#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 2019 Hiroshi Murayama <opiopan@gmail.com>
import io, sys
from math import pi, cos, sin, tan, atan, atan2, acos, asin, sqrt
import dxfgrabber
from gerber.cam import CamFile, FileSettings
from gerber.utils import inch, metric, write_gerber_value, rotate_point
from gerber.gerber_statements import ADParamStmt
from gerber.excellon_statements import ExcellonTool
from gerber.excellon_statements import CoordinateStmt
from gerberex.utility import is_equal_point, is_equal_value
from gerberex.dxf_path import generate_paths, judge_containment
from gerberex.excellon import write_excellon_header
from gerberex.rs274x import write_gerber_header
ACCEPTABLE_ERROR = 0.001
def _normalize_angle(start_angle, end_angle):
angle = end_angle - start_angle
if angle > 0:
start = start_angle % 360
else:
angle = -angle
start = end_angle % 360
angle = min(angle, 360)
start = start - 360 if start > 180 else start
regions = []
while angle > 0:
end = start + angle
if end <= 180:
regions.append((start * pi / 180, end * pi / 180))
angle = 0
else:
regions.append((start * pi / 180, pi))
angle = end - 180
start = -180
return regions
def _intersections_of_line_and_circle(start, end, center, radius, error_range):
x1 = start[0] - center[0]
y1 = start[1] - center[1]
x2 = end[0] - center[0]
y2 = end[1] - center[1]
dx = x2 - x1
dy = y2 - y1
dr = sqrt(dx * dx + dy * dy)
D = x1 * y2 - x2 * y1
distance = abs(dy * x1 - dx * y1) / dr
D2 = D * D
dr2 = dr * dr
r2 = radius * radius
delta = r2 * dr2 - D2
if distance > radius - error_range and distance < radius + error_range:
delta = 0
if delta < 0:
return None
sqrt_D = sqrt(delta)
E_x = -dx * sqrt_D if dy < 0 else dx * sqrt_D
E_y = abs(dy) * sqrt_D
p1_x = (D * dy + E_x) / dr2
p2_x = (D * dy - E_x) / dr2
p1_y = (-D * dx + E_y) / dr2
p2_y = (-D * dx - E_y) / dr2
p1_angle = atan2(p1_y, p1_x)
p2_angle = atan2(p2_y, p2_x)
if dx == 0:
p1_t = (p1_y - y1) / dy
p2_t = (p2_y - y1) / dy
else:
p1_t = (p1_x - x1) / dx
p2_t = (p2_x - x1) / dx
if delta == 0:
return (
(p1_x + center[0], p1_y + center[1]),
None,
p1_angle, None,
p1_t, None
)
else:
return (
(p1_x + center[0], p1_y + center[1]),
(p2_x + center[0], p2_y + center[1]),
p1_angle, p2_angle,
p1_t, p2_t
)
class DxfStatement(object):
def __init__(self, entity):
self.entity = entity
self.start = None
self.end = None
self.is_closed = False
def to_inch(self):
pass
def to_metric(self):
pass
def is_equal_to(self, target, error_range=0):
return False
def reverse(self):
raise Exception('Not implemented')
def offset(self, offset_x, offset_y):
raise Exception('Not supported')
def rotate(self, angle, center=(0, 0)):
raise Exception('Not supported')
class DxfLineStatement(DxfStatement):
@classmethod
def from_entity(cls, entity):
start = (entity.start[0], entity.start[1])
end = (entity.end[0], entity.end[1])
return cls(entity, start, end)
@property
def bounding_box(self):
return (min(self.start[0], self.end[0]),
min(self.start[1], self.end[1]),
max(self.start[0], self.end[0]),
max(self.start[1], self.end[1]))
def __init__(self, entity, start, end):
super(DxfLineStatement, self).__init__(entity)
self.start = start
self.end = end
def to_inch(self):
self.start = (
inch(self.start[0]), inch(self.start[1]))
self.end = (
inch(self.end[0]), inch(self.end[1]))
def to_metric(self):
self.start = (
metric(self.start[0]), metric(self.start[1]))
self.end = (
metric(self.end[0]), metric(self.end[1]))
def is_equal_to(self, target, error_range=0):
if not isinstance(target, DxfLineStatement):
return False
return (is_equal_point(self.start, target.start, error_range) and \
is_equal_point(self.end, target.end, error_range)) or \
