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https://github.com/servo/servo.git
synced 2025-08-14 18:05:36 +01:00
Simon Sapin
Anthony Ramine
parent
be0e84b30f
commit
86904757e6
12 changed files with 2728 additions and 0 deletions
328
components/layout_2020/positioned.rs
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328
components/layout_2020/positioned.rs
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@ -0,0 +1,328 @@
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use super::*;
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use rayon::prelude::*;
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#[derive(Debug)]
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pub(super) struct AbsolutelyPositionedBox {
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pub style: Arc<ComputedValues>,
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pub contents: IndependentFormattingContext,
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}
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#[derive(Debug)]
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pub(super) struct AbsolutelyPositionedFragment<'box_> {
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absolutely_positioned_box: &'box_ AbsolutelyPositionedBox,
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/// The rank of the child from which this absolutely positioned fragment
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/// came from, when doing the layout of a block container. Used to compute
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/// static positions when going up the tree.
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pub(super) tree_rank: usize,
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pub(super) inline_start: AbsoluteBoxOffsets<LengthOrPercentage>,
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inline_size: LengthOrPercentageOrAuto,
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pub(super) block_start: AbsoluteBoxOffsets<LengthOrPercentage>,
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block_size: LengthOrPercentageOrAuto,
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}
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#[derive(Clone, Copy, Debug)]
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pub(super) enum AbsoluteBoxOffsets<NonStatic> {
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StaticStart { start: Length },
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Start { start: NonStatic },
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End { end: NonStatic },
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Both { start: NonStatic, end: NonStatic },
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}
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impl AbsolutelyPositionedBox {
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pub(super) fn layout<'a>(
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&'a self,
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initial_start_corner: Vec2<Length>,
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tree_rank: usize,
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) -> AbsolutelyPositionedFragment {
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let style = &self.style;
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let box_offsets = style.box_offsets();
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let box_size = style.box_size();
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let inline_size = box_size.inline;
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let block_size = box_size.block;
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fn absolute_box_offsets(
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initial_static_start: Length,
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start: LengthOrPercentageOrAuto,
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end: LengthOrPercentageOrAuto,
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) -> AbsoluteBoxOffsets<LengthOrPercentage> {
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match (start.non_auto(), end.non_auto()) {
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(None, None) => AbsoluteBoxOffsets::StaticStart {
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start: initial_static_start,
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},
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(Some(start), Some(end)) => AbsoluteBoxOffsets::Both { start, end },
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(None, Some(end)) => AbsoluteBoxOffsets::End { end },
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(Some(start), None) => AbsoluteBoxOffsets::Start { start },
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}
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}
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let inline_start = absolute_box_offsets(
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initial_start_corner.inline,
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box_offsets.inline_start,
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box_offsets.inline_end,
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);
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let block_start = absolute_box_offsets(
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initial_start_corner.block,
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box_offsets.block_start,
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box_offsets.block_end,
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);
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AbsolutelyPositionedFragment {
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absolutely_positioned_box: self,
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tree_rank,
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inline_start,
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inline_size,
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block_start,
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block_size,
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}
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}
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}
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impl<'a> AbsolutelyPositionedFragment<'a> {
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pub(super) fn in_positioned_containing_block(
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absolute: &[Self],
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fragments: &mut Vec<Fragment>,
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content_rect_size: &Vec2<Length>,
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padding: &Sides<Length>,
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mode: (WritingMode, Direction),
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) {
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if absolute.is_empty() {
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return;
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}
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let padding_rect = Rect {
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size: content_rect_size.clone(),
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// Ignore the content rect’s position in its own containing block:
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start_corner: Vec2::zero(),
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}
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.inflate(&padding);
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let containing_block = DefiniteContainingBlock {
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size: padding_rect.size.clone(),
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mode,
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};
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fragments.push(Fragment::Anonymous(AnonymousFragment {
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children: absolute
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.par_iter()
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.map(|a| a.layout(&containing_block))
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.collect(),
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rect: padding_rect,
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mode,
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}))
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}
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pub(super) fn layout(&self, containing_block: &DefiniteContainingBlock) -> Fragment {
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let style = &self.absolutely_positioned_box.style;
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let cbis = containing_block.size.inline;
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let cbbs = containing_block.size.block;
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let padding = style.padding().percentages_relative_to(cbis);
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let border = style.border_width().percentages_relative_to(cbis);
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let computed_margin = style.margin().percentages_relative_to(cbis);
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let pb = &padding + &border;
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enum Anchor {
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Start(Length),
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End(Length),
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}
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fn solve_axis(
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containing_size: Length,
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padding_border_sum: Length,
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computed_margin_start: LengthOrAuto,
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computed_margin_end: LengthOrAuto,
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solve_margins: impl FnOnce(Length) -> (Length, Length),
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box_offsets: AbsoluteBoxOffsets<LengthOrPercentage>,
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size: LengthOrPercentageOrAuto,
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) -> (Anchor, LengthOrAuto, Length, Length) {
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let size = size.percentage_relative_to(containing_size);
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match box_offsets {
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AbsoluteBoxOffsets::StaticStart { start } => (
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Anchor::Start(start),
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size,
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computed_margin_start.auto_is(Length::zero),
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computed_margin_end.auto_is(Length::zero),
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),
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AbsoluteBoxOffsets::Start { start } => (
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Anchor::Start(start.percentage_relative_to(containing_size)),
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size,
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computed_margin_start.auto_is(Length::zero),
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computed_margin_end.auto_is(Length::zero),
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),
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AbsoluteBoxOffsets::End { end } => (
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Anchor::End(end.percentage_relative_to(containing_size)),
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size,
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computed_margin_start.auto_is(Length::zero),
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computed_margin_end.auto_is(Length::zero),
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),
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AbsoluteBoxOffsets::Both { start, end } => {
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let start = start.percentage_relative_to(containing_size);
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let end = end.percentage_relative_to(containing_size);
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let mut margin_start = computed_margin_start.auto_is(Length::zero);
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let mut margin_end = computed_margin_end.auto_is(Length::zero);
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let size = if let LengthOrAuto::Length(size) = size {
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use LengthOrAuto::Auto;
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let margins = containing_size - start - end - padding_border_sum - size;
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match (computed_margin_start, computed_margin_end) {
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(Auto, Auto) => {
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let (s, e) = solve_margins(margins);
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margin_start = s;
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margin_end = e;
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}
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(Auto, LengthOrAuto::Length(end)) => {
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margin_start = margins - end;
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}
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(LengthOrAuto::Length(start), Auto) => {
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margin_end = margins - start;
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}
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(LengthOrAuto::Length(_), LengthOrAuto::Length(_)) => {}
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}
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size
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} else {
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// FIXME(nox): What happens if that is negative?
