340 lines
13 KiB
Python
340 lines
13 KiB
Python
"""Absolutely positioned boxes management."""
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from ..formatting_structure import boxes
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from .min_max import handle_min_max_width
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from .percent import resolve_percentages, resolve_position_percentages
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from .preferred import shrink_to_fit
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from .replaced import inline_replaced_box_width_height
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from .table import table_wrapper_width
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class AbsolutePlaceholder:
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"""Left where an absolutely-positioned box was taken out of the flow."""
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def __init__(self, box):
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assert not isinstance(box, AbsolutePlaceholder)
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# Work around the overloaded __setattr__
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object.__setattr__(self, '_box', box)
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object.__setattr__(self, '_layout_done', False)
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def set_laid_out_box(self, new_box):
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object.__setattr__(self, '_box', new_box)
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object.__setattr__(self, '_layout_done', True)
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def translate(self, dx=0, dy=0, ignore_floats=False):
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if dx == dy == 0:
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return
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if self._layout_done:
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self._box.translate(dx, dy, ignore_floats)
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else:
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# Descendants do not have a position yet.
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self._box.position_x += dx
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self._box.position_y += dy
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def copy(self):
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new_placeholder = AbsolutePlaceholder(self._box.copy())
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object.__setattr__(new_placeholder, '_layout_done', self._layout_done)
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return new_placeholder
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# Pretend to be the box itself
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def __getattr__(self, name):
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return getattr(self._box, name)
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def __setattr__(self, name, value):
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setattr(self._box, name, value)
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def __repr__(self):
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return '<Placeholder %r>' % self._box
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@handle_min_max_width
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def absolute_width(box, context, cb_x, cb_y, cb_width, cb_height):
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# https://www.w3.org/TR/CSS2/visudet.html#abs-replaced-width
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ltr = (
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box.style.parent_style is None or
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box.style.parent_style['direction'] == 'ltr')
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paddings_borders = (
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box.padding_left + box.padding_right +
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box.border_left_width + box.border_right_width)
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translate_x = 0
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translate_box_width = False
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default_translate_x = cb_x - box.position_x
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if box.left == box.right == box.width == 'auto':
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if box.margin_left == 'auto':
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box.margin_left = 0
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if box.margin_right == 'auto':
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box.margin_right = 0
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available_width = cb_width - (
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paddings_borders + box.margin_left + box.margin_right)
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box.width = shrink_to_fit(context, box, available_width)
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if not ltr:
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translate_box_width = True
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translate_x = default_translate_x + available_width
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elif box.left != 'auto' and box.right != 'auto' and box.width != 'auto':
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width_for_margins = cb_width - (
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box.right + box.left + box.width + paddings_borders)
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if box.margin_left == box.margin_right == 'auto':
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if box.width + paddings_borders + box.right + box.left <= cb_width:
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box.margin_left = box.margin_right = width_for_margins / 2
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else:
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box.margin_left = 0 if ltr else width_for_margins
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box.margin_right = width_for_margins if ltr else 0
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elif box.margin_left == 'auto':
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box.margin_left = width_for_margins
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elif box.margin_right == 'auto':
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box.margin_right = width_for_margins
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elif ltr:
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box.margin_right = width_for_margins
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else:
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box.margin_left = width_for_margins
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translate_x = box.left + default_translate_x
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else:
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if box.margin_left == 'auto':
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box.margin_left = 0
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if box.margin_right == 'auto':
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box.margin_right = 0
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spacing = paddings_borders + box.margin_left + box.margin_right
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if box.left == box.width == 'auto':
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box.width = shrink_to_fit(
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context, box, cb_width - spacing - box.right)
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translate_x = cb_width - box.right - spacing + default_translate_x
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translate_box_width = True
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elif box.left == box.right == 'auto':
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if not ltr:
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available_width = cb_width - (
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paddings_borders + box.margin_left + box.margin_right)
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translate_box_width = True
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translate_x = default_translate_x + available_width
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elif box.width == box.right == 'auto':
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box.width = shrink_to_fit(
