newStitch ]
					i = 0
					nextp = PyEmb.Point(patch.stitches[i].x, -patch.stitches[i].y)

					try:
						for j in xrange(1, 4):
							if locs[-1] == nextp:
								i += 1
								nextp = PyEmb.Point(patch.stitches[i].x, -patch.stitches[i].y)
							locs.append(self.make_preamble_stitch(locs[-1], nextp))
					except IndexError:
						# happens when the patch is very short and we increment i beyond the number of stitches
						pass
					#dbg.write("preamble locations: %s\n" % locs)

					for j in add_preamble[1:]:
						try:
							stitch = deepcopy(locs[int(j)])
							stitch.color = patch.color
							stitch.jumpStitch = False
							emb.addStitch(stitch)
						except IndexError:
							pass

				jumpStitch = False
				lastStitch = newStitch
				lastColor = patch.color

		dx, dy = emb.translate_to_origin()
		emb.scale(1.0/pixels_per_millimeter)

		fp = open(filename, "wb")

		if output_format == "melco":
			fp.write(emb.export_melco(dbg))
		elif output_format == "csv":
			fp.write(emb.export_csv(dbg))
		elif output_format == "gcode":
			fp.write(emb.export_gcode(dbg))
		fp.close()
		emb.scale(pixels_per_millimeter)
		emb.translate(dx, dy)
		return emb

	def emit_inkscape(self, parent, emb):
		emb.scale((1, -1));
		for color, path in emb.export_paths(dbg):
			dbg.write('path: %s %s\n' % (color, repr(path)))
			inkex.etree.SubElement(parent,
				inkex.addNS('path', 'svg'),
				{	'style':simplestyle.formatStyle(
						{ 'stroke': color if color is not None else '#000000',
							'stroke-width':"1",
							'fill': 'none' }),
					'd':simplepath.formatPath(path),
				})

	def bbox(self):
		x = []
		y = []
		for patch in self.patchList.patches:
			for stitch in patch.stitches:
				x.append(stitch.x)
				y.append(stitch.y)
		return (min(x), min(y), max(x), max(y))

class SortOrder:
	def __init__(self, threadcolor, layer, preserve_layers):
		self.threadcolor = threadcolor
		if (preserve_layers):
			#dbg.write("preserve_layers is true: %s %s\n" % (layer, threadcolor));
			self.sorttuple = (layer, threadcolor)
		else:
			#dbg.write("preserve_layers is false:\n");
			self.sorttuple = (threadcolor,)

	def __cmp__(self, other):
		return cmp(self.sorttuple, other.sorttuple)
	
	def __repr__(self):
		return "sort %s color %s" % (self.sorttuple, self.threadcolor)

class Embroider(inkex.Effect):
	def __init__(self, *args, **kwargs):
		#dbg.write("args: %s\n" % repr(sys.argv))
		inkex.Effect.__init__(self)
		self.stacking_order_counter = 0
		self.OptionParser.add_option("-r", "--row_spacing_mm",
			action="store", type="float",
			dest="row_spacing_mm", default=0.4,
			help="row spacing (mm)")
		self.OptionParser.add_option("-z", "--zigzag_spacing_mm",
			action="store", type="float",
			dest="zigzag_spacing_mm", default=1.0,
			help="zigzag spacing (mm)")
		self.OptionParser.add_option("-l", "--max_stitch_len_mm",
			action="store", type="float",
			dest="max_stitch_len_mm", default=3.0,
			help="max stitch length (mm)")
		self.OptionParser.add_option("--running_stitch_len_mm",
			action="store", type="float",
			dest="running_stitch_len_mm", default=3.0,
			help="running stitch length (mm)")
		self.OptionParser.add_option("-c", "--collapse_len_mm",
			action="store", type="float",
			dest="collapse_len_mm", default=0.0,
			help="max collapse length (mm)")
		self.OptionParser.add_option("-f", "--flatness",
			action="store", type="float", 
			dest="flat", default=0.1,
			help="Minimum flatness of the subdivided curves")
		self.OptionParser.add_option("-o", "--preserve_layers",
			action="store", type="choice", 
			choices=["true","false"],
			dest="preserve_layers", default="false",
			help="Sort by stacking order instead of color")
		self.OptionParser.add_option("-H", "--hatch_filled_paths",
			action="store", type="choice",
			choices=["true","false"],
			dest="hatch_filled_paths", default="false",
			help="Use hatching lines instead of equally-spaced lines to fill paths")
		self.OptionParser.add_option("--hide_layers",
			action="store", type="choice",
			choices=["true","false"],
			dest="hide_layers", default="true",
			help="Hide all other layers when the embroidery layer is generated")
		self.OptionParser.add_option("-p", "--add_preamble",
			action="store", type="choice",
			choices=["0","010","01010","01210","012101210"],
			dest="add_preamble", default="0",
			help="Add preamble")
		self.OptionParser.add_option("-O", "--output_format",
			action="store", type="choice",
			choices=["melco", "csv", "gcode"],
			dest="output_format", default="melco",
			help="File output format")
		self.OptionParser.add_option("-F", "--filename",
			action="store", type="string",
			dest="filename", default="embroider-output.exp",
			help="Name (and possibly path) of output file")
		self.patches = []
		self.layer_cache = {}