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containing_size
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- start
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- end
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- padding_border_sum
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- margin_start
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- margin_end
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};
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(
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Anchor::Start(start),
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LengthOrAuto::Length(size),
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margin_start,
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margin_end,
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)
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}
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}
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}
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let (inline_anchor, inline_size, margin_inline_start, margin_inline_end) = solve_axis(
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cbis,
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pb.inline_sum(),
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computed_margin.inline_start,
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computed_margin.inline_end,
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|margins| {
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if margins.px >= 0. {
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(margins / 2., margins / 2.)
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} else {
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(Length::zero(), margins)
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}
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},
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self.inline_start,
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self.inline_size,
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);
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let (block_anchor, block_size, margin_block_start, margin_block_end) = solve_axis(
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cbis,
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pb.block_sum(),
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computed_margin.block_start,
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computed_margin.block_end,
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|margins| (margins / 2., margins / 2.),
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self.block_start,
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self.block_size,
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);
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let margin = Sides {
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inline_start: margin_inline_start,
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inline_end: margin_inline_end,
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block_start: margin_block_start,
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block_end: margin_block_end,
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};
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let inline_size = inline_size.auto_is(|| {
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let available_size = match inline_anchor {
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Anchor::Start(start) => cbis - start - pb.inline_sum() - margin.inline_sum(),
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Anchor::End(end) => cbis - end - pb.inline_sum() - margin.inline_sum(),
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};
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// FIXME(nox): shrink-to-fit.
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available_size
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});
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let containing_block_for_children = ContainingBlock {
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inline_size,
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block_size,
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mode: style.writing_mode(),
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};
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// https://drafts.csswg.org/css-writing-modes/#orthogonal-flows
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assert_eq!(
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containing_block.mode, containing_block_for_children.mode,
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"Mixed writing modes are not supported yet"
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);
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let dummy_tree_rank = 0;
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let mut absolutely_positioned_fragments = vec![];
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let mut flow_children = self.absolutely_positioned_box.contents.layout(
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&containing_block_for_children,
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dummy_tree_rank,
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&mut absolutely_positioned_fragments,
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);
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let inline_start = match inline_anchor {
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Anchor::Start(start) => start + pb.inline_start + margin.inline_start,
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Anchor::End(end) => cbbs - end - pb.inline_end - margin.inline_end - inline_size,
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};
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let block_size = block_size.auto_is(|| flow_children.block_size);
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let block_start = match block_anchor {
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Anchor::Start(start) => start + pb.block_start + margin.block_start,
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Anchor::End(end) => cbbs - end - pb.block_end - margin.block_end - block_size,
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};
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let content_rect = Rect {
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start_corner: Vec2 {
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inline: inline_start,
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block: block_start,
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},
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size: Vec2 {
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inline: inline_size,
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block: block_size,
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},
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};
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AbsolutelyPositionedFragment::in_positioned_containing_block(
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&absolutely_positioned_fragments,
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&mut flow_children.fragments,
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&content_rect.size,
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&padding,
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containing_block_for_children.mode,
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);
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Fragment::Box(BoxFragment {
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style: style.clone(),
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children: flow_children.fragments,
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content_rect,
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padding,
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border,
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margin,
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block_margins_collapsed_with_children: CollapsedBlockMargins::zero(),
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})
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}
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}
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pub(super) fn adjust_static_positions(
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absolutely_positioned_fragments: &mut [AbsolutelyPositionedFragment],
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child_fragments: &mut [Fragment],
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tree_rank_in_parent: usize,
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) {
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for abspos_fragment in absolutely_positioned_fragments {
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let child_fragment_rect = match &child_fragments[abspos_fragment.tree_rank] {
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Fragment::Box(b) => &b.content_rect,
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Fragment::Anonymous(a) => &a.rect,
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_ => unreachable!(),
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};
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abspos_fragment.tree_rank = tree_rank_in_parent;
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if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.inline_start {
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*start += child_fragment_rect.start_corner.inline;
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}
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if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.block_start {
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*start += child_fragment_rect.start_corner.block;
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}
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}
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}
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