mirror of
https://github.com/Kozea/WeasyPrint.git
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271 lines
10 KiB
Python
271 lines
10 KiB
Python
# coding: utf8
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# WeasyPrint converts web documents (HTML, CSS, ...) to PDF.
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# Copyright (C) 2011 Simon Sapin
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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"""
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Functions laying out the block boxes.
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"""
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from __future__ import division
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from .inlines import get_next_linebox, replaced_box_width, replaced_box_height
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from .markers import list_marker_layout
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from .tables import table_layout, fixed_table_layout
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from .percentages import resolve_percentages
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from ..formatting_structure import boxes
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def block_level_layout(box, max_position_y, skip_stack, containing_block,
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device_size, page_is_empty):
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"""Lay out the block-level ``box``.
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:param max_position_y: the absolute vertical position (as in
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``some_box.position_y``) of the bottom of the
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content box of the current page area.
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"""
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if isinstance(box, boxes.TableBox):
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return table_layout(box, max_position_y, containing_block,
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device_size, page_is_empty)
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elif isinstance(box, boxes.BlockBox):
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if box.is_table_wrapper:
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return block_table_wrapper(box, max_position_y, skip_stack,
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containing_block, device_size, page_is_empty)
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else:
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return block_box_layout(box, max_position_y, skip_stack,
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containing_block, device_size, page_is_empty)
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elif isinstance(box, boxes.BlockLevelReplacedBox):
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return block_replaced_box_layout(
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box, containing_block, device_size), None
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else:
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raise TypeError('Layout for %s not handled yet' % type(box).__name__)
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def block_box_layout(box, max_position_y, skip_stack, containing_block,
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device_size, page_is_empty):
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"""Lay out the block ``box``."""
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resolve_percentages(box, containing_block)
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block_level_width(box, containing_block)
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list_marker_layout(box, containing_block)
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return block_level_height(box, max_position_y, skip_stack,
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device_size, page_is_empty)
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def block_replaced_box_layout(box, containing_block, device_size):
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"""Lay out the block :class:`boxes.ReplacedBox` ``box``."""
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assert isinstance(box, boxes.ReplacedBox)
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resolve_percentages(box, containing_block)
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# http://www.w3.org/TR/CSS21/visudet.html#block-replaced-width
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replaced_box_width(box, device_size)
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block_level_width(box, containing_block)
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# http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-height
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replaced_box_height(box, device_size)
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if box.margin_top == 'auto':
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box.margin_top = 0
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if box.margin_bottom == 'auto':
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box.margin_bottom = 0
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return box
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def block_level_width(box, containing_block):
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"""Set the ``box`` width."""
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# 'cb' stands for 'containing block'
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cb_width = containing_block.width
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# http://www.w3.org/TR/CSS21/visudet.html#blockwidth
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# These names are waaay too long
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margin_l = box.margin_left
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margin_r = box.margin_right
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padding_l = box.padding_left
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padding_r = box.padding_right
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border_l = box.style.border_left_width
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border_r = box.style.border_right_width
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width = box.width
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# Only margin-left, margin-right and width can be 'auto'.
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# We want: width of containing block ==
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# margin-left + border-left-width + padding-left + width
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# + padding-right + border-right-width + margin-right
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paddings_plus_borders = padding_l + padding_r + border_l + border_r
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if box.width != 'auto':
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total = paddings_plus_borders + width
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if margin_l != 'auto':
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total += margin_l
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if margin_r != 'auto':
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total += margin_r
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if total > cb_width:
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if margin_l == 'auto':
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margin_l = box.margin_left = 0
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if margin_r == 'auto':
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margin_r = box.margin_right = 0
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if width != 'auto' and margin_l != 'auto' and margin_r != 'auto':
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# The equation is over-constrained
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margin_sum = cb_width - paddings_plus_borders - width
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if containing_block.direction == 'ltr':
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margin_r = box.margin_right = margin_sum - margin_l
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else:
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margin_l = box.margin_left = margin_sum - margin_r
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if width == 'auto':
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if margin_l == 'auto':
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margin_l = box.margin_left = 0
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if margin_r == 'auto':
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margin_r = box.margin_right = 0
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width = box.width = cb_width - (
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paddings_plus_borders + margin_l + margin_r)
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margin_sum = cb_width - paddings_plus_borders - width
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if margin_l == 'auto' and margin_r == 'auto':
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box.margin_left = margin_sum / 2.
