pyx/mesh.py

   1 # -*- coding: ISO-8859-1 -*-
   2 #
   3 #
   4 # Copyright (C) 2006 André Wobst <wobsta@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 # Just a quick'n'dirty ascii art (I'll do a nice PyX plot later on):
  24 #
  25 #
  26 #      node1 *
  27 #            | \
  28 #            |   \  neighbor2
  29 #            |     \
  30 #            |       \
  31 #  neighbor3 |element * node3
  32 #            |       /
  33 #            |     /
  34 #            |   /  neighbor1
  35 #            | /
  36 #      node2 *
  37
  38
  39 import struct, binascii, zlib
  40 import bbox, canvas, color, pdfwriter, unit
  41
  42
  43 class mesh:
  44
  45     def __init__(self, elements):
  46         self.elements = elements
  47
  48
  49 class node_pt:
  50
  51     def __init__(self, coords_pt, value):
  52         self.coords_pt = coords_pt
  53         self.value = value
  54
  55
  56 class node(node_pt):
  57
  58     def __init__(self, coords, value):
  59         node_pt.__init__(self, [unit.topt(coord) for coord in coords], value)
  60
  61
  62 class element:
  63
  64     def __init__(self, nodes, neighbors=None):
  65         self.nodes = nodes
  66         self.neighbors = neighbors
  67
  68
  69 def coords24bit_pt(coords_pt, min_pt, max_pt):
  70     return struct.pack(">I", int((coords_pt-min_pt)*16777215.0/(max_pt-min_pt)))[1:]
  71
  72
  73 class PDFGenericResource(pdfwriter.PDFobject):
  74
  75     def __init__(self, type, name, content):
  76         pdfwriter.PDFobject.__init__(self, type, name)
  77         self.content = content
  78
  79     def write(self, file, writer, registry):
  80         file.write(self.content)
  81
  82
  83 class canvasmesh(mesh, canvas.canvasitem):
  84
  85     def __init__(self, elements, check=1):
  86         mesh.__init__(self, elements)
  87         if check:
  88             colorspacestring = ""
  89             for element in elements:
  90                 if len(element.nodes) != 3:
  91                     raise ValueError("triangular mesh expected")
  92                 try:
  93                     for node in element.nodes:
  94                         if not colorspacestring:
  95                             colorspacestring = node.value.colorspacestring()
  96                         elif node.value.colorspacestring() != colorspacestring:
  97                             raise ValueError("color space mismatch")
  98                 except AttributeError:
  99                     raise ValueError("gray, rgb or cmyk color values expected")
 100                 for node in element.nodes:
 101                     if len(node.coords_pt) != 2:
 102                         raise ValueError("two dimensional coordinates expected")
 103
 104     def bbox(self):
 105         return bbox.bbox_pt(min([node.coords_pt[0] for element in self.elements for node in element.nodes]),
 106                             min([node.coords_pt[1] for element in self.elements for node in element.nodes]),
 107                             max([node.coords_pt[0] for element in self.elements for node in element.nodes]),
 108                             max([node.coords_pt[1] for element in self.elements for node in element.nodes]))
 109
 110     def data(self, bbox):
 111         return "".join(["\000%s%s%s" % (coords24bit_pt(node.coords_pt[0], bbox.llx_pt, bbox.urx_pt),
 112                                         coords24bit_pt(node.coords_pt[1], bbox.lly_pt, bbox.ury_pt),
 113                                         node.value.tostring8bit())
 114                         for element in self.elements for node in element.nodes])
 115
 116     def processPS(self, file, writer, context, registry, bbox):
 117         thisbbox = self.bbox()
 118         bbox += thisbbox
 119         file.write("""<< /ShadingType 4
 120 /ColorSpace %s
 121 /BitsPerCoordinate 24
 122 /BitsPerComponent 8
 123 /BitsPerFlag 8
 124 /Decode [%f %f %f %f %s]
 125 /DataSource currentfile /ASCIIHexDecode filter /FlateDecode filter
 126 >> shfill\n""" % (self.elements[0].nodes[0].value.colorspacestring(),
 127                   thisbbox.llx_pt, thisbbox.urx_pt, thisbbox.lly_pt, thisbbox.ury_pt,
 128                   " ".join(["0 1" for value in self.elements[0].nodes[0].value.tostring8bit()])))
 129         file.write(binascii.b2a_hex(zlib.compress(self.data(thisbbox))))
 130         file.write("\n")
 131
 132     def processPDF(self, file, writer, context, registry, bbox):
 133         thisbbox = self.bbox()
 134         bbox += thisbbox
 135         d = self.data(thisbbox)
 136         if writer.compress:
 137             filter = "/Filter /FlateDecode\n"
 138             d = zlib.compress(d)
 139         else:
 140             filter = ""
 141         name = "shading-%s" % id(self)
 142         shading = PDFGenericResource("shading", name, """<< /ShadingType 4
 143 /ColorSpace %s
 144 /BitsPerCoordinate 24
 145 /BitsPerComponent 8
 146 /BitsPerFlag 8
 147 /Decode [%f %f %f %f %s]
 148 /Length %i
 149 %s>>
 150 stream
 151 %s
 152 endstream\n""" % (self.elements[0].nodes[0].value.colorspacestring(),
 153                   thisbbox.llx_pt, thisbbox.urx_pt, thisbbox.lly_pt, thisbbox.ury_pt,
 154                   " ".join(["0 1" for value in self.elements[0].nodes[0].value.tostring8bit()]),
 155                   len(d), filter, d))
 156         registry.add(shading)
 157         registry.addresource("Shading", name, shading)
 158         file.write("/%s sh\n" % name)