(is_equal_point(self.start, target.end, error_range) and \
is_equal_point(self.end, target.start, error_range))
def reverse(self):
pt = self.start
self.start = self.end
self.end = pt
def dots(self, pitch, width, offset=0):
x0, y0 = self.start
x1, y1 = self.end
y1 = self.end[1]
xp = x1 - x0
yp = y1 - y0
l = sqrt(xp * xp + yp * yp)
xd = xp * pitch / l
yd = yp * pitch / l
x0 += xp * offset / l
y0 += yp * offset / l
if offset > l + width / 2:
return (None, offset - l)
else:
d = offset;
while d < l + width / 2:
yield ((x0, y0), d - l)
x0 += xd
y0 += yd
d += pitch
def offset(self, offset_x, offset_y):
self.start = (self.start[0] + offset_x, self.start[1] + offset_y)
self.end = (self.end[0] + offset_x, self.end[1] + offset_y)
def rotate(self, angle, center=(0, 0)):
self.start = rotate_point(self.start, angle, center)
self.end = rotate_point(self.end, angle, center)
def intersections_with_halfline(self, point_from, point_to, error_range):
denominator = (self.end[0] - self.start[0]) * (point_to[1] - point_from[1]) - \
(self.end[1] - self.start[1]) * (point_to[0] - point_from[0])
de = error_range * error_range
if denominator >= -de and denominator <= de:
return []
from_dx = point_from[0] - self.start[0]
from_dy = point_from[1] - self.start[1]
r = ((point_to[1] - point_from[1]) * from_dx -
(point_to[0] - point_from[0]) * from_dy) / denominator
s = ((self.end[1] - self.start[1]) * from_dx -
(self.end[0] - self.start[0]) * from_dy) / denominator
dx = (self.end[0] - self.start[0])
dy = (self.end[1] - self.start[1])
le = error_range / sqrt(dx * dx + dy * dy)
if s < 0 or r < -le or r > 1 + le:
return []
pt = (self.start[0] + (self.end[0] - self.start[0]) * r,
self.start[1] + (self.end[1] - self.start[1]) * r)
if is_equal_point(pt, self.start, error_range):
return []
else:
return [pt]
def intersections_with_arc(self, center, radius, angle_regions, error_range):
intersection = \
_intersections_of_line_and_circle(self.start, self.end, center, radius, error_range)
if intersection is None:
return []
else:
p1, p2, p1_angle, p2_angle, p1_t, p2_t = intersection
pts = []
if p1_t >= 0 and p1_t <= 1:
for region in angle_regions:
if p1_angle >= region[0] and p1_angle <= region[1]:
pts.append(p1)
break
if p2 is not None and p2_t >= 0 and p2_t <= 1:
for region in angle_regions:
if p2_angle >= region[0] and p2_angle <= region[1]:
pts.append(p2)
break
return pts
class DxfArcStatement(DxfStatement):
def __init__(self, entity):
super(DxfArcStatement, self).__init__(entity)
if entity.dxftype == 'CIRCLE':
self.radius = self.entity.radius
self.center = (self.entity.center[0], self.entity.center[1])
self.start = (self.center[0] + self.radius, self.center[1])
self.end = self.start
self.start_angle = 0
self.end_angle = 360
self.is_closed = True
elif entity.dxftype == 'ARC':
self.start_angle = self.entity.start_angle
self.end_angle = self.entity.end_angle
self.radius = self.entity.radius
self.center = (self.entity.center[0], self.entity.center[1])
self.start = (
self.center[0] + self.radius * cos(self.start_angle / 180. * pi),
self.center[1] + self.radius * sin(self.start_angle / 180. * pi),
)
self.end = (
self.center[0] + self.radius * cos(self.end_angle / 180. * pi),
self.center[1] + self.radius * sin(self.end_angle / 180. * pi),
)
angle = self.end_angle - self.start_angle
self.is_closed = angle >= 360 or angle <= -360
else:
raise Exception('invalid DXF type was specified')
self.angle_regions = _normalize_angle(self.start_angle, self.end_angle)
@property
def bounding_box(self):
return (self.center[0] - self.radius, self.center[1] - self.radius,
self.center[0] + self.radius, self.center[1] + self.radius)
def to_inch(self):
self.radius = inch(self.radius)