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context, box, cb_width - spacing - box.left)
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translate_x = box.left + default_translate_x
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elif box.left == 'auto':
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translate_x = cb_width + default_translate_x - (
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box.right + spacing + box.width)
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elif box.width == 'auto':
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box.width = cb_width - box.right - box.left - spacing
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translate_x = box.left + default_translate_x
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elif box.right == 'auto':
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translate_x = box.left + default_translate_x
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return translate_box_width, translate_x
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def absolute_height(box, context, cb_x, cb_y, cb_width, cb_height):
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# https://www.w3.org/TR/CSS2/visudet.html#abs-non-replaced-height
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paddings_borders = (
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box.padding_top + box.padding_bottom +
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box.border_top_width + box.border_bottom_width)
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translate_y = 0
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translate_box_height = False
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default_translate_y = cb_y - box.position_y
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if box.top == box.bottom == box.height == 'auto':
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# Keep the static position
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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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elif 'auto' not in (box.top, box.bottom, box.height):
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height_for_margins = cb_height - (
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box.top + box.bottom + box.height + paddings_borders)
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if box.margin_top == box.margin_bottom == 'auto':
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box.margin_top = box.margin_bottom = height_for_margins / 2
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elif box.margin_top == 'auto':
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box.margin_top = height_for_margins
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elif box.margin_bottom == 'auto':
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box.margin_bottom = height_for_margins
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else:
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box.margin_bottom = height_for_margins
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translate_y = box.top + default_translate_y
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else:
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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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spacing = paddings_borders + box.margin_top + box.margin_bottom
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if box.top == box.height == 'auto':
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translate_y = (
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cb_height - box.bottom - spacing + default_translate_y)
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translate_box_height = True
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elif box.top == box.bottom == 'auto':
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pass # Keep the static position
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elif box.height == box.bottom == 'auto':
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translate_y = box.top + default_translate_y
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elif box.top == 'auto':
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translate_y = cb_height + default_translate_y - (
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box.bottom + spacing + box.height)
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elif box.height == 'auto':
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box.height = cb_height - box.bottom - box.top - spacing
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translate_y = box.top + default_translate_y
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elif box.bottom == 'auto':
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translate_y = box.top + default_translate_y
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return translate_box_height, translate_y
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def absolute_block(context, box, containing_block, fixed_boxes, bottom_space,
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skip_stack, cb_x, cb_y, cb_width, cb_height):
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from .block import block_container_layout
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from .flex import flex_layout
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translate_box_width, translate_x = absolute_width(
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box, context, cb_x, cb_y, cb_width, cb_height)
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if skip_stack:
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translate_box_height, translate_y = False, 0
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else:
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translate_box_height, translate_y = absolute_height(
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box, context, cb_x, cb_y, cb_width, cb_height)
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bottom_space += -box.position_y if translate_box_height else translate_y
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# This box is the containing block for absolute descendants.
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absolute_boxes = []
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if box.is_table_wrapper:
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table_wrapper_width(context, box, (cb_width, cb_height))
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if isinstance(box, (boxes.BlockBox)):
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new_box, resume_at, _, _, _, _ = block_container_layout(
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context, box, bottom_space, skip_stack, page_is_empty=True,
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absolute_boxes=absolute_boxes, fixed_boxes=fixed_boxes,
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adjoining_margins=None, discard=False, max_lines=None)
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else:
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new_box, resume_at, _, _, _ = flex_layout(
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context, box, bottom_space, skip_stack, containing_block,
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page_is_empty=True, absolute_boxes=absolute_boxes,
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fixed_boxes=fixed_boxes)
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for child_placeholder in absolute_boxes:
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absolute_layout(
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context, child_placeholder, new_box, fixed_boxes, bottom_space,
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skip_stack)
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if translate_box_width:
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translate_x -= new_box.width
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if translate_box_height:
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translate_y -= new_box.height
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new_box.translate(translate_x, translate_y)
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return new_box, resume_at
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def absolute_layout(context, placeholder, containing_block, fixed_boxes,
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bottom_space, skip_stack):
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"""Set the width of absolute positioned ``box``."""
