"""Layout for inline-level boxes.""" import unicodedata from math import inf from ..css import computed_from_cascaded from ..css.computed_values import character_ratio, strut_layout from ..formatting_structure import boxes, build from ..text.line_break import can_break_text, create_layout, split_first_line from .absolute import AbsolutePlaceholder, absolute_layout from .flex import flex_layout from .float import avoid_collisions, float_layout from .grid import grid_layout from .leader import handle_leader from .min_max import handle_min_max_width from .percent import resolve_one_percentage, resolve_percentages from .preferred import inline_min_content_width, shrink_to_fit, trailing_whitespace_size from .replaced import inline_replaced_box_layout from .table import find_in_flow_baseline, table_wrapper_width def iter_line_boxes(context, box, position_y, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, first_letter_style): """Return an iterator of ``(line, resume_at)``. ``line`` is a laid-out LineBox with as much content as possible that fits in the available width. """ resolve_percentages(box, containing_block) if skip_stack is None: # TODO: wrong, see https://github.com/Kozea/WeasyPrint/issues/679 resolve_one_percentage(box, 'text_indent', containing_block.width) else: box.text_indent = 0 while True: line, resume_at = get_next_linebox( context, box, position_y, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, first_letter_style) if line: handle_leader(context, line, containing_block) position_y = line.position_y + line.height if line is None: return yield line, resume_at if resume_at is None: return skip_stack = resume_at box.text_indent = 0 first_letter_style = None def get_next_linebox(context, linebox, position_y, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, first_letter_style): """Return ``(line, resume_at)``.""" skip_stack = skip_first_whitespace(linebox, skip_stack) if skip_stack == 'continue': return None, None skip_stack = first_letter_to_box(linebox, skip_stack, first_letter_style) linebox.position_y = position_y if context.excluded_shapes: # Width and height must be calculated to avoid floats linebox.width = inline_min_content_width( context, linebox, skip_stack=skip_stack, first_line=True) linebox.height, _ = strut_layout(linebox.style, context) else: # No float, width and height will be set by the lines linebox.width = linebox.height = 0 position_x, position_y, available_width = avoid_collisions( context, linebox, containing_block, outer=False) candidate_height = linebox.height excluded_shapes = context.excluded_shapes.copy() while True: original_position_x = linebox.position_x = position_x original_position_y = linebox.position_y = position_y original_width = linebox.width max_x = position_x + available_width position_x += linebox.text_indent line_placeholders = [] line_absolutes = [] line_fixed = [] waiting_floats = [] line_children = [] (line, resume_at, preserved_line_break, first_letter, last_letter, float_width) = split_inline_box( context, linebox, position_x, max_x, bottom_space, skip_stack, containing_block, line_absolutes, line_fixed, line_placeholders, waiting_floats, line_children) linebox.width, linebox.height = line.width, line.height if is_phantom_linebox(line) and not preserved_line_break: line.height = 0 break remove_last_whitespace(context, line) new_position_x, _, new_available_width = avoid_collisions( context, linebox, containing_block, outer=False) offset_x = text_align( context, line, new_available_width, last=(resume_at is None or preserved_line_break)) if containing_block.style['direction'] == 'rtl': offset_x *= -1 offset_x -= line.width bottom, top = line_box_verticality(line) assert top is not None assert bottom is not None line.baseline = -top line.position_y = top line.height = bottom - top offset_y = position_y - top line.margin_top = 0 line.margin_bottom = 0 line.translate(offset_x, offset_y) # Avoid floating point errors, as position_y - top + top != position_y # Removing this line breaks the position == linebox.position test below # See https://github.com/Kozea/WeasyPrint/issues/583 line.position_y = position_y if line.height <= candidate_height: break candidate_height = line.height new_excluded_shapes = context.excluded_shapes context.excluded_shapes = excluded_shapes position_x, position_y, available_width = avoid_collisions( context, line, containing_block, outer=False) if containing_block.style['direction'] == 'ltr': condition = (position_x, position_y) == ( original_position_x, original_position_y) else: condition = (position_x + line.width, position_y) == ( original_position_x + original_width, original_position_y) if condition: context.excluded_shapes = new_excluded_shapes break absolute_boxes.extend(line_absolutes) fixed_boxes.extend(line_fixed) for placeholder in line_placeholders: if 'inline' in placeholder.style.specified['display']: # Inline-level static position: placeholder.translate(0, position_y - placeholder.position_y) else: # Block-level static position: at the start of the next line placeholder.translate( line.position_x - placeholder.position_x, position_y + line.height - placeholder.position_y) float_children = [] waiting_floats_y = line.position_y + line.height for waiting_float in waiting_floats: waiting_float.position_y = waiting_floats_y new_waiting_float, waiting_float_resume_at = float_layout( context, waiting_float, containing_block, absolute_boxes, fixed_boxes, bottom_space, skip_stack=None) float_children.append(new_waiting_float) if waiting_float_resume_at: context.broken_out_of_flow[new_waiting_float] = ( waiting_float, containing_block, waiting_float_resume_at) if float_children: line.children += tuple(float_children) return line, resume_at def skip_first_whitespace(box, skip_stack): """Return ``skip_stack`` to start just after removable leading spaces. See https://www.w3.org/TR/CSS21/text.html#white-space-model """ if skip_stack is None: index = 0 next_skip_stack = None else: (index, next_skip_stack), = skip_stack.items() if isinstance(box, boxes.TextBox): assert next_skip_stack is None white_space = box.style['white_space'] text = box.text.encode() if index == len(text): # Starting a the end of the TextBox, no text to see: Continue return 'continue' if white_space in ('normal', 'nowrap', 'pre-line'): text = text[index:] while text and text.startswith(b' '): index += 1 text = text[1:] return {index: None} if index else None if isinstance(box, (boxes.LineBox, boxes.InlineBox)): if index == 0 and not box.children: return None result = skip_first_whitespace(box.children[index], next_skip_stack) if result == 'continue': index += 1 if index >= len(box.children): return 'continue' result = skip_first_whitespace(box.children[index], None) return {index: result} if (index or result) else None assert skip_stack is None, f'unexpected skip inside {box}' return None def remove_last_whitespace(context, line): """Remove in place space characters at the end of a line. This also reduces the width and position of the inline parents of the modified text. """ ancestors = [] box = line while isinstance(box, (boxes.LineBox, boxes.InlineBox)): ancestors.append(box) if not box.children: return box = box.children[-1] if not (isinstance(box, boxes.TextBox) and box.style['white_space'] in ('normal', 'nowrap', 'pre-line')): return new_text = box.text.rstrip(' ') if new_text: if len(new_text) == len(box.text): return box.text = new_text new_box, resume, _ = split_text_box(context, box, None, 0) assert new_box is not None assert resume is None space_width = box.width - new_box.width box.width = new_box.width else: space_width = box.width box.width = 0 box.text = '' # RTL line, the trailing space is at the left of the box. We have to translate the # box to align the stripped text with the right edge of the box. if box.pango_layout.first_line_direction % 2: for child in line.children: child.translate(dx=-space_width, ignore_floats=True) for ancestor in ancestors: ancestor.width -= space_width # TODO: All tabs (U+0009) are rendered as a horizontal shift that # lines up the start edge of the next glyph with the next tab stop. # Tab stops occur at points that are multiples of 8 times the width # of a space (U+0020) rendered in the block's font from the block's # starting content edge. # TODO: If spaces (U+0020) or tabs (U+0009) at the end of a line have # 'white-space' set to 'pre-wrap', UAs may visually collapse them. def first_letter_to_box(box, skip_stack, first_letter_style): """Create a box for the ::first-letter selector.""" if first_letter_style and box.children: # Some properties must be ignored in first-letter boxes. # https://drafts.csswg.org/selectors-3/#application-in-css # At least, position is ignored to avoid layout troubles. first_letter_style['position'] = 'static' first_letter = '' child = box.children[0] if isinstance(child, boxes.TextBox): letter_style = computed_from_cascaded( cascaded={}, parent_style=first_letter_style, element=None) if child.element_tag.endswith('::first-letter'): letter_box = boxes.InlineBox( f'{box.element_tag}::first-letter', letter_style, box.element, [child]) box.children = ((letter_box, *box.children[1:])) elif child.text: character_found = False if skip_stack: child_skip_stack, = skip_stack.values() if