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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 atom.api import Coerced, Enum, Range, Tuple
from .box_helper import BoxHelper
from .constrainable import Constrainable
from .constraint_helper import ConstraintHelper
from .geometry import Box
from .linear_symbolic import LinearSymbolic
from .sequence_helper import SequenceHelper
from .spacers import Spacer, EqSpacer, FlexSpacer
ORIENT_MAP = {
'horizontal': ('left', 'right'),
'vertical': ('top', 'bottom'),
}
ORTHO_MAP = {
'horizontal': 'vertical',
'vertical': 'horizontal',
}
class LinearBoxHelper(BoxHelper):
""" A box helper for creating traditional linear box layouts.
"""
#: The layout orientation of the items in the box.
orientation = Enum('vertical', 'horizontal')
#: The tuple of items which will be used to generate the constraints.
items = Tuple()
#: The spacing to use between items if not explicitly provided.
spacing = Range(low=0)
#: The margins to use around the edges of the box.
margins = Coerced(Box)
def __init__(self, orientation, items, spacing=10, margins=0):
""" Initialize a LinearBoxHelper.
Parameters
----------
orientation : str
The orientation of the layout box, either 'horizontal'
or 'vertical'.
items : iterable
The iterable of items which should be constrained.
spacing : int, optional
The spacing to use between items if not specifically given
in the sequence of items. The default value is 10 pixels.
margins : int, tuple, or Box, optional
The margins to use around the edges of the box. The default
value is 0 pixels on all sides.
"""
self.orientation = orientation
self.items = self.validate(items)
self.spacing = spacing
self.margins = margins
@staticmethod
def validate(items):
""" Validate an iterable of constrainable box items.
This method asserts that a sequence of items is appropriate for
generating box constraints. The following conditions are verified
of the sequence of items after they are filtered for None:
* All of the items in the sequence are instances of Spacer, int,
LinearSymbolic, Constrainable.
* There are never two adjacent ints or spacers.
Parameters
----------
items : iterable
The iterable of constrainable items to validate.
Returns
-------
result : tuple
A tuple of validated items, with any None values removed.
"""
items = tuple(item for item in items if item is not None)
if len(items) == 0:
return items
was_spacer = False
spacers = (int, Spacer)
types = (LinearSymbolic, Constrainable, Spacer, int)
for item in items:
if not isinstance(item, types):
msg = 'The allowed item types for a constraint sequence are '
msg += 'LinearSymbolic, Constrainable, Spacer, and int. '
msg += 'Got %s instead.'
raise TypeError(msg % type(item).__name__)
is_spacer = isinstance(item, spacers)
if is_spacer and was_spacer:
msg = 'Expected LinearSymbolic or Constrainable after a '
msg += 'spacer. Got %s instead.'
raise TypeError(msg % type(item).__name__)
was_spacer = is_spacer
return items
def constraints(self, component):
""" Generate the box constraints for the given component.
Parameters
----------
component : Constrainable or None
The constrainable object which represents the conceptual
owner of the generated constraints.
Returns
-------
result : list
The list of Constraint objects for the given component.
"""
items = self.items
if len(items) == 0:
return []
# Create the outer boundary box constraints.
cns = self.box_constraints(component)
first, last = ORIENT_MAP[self.orientation]
first_ortho, last_ortho = ORIENT_MAP[ORTHO_MAP[self.orientation]]
first_boundary = getattr(self, first)
last_boundary = getattr(self, last)
first_ortho_boundary = getattr(self, first_ortho)
last_ortho_boundary = getattr(self, last_ortho)
# Create the margin spacers that will be used.
margins = self.margins
if self.orientation == 'vertical':
first_spacer = EqSpacer(margins.top)
last_spacer = EqSpacer(margins.bottom)
first_ortho_spacer = FlexSpacer(margins.left)
last_ortho_spacer = FlexSpacer(margins.right)
else:
first_spacer = EqSpacer(margins.left)
last_spacer = EqSpacer(margins.right)
first_ortho_spacer = FlexSpacer(margins.top)
last_ortho_spacer = FlexSpacer(margins.bottom)
# Add a pre and post padding spacer if the user hasn't specified
# their own spacer as the first/last element of the box items.
spacer_types = (Spacer, int)
if not isinstance(items[0], spacer_types):
pre_items = (first_boundary, first_spacer)
else:
pre_items = (first_boundary,)
if not isinstance(items[-1], spacer_types):
post_items = (last_spacer, last_boundary)
else:
post_items = (last_boundary,)
# Create the helper for the primary orientation. The helper
# validation is bypassed since the sequence is known-valid.
spacing = self.spacing
helper = SequenceHelper(last, first, (), spacing)
helper.items = pre_items + items + post_items
helpers = [helper]
# Add the ortho orientation and nested helpers. The helper
# validation is bypassed since the sequence is known-valid.
for item in items:
if isinstance(item, Constrainable):
helper = SequenceHelper(last_ortho, first_ortho, (), spacing)
helper.items = (first_ortho_boundary, first_ortho_spacer,
item, last_ortho_spacer, last_ortho_boundary)
helpers.append(helper)
if isinstance(item, ConstraintHelper):
helpers.append(item)
# Add in the helper constraints.
for helper in helpers:
cns.extend(helper.create_constraints(None))
return cns
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