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 \item[\texttt{path(centerradius=None, bezierradius=None,
  30 beziersoftness=1)}:] returns a path of the box; the center might be
  31 marked by a small circle of radius \verb|centerradius|; the corners
  32 might be rounded using the parameters \verb|bezierradius| and
  33 \verb|beziersoftness|. For each corner of the box there may be one value
  34 for beziersoftness and two bezierradii. For convenience, it is not necessary
  35 to specify the whole list (for beziersoftness) and the whole list of
  36 lists (bezierradius) here. You may give a single value and/or a 2-tuple instead.
  37 \item[\texttt{transform(*trafos)}:] performs a list of transformations
  38 to the box
  39 \item[\texttt{reltransform(*trafos)}:] performs a list of
  40 transformations to the box relative to the box center
  41
  42 \includegraphics{boxalign}
  43 \centerline{circle and line alignment examples (equal direction and
  44 distance)}
  45
  46 \item[\texttt{circlealignvector(a, dx, dy)}:] returns a vector (a
  47 tuple (x, y)) to align the box at a circle with radius \verb|a| in
  48 the direction (\verb|dx|, \verb|dy|); see figure~\ref{fig:boxalign}
  49 \item[\texttt{linealignvector(a, dx, dy)}:] as above, but align at a
  50 line with distance \verb|a|
  51 \item[\texttt{circlealign(a, dx, dy)}:] as circlealignvector, but
  52 perform the alignment instead of returning the vector
  53 \item[\texttt{linealign(a, dx, dy)}:] as linealignvector, but
  54 perform the alignment instead of returning the vector
  55 \item[\texttt{extent(dx, dy)}:] extent of the box in the direction
  56 (\verb|dx|, \verb|dy|)
  57 \item[\texttt{pointdistance(x, y)}:] distance of the point (\verb|x|,
  58 \verb|y|) to the box; the point must be outside of the box
  59 \item[\texttt{boxdistance(other)}:] distance of the box to the box
  60 \verb|other|; when the boxes are overlapping, \verb|BoxCrossError| is
  61 raised
  62 \item[\texttt{bbox()}:] returns a bounding box instance appropriate to
  63 the box
  64 \end{description}
  65
  66 \section{Functions working on a box list}
  67
  68 \begin{description}
  69 \item[\texttt{circlealignequal(boxes, a, dx, dy)}:] Performs a circle
  70 alignment of the boxes \verb|boxes| using the parameters \verb|a|,
  71 \verb|dx|, and \verb|dy| as in the \verb|circlealign| method. For the
  72 length of the alignment vector its largest value is taken for all
  73 cases.
  74 \item[\texttt{linealignequal(boxes, a, dx, dy)}:] as above, but
  75 performing a line alignment
  76 \item[\texttt{tile(boxes, a, dx, dy)}:] tiles the boxes \verb|boxes|
  77 with a distance \verb|a| between the boxes (in addition the maximal box
  78 extent in the given direction (\verb|dx|, \verb|dy|) is taken into
  79 account)
  80 \end{description}
  81
  82 \section{Rectangular boxes}
  83
  84 For easier creation of rectangular boxes, the module provides the
  85 specialized class \verb|rect|. Its constructor first takes four
  86 parameters, namely the x, y position and the box width and height.
  87 Additionally, for the definition of the position of the center, two
  88 keyword arguments are available. The parameter \verb|relcenter| takes
  89 a tuple containing a relative x, y position of the center (they are
  90 relative to the box extent, thus values between \verb|0| and
  91 \verb|1| should be used). The parameter \verb|abscenter| takes a tuple
  92 containing the x and y position of the center. This values are
  93 measured with respect to the lower left corner of the box. By
  94 default, the center of the rectangular box is set to this lower left
  95 corner.
  96