child_skip_stack: index, = child_skip_stack child.text = child.text[index:] skip_stack = None while child.text: next_letter = child.text[0] category = unicodedata.category(next_letter) if category not in ('Ps', 'Pe', 'Pi', 'Pf', 'Po'): if character_found: break character_found = True first_letter += next_letter child.text = child.text[1:] if first_letter.lstrip('\n'): # "This type of initial letter is similar to an # inline-level element if its 'float' property is 'none', # otherwise it is similar to a floated element." if first_letter_style['float'] == 'none': letter_box = boxes.InlineBox( f'{box.element_tag}::first-letter', first_letter_style, box.element, []) text_box = boxes.TextBox( f'{box.element_tag}::first-letter', letter_style, box.element, first_letter) letter_box.children = (text_box,) box.children = (letter_box, *box.children) else: letter_box = boxes.BlockBox( f'{box.element_tag}::first-letter', first_letter_style, box.element, []) letter_box.first_letter_style = None line_box = boxes.LineBox( f'{box.element_tag}::first-letter', letter_style, box.element, []) letter_box.children = (line_box,) text_box = boxes.TextBox( f'{box.element_tag}::first-letter', letter_style, box.element, first_letter) line_box.children = (text_box,) box.children = (letter_box, *box.children) build.process_text_transform(text_box) if skip_stack and child_skip_stack: index, = skip_stack (child_index, grandchild_skip_stack), = ( child_skip_stack.items()) skip_stack = { index: {child_index + 1: grandchild_skip_stack}} elif isinstance(child, boxes.ParentBox): if skip_stack: child_skip_stack, = skip_stack.values() else: child_skip_stack = None child_skip_stack = first_letter_to_box( child, child_skip_stack, first_letter_style) if skip_stack: index, = skip_stack skip_stack = {index: child_skip_stack} return skip_stack def atomic_box(context, box, position_x, skip_stack, containing_block, absolute_boxes, fixed_boxes): """Compute the width and the height of the atomic ``box``.""" if isinstance(box, boxes.ReplacedBox): box = box.copy() inline_replaced_box_layout(box, containing_block) box.baseline = box.margin_height() elif isinstance(box, boxes.InlineBlockBox): if box.is_table_wrapper: containing_size = (containing_block.width, containing_block.height) table_wrapper_width(context, box, containing_size) width, min_width, max_width = box.width, box.min_width, box.max_width box = inline_block_box_layout( context, box, position_x, skip_stack, containing_block, absolute_boxes, fixed_boxes) if box.is_table_wrapper: box.width, box.min_width, box.max_width = width, min_width, max_width else: # pragma: no cover raise TypeError(f'Layout for {type(box).__name__} not handled yet') return box def inline_block_box_layout(context, box, position_x, skip_stack, containing_block, absolute_boxes, fixed_boxes): from .block import block_container_layout resolve_percentages(box, containing_block) # https://www.w3.org/TR/CSS21/visudet.html#inlineblock-width if box.margin_left == 'auto': box.margin_left = 0 if box.margin_right == 'auto': box.margin_right = 0 # https://www.w3.org/TR/CSS21/visudet.html#block-root-margin if box.margin_top == 'auto': box.margin_top = 0 if box.margin_bottom == 'auto': box.margin_bottom = 0 inline_block_width(box, context, containing_block) box.position_x = position_x box.position_y = 0 box, _, _, _, _, _ = block_container_layout( context, box, bottom_space=-inf, skip_stack=skip_stack, page_is_empty=True, absolute_boxes=absolute_boxes, fixed_boxes=fixed_boxes, adjoining_margins=None, discard=False, max_lines=None) box.baseline = inline_block_baseline(box) return box def inline_block_baseline(box): """Return the y position of the baseline for an inline block. Position is taken from the top of its margin box. https://www.w3.org/TR/CSS21/visudet.html#propdef-vertical-align """ if box.is_table_wrapper: # Inline table's baseline is its first row's baseline for child in box.children: if isinstance(child, boxes.TableBox): if child.children and child.children[0].children: first_row = child.children[0].children[0] return first_row.baseline elif box.style['overflow'] == 'visible': result = find_in_flow_baseline(box, last=True) if result: return result return box.position_y + box.margin_height() @handle_min_max_width def inline_block_width(box, context, containing_block): available_content_width = containing_block.width - ( box.margin_left + box.margin_right + box.border_left_width + box.border_right_width + box.padding_left + box.padding_right) if box.width == 'auto': box.width = shrink_to_fit(context, box, available_content_width) def