151 lines
5.7 KiB
Python
151 lines
5.7 KiB
Python
"""
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weasyprint.layout.percentages
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-----------------------------
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Resolve percentages into fixed values.
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:copyright: Copyright 2011-2019 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 ..formatting_structure import boxes
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def percentage(value, refer_to):
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"""Return the percentage of the reference value, or the value unchanged.
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``refer_to`` is the length for 100%. If ``refer_to`` is not a number, it
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just replaces percentages.
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"""
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if value is None or value == 'auto':
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return value
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elif value.unit == 'px':
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return value.value
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else:
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assert value.unit == '%'
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return refer_to * value.value / 100.
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def resolve_one_percentage(box, property_name, refer_to,
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main_flex_direction=None):
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"""Set a used length value from a computed length value.
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``refer_to`` is the length for 100%. If ``refer_to`` is not a number, it
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just replaces percentages.
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"""
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# box.style has computed values
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value = box.style[property_name]
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# box attributes are used values
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percent = percentage(value, refer_to)
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setattr(box, property_name, percent)
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if property_name in ('min_width', 'min_height') and percent == 'auto':
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if (main_flex_direction is None or
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property_name != ('min_%s' % main_flex_direction)):
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setattr(box, property_name, 0)
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def resolve_position_percentages(box, containing_block):
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cb_width, cb_height = containing_block
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resolve_one_percentage(box, 'left', cb_width)
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resolve_one_percentage(box, 'right', cb_width)
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resolve_one_percentage(box, 'top', cb_height)
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resolve_one_percentage(box, 'bottom', cb_height)
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def resolve_percentages(box, containing_block, main_flex_direction=None):
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"""Set used values as attributes of the box object."""
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if isinstance(containing_block, boxes.Box):
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# cb is short for containing block
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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_width, cb_height = containing_block
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if isinstance(box, boxes.PageBox):
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maybe_height = cb_height
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else:
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maybe_height = cb_width
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resolve_one_percentage(box, 'margin_left', cb_width)
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resolve_one_percentage(box, 'margin_right', cb_width)
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resolve_one_percentage(box, 'margin_top', maybe_height)
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resolve_one_percentage(box, 'margin_bottom', maybe_height)
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resolve_one_percentage(box, 'padding_left', cb_width)
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resolve_one_percentage(box, 'padding_right', cb_width)
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resolve_one_percentage(box, 'padding_top', maybe_height)
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resolve_one_percentage(box, 'padding_bottom', maybe_height)
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resolve_one_percentage(box, 'width', cb_width)
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resolve_one_percentage(box, 'min_width', cb_width, main_flex_direction)
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resolve_one_percentage(box, 'max_width', cb_width, main_flex_direction)
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# XXX later: top, bottom, left and right on positioned elements
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if cb_height == 'auto':
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# Special handling when the height of the containing block
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# depends on its content.
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height = box.style['height']
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if height == 'auto' or height.unit == '%':
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box.height = 'auto'
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else:
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assert height.unit == 'px'
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box.height = height.value
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resolve_one_percentage(box, 'min_height', 0, main_flex_direction)
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resolve_one_percentage(
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box, 'max_height', float('inf'), main_flex_direction)
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else:
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resolve_one_percentage(box, 'height', cb_height)
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resolve_one_percentage(
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box, 'min_height', cb_height, main_flex_direction)
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resolve_one_percentage(
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box, 'max_height', cb_height, main_flex_direction)
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# Used value == computed value
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for side in ['top', 'right', 'bottom', 'left']:
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prop = 'border_{0}_width'.format(side)
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setattr(box, prop, box.style[prop])
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# Shrink *content* widths and heights according to box-sizing
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# Thanks heavens and the spec: Our validator rejects negative values
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# for padding and border-width
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if box.style['box_sizing'] == 'border-box':
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horizontal_delta = (
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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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vertical_delta = (
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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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elif box.style['box_sizing'] == 'padding-box':
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horizontal_delta = box.padding_left + box.padding_right
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vertical_delta = box.padding_top + box.padding_bottom
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else:
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assert box.style['box_sizing'] == 'content-box'
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horizontal_delta = 0
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vertical_delta = 0
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# Keep at least min_* >= 0 to prevent funny output in case box.width or
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# box.height become negative.
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# Restricting max_* seems reasonable, too.
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if horizontal_delta > 0:
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if box.width != 'auto':
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box.width = max(0, box.width - horizontal_delta)
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box.max_width = max(0, box.max_width - horizontal_delta)
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if box.min_width != 'auto':
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box.min_width = max(0, box.min_width - horizontal_delta)
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if vertical_delta > 0:
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if box.height != 'auto':
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box.height = max(0, box.height - vertical_delta)
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box.max_height = max(0, box.max_height - vertical_delta)
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if box.min_height != 'auto':
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box.min_height = max(0, box.min_height - vertical_delta)
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def resolve_radii_percentages(box):
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corners = ('top_left', 'top_right', 'bottom_right', 'bottom_left')
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for corner in corners:
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property_name = 'border_%s_radius' % corner
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rx, ry = box.style[property_name]
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rx = percentage(rx, box.border_width())
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ry = percentage(ry, box.border_height())
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setattr(box, property_name, (rx, ry))
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