self.center = (inch(self.center[0]), inch(self.center[1]))
self.start = (inch(self.start[0]), inch(self.start[1]))
self.end = (inch(self.end[0]), inch(self.end[1]))
def to_metric(self):
self.radius = metric(self.radius)
self.center = (metric(self.center[0]), metric(self.center[1]))
self.start = (metric(self.start[0]), metric(self.start[1]))
self.end = (metric(self.end[0]), metric(self.end[1]))
def is_equal_to(self, target, error_range=0):
if not isinstance(target, DxfArcStatement):
return False
aerror_range = error_range / pi * self.radius * 180
return is_equal_point(self.center, target.center, error_range) and \
is_equal_value(self.radius, target.radius, error_range) and \
((is_equal_value(self.start_angle, target.start_angle, aerror_range) and
is_equal_value(self.end_angle, target.end_angle, aerror_range)) or
(is_equal_value(self.start_angle, target.end_angle, aerror_range) and
is_equal_value(self.end_angle, target.end_angle, aerror_range)))
def reverse(self):
tmp = self.start_angle
self.start_angle = self.end_angle
self.end_angle = tmp
tmp = self.start
self.start = self.end
self.end = tmp
def dots(self, pitch, width, offset=0):
angle = self.end_angle - self.start_angle
afactor = 1 if angle > 0 else -1
aangle = angle * afactor
L = 2 * pi * self.radius
l = L * aangle / 360
pangle = pitch / L * 360
wangle = width / L * 360
oangle = offset / L * 360
if offset > l + width / 2:
yield (None, offset - l)
else:
da = oangle
while da < aangle + wangle / 2:
cangle = self.start_angle + da * afactor
x = self.radius * cos(cangle / 180 * pi) + self.center[0]
y = self.radius * sin(cangle / 180 * pi) + self.center[1]
remain = (da - aangle) / 360 * L
yield((x, y), remain)
da += pangle
def offset(self, offset_x, offset_y):
self.center = (self.center[0] + offset_x, self.center[1] + offset_y)
self.start = (self.start[0] + offset_x, self.start[1] + offset_y)
self.end = (self.end[0] + offset_x, self.end[1] + offset_y)
def rotate(self, angle, center=(0, 0)):
self.start_angle += angle
self.end_angle += angle
self.center = rotate_point(self.center, angle, center)
self.start = rotate_point(self.start, angle, center)
self.end = rotate_point(self.end, angle, center)
self.angle_regions = _normalize_angle(self.start_angle, self.end_angle)
def intersections_with_halfline(self, point_from, point_to, error_range):
intersection = \
_intersections_of_line_and_circle(
point_from, point_to, self.center, self.radius, error_range)
if intersection is None:
return []
else:
p1, p2, p1_angle, p2_angle, p1_t, p2_t = intersection
if is_equal_point(p1, self.start, error_range):
p1 = None
elif p2 is not None and is_equal_point(p2, self.start, error_range):
p2 = None
def is_contained(angle, region, error):
if angle >= region[0] - error and angle <= region[1] + error:
return True
if angle < 0 and region[1] > 0:
angle = angle + 2 * pi
elif angle > 0 and region[0] < 0:
angle = angle - 2 * pi
return angle >= region[0] - error and angle <= region[1] + error
aerror = error_range * self.radius
pts = []
if p1 is not None and p1_t >= 0 and not is_equal_point(p1, self.start, error_range):
for region in self.angle_regions:
if is_contained(p1_angle, region, aerror):
pts.append(p1)
break
if p2 is not None and p2_t >= 0 and not is_equal_point(p2, self.start, error_range):
for region in self.angle_regions:
if is_contained(p2_angle, region, aerror):
pts.append(p2)
break
return pts
def intersections_with_arc(self, center, radius, angle_regions, error_range):
x1 = center[0] - self.center[0]
y1 = center[1] - self.center[1]
r1 = self.radius
r2 = radius
cd_sq = x1 * x1 + y1 * y1
cd = sqrt(cd_sq)
rd = abs(r1 - r2)
if (cd >= 0 and cd <= rd) or cd >= r1 + r2:
return []
A = (cd_sq + r1 * r1 - r2 * r2) / 2
