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# -*- coding: ISO-8859-1 -*-
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# Copyright (C) 2011 Michael Schindler <m-schindler@users.sourceforge.net>
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# This file is part of PyX (http://pyx.sourceforge.net/).
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# PyX is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# PyX is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with PyX; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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from math import atan2, radians
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from pyx import unit, attr, normpath
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from pyx import path as pathmodule
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from mp_path import mp_endpoint, mp_explicit, mp_given, mp_curl, mp_open, mp_end_cycle, mp_make_choices
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# global epsilon (default precision length of metapost, in pt)
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def set(epsilon=None):
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if epsilon is not None:
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################################################################################
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################################################################################
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"""Internal knot as used in MetaPost (mp.c)"""
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def __init__(self, x_pt, y_pt, ltype, lx_pt, ly_pt, rtype, rx_pt, ry_pt):
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# this is a linked list:
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def set_left_tension(self, tens):
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def set_right_tension(self, tens):
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def set_left_curl(self, curl):
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def set_right_curl(self, curl):
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set_left_given = set_left_curl
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set_right_given = set_right_curl
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def left_tension(self):
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def right_tension(self):
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left_given = left_curl
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right_given = right_curl
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"""returns the length of a circularly linked list of knots"""
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if self.ltype == mp_endpoint:
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elif self.ltype == mp_explicit:
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result += "{explicit %s %s}" % (self.lx_pt, self.ly_pt)
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elif self.ltype == mp_given:
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result += "{given %g tens %g}" % (self.lx_pt, self.ly_pt)
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elif self.ltype == mp_curl:
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result += "{curl %g tens %g}" % (self.lx_pt, self.ly_pt)
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elif self.ltype == mp_open:
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result += "{open tens %g}" % (self.ly_pt)
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elif self.ltype == mp_end_cycle:
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result += "{cycle tens %g}" % (self.ly_pt)
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result += "(%g %g)" % (self.x_pt, self.y_pt)
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if self.rtype == mp_endpoint:
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elif self.rtype == mp_explicit:
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result += "{explicit %g %g}" % (self.rx_pt, self.ry_pt)
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elif self.rtype == mp_given:
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result += "{given %g tens %g}" % (self.rx_pt, self.ry_pt)
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elif self.rtype == mp_curl:
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result += "{curl %g tens %g}" % (self.rx_pt, self.ry_pt)
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elif self.rtype == mp_open:
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result += "{open tens %g}" % (self.ry_pt)
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elif self.rtype == mp_end_cycle:
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result += "{cycle tens %g}" % (self.ry_pt)
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class beginknot_pt(_knot):
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"""A knot which interrupts a path, or which allows to continue it with a straight line"""
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def __init__(self, x_pt, y_pt, curl=1, angle=None):
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type, value = mp_curl, curl
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type, value = mp_given, angle
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# tensions are modified by the adjacent curve, but default is 1
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_knot.__init__(self, x_pt, y_pt, mp_endpoint, None, None, type, value, 1)
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class beginknot(beginknot_pt):
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def __init__(self, x, y, curl=1, angle=None):
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if not (angle is None):
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angle = radians(angle)
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beginknot_pt.__init__(self, unit.topt(x), unit.topt(y), curl, angle)
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startknot = beginknot
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class endknot_pt(_knot):
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"""A knot which interrupts a path, or which allows to continue it with a straight line"""
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def __init__(self, x_pt, y_pt, curl=1, angle=None):
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type, value = mp_curl, curl
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type, value = mp_given, angle
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# tensions are modified by the adjacent curve, but default is 1
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_knot.__init__(self, x_pt, y_pt, type, value, 1, mp_endpoint, None, None)
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class endknot(endknot_pt):
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def __init__(self, x, y, curl=1, angle=None):
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if not (angle is None):
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angle = radians(angle)
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endknot_pt.__init__(self, unit.topt(x), unit.topt(y), curl, angle)
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class smoothknot_pt(_knot):
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"""A knot with continous tangent and "mock" curvature."""
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def __init__(self, x_pt, y_pt):
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# tensions are modified by the adjacent curve, but default is 1
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_knot.__init__(self, x_pt, y_pt, mp_open, None, 1, mp_open, None, 1)
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class smoothknot(smoothknot_pt):
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def __init__(self, x, y):
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smoothknot_pt.__init__(self, unit.topt(x), unit.topt(y))
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class roughknot_pt(_knot):
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"""A knot with noncontinous tangent."""
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def __init__(self, x_pt, y_pt, lcurl=1, rcurl=None, langle=None, rangle=None):
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"""Specify either the relative curvatures, or tangent angles left (l)
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or right (r) of the point."""