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assert not placeholder._layout_done
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box = placeholder._box
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new_box, resume_at = absolute_box_layout(
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context, box, containing_block, fixed_boxes, bottom_space, skip_stack)
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placeholder.set_laid_out_box(new_box)
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if resume_at:
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context.broken_out_of_flow[placeholder] = (
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box, containing_block, resume_at)
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def absolute_box_layout(context, box, containing_block, fixed_boxes,
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bottom_space, skip_stack):
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# TODO: handle inline boxes (point 10.1.4.1)
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# https://www.w3.org/TR/CSS2/visudet.html#containing-block-details
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if isinstance(containing_block, boxes.PageBox):
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cb_x = containing_block.content_box_x()
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cb_y = containing_block.content_box_y()
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cb_width = containing_block.width
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cb_height = containing_block.height
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else:
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cb_x = containing_block.padding_box_x()
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cb_y = containing_block.padding_box_y()
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cb_width = containing_block.padding_width()
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cb_height = containing_block.padding_height()
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resolve_percentages(box, (cb_width, cb_height))
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resolve_position_percentages(box, (cb_width, cb_height))
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context.create_block_formatting_context()
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# Absolute tables are wrapped into block boxes
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if isinstance(box, (boxes.BlockBox, boxes.FlexContainerBox)):
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new_box, resume_at = absolute_block(
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context, box, containing_block, fixed_boxes, bottom_space,
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skip_stack, cb_x, cb_y, cb_width, cb_height)
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else:
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assert isinstance(box, boxes.BlockReplacedBox)
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new_box = absolute_replaced(
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context, box, cb_x, cb_y, cb_width, cb_height)
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resume_at = None
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context.finish_block_formatting_context(new_box)
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return new_box, resume_at
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def absolute_replaced(context, box, cb_x, cb_y, cb_width, cb_height):
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inline_replaced_box_width_height(box, (cb_x, cb_y, cb_width, cb_height))
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ltr = (
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box.style.parent_style is None or
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box.style.parent_style['direction'] == 'ltr')
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# https://www.w3.org/TR/CSS21/visudet.html#abs-replaced-width
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if box.left == box.right == 'auto':
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# static position:
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if ltr:
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box.left = box.position_x - cb_x
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else:
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box.right = cb_x + cb_width - box.position_x
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if 'auto' in (box.left, box.right):
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if box.margin_left == 'auto':
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box.margin_left = 0
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if box.margin_right == 'auto':
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box.margin_right = 0
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remaining = cb_width - box.margin_width()
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if box.left == 'auto':
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box.left = remaining - box.right
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if box.right == 'auto':
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box.right = remaining - box.left
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elif 'auto' in (box.margin_left, box.margin_right):
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remaining = cb_width - (box.border_width() + box.left + box.right)
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if box.margin_left == box.margin_right == 'auto':
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if remaining >= 0:
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box.margin_left = box.margin_right = remaining // 2
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else:
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box.margin_left = 0 if ltr else remaining
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box.margin_right = remaining if ltr else 0
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elif box.margin_left == 'auto':
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box.margin_left = remaining
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else:
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box.margin_right = remaining
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else:
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# Over-constrained
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if ltr:
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box.right = cb_width - (box.margin_width() + box.left)
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else:
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box.left = cb_width - (box.margin_width() + box.right)
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# https://www.w3.org/TR/CSS21/visudet.html#abs-replaced-height
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if box.top == box.bottom == 'auto':
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box.top = box.position_y - cb_y
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if 'auto' in (box.top, box.bottom):
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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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remaining = cb_height - box.margin_height()
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if box.top == 'auto':
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box.top = remaining - box.bottom
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if box.bottom == 'auto':
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box.bottom = remaining - box.top
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elif 'auto' in (box.margin_top, box.margin_bottom):
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remaining = cb_height - (box.border_height() + box.top + box.bottom)
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if box.margin_top == box.margin_bottom == 'auto':
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box.margin_top = box.margin_bottom = remaining // 2
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elif box.margin_top == 'auto':
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box.margin_top = remaining
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else:
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box.margin_bottom = remaining
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else:
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# Over-constrained
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box.bottom = cb_height - (box.margin_height() + box.top)
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# No children for replaced boxes, no need to .translate()
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box.position_x = cb_x + box.left
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box.position_y = cb_y + box.top
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return box
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