scale = sqrt(cd_sq * r1 * r1 - A * A) / cd_sq
xl = A * x1 / cd_sq
xr = y1 * scale
yl = A * y1 / cd_sq
yr = x1 * scale
pt1_x = xl + xr
pt1_y = yl - yr
pt2_x = xl - xr
pt2_y = yl + yr
pt1_angle1 = atan2(pt1_y, pt1_x)
pt1_angle2 = atan2(pt1_y - y1, pt1_x - x1)
pt2_angle1 = atan2(pt2_y, pt2_x)
pt2_angle2 = atan2(pt2_y - y1, pt2_x - x1)
aerror = error_range * self.radius
pts=[]
for region in self.angle_regions:
if pt1_angle1 >= region[0] and pt1_angle1 <= region[1]:
for region in angle_regions:
if pt1_angle2 >= region[0] - aerror and pt1_angle2 <= region[1] + aerror:
pts.append((pt1_x + self.center[0], pt1_y + self.center[1]))
break
break
for region in self.angle_regions:
if pt2_angle1 >= region[0] and pt2_angle1 <= region[1]:
for region in angle_regions:
if pt2_angle2 >= region[0] - aerror and pt2_angle2 <= region[1] + aerror:
pts.append((pt2_x + self.center[0], pt2_y + self.center[1]))
break
break
return pts
class DxfPolylineStatement(DxfStatement):
def __init__(self, entity):
super(DxfPolylineStatement, self).__init__(entity)
self.start = (self.entity.points[0][0], self.entity.points[0][1])
self.is_closed = self.entity.is_closed
if self.is_closed:
self.end = self.start
else:
self.end = (self.entity.points[-1][0], self.entity.points[-1][1])
def disassemble(self):
class Item:
pass
def ptseq():
for i in range(1, len(self.entity.points)):
yield i
if self.entity.is_closed:
yield 0
x0 = self.entity.points[0][0]
y0 = self.entity.points[0][1]
b = self.entity.bulge[0]
for idx in ptseq():
pt = self.entity.points[idx]
x1 = pt[0]
y1 = pt[1]
if b == 0:
item = Item()
item.dxftype = 'LINE'
item.start = (x0, y0)
item.end = (x1, y1)
item.is_closed = False
yield DxfLineStatement.from_entity(item)
else:
ang = 4 * atan(b)
xm = x0 + x1
ym = y0 + y1
t = 1 / tan(ang / 2)
xc = (xm - t * (y1 - y0)) / 2
yc = (ym + t * (x1 - x0)) / 2
r = sqrt((x0 - xc)*(x0 - xc) + (y0 - yc)*(y0 - yc))
rx0 = x0 - xc
ry0 = y0 - yc
rc = max(min(rx0 / r, 1.0), -1.0)
start_angle = acos(rc) if ry0 > 0 else 2 * pi - acos(rc)
start_angle *= 180 / pi
end_angle = start_angle + ang * 180 / pi
item = Item()
item.dxftype = 'ARC'
item.start = (x0, y0)
item.end = (x1, y1)
item.start_angle = start_angle
item.end_angle = end_angle
item.radius = r
item.center = (xc, yc)
item.is_closed = end_angle - start_angle >= 360
yield DxfArcStatement(item)
x0 = x1
y0 = y1
b = self.entity.bulge[idx]
def to_inch(self):
self.start = (inch(self.start[0]), inch(self.start[1]))
self.end = (inch(self.end[0]), inch(self.end[1]))
for idx in range(0, len(self.entity.points)):
self.entity.points[idx] = (
inch(self.entity.points[idx][0]), inch(self.entity.points[idx][1]))
def to_metric(self):
self.start = (metric(self.start[0]), metric(self.start[1]))
self.end = (metric(self.end[0]), metric(self.end[1]))
for idx in range(0, len(self.entity.points)):
self.entity.points[idx] = (
metric(self.entity.points[idx][0]), metric(self.entity.points[idx][1]))
def offset(self, offset_x, offset_y):
for idx in range(len(self.entity.points)):
self.entity.points[idx] = (
self.entity.points[idx][0] + offset_x, self.entity.points[idx][1] + offset_y)
def rotate(self, angle, center=(0, 0)):
for idx in range(len(self.entity.points)):
self.entity.points[idx] = rotate_point(self.entity.points[idx], angle, center)
class DxfStatements(object):
def __init__(self, statements, units, dcode=10, draw_mode=None, fill_mode=None):
if draw_mode is None:
draw_mode = DxfFile.DM_LINE
if fill_mode is None:
fill_mode = DxfFile.FM_TURN_OVER
self._units = units
self.dcode = dcode
self.draw_mode = draw_mode
self.fill_mode = fill_mode
self.pitch = inch(1) if self._units == 'inch' else 1
self.width = 0
self.error_range = inch(ACCEPTABLE_ERROR) if self._units == 'inch' else ACCEPTABLE_ERROR
