manual/pattern.tex

   1 \chapter{Module \module{pattern}}
   2 \label{pattern}
   3
   4 \sectionauthor{J\"org Lehmann}{joergl@users.sourceforge.net}
   5
   6 This module contains the \class{pattern} class, whichs allows the definition of PostScript Tiling
   7 patterns (cf.\ Sect.~4.9 of the PostScript Language Reference Manual)
   8 which may then be used to fill paths. In addition, a number of
   9 predefined hatch patterns are included.
  10
  11
  12 \declaremodule{}{pattern}
  13
  14 \section{Class \class{pattern}}
  15
  16 The classes \class{pattern} and \class{canvas} differ only in their
  17 constructor and in the absence of a \method{writeEPSfile()} method in
  18 the former. The \class{pattern} constructor accepts the following
  19 keyword arguments:
  20
  21 \medskip
  22 \begin{tabularx}{\linewidth}{l>{\raggedright\arraybackslash}X}
  23 keyword&description\\
  24 \hline
  25 \texttt{painttype}&\texttt{1} (default) for coloured patterns or
  26 \texttt{2} for uncoloured patterns\\
  27 \texttt{tilingtype}&\texttt{1} (default) for constant spacing tilings
  28 (patterns are spaced constantly by a multiple of a device pixel),
  29 \texttt{2} for undistorted pattern cell, whereby the spacing may vary
  30 by as much as one device pixel, or \texttt{3} for constant spacing and
  31 faster tiling which behaves as tiling type \texttt{1} but with
  32 additional distortion allowed to permit a more efficient
  33 implementation.\\
  34 \texttt{xstep}&desired horizontal spacing between pattern cells, use
  35 \texttt{None} (default) for automatic calculation from pattern
  36 bounding box.\\
  37 \texttt{ystep}&desired vertical spacing between pattern cells, use
  38 \texttt{None} (default) for automatic calculation from pattern
  39 bounding box.\\
  40 \texttt{bbox}&bounding box of pattern. Use \texttt{None} for an
  41 automatic determination of the bounding box (including an
  42 enlargement by \texttt{bboxenlarge} pts on each side.)\\
  43 \texttt{trafo}&additional transformation applied to pattern or
  44 \texttt{None} (default). This may be used to rotate the pattern or to
  45 shift its phase (by a translation).\\
  46 \texttt{bboxenlarge}&enlargement when using the automatic bounding box
  47 determination; default is 5 pts.
  48 \end{tabularx}
  49 \medskip
  50
  51 After you have created a pattern instance, you define the pattern
  52 shape by drawing in it like in an ordinary canvas. To use the pattern,
  53 you simply pass the pattern instance to a \method{stroke()},
  54 \method{fill()}, \method{draw()} or \method{set()} method of the
  55 canvas, just like you would do with a colour, etc.
  56
  57
  58
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