pyx/connector.py

   1 #!/usr/bin/env python
   2 # -*- coding: ISO-8859-1 -*-
   3 #
   4 #
   5 # Copyright (C) 2003-2006 Michael Schindler <m-schindler@users.sourceforge.net>
   6 #
   7 # This file is part of PyX (http://pyx.sourceforge.net/).
   8 #
   9 # PyX is free software; you can redistribute it and/or modify
  10 # it under the terms of the GNU General Public License as published by
  11 # the Free Software Foundation; either version 2 of the License, or
  12 # (at your option) any later version.
  13 #
  14 # PyX is distributed in the hope that it will be useful,
  15 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 # GNU General Public License for more details.
  18 #
  19 # You should have received a copy of the GNU General Public License
  20 # along with PyX; if not, write to the Free Software
  21 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  22
  23
  24 import math
  25 from math import pi, sin, cos, atan2, tan, hypot, acos, sqrt
  26 import path, unit, mathutils, normpath
  27 try:
  28     from math import radians, degrees
  29 except ImportError:
  30     # fallback implementation for Python 2.1 and below
  31     def radians(x): return x*pi/180
  32     def degrees(x): return x*180/pi
  33
  34
  35 #########################
  36 ##   helpers
  37 #########################
  38
  39 class connector_pt(normpath.normpath):
  40
  41     def omitends(self, box1, box2):
  42         """intersects a path with the boxes' paths"""
  43
  44         # cut off the start of self
  45         # XXX how can decoration of this box1.path() be handled?
  46         sp = self.intersect(box1.path())[0]
  47         if sp:
  48             self.normsubpaths = self.split(sp[-1:])[1].normsubpaths
  49
  50         # cut off the end of self
  51         sp = self.intersect(box2.path())[0]
  52         if sp:
  53             self.normsubpaths = self.split(sp[:1])[0].normsubpaths
  54
  55     def shortenpath(self, dists):
  56         """shortens a path by the given distances"""
  57
  58         # XXX later, this should be done by extended boxes instead of intersecting with circles
  59         # cut off the start of self
  60         center = self.atbegin_pt()
  61         cutpath = path.circle_pt(center[0], center[1], dists[0])
  62         try:
  63             cutpath = cutpath.normpath()
  64         except normpath.NormpathException:
  65             pass
  66         else:
  67             sp = self.intersect(cutpath)[0]
  68             self.normsubpaths = self.split(sp[-1:])[1].normsubpaths
  69
  70         # cut off the end of self
  71         center = self.atend_pt()
  72         cutpath = path.circle_pt(center[0], center[1], dists[1])
  73         try:
  74             cutpath = cutpath.normpath()
  75         except normpath.NormpathException:
  76             pass
  77         else:
  78             sp = self.intersect(cutpath)[0]
  79             if sp:
  80                 self.normsubpaths = self.split(sp[:1])[0].normsubpaths
  81
  82
  83 ################
  84 ## classes
  85 ################
  86
  87
  88 class line_pt(connector_pt):
  89
  90     def __init__(self, box1, box2, boxdists=[0,0]):
  91
  92         self.box1 = box1
  93         self.box2 = box2
  94
  95         connector_pt.__init__(self,
  96             [path.normsubpath([path.normline_pt(self.box1.center[0], self.box1.center[1],
  97                                                 self.box2.center[0], self.box2.center[1])], closed=0)])
  98
  99         self.omitends(box1, box2)
 100         self.shortenpath(boxdists)
 101
 102
 103 class arc_pt(connector_pt):
 104
 105     def __init__(self, box1, box2, relangle=45,
 106                  absbulge=None, relbulge=None, boxdists=[0,0]):
 107
 108         # the deviation of arc from the straight line can be specified:
 109         # 1. By an angle between a straight line and the arc
 110         #    This angle is measured at the centers of the box.
 111         # 2. By the largest normal distance between line and arc: absbulge
 112         #    or, equivalently, by the bulge relative to the length of the
 113         #    straight line from center to center.
 114         # Only one can be used.