split_inline_level(context, box, position_x, max_x, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, line_placeholders, waiting_floats, line_children): """Fit as much content as possible from an inline-level box in a width. Return ``(new_box, resume_at, preserved_line_break, first_letter, last_letter)``. ``resume_at`` is ``None`` if all of the content fits. Otherwise it can be passed as a ``skip_stack`` parameter to resume where we left off. ``new_box`` is non-empty (unless the box is empty) and as big as possible while being narrower than ``available_width``, if possible (may overflow is no split is possible.) """ resolve_percentages(box, containing_block) float_widths = {'left': 0, 'right': 0} if isinstance(box, boxes.TextBox): box.position_x = position_x if skip_stack is None: skip = 0 else: (skip, skip_stack), = skip_stack.items() skip = skip or 0 assert skip_stack is None is_line_start = len(line_children) == 0 new_box, skip, preserved_line_break = split_text_box( context, box, max_x - position_x, skip, is_line_start=is_line_start) if skip is None: resume_at = None else: resume_at = {skip: None} if box.text: first_letter = box.text[0] if skip is None: last_letter = box.text[-1] else: last_letter = box.text.encode()[:skip].decode()[-1] else: first_letter = last_letter = None elif isinstance(box, boxes.InlineBox): if box.margin_left == 'auto': box.margin_left = 0 if box.margin_right == 'auto': box.margin_right = 0 (new_box, resume_at, preserved_line_break, first_letter, last_letter, float_widths) = split_inline_box( context, box, position_x, max_x, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, line_placeholders, waiting_floats, line_children) elif isinstance(box, boxes.AtomicInlineLevelBox): new_box = atomic_box( context, box, position_x, skip_stack, containing_block, absolute_boxes, fixed_boxes) new_box.position_x = position_x resume_at = None preserved_line_break = False # See https://www.w3.org/TR/css-text-3/#line-breaking # Atomic inlines behave like ideographic characters. first_letter = '\u2e80' last_letter = '\u2e80' elif isinstance(box, boxes.InlineFlexBox): box.position_x = position_x box.position_y = 0 for side in ('top', 'right', 'bottom', 'left'): if getattr(box, f'margin_{side}') == 'auto': setattr(box, f'margin_{side}', 0) new_box, resume_at, _, _, _ = flex_layout( context, box, -inf, skip_stack, containing_block, False, absolute_boxes, fixed_boxes, False) preserved_line_break = False first_letter = '\u2e80' last_letter = '\u2e80' elif isinstance(box, boxes.InlineGridBox): box.position_x = position_x box.position_y = 0 for side in ('top', 'right', 'bottom', 'left'): if getattr(box, f'margin_{side}') == 'auto': setattr(box, f'margin_{side}', 0) new_box, resume_at, _, _, _ = grid_layout( context, box, -inf, skip_stack, containing_block, False, absolute_boxes, fixed_boxes) preserved_line_break = False first_letter = '\u2e80' last_letter = '\u2e80' else: # pragma: no cover raise TypeError(f'Layout for {type(box).__name__} not handled yet') return ( new_box, resume_at, preserved_line_break, first_letter, last_letter, float_widths) def _out_of_flow_layout(context, box, containing_block, index, child, children, line_children, waiting_children, waiting_floats, absolute_boxes, fixed_boxes, line_placeholders, float_widths, max_x, position_x, bottom_space): if child.is_absolutely_positioned(): child.position_x = position_x placeholder = AbsolutePlaceholder(child) line_placeholders.append(placeholder) waiting_children.append((index, placeholder, child)) if child.style['position'] == 'absolute': absolute_boxes.append(placeholder) else: fixed_boxes.append(placeholder) elif child.is_floated(): child.position_x = position_x float_width = shrink_to_fit(context, child, containing_block.width) # To retrieve the real available space for floats, we must remove # the trailing whitespaces from the line non_floating_children = [ child_ for _, child_, _ in (children + waiting_children) if not child_.is_floated()] if non_floating_children: float_width -= trailing_whitespace_size( context, non_floating_children[-1]) if float_width > max_x - position_x or waiting_floats: # TODO: the absolute and fixed boxes in the floats must be # added here, and not in iter_line_boxes waiting_floats.append(child) else: new_child, float_resume_at = float_layout( context, child, containing_block, absolute_boxes, fixed_boxes, bottom_space, skip_stack=None) if float_resume_at: context.broken_out_of_flow[child] = ( child, containing_block, float_resume_at) waiting_children.append((index, new_child, child)) child = new_child # Translate previous line children dx = max(child.margin_width(), 