	def get_sort_order(self, threadcolor, node):
		#print >> sys.stderr, "node", node.get("id"), self.layer_cache.get(node.get("id"))
		return SortOrder(threadcolor, self.layer_cache.get(node.get("id")), self.options.preserve_layers=="true")

	def process_one_path(self, node, shpath, threadcolor, sortorder, angle):
		#self.add_shapely_geo_to_svg(shpath.boundary, color="#c0c000")

		hatching = get_boolean_param(node, "hatching", self.hatching)
		row_spacing_px = get_float_param(node, "row_spacing", self.row_spacing_px)
		max_stitch_len_px = get_float_param(node, "max_stitch_length", self.max_stitch_len_px)

		rows_of_segments = self.intersect_region_with_grating(shpath, row_spacing_px, angle)
		segments = self.visit_segments_one_by_one(rows_of_segments)

		def small_stitches(patch, beg, end):
			vector = (end-beg)
			patch.addStitch(beg)
			old_dist = vector.length()
			if (old_dist < max_stitch_len_px):
				patch.addStitch(end)
				return
			one_stitch = vector.mul(1.0 / old_dist * max_stitch_len_px * random.random())
			beg = beg + one_stitch
			while (True):
				vector = (end-beg)
				dist = vector.length()
				assert(old_dist==None or dist<old_dist)
				old_dist = dist
				patch.addStitch(beg)
				if (dist < max_stitch_len_px):
					patch.addStitch(end)
					return

				one_stitch = vector.mul(1.0/dist*max_stitch_len_px)
				beg = beg + one_stitch
				
		swap = False
		patch = Patch(color=threadcolor,sortorder=sortorder)
		for (beg,end) in segments:
			if (swap):
				(beg,end)=(end,beg)
			if not hatching:
				swap = not swap
			small_stitches(patch, PyEmb.Point(*beg),PyEmb.Point(*end))
		return [patch]

	def intersect_region_with_grating(self, shpath, row_spacing_px, angle):
		#dbg.write("bounds = %s\n" % str(shpath.bounds))
		rotated_shpath = affinity.rotate(shpath, angle, use_radians = True)
		bbox = rotated_shpath.bounds
		delta = row_spacing_px * 50 # *2 should be enough but isn't.  TODO: find out why, and if this always works.
		bbox = affinity.rotate(shgeo.LinearRing(((bbox[0] - delta, bbox[1] - delta), (bbox[2] + delta, bbox[1] - delta), (bbox[2] + delta, bbox[3] + delta), (bbox[0] - delta, bbox[3] + delta))), -angle, use_radians = True).coords
		
		p0 = PyEmb.Point(bbox[0][0], bbox[0][1])
		p1 = PyEmb.Point(bbox[1][0], bbox[1][1])
		p2 = PyEmb.Point(bbox[3][0], bbox[3][1])
		count = (p2 - p0).length() / row_spacing_px
		p_inc = (p2 - p0).mul(1 / count)
		count += 2

