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#------------------------------------------------------------------------------
# Copyright (c) 2013-2025, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
#------------------------------------------------------------------------------
from abc import ABCMeta
from atom.api import Atom, Constant, DefaultValue, Enum
import kiwisolver as kiwi
class Constrainable(object, metaclass=ABCMeta):
""" An abstract base class for defining constrainable objects.
Implementations must provide `top`, `bottom`, `left`, `right`,
`width`, `height`, `v_center` and `h_center` attributes which
are instances of 'LinearSymbolic'.
It must also provide 'hug_width', 'hug_height', 'resist_width',
'resist_height', 'limit_width', and 'limit_height' attributes
which are valid PolicyEnum values.
"""
class ContentsConstrainable(Constrainable):
""" An abstract base class for contents constrainable objects.
A contents constrainable object has additional linear symbolic
attributes with the prefix 'contents_' for all of the symbolic
attributes defined by Constrainable.
"""
pass
class ConstraintMember(Constant):
""" A custom Constant member that generates a kiwi Variable.
"""
__slots__ = ()
def __init__(self):
super(ConstraintMember, self).__init__()
mode = DefaultValue.MemberMethod_Object
self.set_default_value_mode(mode, 'default')
def default(self, owner):
return kiwi.Variable(self.name)
#: An atom enum which defines the allowable constraints strengths.
#: Clones will be made by selecting a new default via 'select'.
PolicyEnum = Enum('ignore', 'weak', 'medium', 'strong', 'required')
class ConstrainableMixin(Atom):
""" An atom mixin class which defines constraint members.
This class implements the Constrainable interface.
"""
#: The symbolic left boundary of the constrainable.
left = ConstraintMember()
#: The symbolic top boundary of the constrainable.
top = ConstraintMember()
#: The symbolic width of the constrainable.
width = ConstraintMember()
#: The symbolic height of the constrainable.
height = ConstraintMember()
#: A symbolic expression representing the top boundary.
right = Constant()
#: A symbolic expression representing the bottom boundary.
bottom = Constant()
#: A symbolic expression representing the horizontal center.
h_center = Constant()
#: A symbolic expression representing the vertical center.
v_center = Constant()
#: How strongly a widget hugs it's width hint. This is equivalent
#: to the constraint::
#:
#: (width == hint) | hug_width
hug_width = PolicyEnum('strong')
#: How strongly a widget hugs it's height hint. This is equivalent
#: to the constraint::
#:
#: (height == hint) | hug_height
hug_height = PolicyEnum('strong')
#: How strongly a widget resists clipping its width hint. This is
#: equivalent to the constraint:
#:
#: (width >= hint) | resist_width
resist_width = PolicyEnum('strong')
#: How strongly a widget resists clipping its height hint. This is
#: equivalent to the constraint::
#:
#: (height >= hint) | resist_height
resist_height = PolicyEnum('strong')
#: How strongly a widget resists expanding its width hint. This is
#: equivalent to the constraint::
#:
#: (width <= hint) | limit_width
limit_width = PolicyEnum('ignore')
#: How strongly a widget resists expanding its height hint. This is
#: equivalent to the constraint::
#:
#: (height <= hint) | limit_height
limit_height = PolicyEnum('ignore')
def _default_right(self):
return self.left + self.width
def _default_bottom(self):
return self.top + self.height
def _default_h_center(self):
return self.left + 0.5 * self.width
def _default_v_center(self):
return self.top + 0.5 * self.height
Constrainable.register(ConstrainableMixin)
class ContentsConstrainableMixin(ConstrainableMixin):
""" An atom mixin class which defines contents constraint members.
This class implements the ContentsConstrainable interface.
"""
#: The symbolic left contents boundary of the constrainable.
contents_left = ConstraintMember()
#: The symbolic right contents boundary of the constrainable.
contents_right = ConstraintMember()
#: The symbolic top contents boundary of the constrainable.
contents_top = ConstraintMember()
#: The symbolic bottom contents boundary of the constrainable.
contents_bottom = ConstraintMember()
#: A symbolic expression representing the content width.
contents_width = Constant()
#: A symbolic expression representing the content height.
contents_height = Constant()
#: A symbolic expression representing the content horizontal center.
contents_h_center = Constant()
#: A symbolic expression representing the content vertical center.
contents_v_center = Constant()
def _default_contents_width(self):
return self.contents_right - self.contents_left
def _default_contents_height(self):
return self.contents_bottom - self.contents_top
def _default_contents_h_center(self):
return self.contents_left + 0.5 * self.contents_width
def _default_contents_v_center(self):
return self.contents_top + 0.5 * self.contents_height
ContentsConstrainable.register(ContentsConstrainableMixin)
|
