mirror of
https://github.com/servo/servo.git
synced 2025-06-12 18:34:39 +00:00
642 lines
24 KiB
Rust
642 lines
24 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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use crate::context::LayoutContext;
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use crate::dom_traversal::{Contents, NodeExt};
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use crate::formatting_contexts::IndependentFormattingContext;
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use crate::fragments::{AnonymousFragment, BoxFragment, CollapsedBlockMargins, Fragment};
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use crate::geom::flow_relative::{Rect, Sides, Vec2};
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use crate::sizing::ContentSizesRequest;
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use crate::style_ext::{ComputedValuesExt, DisplayInside};
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use crate::{ContainingBlock, DefiniteContainingBlock};
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use rayon::iter::{IntoParallelRefIterator, ParallelExtend};
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use rayon_croissant::ParallelIteratorExt;
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use servo_arc::Arc;
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use style::computed_values::position::T as Position;
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use style::properties::ComputedValues;
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use style::values::computed::{Length, LengthOrAuto, LengthPercentage, LengthPercentageOrAuto};
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use style::Zero;
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#[derive(Debug)]
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pub(crate) struct AbsolutelyPositionedBox {
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pub contents: IndependentFormattingContext,
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}
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pub(crate) struct PositioningContext<'box_tree> {
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for_nearest_positioned_ancestor: Option<Vec<HoistedAbsolutelyPositionedBox<'box_tree>>>,
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for_initial_containing_block: Vec<HoistedAbsolutelyPositionedBox<'box_tree>>,
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}
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#[derive(Debug)]
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pub(crate) struct HoistedAbsolutelyPositionedBox<'box_tree> {
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absolutely_positioned_box: &'box_tree 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(crate) tree_rank: usize,
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box_offsets: Vec2<AbsoluteBoxOffsets>,
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}
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#[derive(Clone, Copy, Debug)]
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pub(crate) enum AbsoluteBoxOffsets {
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StaticStart {
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start: Length,
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},
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Start {
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start: LengthPercentage,
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},
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End {
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end: LengthPercentage,
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},
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Both {
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start: LengthPercentage,
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end: LengthPercentage,
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},
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}
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impl AbsolutelyPositionedBox {
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pub fn construct<'dom>(
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context: &LayoutContext,
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style: Arc<ComputedValues>,
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display_inside: DisplayInside,
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contents: Contents<impl NodeExt<'dom>>,
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) -> Self {
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// "Shrink-to-fit" in https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-width
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let content_sizes = ContentSizesRequest::inline_if(
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// If inline-size is non-auto, that value is used without shrink-to-fit
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!style.inline_size_is_length() &&
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// If it is, then the only case where shrink-to-fit is *not* used is
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// if both offsets are non-auto, leaving inline-size as the only variable
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// in the constraint equation.
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!style.inline_box_offsets_are_both_non_auto(),
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);
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Self {
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contents: IndependentFormattingContext::construct(
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context,
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style,
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display_inside,
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contents,
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content_sizes,
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),
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}
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}
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pub(crate) fn layout(
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&self,
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initial_start_corner: Vec2<Length>,
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tree_rank: usize,
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) -> HoistedAbsolutelyPositionedBox {
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fn absolute_box_offsets(
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initial_static_start: Length,
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start: LengthPercentageOrAuto,
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end: LengthPercentageOrAuto,
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) -> AbsoluteBoxOffsets {
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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 box_offsets = self.contents.style.box_offsets();
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HoistedAbsolutelyPositionedBox {
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absolutely_positioned_box: self,
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tree_rank,
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box_offsets: Vec2 {
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inline: 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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block: 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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},
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}
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}
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}
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impl<'box_tree> PositioningContext<'box_tree> {
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pub(crate) fn new_for_initial_containing_block() -> Self {
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Self {
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for_nearest_positioned_ancestor: None,
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for_initial_containing_block: Vec::new(),
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}
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}
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pub(crate) fn new_for_rayon(has_positioned_ancestor: bool) -> Self {
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Self {
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for_nearest_positioned_ancestor: if has_positioned_ancestor {
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Some(Vec::new())
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} else {
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None
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},
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for_initial_containing_block: Vec::new(),
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}
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}
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pub(crate) fn has_positioned_ancestor(&self) -> bool {
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self.for_nearest_positioned_ancestor.is_some()
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}
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pub(crate) fn for_maybe_position_relative(
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&mut self,
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layout_context: &LayoutContext,
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containing_block: &ContainingBlock,
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style: &ComputedValues,
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f: impl FnOnce(&mut Self) -> BoxFragment,
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) -> BoxFragment {
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if style.clone_position() == Position::Relative {
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let mut fragment =
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// Establing a containing block for absolutely positioned descendants
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Self::for_positioned(layout_context, &mut self.for_initial_containing_block, f);
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fragment.content_rect.start_corner += &relative_adjustement(style, containing_block);
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fragment
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} else {
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f(self)
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}
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}
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fn for_positioned(
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layout_context: &LayoutContext,
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for_initial_containing_block: &mut Vec<HoistedAbsolutelyPositionedBox<'box_tree>>,
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f: impl FnOnce(&mut Self) -> BoxFragment,
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) -> BoxFragment {
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let mut new = Self {
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for_nearest_positioned_ancestor: Some(Vec::new()),
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for_initial_containing_block: std::mem::take(for_initial_containing_block),
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};
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let mut positioned_box_fragment = f(&mut new);
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new.layout_in_positioned_ancestor(layout_context, &mut positioned_box_fragment);
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*for_initial_containing_block = new.for_initial_containing_block;
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positioned_box_fragment
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}
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pub(crate) fn push(&mut self, box_: HoistedAbsolutelyPositionedBox<'box_tree>) {
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if let Some(nearest) = &mut self.for_nearest_positioned_ancestor {
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match box_