		rows = []
		steps = 0
		while (steps < count):
			try:
				steps += 1
				p0 += p_inc
				p1 += p_inc
				endpoints = [p0.as_tuple(), p1.as_tuple()]
				shline = shgeo.LineString(endpoints)
				res = shline.intersection(shpath)
				if (isinstance(res, shgeo.MultiLineString)):
					runs = map(shapelyLineSegmentToPyTuple, res.geoms)
				else:
					runs = [shapelyLineSegmentToPyTuple(res)]
				if self.hatching and len(rows) > 0:
					rows.append([(rows[-1][0][1], runs[0][0])])
				rows.append(runs)
			except Exception, ex:
				dbg.write("--------------\n")
				dbg.write("%s\n" % ex)
				dbg.write("%s\n" % shline)
				dbg.write("%s\n" % shpath)
				dbg.write("==============\n")
				continue
		return rows
		
	def visit_segments_one_by_one(self, rows):
		def pull_runs(rows):
			new_rows = []
			run = []
			for r in rows:
				(first,rest) = (r[0], r[1:])
				run.append(first)
				if (len(rest)>0):
					new_rows.append(rest)
			return (run, new_rows)

		linearized_runs = []
		count = 0
		while (len(rows) > 0):
			(one_run,rows) = pull_runs(rows)
			linearized_runs.extend(one_run)

			rows = rows[::-1]
			count += 1
			if (count>100): raise "kablooey"
		return linearized_runs

	def handle_node(self, node):
		if (node.tag == inkex.addNS('g', 'svg')):
			#dbg.write("%s\n"%str((id, etree.tostring(node, pretty_print=True))))
			#dbg.write("not a path; recursing:\n")
			for child in node.iter(self.svgpath):
				self.handle_node(child)
			return

		#dbg.write("Node: %s\n"%str((id, etree.tostring(node, pretty_print=True))))

		israw = parse_boolean(node.get('embroider_raw'))
		if (israw):
			self.patchList.patches.extend(self.path_to_patch_list(node))
		else:
			if (self.get_style(node, "fill")!=None):
				self.patchList.patches.extend(self.filled_region_to_patchlist(node))
			if (self.get_style(node, "stroke")!=None):
				self.patchList.patches.extend(self.path_to_patch_list(node))

	def get_style(self, node, style_name):
		style = simplestyle.parseStyle(node.get("style"))
		if (style_name not in style):
			return None
		value = style[style_name]
		if (value==None or value=="none"):
			return None
		return value
		
	def cache_layers(self):
		self.layer_cache = {}

		layer_tag = inkex.addNS("g", "svg")
		group_attr = inkex.addNS('groupmode', 'inkscape')


		def is_layer(node):
			return node.tag == layer_tag and node.get(group_attr) == "layer"
			
		def process(node, layer=0):
			if is_layer(node):
				layer += 1
			else:
				self.layer_cache[node.get("id")] = layer

			for child in node:
				layer = process(child, layer)

			return layer

		process(self.document.getroot())

	def effect(self):
		if self.options.preserve_layers == "true":
			self.cache_layers()
			#print >> sys.stderr, "cached stacking order:", self.stacking_order

		self.row_spacing_px = self.options.row_spacing_mm * pixels_per_millimeter
		self.zigzag_spacing_px = self.options.zigzag_spacing_mm * pixels_per_millimeter
		self.max_stitch_len_px = self.options.max_stitch_len_mm*pixels_per_millimeter
		self.running_stitch_len_px = self.options.running_stitch_len_mm*pixels_per_millimeter
		self.collapse_len_px = self.options.collapse_len_mm*pixels_per_millimeter
		self.hatching = self.options.hatch_filled_paths == "true"

		self.svgpath = inkex.addNS('path', 'svg')
		self.patchList = PatchList([])
		for node in self.selected.itervalues():
			self.handle_node(node)

                if not self.patchList:
                    inkex.errormsg("No paths selected.")
                    return

		self.patchList = self.patchList.tsp_by_color()
		#dbg.write("patch count: %d\n" % len(self.patchList.patches))

		if self.options.hide_layers:
			self.hide_layers()

		eo = EmbroideryObject(self.patchList, self.row_spacing_px)
		emb = eo.emit_file(self.options.filename, self.options.output_format,
			     self.collapse_len_px, self.options.add_preamble)

		new_layer = inkex.etree.SubElement(self.document.getroot(),
				inkex.addNS('g', 'svg'), {})
		new_layer.set('id', self.uniqueId("embroidery"))
		new_layer.set(inkex.addNS('label', 'inkscape'), 'Embroidery')
		new_layer.set(inkex.addNS('groupmode', 'inkscape'), 'layer')
		eo.emit_inkscape(new_layer, emb)

