python-gaphas 0.7.2-1 / usr / share / pyshared / gaphas / connector.py

"""
Basic connectors such as Ports and Handles.
"""

__version__ = "$Revision: 2341 $"
# $HeadURL: https://svn.devjavu.com/gaphor/gaphas/trunk/gaphas/item.py $

from gaphas.solver import solvable, WEAK, NORMAL, STRONG, VERY_STRONG
from gaphas.state import observed, reversible_property
from gaphas.geometry import distance_line_point, distance_point_point
from gaphas.constraint import LineConstraint, PositionConstraint


def deprecated(e):
    return e


class Position(object):
    """
    A point constructed of two `Variable`'s.

    >>> vp = Position((3, 5))
    >>> vp.x, vp.y
    (Variable(3, 20), Variable(5, 20))
    >>> vp.pos
    (Variable(3, 20), Variable(5, 20))
    >>> vp[0], vp[1]
    (Variable(3, 20), Variable(5, 20))
    """

    _x = solvable(varname='_v_x')
    _y = solvable(varname='_v_y')

    def __init__(self, pos, strength=NORMAL):
        self._x, self._y = pos
        self._x.strength = strength
        self._y.strength = strength

    # _x is a Variable, therefore observed
    def _set_x(self, x):
        self._x = x

    x = property(lambda s: s._x, _set_x)

    # _y is a Variable, therefore observed
    def _set_y(self, y):
        self._y = y

    y = property(lambda s: s._y, _set_y)

    @observed
    def _set_pos(self, pos):
        """
        Set handle position (Item coordinates).
        """
        self.x, self.y = pos

    pos = property(lambda s: (s.x, s.y), _set_pos)

    def __str__(self):
        return '<%s object on (%g, %g)>' % (self.__class__.__name__, float(self._x), float(self._y))
    __repr__ = __str__

    def __getitem__(self, index):
        """
        Shorthand for returning the x(0) or y(1) component of the point.

        >>> h = Position((3, 5))
        >>> h[0]
        Variable(3, 20)
        >>> h[1]
        Variable(5, 20)
        """
        return (self.x, self.y)[index]


class Handle(object):
    """
    Handles are used to support modifications of Items.

    If the handle is connected to an item, the ``connected_to`` property should
    refer to the item. A ``disconnect`` handler should be provided that handles
    all disconnect behaviour (e.g. clean up constraints and ``connected_to``).

      Note for those of you that use the Pickle module to persist a canvas:
      The property ``disconnect`` should contain a callable object (with
      __call__() method), so the pickle handler can also pickle that. Pickle is
      not capable of pickling ``instancemethod`` or ``function`` objects.
    """

    def __init__(self, pos=(0, 0), strength=NORMAL, connectable=False, movable=True):
        self._pos = Position(pos, strength)
        self._connectable = connectable
        self._movable = movable
        self._visible = True


    def _set_pos(self, pos):
        """
        Shortcut for ``handle.pos.pos = pos``

        >>> h = Handle((10, 10))
        >>> h.pos
        <Position object on (10, 10)>
        >>> h.pos = (20, 15)
        >>> h.pos
        <Position object on (20, 15)>
        """
        self._pos.pos = pos

    pos = property(lambda s: s._pos, _set_pos)

    def _set_x(self, x):
        """
        Shortcut for ``handle.pos.x = x``
        """
        self._pos.x = x

    def _get_x(self): return self._pos.x

    x = property(deprecated(_get_x), deprecated(_set_x))

    def _set_y(self, y):
        """
        Shortcut for ``handle.pos.y = y``
        """
        self._pos.y = y

    def _get_y(self): return self._pos.y

    y = property(deprecated(_get_y), deprecated(_set_y))


    @observed
    def _set_connectable(self, connectable):
        self._connectable = connectable

    connectable = reversible_property(lambda s: s._connectable, _set_connectable)


    @observed
    def _set_movable(self, movable):
        self._movable = movable

    movable = reversible_property(lambda s: s._movable, _set_movable)


    @observed
    def _set_visible(self, visible):
        self._visible = visible

    visible = reversible_property(lambda s: s._visible, _set_visible)


    def __str__(self):
        return '<%s object on (%g, %g)>' % (self.__class__.__name__, float(self._pos.x), float(self._pos.y))
    __repr__ = __str__


class Port(object):
    """
    Port connectable part of an item. Item's handle connects to a port.
    """

    def __init__(self):
        super(Port, self).__init__()

        self._connectable = True


    @observed
    def _set_connectable(self, connectable):
        self._connectable = connectable

    connectable = reversible_property(lambda s: s._connectable, _set_connectable)


    def glue(self, pos):
        """
        Get glue point on the port and distance to the port.
        """
        raise NotImplemented('Glue method not implemented')


    def constraint(self, canvas, item, handle, glue_item):
        """
        Create connection constraint between item's handle and glue item.
        """
        raise NotImplemented('Constraint method not implemented')


class LinePort(Port):
    """
    Port defined as a line between two handles.
    """

    def __init__(self, start, end):
        super(LinePort, self).__init__()

        self.start = start
        self.end = end


    def glue(self, pos):
        """
        Get glue point on the port and distance to the port.

        >>> p1, p2 = (0.0, 0.0), (100.0, 100.0)
        >>> port = LinePort(p1, p2)
        >>> port.glue((50, 50))
        ((50.0, 50.0), 0.0)
        >>> port.glue((0, 10))
        ((5.0, 5.0), 7.0710678118654755)
        """
        d, pl = distance_line_point(self.start, self.end, pos)
        return pl, d


    def constraint(self, canvas, item, handle, glue_item):
        """
        Create connection line constraint between item's handle and the
        port.
        """
        line = canvas.project(glue_item, self.start, self.end)
        point = canvas.project(item, handle.pos)
        return LineConstraint(line, point)


class PointPort(Port):
    """
    Port defined as a point.
    """

    def __init__(self, point):
        super(PointPort, self).__init__()
        self.point = point


    def glue(self, pos):
        """
        Get glue point on the port and distance to the port.

        >>> h = Handle((10, 10))
        >>> port = PointPort(h.pos)
        >>> port.glue((10, 0))
        (<Position object on (10, 10)>, 10.0)
        """
        d = distance_point_point(self.point, pos)
        return self.point, d


    def constraint(self, canvas, item, handle, glue_item):
        """
        Return connection position constraint between item's handle and the
        port.
        """
        origin = canvas.project(glue_item, self.point)
        point = canvas.project(item, handle.pos)
        c = PositionConstraint(origin, point)
        return c #PositionConstraint(origin, point)


# vim: sw=4:et:ai