 115
 116         self.box1 = box1
 117         self.box2 = box2
 118
 119         tangent = (self.box2.center[0] - self.box1.center[0],
 120                    self.box2.center[1] - self.box1.center[1])
 121         distance = hypot(*tangent)
 122         tangent = tangent[0] / distance, tangent[1] / distance
 123
 124         if relbulge is not None or absbulge is not None:
 125             # usage of bulge overrides the relangle parameter
 126             bulge = 0
 127             if absbulge is not None:
 128                 bulge += absbulge
 129             if relbulge is not None:
 130                 bulge += relbulge*distance
 131         else:
 132             # otherwise use relangle, which should be present
 133             bulge = 0.5 * distance * math.tan(0.5*radians(relangle))
 134
 135         if abs(bulge) < normpath._epsilon:
 136             # fallback solution for too straight arcs
 137             connector_pt.__init__(self,
 138                 [path.normsubpath([path.normline_pt(*(self.box1.center+self.box2.center))], closed=0)])
 139         else:
 140             radius = abs(0.5 * (bulge + 0.25 * distance**2 / bulge))
 141             centerdist = mathutils.sign(bulge) * (radius - abs(bulge))
 142             center = (0.5 * (self.box1.center[0] + self.box2.center[0]) + tangent[1]*centerdist,
 143                       0.5 * (self.box1.center[1] + self.box2.center[1]) - tangent[0]*centerdist)
 144             angle1 = atan2(self.box1.center[1] - center[1], self.box1.center[0] - center[0])
 145             angle2 = atan2(self.box2.center[1] - center[1], self.box2.center[0] - center[0])
 146
 147             if bulge > 0:
 148                 connectorpath = path.path(path.moveto_pt(*self.box1.center),
 149                                           path.arcn_pt(center[0], center[1], radius, degrees(angle1), degrees(angle2)))
 150                 connector_pt.__init__(self, connectorpath.normpath().normsubpaths)
 151             else:
 152                 connectorpath = path.path(path.moveto_pt(*self.box1.center),
 153                                           path.arc_pt(center[0], center[1], radius, degrees(angle1), degrees(angle2)))
 154                 connector_pt.__init__(self, connectorpath.normpath().normsubpaths)
 155
 156         self.omitends(box1, box2)
 157         self.shortenpath(boxdists)
 158
 159
 160 class curve_pt(connector_pt):
 161
 162     def __init__(self, box1, box2,
 163                  relangle1=45, relangle2=45,
 164                  absangle1=None, absangle2=None,
 165                  absbulge=0, relbulge=0.39, boxdists=[0,0]):
 166
 167         # The deviation of the curve from a straight line can be specified:
 168         # A. By an angle at each center
 169         #    These angles are either absolute angles with origin at the positive x-axis
 170         #    or the relative angle with origin at the straight connection line
 171         # B. By the (expected) largest normal distance between line and arc: absbulge
 172         #    and/or by the (expected) bulge relative to the length of the
 173         #    straight line from center to center.
 174         # Here, we need both informations.
 175         #
 176         # a curve with relbulge=0.39 and relangle1,2=45 leads
 177         # approximately to the arc with angle=45
 178
 179         self.box1 = box1
 180         self.box2 = box2
 181
 182         rel = (self.box2.center[0] - self.box1.center[0],
 183                self.box2.center[1] - self.box1.center[1])
 184         distance = hypot(*rel)
 185         # absolute angle of the straight connection
 186         dangle = atan2(rel[1], rel[0])
 187
 188         # calculate the armlength and absolute angles for the control points:
 189         # absolute and relative bulges are added
 190         bulge = abs(distance*relbulge + absbulge)
 191
 192         if absangle1 is not None:
 193             angle1 = radians(absangle1)
 194         else:
 195             angle1 = dangle + radians(relangle1)
 196         if absangle2 is not None:
 197             angle2 = radians(absangle2)
 198         else:
 199             angle2 = dangle + radians(relangle2)
 200
 201         # get the control points
 202         control1 = (cos(angle1), sin(angle1))
 203         control2 = (cos(angle2), sin(angle2))
 204         control1 = (self.box1.center[0] + control1[0] * bulge, self.box1.center[1] + control1[1] * bulge)
 205         control2 = (self.box2.center[0] - control2[0] * bulge, self.box2.center[1] - control2[1] * bulge)
 206
 207         connector_pt.__init__(self,
 208                [path.normsubpath([path.normcurve_pt(*(self.box1.center +
 209                                                    control1 +
