mirror of
https://github.com/Kozea/WeasyPrint.git
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575 lines
18 KiB
Python
575 lines
18 KiB
Python
# coding: utf8
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"""
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weasyprint.formatting_structure.boxes
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-------------------------------------
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Classes for all types of boxes in the CSS formatting structure / box model.
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See http://www.w3.org/TR/CSS21/visuren.html
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Names are the same as in CSS 2.1 with the exception of ``TextBox``. In
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WeasyPrint, any text is in a ``TextBox``. What CSS calls anonymous
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inline boxes are text boxes but not all text boxes are anonymous
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inline boxes.
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See http://www.w3.org/TR/CSS21/visuren.html#anonymous
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Abstract classes, should not be instantiated:
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* Box
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* BlockLevelBox
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* InlineLevelBox
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* BlockContainerBox
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* ReplacedBox
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* ParentBox
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* AtomicInlineLevelBox
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Concrete classes:
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* PageBox
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* BlockBox
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* InlineBox
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* InlineBlockBox
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* BlockReplacedBox
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* InlineReplacedBox
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* TextBox
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* LineBox
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* Various table-related Box subclasses
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All concrete box classes whose name contains "Inline" or "Block" have
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one of the following "outside" behavior:
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* Block-level (inherits from :class:`BlockLevelBox`)
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* Inline-level (inherits from :class:`InlineLevelBox`)
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and one of the following "inside" behavior:
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* Block container (inherits from :class:`BlockContainerBox`)
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* Inline content (InlineBox and :class:`TextBox`)
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* Replaced content (inherits from :class:`ReplacedBox`)
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... with various combinasions of both.
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See respective docstrings for details.
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:copyright: Copyright 2011-2012 Simon Sapin and contributors, see AUTHORS.
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:license: BSD, see LICENSE for details.
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"""
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from __future__ import division, unicode_literals
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from ..compat import xrange
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from ..css.computed_values import ZERO_PIXELS
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# The *Box classes have many attributes and methods, but that's the way it is
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# pylint: disable=R0904,R0902
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class Box(object):
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"""Abstract base class for all boxes."""
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# Definitions for the rules generating anonymous table boxes
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# http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes
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proper_table_child = False
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internal_table_or_caption = False
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tabular_container = False
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# Default, may be overriden on instances.
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is_table_wrapper = False
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is_for_root_element = False
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bookmark_label = None
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bookmark_level = None
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def __init__(self, element_tag, sourceline, style):
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self.element_tag = element_tag
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self.sourceline = sourceline # for debugging only
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# Copying might not be needed, but let’s be careful with mutable
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# objects.
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self.style = style.copy()
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bookmark_level = style.bookmark_level
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if bookmark_level != 'none':
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self.bookmark_level = bookmark_level
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def __repr__(self):
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return '<%s %s %s>' % (
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type(self).__name__, self.element_tag, self.sourceline)
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@classmethod
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def anonymous_from(cls, parent, *args, **kwargs):
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"""Return an anonymous box that inherits from ``parent``."""
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return cls(parent.element_tag, parent.sourceline,
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parent.style.inherit_from(),
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*args, **kwargs)
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def copy(self):
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"""Return shallow copy of the box."""
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cls = type(self)
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# Create a new instance without calling __init__: initializing
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# styles may be kinda expensive, no need to do it again.
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new_box = cls.__new__(cls)
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# Copy attributes
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new_box.__dict__.update(self.__dict__)
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new_box.style = self.style.copy()
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return new_box
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def translate(self, dx=0, dy=0):
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"""Change the box’s position.
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Also update the children’s positions accordingly.
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"""
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# Overridden in ParentBox to also translate children, if any.
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self.position_x += dx
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self.position_y += dy
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# Heights and widths
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def padding_width(self):
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"""Width of the padding box."""
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return self.width + self.padding_left + self.padding_right
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def padding_height(self):
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"""Height of the padding box."""
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return self.height + self.padding_top + self.padding_bottom
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def border_width(self):
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"""Width of the border box."""
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return self.padding_width() + self.border_left_width + \
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self.border_right_width
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def border_height(self):
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"""Height of the border box."""
