manual/bbox.rst

   1
   2 .. _bbox_module:
   3
   4 .. module:: bbox
   5
   6 ******************
   7 Module :mod:`bbox`
   8 ******************
   9
  10 The :mod:`bbox`` module contains the definition of the :class:`bbox` class representing
  11 bounding boxes of graphical elements like paths, canvases, etc. used in PyX.
  12 Usually, you obtain ``bbox`` instances as return values of the corresponding
  13 ``bbox())`` method, but you may also construct a bounding box by yourself.
  14
  15
  16 :class:`bbox` constructor
  17 =========================
  18
  19 The ``bbox`` constructor accepts the following keyword arguments
  20
  21 +---------+-----------------------------------------------+
  22 | keyword | description                                   |
  23 +=========+===============================================+
  24 | ``llx`` | ``None`` (default) for :math:`-\infty` or     |
  25 |         | :math:`x`\ -position of the lower left corner |
  26 |         | of the bbox (in user units)                   |
  27 +---------+-----------------------------------------------+
  28 | ``lly`` | ``None`` (default) for :math:`-\infty` or     |
  29 |         | :math:`y`\ -position of the lower left corner |
  30 |         | of the bbox (in user units)                   |
  31 +---------+-----------------------------------------------+
  32 | ``urx`` | ``None`` (default) for :math:`\infty` or      |
  33 |         | :math:`x`\ -position of the upper right       |
  34 |         | corner of the bbox (in user units)            |
  35 +---------+-----------------------------------------------+
  36 | ``ury`` | ``None`` (default) for :math:`\infty` or      |
  37 |         | :math:`y`\ -position of the upper right       |
  38 |         | corner of the bbox (in user units)            |
  39 +---------+-----------------------------------------------+
  40
  41
  42 :class:`bbox` methods
  43 =====================
  44
  45 +-------------------------------------------+-----------------------------------------------+
  46 | ``bbox`` method                           | function                                      |
  47 +===========================================+===============================================+
  48 | ``intersects(other)``                     | returns ``1`` if the ``bbox`` instance and    |
  49 |                                           | ``other`` intersect with each other.          |
  50 +-------------------------------------------+-----------------------------------------------+
  51 | ``transformed(self, trafo)``              | returns ``self`` transformed by               |
  52 |                                           | transformation ``trafo``.                     |
  53 +-------------------------------------------+-----------------------------------------------+
  54 | ``enlarged(all=0, bottom=None, left=None, | return the bounding box enlarged by the given |
  55 | top=None, right=None)``                   | amount (in visual units). ``all`` is the      |
  56 |                                           | default for all other directions, which is    |
  57 |                                           | used whenever ``None`` is given for the       |
  58 |                                           | corresponding direction.                      |
  59 +-------------------------------------------+-----------------------------------------------+
  60 | ``path()`` or ``rect()``                  | return the ``path`` corresponding to the      |
  61 |                                           | bounding box rectangle.                       |
  62 +-------------------------------------------+-----------------------------------------------+
  63 | ``height()``                              | returns the height of the bounding box (in    |
  64 |                                           | PyX lengths).                                 |
  65 +-------------------------------------------+-----------------------------------------------+
  66 | ``width()``                               | returns the width of the bounding box (in PyX |
  67 |                                           | lengths).                                     |
  68 +-------------------------------------------+-----------------------------------------------+
  69 | ``top()``                                 | returns the :math:`y`\ -position of the top   |
  70 |                                           | of the bounding box (in PyX lengths).         |
  71 +-------------------------------------------+-----------------------------------------------+
  72 | ``bottom()``                              | returns the :math:`y`\ -position of the       |
  73 |                                           | bottom of the bounding box (in PyX lengths).  |
  74 +-------------------------------------------+-----------------------------------------------+
  75 | ``left()``                                | returns the :math:`x`\ -position of the left  |
  76 |                                           | side of the bounding box (in PyX lengths).    |
  77 +-------------------------------------------+-----------------------------------------------+
  78 | ``right()``                               | returns the :math:`x`\ -position of the right |
  79 |                                           | side of the bounding box (in PyX lengths).    |
  80 +-------------------------------------------+-----------------------------------------------+
  81
  82 Furthermore, two bounding boxes can be added (giving the bounding box enclosing
  83 both) and multiplied (giving the intersection of both bounding boxes).
  84