 210                                                    control2 + self.box2.center))], 0)])
 211
 212         self.omitends(box1, box2)
 213         self.shortenpath(boxdists)
 214
 215
 216 class twolines_pt(connector_pt):
 217
 218     def __init__(self, box1, box2,
 219                  absangle1=None, absangle2=None,
 220                  relangle1=None, relangle2=None, relangleM=None,
 221                  length1=None, length2=None,
 222                  bezierradius=None, beziersoftness=1,
 223                  arcradius=None,
 224                  boxdists=[0,0]):
 225
 226         # The connection with two lines can be done in the following ways:
 227         # 1. an angle at each box-center
 228         # 2. two armlengths (if they are long enough)
 229         # 3. angle and armlength at the same box
 230         # 4. angle and armlength at different boxes
 231         # 5. one armlength and the angle between the arms
 232         #
 233         # Angles at the box-centers can be relative or absolute
 234         # The angle in the middle is always relative
 235         # lengths are always absolute
 236
 237         self.box1 = box1
 238         self.box2 = box2
 239
 240         begin = self.box1.center
 241         end = self.box2.center
 242         rel = (self.box2.center[0] - self.box1.center[0],
 243                self.box2.center[1] - self.box1.center[1])
 244         distance = hypot(*rel)
 245         dangle = atan2(rel[1], rel[0])
 246
 247         # find out what arguments are given:
 248         if relangle1 is not None: relangle1 = radians(relangle1)
 249         if relangle2 is not None: relangle2 = radians(relangle2)
 250         if relangleM is not None: relangleM = radians(relangleM)
 251         # absangle has priority over relangle:
 252         if absangle1 is not None: relangle1 = dangle - radians(absangle1)
 253         if absangle2 is not None: relangle2 = math.pi - dangle + radians(absangle2)
 254
 255         # check integrity of arguments
 256         no_angles, no_lengths=0,0
 257         for anangle in (relangle1, relangle2, relangleM):
 258             if anangle is not None: no_angles += 1
 259         for alength in (length1, length2):
 260             if alength is not None: no_lengths += 1
 261
 262         if no_angles + no_lengths != 2:
 263             raise NotImplementedError, "Please specify exactly two angles or lengths"
 264
 265         # calculate necessary angles and armlengths
 266         # always length1 and relangle1
 267
 268         # the case with two given angles
 269         # use the "sine-theorem" for calculating length1
 270         if no_angles == 2:
 271             if relangle1 is None: relangle1 = math.pi - relangle2 - relangleM
 272             elif relangle2 is None: relangle2 = math.pi - relangle1 - relangleM
 273             elif relangleM is None: relangleM = math.pi - relangle1 - relangle2
 274             length1 = distance * abs(sin(relangle2)/sin(relangleM))
 275             middle = self._middle_a(begin, dangle, length1, relangle1)
 276         # the case with two given lengths
 277         # uses the "cosine-theorem" for calculating length1
 278         elif no_lengths == 2:
 279             relangle1 = acos((distance**2 + length1**2 - length2**2) / (2.0*distance*length1))
 280             middle = self._middle_a(begin, dangle, length1, relangle1)
 281         # the case with one length and one angle
 282         else:
 283             if relangle1 is not None:
 284                 if length1 is not None:
 285                     middle = self._middle_a(begin, dangle, length1, relangle1)
 286                 elif length2 is not None:
 287                     length1 = self._missinglength(length2, distance, relangle1)
 288                     middle = self._middle_a(begin, dangle, length1, relangle1)
 289             elif relangle2 is not None:
 290                 if length1 is not None:
 291                     length2 = self._missinglength(length1, distance, relangle2)
 292                     middle = self._middle_b(end, dangle, length2, relangle2)
 293                 elif length2 is not None:
 294                     middle = self._middle_b(end, dangle, length2, relangle2)
 295             elif relangleM is not None:
 296                 if length1 is not None:
 297                     length2 = self._missinglength(distance, length1, relangleM)
 298                     relangle1 = acos((distance**2 + length1**2 - length2**2) / (2.0*distance*length1))
 299                     middle = self._middle_a(begin, dangle, length1, relangle1)
 300                 elif length2 is not None:
 301                     length1 = self._missinglength(distance, length2, relangleM)
