pyx/canvas.py

   1 # -*- coding: ISO-8859-1 -*-
   2 #
   3 #
   4 # Copyright (C) 2002-2006 Jörg Lehmann <joergl@users.sourceforge.net>
   5 # Copyright (C) 2002-2006 André Wobst <wobsta@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 """The canvas module provides a PostScript canvas class and related classes
  24
  25 A canvas holds a collection of all elements and corresponding attributes to be
  26 displayed. """
  27
  28 #
  29 # canvas item
  30 #
  31
  32 from __future__ import nested_scopes
  33 import os
  34
  35 class canvasitem:
  36
  37     """Base class for everything which can be inserted into a canvas"""
  38
  39     def bbox(self):
  40         """return bounding box of canvasitem"""
  41         pass
  42
  43     def processPS(self, file, writer, context, registry, bbox):
  44         """process canvasitem by writing the corresponding PS code to file and
  45         by updating context, registry as well as bbox
  46
  47         - the PS code corresponding to the canvasitem has to be written in the
  48           stream file, which provides a write(string) method
  49         - writer is the PSwriter used for the output
  50         - context is an instance of pswriter.context which is used for keeping
  51           track of the graphics state (current linewidth, colorspace and font))
  52         - registry is used for tracking resources needed by the canvasitem
  53         - bbox has to be updated to include the bounding box of the canvasitem
  54         """
  55         raise NotImplementedError()
  56
  57     def processPDF(self, file, writer, context, registry, bbox):
  58         """process canvasitem by writing the corresponding PDF code to file and
  59         by updating context, registry as well as bbox
  60
  61         - the PDF code corresponding to the canvasitem has to be written in the
  62           stream file, which provides a write(string) method
  63         - writer is the PDFwriter used for the output, which contains properties
  64           like whether streamcompression is used
  65         - context is an instance of pdfwriter.context which is used for keeping
  66           track of the graphics state, in particular for the emulation of PS
  67           behaviour regarding fill and stroke styles, for keeping track of the
  68           currently selected font as well as of text regions.
  69         - registry is used for tracking resources needed by the canvasitem
  70         - bbox has to be updated to include the bounding box of the canvasitem
  71         """
  72         raise NotImplementedError()
  73
  74
  75 import attr, deco, deformer, document, style, trafo, type1font
  76 import bbox as bboxmodule
  77
  78
  79 #
  80 # clipping class
  81 #
  82
  83 class clip(canvasitem):
  84
  85     """class for use in canvas constructor which clips to a path"""
  86
  87     def __init__(self, path):
  88         """construct a clip instance for a given path"""
  89         self.path = path
  90
  91     def bbox(self):
  92         # as a canvasitem a clipping path has NO influence on the bbox...
  93         return bboxmodule.empty()
  94
  95     def clipbbox(self):
  96         # ... but for clipping, we nevertheless need the bbox
  97         return self.path.bbox()
  98
  99     def processPS(self, file, writer, context, registry, bbox):
 100         file.write("newpath\n")
 101         self.path.outputPS(file, writer)
 102         file.write("clip\n")
 103
 104     def processPDF(self, file, writer, context, registry, bbox):
 105         self.path.outputPDF(file, writer)
 106         file.write("W n\n")
 107
 108
 109 #
 110 # general canvas class
 111 #
 112
 113 class _canvas(canvasitem):
 114
 115     """a canvas holds a collection of canvasitems"""
 116
 117     def __init__(self, attrs=[], texrunner=None):
 118
 119         """construct a canvas
 120
 121         The canvas can be modfied by supplying args, which have
 122         to be instances of one of the following classes:
 123          - trafo.trafo (leading to a global transformation of the canvas)
 124          - canvas.clip (clips the canvas)
 125          - style.strokestyle, style.fillstyle (sets some global attributes of the canvas)
 126
 127         Note that, while the first two properties are fixed for the
 128         whole canvas, the last one can be changed via canvas.set().