0) float_widths[child.style['float']] += dx if child.style['float'] == 'left': if isinstance(box, boxes.LineBox): # The parent is the line, update the current position # for the next child. When the parent is not the line # (it is an inline block), the current position of the # line is updated by the box itself (see next # split_inline_level call). position_x += dx elif child.style['float'] == 'right': # Update the maximum x position for the next children max_x -= dx for _, old_child in line_children: if not old_child.is_in_normal_flow(): continue if ((child.style['float'] == 'left' and box.style['direction'] == 'ltr') or (child.style['float'] == 'right' and box.style['direction'] == 'rtl')): old_child.translate(dx=dx) elif child.is_running(): running_name = child.style['position'][1] page = context.current_page context.running_elements[running_name][page].append(child) def _break_waiting_children(context, box, max_x, bottom_space, initial_skip_stack, absolute_boxes, fixed_boxes, line_placeholders, waiting_floats, line_children, children, waiting_children): if waiting_children: # Too wide, try to cut inside waiting children, starting from the end. # TODO: we should take care of children added into absolute_boxes, # fixed_boxes and other lists. waiting_children_copy = waiting_children.copy() while waiting_children_copy: child_index, child, original_child = waiting_children_copy.pop() if not child.is_in_normal_flow() or not can_break_inside(child): continue if initial_skip_stack and child_index in initial_skip_stack: child_skip_stack = initial_skip_stack[child_index] else: child_skip_stack = None # 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, original_child, child.position_x, max_x, bottom_space, child_skip_stack, 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, child)) return {child_index: child_resume_at} if children: # Too wide, can't break waiting children and the inline is # non-empty: put child entirely on the next line. return {children[-1][0] + 1: None} def split_inline_box(context, box, position_x, max_x, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, line_placeholders, waiting_floats, line_children): """Same behavior as split_inline_level.""" # In some cases (shrink-to-fit result being the preferred width) # max_x is coming from Pango itself, # but floating point errors have accumulated: # width2 = (width + X) - X # in some cases, width2 < width # Increase the value a bit to compensate and not introduce # an unexpected line break. The 1e-9 value comes from PEP 485. max_x *= 1 + 1e-9 is_start = skip_stack is None initial_position_x = position_x initial_skip_stack = skip_stack assert isinstance(box, (boxes.LineBox, boxes.InlineBox)) left_spacing = ( box.padding_left + box.margin_left + box.border_left_width) right_spacing = ( box.padding_right + box.margin_right + box.border_right_width) content_box_left = position_x children = [] waiting_children = [] preserved_line_break = False first_letter = last_letter = None float_widths = {'left': 0, 'right': 0} float_resume_index = 0 if box.style['position'] == 'relative': absolute_boxes = [] if is_start: skip = 0 else: (skip, skip_stack), = skip_stack.items() for i, child in enumerate(box.children[skip:]): index = i + skip child.position_y = box.position_y if not child.is_in_normal_flow(): _out_of_flow_layout( context, box, containing_block, index, child, children, line_children, waiting_children, waiting_floats, absolute_boxes, fixed_boxes, line_placeholders, float_widths, max_x, position_x, bottom_space) if child.is_floated(): float_resume_index = index + 1 if child not in waiting_floats: max_x -= child.margin_width() continue is_last_child = (index == len(box.children) - 1) available_width = max_x child_waiting_floats = [] new_child, resume_at, preserved, first, last, new_float_widths = ( split_inline_level( context, child, position_x, available_width, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, line_placeholders, child_waiting_floats, line_children)) if box.style['direction'] == 'rtl': end_spacing = left_spacing max_x -= new_float_widths['left'] else: end_spacing = right_spacing max_x -= new_float_widths['right'] if is_last_child and end_spacing and resume_at is None: # TODO: we should take care of children added into absolute_boxes, # fixed_boxes and other lists. available_width -= end_spacing new_child, resume_at, preserved, first, last, new_float_widths = ( split_inline_level( context, child, position_x, available_width, bottom_space, skip_stack, containing_block, absolute_boxes, fixed_boxes, line_placeholders, child_waiting_floats, line_children)) skip_stack = None if preserved: preserved_line_break = True can_break = None if last_letter is True: last_letter = ' ' elif last_letter is False: last_letter = ' ' # no-break space elif box.style['white_space'] in ('pre', 'nowrap'): can_break = False if can_break is None: if None in (last_letter, first): can_break = False elif first in (True, False): can_break = first else: can_break = can_break_text( last_letter + first, child.style['lang']) if can_break: children.extend(waiting_children) waiting_children = [] if first_letter is None: first_letter = first if child.trailing_collapsible_space: last_letter = True else: last_letter = last if new_child is None: # May be None where we have an empty TextBox. assert isinstance(child, boxes.TextBox) else: if isinstance(box, boxes.LineBox): line_children.append((index, new_child)) trailing_whitespace = ( isinstance(new_child, boxes.TextBox) and 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: previous_resume_at = _break_waiting_children( context, containing_block, max_x, bottom_space, initial_skip_stack, absolute_boxes, fixed_boxes, line_placeholders, waiting_floats, line_children, children, waiting_children) if previous_resume_at: resume_at = previous_resume_at break position_x = new_position_x waiting_children.append((index, new_child, child)) waiting_floats.extend(child_waiting_floats) if resume_at is not None: children.extend(waiting_children) resume_at = {index: resume_at} break else: children.extend(waiting_children) resume_at = None # Reorder inline blocks when direction is rtl if box.style['direction'] == 'rtl' and len(children) > 1: in_flow_children = [ box_child for _, box_child, _ in children if box_child.is_in_normal_flow()] position_x = in_flow_children[0].position_x for child in in_flow_children[::-1]: child.translate( dx=(position_x - child.position_x), ignore_floats=True) position_x += child.margin_width() is_end = resume_at is None new_box = box.copy_with_children( [box_child for index, box_child, _ in children]) new_box.remove_decoration(start=not is_start, end=not is_end) if isinstance(box, boxes.LineBox): # We must reset line box width according to its new children new_box.width = 0 children = new_box.children if new_box.style['direction'] == 'ltr': children = children[::-1] for child in children: if child.is_in_normal_flow(): new_box.width = ( child.position_x + child.margin_width() - new_box.position_x) break else: new_box.position_x = initial_position_x if box.style['box_decoration_break'] == 'clone': translation_needed = True else: translation_needed = ( is_start if box.style['direction'] == 'ltr' else is_end) if translation_needed: for child in new_box.children: child.translate(dx=left_spacing) new_box.width = position_x - content_box_left new_box.translate(dx=float_widths['left'], ignore_floats=True) line_height, new_box.baseline = strut_layout(box.style, context) new_box.height = box.style['font_size'] half_leading = (line_height - new_box.height) / 2 # Set margins to the half leading but also compensate for borders and # paddings. We want margin_height() == line_height new_box.margin_top = ( half_leading - new_box.border_top_width - new_box.padding_top) new_box.margin_bottom = ( half_leading - new_box.border_bottom_width - new_box.padding_bottom) if new_box.style['position'] == 'relative': for absolute_box in absolute_boxes: absolute_layout( context, absolute_box, new_box, fixed_boxes, bottom_space, skip_stack=None) if resume_at is not None: index = next(iter(resume_at)) if index < float_resume_index: resume_at = {float_resume_index: None} if box.is_leader: first_letter = True last_letter = False return ( new_box, resume_at, preserved_line_break, first_letter, last_letter, float_widths) def split_text_box(context, box, available_width, skip, is_line_start=True): """Keep as much text as possible from a TextBox in a limited width. Try not to overflow but always have some text in ``new_box``. Return ``(new_box, skip, preserved_line_break)``. ``skip`` is the number of UTF-8 bytes to skip form the start of the TextBox for the next line, or ``None`` if all of the text fits. Also break on preserved line breaks. """ assert isinstance(box, boxes.TextBox) font_size = box.style['font_size'] text = box.text.encode()[skip:] if font_size == 0 or not text: return None, None, False layout, length, resume_index, width, height, baseline = split_first_line( text.decode(), box.style, context, available_width, box.justification_spacing, is_line_start=is_line_start) assert resume_index != 0 if length > 0: box = box.copy_with_text(layout.text) box.width = width box.pango_layout = layout # "The height of the