self.statements = list(filter(
lambda i: not (isinstance(i, DxfLineStatement) and \
is_equal_point(i.start, i.end, self.error_range)),
statements
))
self.close_paths, self.open_paths = generate_paths(self.statements, self.error_range)
self.sorted_close_paths = []
self.polarity = True # True means dark, False means clear
@property
def units(self):
return _units
def _polarity_command(self, polarity=None):
if polarity is None:
polarity = self.polarity
return '%LPD*%' if polarity else '%LPC*%'
def _prepare_sorted_close_paths(self):
if self.sorted_close_paths:
return
for i in range(0, len(self.close_paths)):
for j in range(i + 1, len(self.close_paths)):
containee, container = judge_containment(
self.close_paths[i], self.close_paths[j], self.error_range)
if containee is not None:
containee.containers.append(container)
self.sorted_close_paths = sorted(self.close_paths, key=lambda path: len(path.containers))
def to_gerber(self, settings=FileSettings()):
def gerbers():
yield 'G75*'
yield self._polarity_command()
yield 'D{0}*'.format(self.dcode)
if self.draw_mode == DxfFile.DM_FILL:
yield 'G36*'
if self.fill_mode == DxfFile.FM_TURN_OVER:
self._prepare_sorted_close_paths()
polarity = self.polarity
level = 0
for path in self.sorted_close_paths:
if len(path.containers) > level:
level = len(path.containers)
polarity = not polarity
yield 'G37*'
yield self._polarity_command(polarity)
yield 'G36*'
yield path.to_gerber(settings)
else:
for path in self.close_paths:
yield path.to_gerber(settings)
yield 'G37*'
else:
pitch = self.pitch if self.draw_mode == DxfFile.DM_MOUSE_BITES else 0
for path in self.open_paths:
yield path.to_gerber(settings, pitch=pitch, width=self.width)
for path in self.close_paths:
yield path.to_gerber(settings, pitch=pitch, width=self.width)
return '\n'.join(gerbers())
def to_excellon(self, settings=FileSettings()):
if self.draw_mode == DxfFile.DM_FILL:
return
def drills():
pitch = self.pitch if self.draw_mode == DxfFile.DM_MOUSE_BITES else 0
for path in self.open_paths:
yield path.to_excellon(settings, pitch=pitch, width=self.width)
for path in self.close_paths:
yield path.to_excellon(settings, pitch=pitch, width=self.width)
return '\n'.join(drills())
def to_inch(self):
if self._units == 'metric':
self._units = 'inch'
self.pitch = inch(self.pitch)
self.width = inch(self.width)
self.error_range = inch(self.error_range)
for path in self.open_paths:
path.to_inch()
for path in self.close_paths:
path.to_inch()
def to_metric(self):
if self._units == 'inch':
self._units = 'metric'
self.pitch = metric(self.pitch)
self.width = metric(self.width)
self.error_range = metric(self.error_range)
for path in self.open_paths:
path.to_metric()
for path in self.close_paths:
path.to_metric()
def offset(self, offset_x, offset_y):
for path in self.open_paths:
path.offset(offset_x, offset_y)
for path in self.close_paths:
path.offset(offset_x, offset_y)
def rotate(self, angle, center=(0, 0)):
for path in self.open_paths:
path.rotate(angle, center)
for path in self.close_paths:
path.rotate(angle, center)
class DxfFile(CamFile):
DM_LINE = 0
DM_FILL = 1
DM_MOUSE_BITES = 2
FM_SIMPLE = 0
FM_TURN_OVER = 1
FT_RX274X = 0
FT_EXCELLON = 1
@classmethod
def from_dxf(cls, dxf, settings=None, draw_mode=None, filename=None):
fsettings = settings if settings else \
FileSettings(zero_suppression='leading')
if dxf.header['$INSUNITS'] == 1:
fsettings.units = 'inch'
if not settings:
fsettings.format = (2, 5)
else:
fsettings.units = 'metric'
if not settings:
fsettings.format = (3, 4)
statements = []
for entity in dxf.entities:
if entity.dxftype == 'LWPOLYLINE':
statements.append(DxfPolylineStatement(entity))