 129
 130         The texrunner instance used for the text method can be specified
 131         using the texrunner argument. It defaults to text.defaulttexrunner
 132
 133         """
 134
 135         self.items     = []
 136         self.trafo     = trafo.trafo()
 137         self.clipbbox  = None
 138         if texrunner is not None:
 139             self.texrunner = texrunner
 140         else:
 141             # prevent cyclic imports
 142             import text
 143             self.texrunner = text.defaulttexrunner
 144
 145         attr.checkattrs(attrs, [trafo.trafo_pt, clip, style.strokestyle, style.fillstyle])
 146         # We have to reverse the trafos such that the PostScript concat operators
 147         # are in the right order. Correspondingly, we below multiply the current self.trafo
 148         # from the right.
 149         # Note that while for the stroke and fill styles the order doesn't matter at all,
 150         # this is not true for the clip operation.
 151         attrs = attrs[:]
 152         attrs.reverse()
 153         for aattr in attrs:
 154             if isinstance(aattr, trafo.trafo_pt):
 155                 self.trafo = self.trafo * aattr
 156             elif isinstance(aattr, clip):
 157                 if self.clipbbox is None:
 158                     self.clipbbox = aattr.clipbbox().transformed(self.trafo)
 159                 else:
 160                     self.clippbox *= aattr.clipbbox().transformed(self.trafo)
 161             self.items.append(aattr)
 162
 163     def __len__(self):
 164         return len(self.items)
 165
 166     def __getitem__(self, i):
 167         return self.items[i]
 168
 169     def bbox(self):
 170         """returns bounding box of canvas
 171
 172         Note that this bounding box doesn't take into account the linewidths, so
 173         is less accurate than the one used when writing the output to a file.
 174         """
 175         obbox = bboxmodule.empty()
 176         for cmd in self.items:
 177             obbox += cmd.bbox()
 178
 179         # transform according to our global transformation and
 180         # intersect with clipping bounding box (which has already been
 181         # transformed in canvas.__init__())
 182         obbox.transform(self.trafo)
 183         if self.clipbbox is not None:
 184             obbox *= self.clipbbox
 185         return obbox
 186
 187     def processPS(self, file, writer, context, registry, bbox):
 188         context = context()
 189         if self.items:
 190             file.write("gsave\n")
 191             nbbox = bboxmodule.empty()
 192             for item in self.items:
 193                 item.processPS(file, writer, context, registry, nbbox)
 194             # update bounding bbox
 195             nbbox.transform(self.trafo)
 196             if self.clipbbox is not None:
 197                 nbbox *= self.clipbbox
 198             bbox += nbbox
 199             file.write("grestore\n")
 200
 201     def processPDF(self, file, writer, context, registry, bbox):
 202         context = context()
 203         if self.items:
 204             file.write("q\n") # gsave
 205             nbbox = bboxmodule.empty()
 206             for item in self.items:
 207                 if isinstance(item, type1font.text_pt):
 208                     if not context.textregion:
 209                         file.write("BT\n")
 210                         context.textregion = 1
 211                 else:
 212                     if context.textregion:
 213                         file.write("ET\n")
 214                         context.textregion = 0
 215                         context.font = None
 216                 item.processPDF(file, writer, context, registry, nbbox)
 217             if context.textregion:
 218                 file.write("ET\n")
 219                 context.textregion = 0
 220                 context.font = None
 221             # update bounding bbox
 222             nbbox.transform(self.trafo)
 223             if self.clipbbox is not None:
 224                 nbbox *= self.clipbbox
 225             bbox += nbbox
 226             file.write("Q\n") # grestore
 227
 228     def insert(self, item, attrs=None):
 229         """insert item in the canvas.
 230
 231         If attrs are passed, a canvas containing the item is inserted applying attrs.
 232
 233         returns the item
 234
 235         """
 236
 237         if not isinstance(item, canvasitem):
 238             raise RuntimeError("only instances of base.canvasitem can be inserted into a canvas")
 239
 240         if attrs:
 241             sc = _canvas(attrs)
 242             sc.insert(item)
 243             self.items.append(sc)
 244         else:
 245             self.items.append(item)
 246         return item
 247
 248     def draw(self, path, attrs):
 249         """draw path on canvas using the style given by args
 250
 251         The argument attrs consists of PathStyles, which modify
 252         the appearance of the path, PathDecos, which add some new
 253         visual elements to the path, or trafos, which are applied
 254         before drawing the path.