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ltype, lvalue = mp_curl, lcurl
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ltype, lvalue = mp_given, langle
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if rcurl is not None:
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rtype, rvalue = mp_curl, rcurl
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elif rangle is not None:
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rtype, rvalue = mp_given, rangle
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rtype, rvalue = ltype, lvalue
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# tensions are modified by the adjacent curve, but default is 1
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_knot.__init__(self, x_pt, y_pt, ltype, lvalue, 1, rtype, rvalue, 1)
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class roughknot(roughknot_pt):
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def __init__(self, x, y, lcurl=1, rcurl=None, langle=None, rangle=None):
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if langle is not None:
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langle = radians(langle)
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if rangle is not None:
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rangle = radians(rangle)
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roughknot_pt.__init__(self, unit.topt(x), unit.topt(y), lcurl, rcurl, langle, rangle)
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################################################################################
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################################################################################
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def set_knots(self, left_knot, right_knot):
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"""Sets the internal properties of the metapost knots"""
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"""A straight line"""
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def __init__(self, keepangles=False):
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"""The option keepangles will guarantee a continuous tangent. The
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curvature may become discontinuous, however"""
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self.keepangles = keepangles
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def set_knots(self, left_knot, right_knot):
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left_knot.rtype = mp_endpoint
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right_knot.ltype = mp_endpoint
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left_knot.rx_pt, left_knot.ry_pt = None, None
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right_knot.lx_pt, right_knot.ly_pt = None, None
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angle = atan2(right_knot.y_pt-left_knot.y_pt, right_knot.x_pt-left_knot.x_pt)
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left_knot.ltype = mp_given
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left_knot.set_left_given(angle)
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right_knot.rtype = mp_given
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right_knot.set_right_given(angle)
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class controlcurve_pt(_link):
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"""A cubic Bezier curve which has its control points explicity set"""
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def __init__(self, lcontrol_pt, rcontrol_pt):
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"""The control points at the beginning (l) and the end (r) must be
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self.lcontrol_pt = lcontrol_pt
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self.rcontrol_pt = rcontrol_pt
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def set_knots(self, left_knot, right_knot):
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left_knot.rtype = mp_explicit
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right_knot.ltype = mp_explicit
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left_knot.rx_pt, left_knot.ry_pt = self.lcontrol_pt
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right_knot.lx_pt, right_knot.ly_pt = self.rcontrol_pt
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class controlcurve(controlcurve_pt):
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def __init__(self, lcontrol, rcontrol):
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controlcurve_pt.__init__(self, (unit.topt(lcontrol[0]), unit.topt(lcontrol[1])),
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(unit.topt(rcontrol[0]), unit.topt(rcontrol[1])))
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class tensioncurve(_link):
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"""A yet unspecified cubic Bezier curve"""
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def __init__(self, ltension=1, latleast=False, rtension=None, ratleast=None):
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"""The tension parameters indicate the tensions at the beginning (l)
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and the end (r) of the curve. Set the parameters (l/r)atleast to True
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if you want to avoid inflection points."""
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# make sure that tension >= 0.75 (p. 9 mpman.pdf)
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self.ltension = max(0.75, abs(ltension))
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self.rtension = max(0.75, abs(rtension))
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self.ltension = -self.ltension
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self.rtension = -self.rtension
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def set_knots(self, left_knot, right_knot):
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if left_knot.rtype <= mp_explicit or right_knot.ltype <= mp_explicit:
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raise Exception("metapost curve with given tension cannot have explicit knots")
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left_knot.set_right_tension(self.ltension)
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right_knot.set_left_tension(self.rtension)
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################################################################################
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# Path creation class
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################################################################################
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class path(pathmodule.path):
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"""A MetaPost-like path, which finds an optimal way through given points.
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At points, you can either specify a given tangent direction (angle in
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degrees) or a certain "curlyness" (relative to the curvature at the other
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end of a curve), or nothing. In the latter case, both the tangent and the
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"mock" curvature (an approximation to the real curvature, introduced by
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J.D. Hobby in MetaPost) will be continuous.
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The shape of the cubic Bezier curves between two points is controlled by
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its "tension", unless you choose to set the control points manually."""
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def __init__(self, elems, epsilon=None):
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"""elems should contain metapost knots or links"""
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for i, elem in enumerate(elems):
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if isinstance(elem, _link):
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elem.set_knots(elems[i-1], elems[(i+1)%len(elems)])
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elif isinstance(elem, _knot):
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if elem.ltype == mp_endpoint or elem.rtype == mp_endpoint:
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# link the knots among each other
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for i in range(len(knots)):
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knots[i-1].next = knots[i]
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# determine the control points
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mp_make_choices(knots[0], epsilon)
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pathmodule.path.__init__(self)
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for i, elem in enumerate(elems):
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if isinstance(elem, _link):
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if isinstance(elem, line):
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do_lineto, do_curveto = True, False
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do_lineto, do_curveto = False, True
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elif isinstance(elem, _knot):
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self.append(pathmodule.moveto_pt(elem.x_pt, elem.y_pt))
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self.append(pathmodule.lineto_pt(elem.x_pt, elem.y_pt))
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self.append(pathmodule.curveto_pt(prev.rx_pt, prev.ry_pt, elem.lx_pt, elem.ly_pt, elem.x_pt, elem.y_pt))
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# close the path if necessary
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if knots[0].ltype == mp_explicit:
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if do_lineto and is_closed:
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self.append(pathmodule.closepath())
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self.append(pathmodule.curveto_pt(prev.rx_pt, prev.ry_pt, elem.lx_pt, elem.ly_pt, elem.x_pt, elem.y_pt))
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self.append(pathmodule.closepath())
added
removed
pyx/metapost/path.py