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return self.padding_height() + self.border_top_width + \
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self.border_bottom_width
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def margin_width(self):
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"""Width of the margin box (aka. outer box)."""
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return self.border_width() + self.margin_left + self.margin_right
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def margin_height(self):
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"""Height of the margin box (aka. outer box)."""
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return self.border_height() + self.margin_top + self.margin_bottom
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def horizontal_surroundings(self):
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"""Sum of all horizontal margins, paddings and borders."""
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return self.margin_left + self.margin_right + \
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self.padding_left + self.padding_right + \
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self.border_left_width + self.border_right_width
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def vertical_surroundings(self):
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"""Sum of all vertical margins, paddings and borders."""
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return self.margin_top + self.margin_bottom + \
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self.padding_top + self.padding_bottom + \
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self.border_top_width + self.border_bottom_width
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# Corners positions
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def content_box_x(self):
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"""Absolute horizontal position of the content box."""
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return self.position_x + self.margin_left + self.padding_left + \
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self.border_left_width
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def content_box_y(self):
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"""Absolute vertical position of the content box."""
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return self.position_y + self.margin_top + self.padding_top + \
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self.border_top_width
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def padding_box_x(self):
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"""Absolute horizontal position of the padding box."""
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return self.position_x + self.margin_left + self.border_left_width
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def padding_box_y(self):
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"""Absolute vertical position of the padding box."""
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return self.position_y + self.margin_top + self.border_top_width
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def border_box_x(self):
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"""Absolute horizontal position of the border box."""
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return self.position_x + self.margin_left
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def border_box_y(self):
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"""Absolute vertical position of the border box."""
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return self.position_y + self.margin_top
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def get_wrapped_table(self):
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"""Get the table wrapped by the box."""
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if self.is_table_wrapper:
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for child in self.children:
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if isinstance(child, TableBox):
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return child
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else: # pragma: no cover
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raise ValueError('Table wrapper without a table')
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# Positioning schemes
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def is_floated(self):
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"""Return whether this box is floated."""
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return self.style.float != 'none'
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def is_absolutely_positioned(self):
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"""Return whether this box is in the absolute positioning scheme."""
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return self.style.position in ('absolute', 'fixed')
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def is_in_normal_flow(self):
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"""Return whether this box is in normal flow."""
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return not (self.is_floated() or self.is_absolutely_positioned())
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class ParentBox(Box):
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"""A box that has children."""
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def __init__(self, element_tag, sourceline, style, children):
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super(ParentBox, self).__init__(element_tag, sourceline, style)
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self.children = tuple(children)
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def enumerate_skip(self, skip_num=0):
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"""Yield ``(child, child_index)`` tuples for each child.
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``skip_num`` children are skipped before iterating over them.
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"""
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for index in xrange(skip_num, len(self.children)):
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yield index, self.children[index]
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def _reset_spacing(self, side):
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"""Set to 0 the margin, padding and border of ``side``."""
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setattr(self, 'margin_%s' % side, 0)
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setattr(self, 'padding_%s' % side, 0)
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setattr(self, 'border_%s_width' % side, 0)
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self.style['margin_%s' % side] = ZERO_PIXELS
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self.style['padding_%s' % side] = ZERO_PIXELS
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self.style['border_%s_width' % side] = 0
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def _remove_decoration(self, start, end):
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if start:
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self._reset_spacing('top')
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if end:
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self._reset_spacing('bottom')
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def copy_with_children(self, children, is_start=True, is_end=True):
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"""Create a new equivalent box with given ``children``."""
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new_box = self.copy()
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new_box.children = tuple(children)
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if not is_start:
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new_box.outside_list_marker = None
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if new_box.bookmark_level:
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del new_box.bookmark_level
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new_box._remove_decoration(not is_start, not is_end)
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return new_box
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def descendants(self):
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"""A flat generator for a box, its children and descendants."""
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yield self
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for child in self.children:
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if hasattr(child, 'descendants'):
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for grand_child in child.descendants():
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yield grand_child
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else:
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yield child
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def translate(self, dx=0, dy=0):
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"""Change the position of the box.
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Also update the children’s positions accordingly.
