7 .. sectionauthor:: Jörg Lehmann <joergl@users.sourceforge.net>
10 One of the central modules for the PostScript access in PyX is named ``canvas``.
11 Besides providing the class ``canvas``, which presents a collection of visual
12 elements like paths, other canvases, TeX or LaTeX elements, it contains the
13 class ``canvas.clip`` which allows clipping of the output.
15 A canvas may also be embedded in another one using its ``insert`` method. This
16 may be useful when you want to apply a transformation on a whole set of
26 This is the basic class of the canvas module, which serves to collect various
27 graphical and text elements you want to write eventually to an (E)PS file.
30 .. class:: canvas(attrs=[], texrunner=None)
32 Construct a new canvas, applying the given *attrs*, which can be instances of
33 :class:`trafo.trafo`, :class:`canvas.clip`, :class:`style.strokestyle` or
34 :class:`style.fillstyle`. The *texrunner* argument can be used to specify the
35 texrunner instance used for the :meth:`text` method of the canvas. If not
36 specified, it defaults to *text.defaulttexrunner*.
38 Paths can be drawn on the canvas using one of the following methods:
41 .. method:: canvas.draw(path, attrs)
43 Draws *path* on the canvas applying the given *attrs*.
46 .. method:: canvas.fill(path, attrs=[])
48 Fills the given *path* on the canvas applying the given *attrs*.
51 .. method:: canvas.stroke(path, attrs=[])
53 Strokes the given *path* on the canvas applying the given *attrs*.
55 Arbitrary allowed elements like other :class:`canvas` instances can be inserted
59 .. method:: canvas.insert(item, attrs=[])
61 Inserts an instance of :class:`base.canvasitem` into the canvas. If *attrs* are
62 present, *item* is inserted into a new :class:`canvas`\ instance with *attrs* as
63 arguments passed to its constructor is created. Then this :class:`canvas`
64 instance is inserted itself into the canvas.
66 Text output on the canvas is possible using
69 .. method:: canvas.text(x, y, text, attrs=[])
71 Inserts *text* at position (*x*, *y*) into the canvas applying *attrs*. This is
72 a shortcut for ``insert(texrunner.text(x, y, text, attrs))``).
74 The :class:`canvas` class provides access to the total geometrical size of its
78 .. method:: canvas.bbox()
80 Returns the bounding box enclosing all elements of the canvas.
82 A canvas also allows one to set its TeX runner:
85 .. method:: canvas.settexrunner(texrunner)
87 Sets a new *texrunner* for the canvas.
89 The contents of the canvas can be written using the following two convenience
90 methods, which wrap the canvas into a single page document.
93 .. method:: canvas.writeEPSfile(file, *args, **kwargs)
95 Writes the canvas to *file* using the EPS format. *file* either has to provide a
96 write method or it is used as a string containing the filename (the extension
97 ``.eps`` is appended automatically, if it is not present). This method
98 constructs a single page document, passing *args* and *kwargs* to the
99 :class:`document.page` constructor and the calls the :meth:`writeEPSfile` method
100 of this :class:`document.document` instance passing the *file*.
103 .. method:: canvas.writePSfile(file, *args, **kwargs)
105 Similar to :meth:`writeEPSfile` but using the PS format.
108 .. method:: canvas.writePDFfile(file, *args, **kwargs)
110 Similar to :meth:`writeEPSfile` but using the PDF format.
113 .. method:: canvas.writetofile(filename, *args, **kwargs)
115 Determine the file type (EPS, PS, or PDF) from the file extension of *filename*
116 and call the corresponding write method with the given arguments *arg* and
120 .. method:: canvas.pipeGS(filename="-", device=None, resolution=100, gscommand="gs", gsoptions="", textalphabits=4, graphicsalphabits=4, ciecolor=False, input="eps", **kwargs)
122 This method pipes the content of a canvas to the ghostscript interpreter
123 directly to generate other output formats. At least *filename* or *device* must
124 be set. *filename* specifies the name of the output file. No file extension will
125 be added to that name in any case. When no *filename* is specified, the output
126 is written to stdout. *device* specifies a ghostscript output device by a
127 string. Depending on your ghostscript configuration ``"png16"``, ``"png16m"``,
128 ``"png256"``, ``"png48"``, ``"pngalpha"``, ``"pnggray"``, ``"pngmono"``,
129 ``"jpeg"``, and ``"jpeggray"`` might be available among others. See the output
130 of ``gs --help`` and the ghostscript documentation for more information. When
131 *filename* is specified but the device is not set, ``"png16m"`` is used when the
132 filename ends in ``.png`` and ``"jpeg"`` is used when the filename ends in
135 *resolution* specifies the resolution in dpi (dots per inch). *gscmd* is the
136 command to be used to invoke ghostscript. *gsoptions* are an option string
137 passed to the ghostscript interpreter. *textalphabits* are *graphicsalphabits*
138 are conventient parameters to set the ``TextAlphaBits`` and
139 ``GraphicsAlphaBits`` options of ghostscript. You can skip the addition of those
140 option by set their value to ``None``. *ciecolor* adds the ``-dUseCIEColor``
141 flag to improve the CMYK to RGB color conversion. *input* can be either
142 ``"eps"`` or ``"pdf"`` to select the input type to be passed to ghostscript
143 (note slightly different features available in the different input types).
145 *kwargs* are passed to the :meth:`writeEPSfile` method (not counting the *file*
146 parameter), which is used to generate the input for ghostscript. By that you
147 gain access to the :class:`document.page` constructor arguments.
149 For more information about the possible arguments of the :class:`document.page`
150 constructor, we refer to Sect. :ref:`document`.
152 .. % %% Local Variables:
154 .. % %% TeX-master: "manual.tex"