content area should be based on the font, # but this specification does not specify how." # https://www.w3.org/TR/CSS21/visudet.html#inline-non-replaced # We trust Pango and use the height of the LayoutLine. box.height = height # "only the 'line-height' is used when calculating the height # of the line box." # Set margins so that margin_height() == line_height line_height, _ = strut_layout(box.style, context) half_leading = (line_height - height) / 2 box.margin_top = half_leading box.margin_bottom = half_leading # form the top of the content box box.baseline = baseline # form the top of the margin box box.baseline += box.margin_top else: box = None if resume_index is None: preserved_line_break = False else: between = text[length:resume_index].decode() preserved_line_break = ( (length != resume_index) and between.strip(' ')) if preserved_line_break: # See https://unicode.org/reports/tr14/ # \r is already handled by process_whitespace line_breaks = ('\n', '\t', '\f', '\u0085', '\u2028', '\u2029') assert between in line_breaks, ( 'Got %r between two lines. ' 'Expected nothing or a preserved line break' % (between,)) resume_index += skip return box, resume_index, preserved_line_break def line_box_verticality(box): """Handle ``vertical-align`` within a :class:`LineBox`. Place all boxes vertically assuming that the baseline of ``box`` is at `y = 0`. Return ``(max_y, min_y)``, the maximum and minimum vertical position of margin boxes. """ top_bottom_subtrees = [] max_y, min_y = aligned_subtree_verticality( box, top_bottom_subtrees, baseline_y=0) subtrees_with_min_max = [ (subtree, sub_max_y, sub_min_y) for subtree in top_bottom_subtrees for sub_max_y, sub_min_y in [ (None, None) if subtree.is_floated() else aligned_subtree_verticality( subtree, top_bottom_subtrees, baseline_y=0)]] if subtrees_with_min_max: sub_positions = [ sub_max_y - sub_min_y for subtree, sub_max_y, sub_min_y in subtrees_with_min_max if not subtree.is_floated()] if sub_positions: highest_sub = max(sub_positions) max_y = max(max_y, min_y + highest_sub) for subtree, sub_max_y, sub_min_y in subtrees_with_min_max: if subtree.is_floated(): dy = min_y - subtree.position_y elif subtree.style['vertical_align'] == 'top': dy = min_y - sub_min_y else: assert subtree.style['vertical_align'] == 'bottom' dy = max_y - sub_max_y translate_subtree(subtree, dy) return max_y, min_y def translate_subtree(box, dy): if isinstance(box, boxes.InlineBox): box.position_y += dy if box.style['vertical_align'] in ('top', 'bottom'): for child in box.children: translate_subtree(child, dy) else: # Text or atomic boxes box.translate(dy=dy) def aligned_subtree_verticality(box, top_bottom_subtrees, baseline_y): max_y, min_y = inline_box_verticality(box, top_bottom_subtrees, baseline_y) # Account for the line box itself: top = baseline_y - box.baseline bottom = top + box.margin_height() if min_y is None or top < min_y: min_y = top if max_y is None or bottom > max_y: max_y = bottom return max_y, min_y def inline_box_verticality(box, top_bottom_subtrees, baseline_y): """Handle ``vertical-align`` within an :class:`InlineBox`. Place all boxes vertically assuming that the baseline of ``box`` is at `y = baseline_y`. Return ``(max_y, min_y)``, the maximum and minimum vertical position of margin boxes. """ max_y = None min_y = None if not isinstance(box, (boxes.LineBox, boxes.InlineBox)): return max_y, min_y for child in box.children: if not child.is_in_normal_flow(): if child.is_floated(): top_bottom_subtrees.append(child) continue vertical_align = child.style['vertical_align'] if vertical_align == 'baseline': child_baseline_y = baseline_y elif vertical_align == 'middle': one_ex = box.style['font_size'] * character_ratio(box.style, 'x') top = baseline_y - (one_ex + child.margin_height()) / 2 child_baseline_y = top + child.baseline elif vertical_align == 'text-top': # align top with the top of the parent’s content area top = (baseline_y - box.baseline + box.margin_top + box.border_top_width + box.padding_top) child_baseline_y = top + child.baseline elif vertical_align == 'text-bottom': # align bottom with the bottom of the parent’s content area bottom = (baseline_y - box.baseline + box.margin_top + box.border_top_width + box.padding_top + box.height) child_baseline_y = bottom - child.margin_height() + child.baseline elif vertical_align in ('top', 'bottom'): # TODO: actually implement vertical-align: top and bottom # Later, we will assume for this subtree that its baseline # is at y=0. child_baseline_y = 0 else: # Numeric value: The child’s baseline is `vertical_align` above # (lower y) the parent’s baseline. child_baseline_y = baseline_y - vertical_align # the child’s `top` is `child.baseline` above (lower y) its baseline. top = child_baseline_y - child.baseline box_types = (boxes.InlineBlockBox, boxes.InlineFlexBox, boxes.InlineGridBox) if isinstance(child, box_types): # This also includes table wrappers for inline tables. child.translate(dy=top - child.position_y) else: child.position_y = top # grand-children for inline boxes are handled below if vertical_align in ('top', 'bottom'): # top or bottom are special, they need to be handled in # a later pass. top_bottom_subtrees.append(child) continue bottom = top + child.margin_height() if min_y is None or top < min_y: min_y = top if max_y is None or bottom > max_y: max_y = bottom if isinstance(child, boxes.InlineBox): children_max_y, children_min_y = inline_box_verticality( child, top_bottom_subtrees, child_baseline_y) if children_min_y is not None and children_min_y < min_y: min_y = children_min_y if children_max_y is not None and children_max_y > max_y: max_y = children_max_y return max_y, min_y def text_align(context, line, available_width, last): """Return the line horizontal offset according to ``text-align``.""" # "When the total width of the inline-level boxes on a line is less than # the width of the line box containing them, their horizontal distribution # within the line box is determined by the 'text-align' property." if line.width >= available_width: return 0 align = line.style['text_align_all'] if last: align_last = line.style['text_align_last'] align = align if align_last == 'auto' else align_last space_collapse = line.style['white_space'] in ( 'normal', 'nowrap', 'pre-line') if align in ('left', 'right'): if (align == 'left') ^ (line.style['direction'] == 'rtl'): align = 'start' else: align = 'end' if align == 'start': return 0 offset = available_width - line.width if align == 'justify': if space_collapse: # Justification of texts where white space is not collapsing is # - forbidden by CSS 2, and # - not required by CSS 3 Text. justify_line(context, line, offset) return 0 if align == 'center': return offset / 2 else: assert align == 'end' return offset def justify_line(context, line, extra_width): # TODO: We should use a better algorithm here, see # https://www.w3.org/TR/css-text-3/#justify-algos if (nb_spaces := count_expandable_spaces(line)): add_word_spacing(context, line, extra_width / nb_spaces, 0) def count_expandable_spaces(box): """Count expandable spaces (space and nbsp) for justification.""" if isinstance(box, boxes.TextBox): # TODO: remove trailing spaces correctly return box.text.count(' ') + box.text.count('\u00a0') elif isinstance(box, (boxes.LineBox, boxes.InlineBox)): return sum(count_expandable_spaces(child) for child in box.children) else: return 0 def add_word_spacing(context, box, justification_spacing, x_advance): if isinstance(box, boxes.TextBox): box.justification_spacing = justification_spacing box.position_x += x_advance nb_spaces = count_expandable_spaces(box) if nb_spaces > 0: layout = create_layout( box.text, box.style, context, max_width=None, justification_spacing=box.justification_spacing) layout.deactivate() extra_space = justification_spacing * nb_spaces x_advance += extra_space box.width += extra_space box.pango_layout = layout elif isinstance(box, (boxes.LineBox, boxes.InlineBox)): box.position_x += x_advance previous_x_advance = x_advance children = box.children if box.style['direction'] == 'rtl': children = children[::-1] for child in children: if child.is_in_normal_flow(): x_advance = add_word_spacing( context, child, justification_spacing, x_advance) box.width += x_advance - previous_x_advance else: # Atomic inline-level box box.translate(x_advance, 0) return x_advance def is_phantom_linebox(linebox): # See https://www.w3.org/TR/CSS21/visuren.html#phantom-line-box for child in linebox.children: if isinstance(child, boxes.InlineBox): if not is_phantom_linebox(child): return False for side in ('top', 'right', 'bottom', 'left'): if (getattr(child.style[f'margin_{side}'], 'value', None) or child.style[f'border_{side}_width'] or child.style[f'padding_{side}'].value): return False elif child.is_in_normal_flow(): return False return True def can_break_inside(box): # See https://www.w3.org/TR/css-text-3/#white-space-property text_wrap = box.style['white_space'] in ('normal', 'pre-wrap', 'pre-line') if isinstance(box, boxes.AtomicInlineLevelBox): return False elif text_wrap and isinstance(box, boxes.TextBox): return can_break_text(box.text, box.style['lang']) elif text_wrap and isinstance(box, boxes.ParentBox): return any(can_break_inside(child) for child in box.children) return False