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box.margin_right = margin_sum / 2.
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elif margin_l == 'auto' and margin_r != 'auto':
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box.margin_left = margin_sum - margin_r
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elif margin_l != 'auto' and margin_r == 'auto':
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box.margin_right = margin_sum - margin_l
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def block_level_height(box, max_position_y, skip_stack,
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device_size, page_is_empty):
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"""Set the ``box`` height."""
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assert isinstance(box, boxes.BlockContainerBox)
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if box.style.overflow != 'visible':
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raise NotImplementedError
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if box.margin_top == 'auto':
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box.margin_top = 0
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if box.margin_bottom == 'auto':
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box.margin_bottom = 0
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position_x = box.content_box_x()
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position_y = box.content_box_y()
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initial_position_y = position_y
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new_children = []
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if skip_stack is None:
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skip = 0
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else:
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skip, skip_stack = skip_stack
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for index, child in box.enumerate_skip(skip):
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if not child.is_in_normal_flow():
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continue
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# TODO: collapse margins
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# See http://www.w3.org/TR/CSS21/visudet.html#normal-block
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child.position_x = position_x
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child.position_y = position_y
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if isinstance(child, boxes.LineBox):
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assert len(box.children) == 1, (
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'line box with siblings before layout')
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is_page_break = False
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while 1:
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new_containing_block = box
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line, resume_at = get_next_linebox(
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child, position_y, skip_stack,
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new_containing_block, device_size)
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if line is None:
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break
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new_position_y = position_y + line.height
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# Allow overflow if the first line of the page is higher
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# than the page itself so that we put *something* on this
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# page and can advance in the document.
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if new_position_y > max_position_y and not page_is_empty:
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if not new_children:
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# Page break before any content, cancel the whole box.
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return None, None
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# Page break here, resume before this line
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resume_at = (index, skip_stack)
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is_page_break = True
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break
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new_children.append(line)
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page_is_empty = False
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position_y = new_position_y
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if resume_at is None:
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break
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skip_stack = resume_at
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if is_page_break:
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break
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else:
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new_containing_block = box
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new_child, resume_at = block_level_layout(
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child, max_position_y, skip_stack,
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new_containing_block, device_size, page_is_empty)
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skip_stack = None
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if new_child is None:
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if new_children:
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resume_at = (index, None)
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break
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else:
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# This was the first child of this box, cancel the box
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# completly
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return None, None
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new_position_y = position_y + new_child.margin_height()
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# Bottom borders may overflow here
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# TODO: back-track somehow when all lines fit but not borders
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new_children.append(new_child)
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page_is_empty = False
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position_y = new_position_y
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if resume_at is not None:
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resume_at = (index, resume_at)
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break
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else:
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resume_at = None
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new_box = box.copy_with_children(new_children)
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if new_box.height == 'auto':
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new_box.height = position_y - initial_position_y
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if resume_at is not None:
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# If there was a list marker, we kept it on `new_box`.
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# Do not repeat it on `box` on the next page.
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# TODO: Do this non-destructively
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box.outside_list_marker = None
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box.reset_spacing('top')
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new_box.reset_spacing('bottom')
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return new_box, resume_at
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def block_table_wrapper(wrapper, max_position_y, skip_stack, containing_block,
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device_size, page_is_empty):
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"""Layout for the wrapper of a block-level table wrapper."""
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for child in wrapper.children:
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if isinstance(child, boxes.TableBox):
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table = child
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break
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else:
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raise ValueError('Table wrapper without a table')
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resolve_percentages(wrapper, containing_block)
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resolve_percentages(table, containing_block)
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# Count the wrapper margins in case of `width: auto`
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table.margin_left = wrapper.margin_left
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table.margin_right = wrapper.margin_right
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block_level_width(table, containing_block)
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# The table margins are on the table wrapper box, not on the table box
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table.margin_left = 0
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table.margin_right = 0
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fixed_table_layout(table)
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wrapper.width = wrapper.style.width = table.border_width()
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return block_box_layout(wrapper, max_position_y, skip_stack,
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containing_block, device_size, page_is_empty)
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