elif entity.dxftype == 'LINE':
statements.append(DxfLineStatement.from_entity(entity))
elif entity.dxftype == 'CIRCLE':
statements.append(DxfArcStatement(entity))
elif entity.dxftype == 'ARC':
statements.append(DxfArcStatement(entity))
return cls(statements, fsettings, draw_mode, filename)
@classmethod
def rectangle(cls, width, height, left=0, bottom=0, units='metric', draw_mode=None, filename=None):
if units == 'metric':
settings = FileSettings(units=units, zero_suppression='leading', format=(3,4))
else:
settings = FileSettings(units=units, zero_suppression='leading', format=(2,5))
statements = [
DxfLineStatement(None, (left, bottom), (left + width, bottom)),
DxfLineStatement(None, (left + width, bottom), (left + width, bottom + height)),
DxfLineStatement(None, (left + width, bottom + height), (left, bottom + height)),
DxfLineStatement(None, (left, bottom + height), (left, bottom)),
]
return cls(statements, settings, draw_mode, filename)
def __init__(self, statements, settings=None, draw_mode=None, filename=None):
if not settings:
settings = FileSettings(units='metric', format=(3,4), zero_suppression='leading')
if draw_mode == None:
draw_mode = self.DM_LINE
super(DxfFile, self).__init__(settings=settings, filename=filename)
self._draw_mode = draw_mode
self._fill_mode = self.FM_TURN_OVER
self.aperture = ADParamStmt.circle(dcode=10, diameter=0.0)
if settings.units == 'inch':
self.aperture.to_inch()
else:
self.aperture.to_metric()
self.statements = DxfStatements(
statements, self.units, dcode=self.aperture.d, draw_mode=self.draw_mode, fill_mode=self.filename)
@property
def dcode(self):
return self.aperture.dcode
@dcode.setter
def dcode(self, value):
self.aperture.d = value
self.statements.dcode = value
@property
def width(self):
return self.aperture.modifiers[0][0]
@width.setter
def width(self, value):
self.aperture.modifiers = ([float(value),],)
self.statements.width = value
@property
def draw_mode(self):
return self._draw_mode
@draw_mode.setter
def draw_mode(self, value):
self._draw_mode = value
self.statements.draw_mode = value
@property
def fill_mode(self):
return self._fill_mode
@fill_mode.setter
def fill_mode(self, value):
self._fill_mode = value
self.statements.fill_mode = value
@property
def pitch(self):
return self.statements.pitch
@pitch.setter
def pitch(self, value):
self.statements.pitch = value
def write(self, filename=None, filetype=FT_RX274X):
self.settings.notation = 'absolute'
self.settings.zeros = 'trailing'
filename = filename if filename is not None else self.filename
with open(filename, 'w') as f:
if filetype == self.FT_RX274X:
write_gerber_header(f, self.settings)
f.write(self.aperture.to_gerber(self.settings) + '\n')
f.write(self.statements.to_gerber(self.settings) + '\n')
f.write('M02*\n')
else:
tools = [ExcellonTool(self.settings, number=1, diameter=self.width)]
write_excellon_header(f, self.settings, tools)
f.write('T01\n')
f.write(self.statements.to_excellon(self.settings) + '\n')
f.write('M30\n')
def to_inch(self):
if self.units == 'metric':
self.aperture.to_inch()
self.statements.to_inch()
self.pitch = inch(self.pitch)
self.units = 'inch'
def to_metric(self):
if self.units == 'inch':
self.aperture.to_metric()
self.statements.to_metric()
self.pitch = metric(self.pitch)
self.units = 'metric'
def offset(self, offset_x, offset_y):
self.statements.offset(offset_x, offset_y)
def rotate(self, angle, center=(0, 0)):
self.statements.rotate(angle, center)
def negate_polarity(self):
self.statements.polarity = not self.statements.polarity
def loads(data, filename=None):
if sys.version_info.major == 2:
data = unicode(data)
stream = io.StringIO(data)
dxf = dxfgrabber.read(stream)
return DxfFile.from_dxf(dxf)