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WeasyPrint/weasyprint/layout/leader.py
2022-02-14 07:11:30 +01:00

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"""Leaders management."""
from ..formatting_structure import boxes
def leader_index(box):
"""Get the index of the first leader box in ``box``."""
for i, child in enumerate(box.children):
if child.is_leader:
return (i, None), child
if isinstance(child, boxes.ParentBox):
child_leader_index, child_leader = leader_index(child)
if child_leader_index is not None:
return (i, child_leader_index), child_leader
return None, None
def handle_leader(context, line, containing_block):
"""Find a leader box in ``line`` and handle its text and its position."""
index, leader_box = leader_index(line)
extra_width = 0
if index is not None and leader_box.children:
text_box, = leader_box.children
# Abort if the leader text has no width
if text_box.width <= 0:
return
# Extra width is the additional width taken by the leader box
extra_width = containing_block.width - sum(
child.width for child in line.children
if child.is_in_normal_flow())
# Take care of excluded shapes
for shape in context.excluded_shapes:
if shape.position_y + shape.height > line.position_y:
extra_width -= shape.width
# Available width is the width available for the leader box
available_width = extra_width + text_box.width
line.width = containing_block.width
# Add text boxes into the leader box
number_of_leaders = int(line.width // text_box.width)
position_x = line.position_x + line.width
children = []
for i in range(number_of_leaders):
position_x -= text_box.width
if position_x < leader_box.position_x:
# Dont add leaders behind the text on the left
continue
elif (position_x + text_box.width >
leader_box.position_x + available_width):
# Dont add leaders behind the text on the right
continue
text_box = text_box.copy()
text_box.position_x = position_x
children.append(text_box)
leader_box.children = tuple(children)
if line.style['direction'] == 'rtl':
leader_box.translate(dx=-extra_width)
# Widen leader parent boxes and translate following boxes
box = line
while index is not None:
for child in box.children[index[0] + 1:]:
if child.is_in_normal_flow():
if line.style['direction'] == 'ltr':
child.translate(dx=extra_width)
else:
child.translate(dx=-extra_width)
box = box.children[index[0]]
box.width += extra_width
index = index[1]