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"""
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super(ParentBox, self).translate(dx, dy)
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for child in self.children:
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child.translate(dx, dy)
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class BlockLevelBox(Box):
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"""A box that participates in an block formatting context.
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An element with a ``display`` value of ``block``, ``list-item`` or
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``table`` generates a block-level box.
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"""
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class BlockContainerBox(ParentBox):
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"""A box that contains only block-level boxes or only line boxes.
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A box that either contains only block-level boxes or establishes an inline
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formatting context and thus contains only line boxes.
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A non-replaced element with a ``display`` value of ``block``,
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``list-item``, ``inline-block`` or 'table-cell' generates a block container
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box.
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"""
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class BlockBox(BlockContainerBox, BlockLevelBox):
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"""A block-level box that is also a block container.
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A non-replaced element with a ``display`` value of ``block``, ``list-item``
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generates a block box.
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"""
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# TODO: remove this when outside list marker are absolute children
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def translate(self, dx=0, dy=0):
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"""Change the position of the box.
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Also update the children’s positions accordingly.
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"""
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super(BlockBox, self).translate(dx, dy)
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marker = getattr(self, 'outside_list_marker', None)
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if marker:
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marker.translate(dx, dy)
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class LineBox(ParentBox):
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"""A box that represents a line in an inline formatting context.
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Can only contain inline-level boxes.
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In early stages of building the box tree a single line box contains many
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consecutive inline boxes. Later, during layout phase, each line boxes will
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be split into multiple line boxes, one for each actual line.
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"""
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def __init__(self, element_tag, sourceline, style, children):
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assert style.anonymous
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super(LineBox, self).__init__(element_tag, sourceline, style, children)
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class InlineLevelBox(Box):
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"""A box that participates in an inline formatting context.
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An inline-level box that is not an inline box is said to be "atomic". Such
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boxes are inline blocks, replaced elements and inline tables.
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An element with a ``display`` value of ``inline``, ``inline-table``, or
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``inline-block`` generates an inline-level box.
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"""
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def _remove_decoration(self, start, end):
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ltr = self.style.direction == 'ltr'
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if start:
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self._reset_spacing('left' if ltr else 'right')
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if end:
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self._reset_spacing('right' if ltr else 'left')
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class InlineBox(InlineLevelBox, ParentBox):
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"""An inline box with inline children.
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A box that participates in an inline formatting context and whose content
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also participates in that inline formatting context.
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A non-replaced element with a ``display`` value of ``inline`` generates an
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inline box.
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"""
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class TextBox(InlineLevelBox):
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"""A box that contains only text and has no box children.
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Any text in the document ends up in a text box. What CSS calls "anonymous
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inline boxes" are also text boxes.
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"""
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def __init__(self, element_tag, sourceline, style, text):
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assert style.anonymous
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assert text
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super(TextBox, self).__init__(element_tag, sourceline, style)
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text_transform = style.text_transform
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if text_transform != 'none':
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text = {
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'uppercase': lambda t: t.upper(),
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'lowercase': lambda t: t.lower(),
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# Python’s unicode.captitalize is not the same.
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'capitalize': lambda t: t.title(),
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}[text_transform](text)
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self.text = text
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def copy_with_text(self, text):
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"""Return a new TextBox identical to this one except for the text."""
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assert text
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new_box = self.copy()
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new_box.text = text
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return new_box
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class AtomicInlineLevelBox(InlineLevelBox):
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"""An atomic box in an inline formatting context.
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This inline-level box cannot be split for line breaks.
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"""
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class InlineBlockBox(AtomicInlineLevelBox, BlockContainerBox):
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"""A box that is both inline-level and a block container.
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It behaves as inline on the outside and as a block on the inside.
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A non-replaced element with a 'display' value of 'inline-block' generates
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an inline-block box.
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"""
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class ReplacedBox(Box):
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"""A box whose content is replaced.
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For example, ``<img>`` are replaced: their content is rendered externally
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and is opaque from CSS’s point of view.
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"""
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def __init__(self, element_tag, sourceline, style, replacement):
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super(ReplacedBox, self).__init__(element_tag, sourceline, style)
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self.replacement = replacement
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class BlockReplacedBox(ReplacedBox, BlockLevelBox):
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"""A box that is both replaced and block-level.
