pyx/connector.py

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