pyx/connector.py

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