	def emit_inkscape_bbox(self, parent, eo):
		(x0, y0, x1, y1) = eo.bbox()
		new_path = []
		new_path.append(['M', (x0,y0)])
		new_path.append(['L', (x1,y0)])
		new_path.append(['L', (x1,y1)])
		new_path.append(['L', (x0,y1)])
		new_path.append(['L', (x0,y0)])
		inkex.etree.SubElement(parent,
			inkex.addNS('path', 'svg'),
			{	'style':simplestyle.formatStyle(
					{ 'stroke': '#ff00ff',
						'stroke-width':str(1),
						'fill': 'none' }),
				'd':simplepath.formatPath(new_path),
			})

	def hide_layers(self):
		for g in self.document.getroot().findall(inkex.addNS("g","svg")):
			if g.get(inkex.addNS("groupmode", "inkscape")) == "layer":
				g.set("style", "display:none")

	def path_to_patch_list(self, node):
		threadcolor = simplestyle.parseStyle(node.get("style"))["stroke"]
		stroke_width_str = simplestyle.parseStyle(node.get("style"))["stroke-width"]
		if (stroke_width_str.endswith("px")):
			# don't really know how we should be doing unit conversions.
			# but let's hope px are kind of like pts?
			stroke_width_str = stroke_width_str[:-2]
		stroke_width = float(stroke_width_str)
		#dbg.write("stroke_width is <%s>\n" % repr(stroke_width))
		#dbg.flush()

		running_stitch_len_px = get_float_param(node, "stitch_length", self.running_stitch_len_px)
		zigzag_spacing_px = get_float_param(node, "zigzag_spacing", self.zigzag_spacing_px)
		repeats = get_int_param(node, "repeats", 1)

		sortorder = self.get_sort_order(threadcolor, node)
		paths = flatten(parse_path(node), self.options.flat)

		# regularize the points lists.
		# (If we're parsing beziers, there will be a list of multi-point
		# subarrays.)

		patches = []
		
		for path in paths:
			path = [PyEmb.Point(x, y) for x, y in path]
			if (stroke_width <= STROKE_MIN):
				#dbg.write("self.max_stitch_len_px = %s\n" % self.max_stitch_len_px)
				patch = self.stroke_points(path, running_stitch_len_px, 0.0, repeats, threadcolor, sortorder)
			else:
				patch = self.stroke_points(path, zigzag_spacing_px*0.5, stroke_width, repeats, threadcolor, sortorder)
			patches.extend(patch)

		return patches

	def stroke_points(self, emb_point_list, zigzag_spacing_px, stroke_width, repeats, threadcolor, sortorder):
		patch = Patch(color=threadcolor, sortorder=sortorder)
		p0 = emb_point_list[0]
		rho = 0.0
		fact = 1

		for repeat in xrange(repeats):
			if repeat % 2 == 0:
				order = range(1, len(emb_point_list))
			else:
				order = range(-2, -len(emb_point_list) - 1, -1)

			for segi in order:
				p1 = emb_point_list[segi]

				# how far we have to go along segment
				seg_len = (p1 - p0).length()
				if (seg_len == 0):
					continue

				# vector pointing along segment
				along = (p1 - p0).unit()
				# vector pointing to edge of stroke width
				perp = along.rotate_left().mul(stroke_width*0.5)

				# iteration variable: how far we are along segment
				while (rho <= seg_len):
					left_pt = p0+along.mul(rho)+perp.mul(fact)
					patch.addStitch(left_pt)
					rho += zigzag_spacing_px
					fact = -fact

				p0 = p1
				rho -= seg_len

		return [patch]

	def filled_region_to_patchlist(self, node):
		angle = math.radians(float(get_float_param(node,'angle',0)))
		paths = flatten(parse_path(node), self.options.flat)
		shapelyPolygon = cspToShapelyPolygon(paths)
		threadcolor = simplestyle.parseStyle(node.get("style"))["fill"]
		sortorder = self.get_sort_order(threadcolor, node)
		return self.process_one_path(
				node,
				shapelyPolygon,
				threadcolor,
				sortorder,
				angle)

	#TODO def make_stroked_patch(self, node):

if __name__ == '__main__':
	sys.setrecursionlimit(100000);
	e = Embroider()
	e.affect()
	#dbg.write("aaaand, I'm done. seeeya!\n")
	dbg.flush()

dbg.close()