manual/box.tex

   1 \chapter{Module box: convex box handling}
   2 \label{module:box}
   3
   4 This module has a quite internal character, but might still be useful
   5 from the users point of view. It might also get further enhanced to
   6 cover a broader range of standard arranging problems.
   7
   8 In the context of this module a box is a convex polygon having
   9 optionally a center coordinate, which plays an important role for the
  10 box alignment. The center might not at all be central, but it should
  11 be within the box. The convexity is necessary in order to keep the
  12 problems to be solved by this module quite a bit easier and
  13 unambiguous.
  14
  15 Directions (for the alignment etc.) are usually provided as pairs
  16 (dx, dy) within this module. It is required, that at least one of
  17 these two numbers is unequal to zero. No further assumptions are taken.
  18
  19 \section{Polygon}
  20
  21 A polygon is the most general case of a box. It is an instance of the
  22 class \verb|polygon|. The constructor takes a list of points (which
  23 are (x, y) tuples) in the keyword argument \verb|corners| and
  24 optionally another (x, y) tuple as the keyword argument \verb|center|.
  25 The corners have to be ordered counterclockwise. In the following list
  26 some methods of this \verb|polygon| class are explained:
  27
  28 \begin{description}
  29 \raggedright
  30 \item[\texttt{path(centerradius=None, bezierradius=None,
  31 beziersoftness=1)}:] returns a path of the box; the center might be
  32 marked by a small circle of radius \verb|centerradius|; the corners
  33 might be rounded using the parameters \verb|bezierradius| and
  34 \verb|beziersoftness|. For each corner of the box there may be one value
  35 for beziersoftness and two bezierradii. For convenience, it is not necessary
  36 to specify the whole list (for beziersoftness) and the whole list of
  37 lists (bezierradius) here. You may give a single value and/or a 2-tuple instead.
  38 \item[\texttt{transform(*trafos)}:] performs a list of transformations
  39 to the box
  40 \item[\texttt{reltransform(*trafos)}:] performs a list of
  41 transformations to the box relative to the box center
  42
  43 \begin{figure}
  44 \centerline{\includegraphics{boxalign}}
  45 \caption{circle and line alignment examples (equal direction and
  46 distance)}
  47 \label{fig:boxalign}
  48 \end{figure}
  49
  50 \item[\texttt{circlealignvector(a, dx, dy)}:] returns a vector (a
  51 tuple (x, y)) to align the box at a circle with radius \verb|a| in
  52 the direction (\verb|dx|, \verb|dy|); see figure~\ref{fig:boxalign}
  53 \item[\texttt{linealignvector(a, dx, dy)}:] as above, but align at a
  54 line with distance \verb|a|
  55 \item[\texttt{circlealign(a, dx, dy)}:] as circlealignvector, but
  56 perform the alignment instead of returning the vector
  57 \item[\texttt{linealign(a, dx, dy)}:] as linealignvector, but
  58 perform the alignment instead of returning the vector
  59 \item[\texttt{extent(dx, dy)}:] extent of the box in the direction
  60 (\verb|dx|, \verb|dy|)
  61 \item[\texttt{pointdistance(x, y)}:] distance of the point (\verb|x|,
  62 \verb|y|) to the box; the point must be outside of the box
  63 \item[\texttt{boxdistance(other)}:] distance of the box to the box
  64 \verb|other|; when the boxes are overlapping, \verb|BoxCrossError| is
  65 raised
  66 \item[\texttt{bbox()}:] returns a bounding box instance appropriate to
  67 the box
  68 \end{description}
  69
  70 \section{Functions working on a box list}
  71
  72 \begin{description}
  73 \raggedright
  74 \item[\texttt{circlealignequal(boxes, a, dx, dy)}:] Performs a circle
  75 alignment of the boxes \verb|boxes| using the parameters \verb|a|,
  76 \verb|dx|, and \verb|dy| as in the \verb|circlealign| method. For the
  77 length of the alignment vector its largest value is taken for all
  78 cases.
  79 \item[\texttt{linealignequal(boxes, a, dx, dy)}:] as above, but
  80 performing a line alignment
  81 \item[\texttt{tile(boxes, a, dx, dy)}:] tiles the boxes \verb|boxes|
  82 with a distance \verb|a| between the boxes (in addition the maximal box
  83 extent in the given direction (\verb|dx|, \verb|dy|) is taken into
  84 account)
  85 \end{description}
  86
  87 \section{Rectangular boxes}
  88
  89 For easier creation of rectangular boxes, the module provides the
  90 specialized class \verb|rect|. Its constructor first takes four
  91 parameters, namely the x, y position and the box width and height.
  92 Additionally, for the definition of the position of the center, two
  93 keyword arguments are available. The parameter \verb|relcenter| takes
  94 a tuple containing a relative x, y position of the center (they are
  95 relative to the box extent, thus values between \verb|0| and
  96 \verb|1| should be used). The parameter \verb|abscenter| takes a tuple
  97 containing the x and y position of the center. This values are
  98 measured with respect to the lower left corner of the box. By
  99 default, the center of the rectangular box is set to this lower left
 100 corner.
 101