 302                     relangle1 = acos((distance**2 + length1**2 - length2**2) / (2.0*distance*length1))
 303                     middle = self._middle_a(begin, dangle, length1, relangle1)
 304             else:
 305                 raise NotImplementedError, "I found a strange combination of arguments"
 306
 307         connectorpath = path.path(path.moveto_pt(*self.box1.center),
 308                                   path.lineto_pt(*middle),
 309                                   path.lineto_pt(*self.box2.center))
 310         connector_pt.__init__(self, connectorpath.normpath().normsubpaths)
 311
 312         self.omitends(box1, box2)
 313         self.shortenpath(boxdists)
 314
 315     def _middle_a(self, begin, dangle, length1, angle1):
 316         a = dangle - angle1
 317         dir = cos(a), sin(a)
 318         return begin[0] + length1*dir[0], begin[1] + length1*dir[1]
 319
 320     def _middle_b(self, end, dangle, length2, angle2):
 321         # a = -math.pi + dangle + angle2
 322         return self._middle_a(end, -math.pi+dangle, length2, -angle2)
 323
 324     def _missinglength(self, lenA, lenB, angleA):
 325         # calculate lenC, where side A and angleA are opposite
 326         tmp1 = lenB * cos(angleA)
 327         tmp2 = sqrt(tmp1**2 - lenB**2 + lenA**2)
 328         if tmp1 > tmp2: return tmp1 - tmp2
 329         return tmp1 + tmp2
 330
 331
 332
 333 class line(line_pt):
 334
 335     """a line is the straight connector between the centers of two boxes"""
 336
 337     def __init__(self, box1, box2, boxdists=(0,0)):
 338         line_pt.__init__(self, box1, box2, boxdists=map(unit.topt, boxdists))
 339
 340
 341 class curve(curve_pt):
 342
 343     """a curve is the curved connector between the centers of two boxes.
 344     The constructor needs both angle and bulge"""
 345
 346
 347     def __init__(self, box1, box2,
 348                  relangle1=45, relangle2=45,
 349                  absangle1=None, absangle2=None,
 350                  absbulge=0, relbulge=0.39,
 351                  boxdists=[0,0]):
 352         curve_pt.__init__(self, box1, box2,
 353                           relangle1=relangle1, relangle2=relangle2,
 354                           absangle1=absangle1, absangle2=absangle2,
 355                           absbulge=unit.topt(absbulge), relbulge=relbulge,
 356                           boxdists=map(unit.topt, boxdists))
 357
 358 class arc(arc_pt):
 359
 360     """an arc is a round connector between the centers of two boxes.
 361     The constructor gets
 362          either an angle in (-pi,pi)
 363          or a bulge parameter in (-distance, distance)
 364            (relbulge and absbulge are added)"""
 365
 366     def __init__(self, box1, box2, relangle=45,
 367                  absbulge=None, relbulge=None, boxdists=[0,0]):
 368         if absbulge is not None:
 369             absbulge = unit.topt(absbulge)
 370         arc_pt.__init__(self, box1, box2,
 371                         relangle=relangle,
 372                         absbulge=absbulge, relbulge=relbulge,
 373                         boxdists=map(unit.topt, boxdists))
 374
 375
 376 class twolines(twolines_pt):
 377
 378     """a twolines is a connector consisting of two straight lines.
 379     The construcor takes a combination of angles and lengths:
 380       either two angles (relative or absolute)
 381       or two lenghts
 382       or one length and one angle"""
 383
 384     def __init__(self, box1, box2,
 385                  absangle1=None, absangle2=None,
 386                  relangle1=None, relangle2=None, relangleM=None,
 387                  length1=None, length2=None,
 388                  bezierradius=None, beziersoftness=1,
 389                  arcradius=None,
 390                  boxdists=[0,0]):
 391         if length1 is not None:
 392             length1 = unit.topt(length1)
 393         if length2 is not None:
 394             length2 = unit.topt(length2)
 395         if bezierradius is not None:
 396             bezierradius = unit.topt(bezierradius)
 397         if arcradius is not None:
 398             arcradius = unit.topt(arcradius)
 399         twolines_pt.__init__(self, box1, box2,
 400                              absangle1=absangle1, absangle2=absangle2,
 401                              relangle1=relangle1, relangle2=relangle2,
 402                              relangleM=relangleM,
 403                              length1=length1, length2=length2,
 404                              bezierradius=bezierradius, beziersoftness=1,
 405                              arcradius=arcradius,
 406                              boxdists=map(unit.topt, boxdists))
 407
 408
 409