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Fix line break when breaks occur between a nbsp and an inline block
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This commit:

- fixes the trailing space detection, by handling all trailing spacing
  characters that could be ignored by Pango’s line break algorithm;
- tries harder to break waiting children when a line break occurs in an
  inline block that can’t be separated from the previous one.

Fix #1562.
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@liZe
liZe committed Feb 8, 2022
1 parent e4a35cb commit 562a249
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Showing 2 changed files with 79 additions and 50 deletions.
20 changes: 20 additions & 0 deletions tests/test_text.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,26 @@ def test_line_breaking_rtl():
'ايبسوم دولا')


@assert_no_logs
def test_line_breaking_nbsp():
# Test regression: https://github.com/Kozea/WeasyPrint/issues/1561
page, = render_pages('''
<style>
@font-face {src: url(weasyprint.otf); font-family: weasyprint}
body { font-family: weasyprint; width: 7.5em }
</style>
<body>a <span>b</span> c d&nbsp;<span>ef
''')
html, = page.children
body, = html.children
line_1, line_2 = body.children
assert line_1.children[0].text == 'a '
assert line_1.children[1].children[0].text == 'b'
assert line_1.children[2].text == ' c'
assert line_2.children[0].text == 'd\xa0'
assert line_2.children[1].children[0].text == 'ef'


@assert_no_logs
def test_text_dimension():
string = 'This is a text for test. This is a test for text.py'
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109 changes: 59 additions & 50 deletions weasyprint/layout/inline.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -609,59 +609,68 @@ def _break_waiting_children(context, box, max_x, bottom_space,
waiting_children_copy = waiting_children.copy()
while waiting_children_copy:
child_index, child = waiting_children_copy.pop()
if child.is_in_normal_flow() and can_break_inside(child):
# Break the waiting child at its last possible breaking point.
# TODO: The dirty solution chosen here is to decrease the
# actual size by 1 and render the waiting child again with this
# constraint. We may find a better way.
max_x = child.position_x + child.margin_width() - 1
if not child.is_in_normal_flow() or not can_break_inside(child):
continue

# Break the waiting child at its last possible breaking point.
# TODO: The dirty solution chosen here is to decrease the
# actual size by 1 and render the waiting child again with this
# constraint. We may find a better way.
max_x = child.position_x + child.margin_width() - 1
while max_x > child.position_x:
new_child, child_resume_at, _, _, _, _ = split_inline_level(
context, child, child.position_x, max_x, bottom_space,
None, box, absolute_boxes, fixed_boxes, line_placeholders,
waiting_floats, line_children)
if child_resume_at:
break
max_x -= 1
else:
# No line break found
continue

children.extend(waiting_children_copy)
if new_child is None:
# May be None where we have an empty TextBox.
assert isinstance(child, boxes.TextBox)
else:
children.append((child_index, new_child))

# As this child has already been broken following the original
# skip stack, we have to add the original skip stack to the
# partial skip stack we get after the new rendering.

# Combining skip stacks is a bit complicated. We have to:
# - set `child_index` as the first number
# - append the new stack if it's an absolute one
# - otherwise append the combined stacks
# (resume_at + initial_skip_stack)

# extract the initial index
if initial_skip_stack is None:
current_skip_stack = None
initial_index = 0
else:
(initial_index, current_skip_stack), = (
initial_skip_stack.items())
# child_resume_at is an absolute skip stack
if child_index > initial_index:
return {child_index: child_resume_at}

# combine the stacks
current_resume_at = child_resume_at
stack = []
while current_skip_stack and current_resume_at:
(skip, current_skip_stack), = current_skip_stack.items()
(resume, current_resume_at), = current_resume_at.items()
stack.append(skip + resume)
if resume != 0:
break
resume_at = current_resume_at
while stack:
resume_at = {stack.pop(): resume_at}
# insert the child index
return {child_index: resume_at}
children.extend(waiting_children_copy)
if new_child is None:
# May be None where we have an empty TextBox.
assert isinstance(child, boxes.TextBox)
else:
children.append((child_index, new_child))

# As this child has already been broken following the original
# skip stack, we have to add the original skip stack to the
# partial skip stack we get after the new rendering.

# Combining skip stacks is a bit complicated. We have to:
# - set `child_index` as the first number
# - append the new stack if it's an absolute one
# - otherwise append the combined stacks
# (resume_at + initial_skip_stack)

# extract the initial index
if initial_skip_stack is None:
current_skip_stack = None
initial_index = 0
else:
(initial_index, current_skip_stack), = (
initial_skip_stack.items())
# child_resume_at is an absolute skip stack
if child_index > initial_index:
return {child_index: child_resume_at}

# combine the stacks
current_resume_at = child_resume_at
stack = []
while current_skip_stack and current_resume_at:
(skip, current_skip_stack), = current_skip_stack.items()
(resume, current_resume_at), = current_resume_at.items()
stack.append(skip + resume)
if resume != 0:
break
resume_at = current_resume_at
while stack:
resume_at = {stack.pop(): resume_at}
# insert the child index
return {child_index: resume_at}

if children:
# Too wide, can't break waiting children and the inline is
Expand Down Expand Up @@ -785,10 +794,10 @@ def split_inline_box(context, box, position_x, max_x, bottom_space, skip_stack,
else:
if isinstance(box, boxes.LineBox):
line_children.append((index, new_child))
# TODO: we should try to find a better condition here.
trailing_whitespace = (
isinstance(new_child, boxes.TextBox) and
not new_child.text.strip())
new_child.text and
unicodedata.category(new_child.text[-1]) == 'Zs')
new_position_x = new_child.position_x + new_child.margin_width()

if new_position_x > max_x and not trailing_whitespace:
Expand Down

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