 255
 256         """
 257
 258         attrs = attr.mergeattrs(attrs)
 259         attr.checkattrs(attrs, [deco.deco, deformer.deformer, style.fillstyle, style.strokestyle])
 260
 261         for adeformer in attr.getattrs(attrs, [deformer.deformer]):
 262             path = adeformer.deform(path)
 263
 264         styles = attr.getattrs(attrs, [style.fillstyle, style.strokestyle])
 265         dp = deco.decoratedpath(path, styles=styles)
 266
 267         # add path decorations and modify path accordingly
 268         for adeco in attr.getattrs(attrs, [deco.deco]):
 269             adeco.decorate(dp, self.texrunner)
 270
 271         self.insert(dp)
 272
 273     def stroke(self, path, attrs=[]):
 274         """stroke path on canvas using the style given by args
 275
 276         The argument attrs consists of PathStyles, which modify
 277         the appearance of the path, PathDecos, which add some new
 278         visual elements to the path, or trafos, which are applied
 279         before drawing the path.
 280
 281         """
 282
 283         self.draw(path, [deco.stroked]+list(attrs))
 284
 285     def fill(self, path, attrs=[]):
 286         """fill path on canvas using the style given by args
 287
 288         The argument attrs consists of PathStyles, which modify
 289         the appearance of the path, PathDecos, which add some new
 290         visual elements to the path, or trafos, which are applied
 291         before drawing the path.
 292
 293         """
 294
 295         self.draw(path, [deco.filled]+list(attrs))
 296
 297     def settexrunner(self, texrunner):
 298         """sets the texrunner to be used to within the text and text_pt methods"""
 299
 300         self.texrunner = texrunner
 301
 302     def text(self, x, y, atext, *args, **kwargs):
 303         """insert a text into the canvas
 304
 305         inserts a textbox created by self.texrunner.text into the canvas
 306
 307         returns the inserted textbox"""
 308
 309         return self.insert(self.texrunner.text(x, y, atext, *args, **kwargs))
 310
 311
 312     def text_pt(self, x, y, atext, *args):
 313         """insert a text into the canvas
 314
 315         inserts a textbox created by self.texrunner.text_pt into the canvas
 316
 317         returns the inserted textbox"""
 318
 319         return self.insert(self.texrunner.text_pt(x, y, atext, *args))
 320
 321 #
 322 # user canvas class which adds a few convenience methods for single page output
 323 #
 324
 325 def _wrappedindocument(method):
 326     def wrappedindocument(self, file, *args, **kwargs):
 327         d = document.document([document.page(self, *args, **kwargs)])
 328         self.__name__ = method.__name__
 329         self.__doc__ = method.__doc__
 330         return method(d, file)
 331     return wrappedindocument
 332
 333
 334 class canvas(_canvas):
 335
 336     """a canvas holds a collection of canvasitems"""
 337
 338     writeEPSfile = _wrappedindocument(document.document.writeEPSfile)
 339     writePSfile = _wrappedindocument(document.document.writePSfile)
 340     writePDFfile = _wrappedindocument(document.document.writePDFfile)
 341     writetofile = _wrappedindocument(document.document.writetofile)
 342
 343     def pipeGS(self, filename="-", device=None, resolution=100,
 344                gscommand="gs", gsoptions="",
 345                textalphabits=4, graphicsalphabits=4,
 346                **kwargs):
 347         if device is None:
 348             if filename.endswith(".png"):
 349                 device = "png16m"
 350             if filename.endswith(".jpg"):
 351                 device = "jpeg"
 352         gscommand += " -dEPSCrop -dNOPAUSE -dQUIET -dBATCH -r%i -sDEVICE=%s -sOutputFile=%s" % (resolution, device, filename)
 353         if gsoptions:
 354             gscommand += " %s" % gsoptions
 355         if textalphabits is not None:
 356             gscommand += " -dTextAlphaBits=%i" % textalphabits
 357         if graphicsalphabits is not None:
 358             gscommand += " -dGraphicsAlphaBits=%i" % graphicsalphabits
 359         gscommand += " -"
 360         input = os.popen(gscommand, "w")
 361         self.writeEPSfile(input, **kwargs)