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A replaced element with a ``display`` value of ``block``, ``liste-item`` or
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``table`` generates a block-level replaced box.
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"""
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class InlineReplacedBox(ReplacedBox, AtomicInlineLevelBox):
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"""A box that is both replaced and inline-level.
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A replaced element with a ``display`` value of ``inline``,
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``inline-table``, or ``inline-block`` generates an inline-level replaced
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box.
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"""
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class TableBox(BlockLevelBox, ParentBox):
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"""Box for elements with ``display: table``"""
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# Definitions for the rules generating anonymous table boxes
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# http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes
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tabular_container = True
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def translate(self, dx=0, dy=0):
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"""Change the position of the box.
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Also update the children’s positions accordingly.
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"""
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super(TableBox, self).translate(dx, dy)
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for child in self.column_groups:
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# TODO: why did we not put these in .children again?
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child.translate(dx, dy)
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class InlineTableBox(TableBox):
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"""Box for elements with ``display: inline-table``"""
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class TableRowGroupBox(ParentBox):
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"""Box for elements with ``display: table-row-group``"""
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proper_table_child = True
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internal_table_or_caption = True
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tabular_container = True
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proper_parents = (TableBox, InlineTableBox)
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# Default values. May be overriden on instances.
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is_header = False
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is_footer = False
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class TableRowBox(ParentBox):
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"""Box for elements with ``display: table-row``"""
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proper_table_child = True
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internal_table_or_caption = True
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tabular_container = True
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proper_parents = (TableBox, InlineTableBox, TableRowGroupBox)
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class TableColumnGroupBox(ParentBox):
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"""Box for elements with ``display: table-column-group``"""
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proper_table_child = True
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internal_table_or_caption = True
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proper_parents = (TableBox, InlineTableBox)
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# Default value. May be overriden on instances.
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span = 1
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# Columns groups never have margins or paddings
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margin_top = 0
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margin_bottom = 0
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margin_left = 0
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margin_right = 0
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padding_top = 0
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padding_bottom = 0
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padding_left = 0
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padding_right = 0
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# Not really a parent box, but pretending to be removes some special cases.
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class TableColumnBox(ParentBox):
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"""Box for elements with ``display: table-column``"""
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proper_table_child = True
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internal_table_or_caption = True
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proper_parents = (TableBox, InlineTableBox, TableColumnGroupBox)
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# Default value. May be overriden on instances.
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span = 1
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# Columns never have margins or paddings
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margin_top = 0
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margin_bottom = 0
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margin_left = 0
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margin_right = 0
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padding_top = 0
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padding_bottom = 0
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padding_left = 0
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padding_right = 0
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class TableCellBox(BlockContainerBox):
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"""Box for elements with ``display: table-cell``"""
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internal_table_or_caption = True
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# Default values. May be overriden on instances.
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colspan = 1
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rowspan = 1
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class TableCaptionBox(BlockBox):
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"""Box for elements with ``display: table-caption``"""
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proper_table_child = True
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internal_table_or_caption = True
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proper_parents = (TableBox, InlineTableBox)
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class PageBox(ParentBox):
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"""Box for a page.
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Initially the whole document will be in the box for the root element.
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During layout a new page box is created after every page break.
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"""
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def __init__(self, page_type, style):
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self.page_type = page_type
|
||
# Page boxes are not linked to any element.
|
||
self.fixed_boxes = []
|
||
super(PageBox, self).__init__(
|
||
element_tag=None, sourceline=None, style=style, children=[])
|
||
|
||
def __repr__(self):
|
||
return '<%s %s>' % (type(self).__name__, self.page_type)
|
||
|
||
|
||
class MarginBox(BlockContainerBox):
|
||
"""Box in page margins, as defined in CSS3 Paged Media"""
|
||
def __init__(self, at_keyword, style, children=[]):
|
||
self.at_keyword = at_keyword
|
||
# Margin boxes are not linked to any element.
|
||
super(MarginBox, self).__init__(
|
||
element_tag=None, sourceline=None, style=style, children=children)
|
||
|
||
def __repr__(self):
|
||
return '<%s %s>' % (type(self).__name__, self.at_keyword)
|