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.absolutely_positioned_box
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.contents
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.style
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.clone_position()
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{
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Position::Fixed => {}, // fall through
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Position::Absolute => return nearest.push(box_),
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Position::Static | Position::Relative => unreachable!(),
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}
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}
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self.for_initial_containing_block.push(box_)
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}
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pub(crate) fn append(&mut self, other: Self) {
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vec_append_owned(
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&mut self.for_initial_containing_block,
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other.for_initial_containing_block,
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);
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match (
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self.for_nearest_positioned_ancestor.as_mut(),
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other.for_nearest_positioned_ancestor,
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) {
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(Some(a), Some(b)) => vec_append_owned(a, b),
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(None, None) => {},
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_ => unreachable!(),
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}
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}
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pub(crate) fn adjust_static_positions(
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&mut self,
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tree_rank_in_parent: usize,
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f: impl FnOnce(&mut Self) -> Vec<Fragment>,
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) -> Vec<Fragment> {
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let for_icb_so_far = self.for_initial_containing_block.len();
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let for_nearest_so_far = self
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.for_nearest_positioned_ancestor
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.as_ref()
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.map(|v| v.len());
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let fragments = f(self);
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adjust_static_positions(
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&mut self.for_initial_containing_block[for_icb_so_far..],
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&fragments,
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tree_rank_in_parent,
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);
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if let Some(nearest) = &mut self.for_nearest_positioned_ancestor {
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adjust_static_positions(
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&mut nearest[for_nearest_so_far.unwrap()..],
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&fragments,
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tree_rank_in_parent,
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);
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}
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fragments
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}
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pub(crate) fn layout_in_initial_containing_block(
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&mut self,
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layout_context: &LayoutContext,
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initial_containing_block: &DefiniteContainingBlock,
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fragments: &mut Vec<Fragment>,
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) {
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debug_assert!(self.for_nearest_positioned_ancestor.is_none());
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// Loop because it’s possible that we discover (the static position of)
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// more absolutely-positioned boxes while doing layout for others.
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while !self.for_initial_containing_block.is_empty() {
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HoistedAbsolutelyPositionedBox::layout_many(
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layout_context,
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&std::mem::take(&mut self.for_initial_containing_block),
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fragments,
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&mut self.for_initial_containing_block,
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initial_containing_block,
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)
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}
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}
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fn layout_in_positioned_ancestor(
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&mut self,
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layout_context: &LayoutContext,
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positioned_box_fragment: &mut BoxFragment,
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) {
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let for_here = self.for_nearest_positioned_ancestor.take().unwrap();
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if !for_here.is_empty() {
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let padding_rect = Rect {
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size: positioned_box_fragment.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(&positioned_box_fragment.padding);
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let containing_block = DefiniteContainingBlock {
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size: padding_rect.size.clone(),
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style: &positioned_box_fragment.style,
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};
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let mut children = Vec::new();
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HoistedAbsolutelyPositionedBox::layout_many(
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layout_context,
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&for_here,
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&mut children,
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&mut self.for_initial_containing_block,
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&containing_block,
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);
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positioned_box_fragment
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.children
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.push(Fragment::Anonymous(AnonymousFragment {
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children,
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rect: padding_rect,
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mode: positioned_box_fragment.style.writing_mode,
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}))
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}
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}
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}
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impl<'box_tree> HoistedAbsolutelyPositionedBox<'box_tree> {
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pub(crate) fn layout_many(
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layout_context: &LayoutContext,
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boxes: &[Self],
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fragments: &mut Vec<Fragment>,
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for_initial_containing_block: &mut Vec<HoistedAbsolutelyPositionedBox<'box_tree>>,
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containing_block: &DefiniteContainingBlock,
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) {
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if layout_context.use_rayon {
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fragments.par_extend(boxes.par_iter().mapfold_reduce_into(
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for_initial_containing_block,
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|for_initial_containing_block, box_| {
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Fragment::Box(box_.layout(
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layout_context,
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for_initial_containing_block,
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containing_block,
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))
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},
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Vec::new,
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vec_append_owned,
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))
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} else {
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fragments.extend(boxes.iter().map(|box_| {
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Fragment::Box(box_.layout(
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layout_context,
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for_initial_containing_block,
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containing_block,
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))
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}))
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}
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}
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pub(crate) fn layout(
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&self,
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layout_context: &LayoutContext,
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for_initial_containing_block: &mut Vec<HoistedAbsolutelyPositionedBox<'box_tree>>,
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containing_block: &DefiniteContainingBlock,
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) -> BoxFragment {
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let style = &self.absolutely_positioned_box.contents.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 size;
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let replaced_used_size;
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match self.absolutely_positioned_box.contents.as_replaced() {
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Ok(replaced) => {
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// https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
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// https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
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let u = replaced.used_size_as_if_inline_element(&containing_block.into(), style);
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size = Vec2 {
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inline: LengthOrAuto::LengthPercentage(u.inline),
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block: LengthOrAuto::LengthPercentage(u.block),
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};
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replaced_used_size = Some(u);
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},
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Err(_non_replaced) => {
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let box_size = style.box_size();
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size = Vec2 {
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inline: box_size.inline.percentage_relative_to(cbis),
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block: box_size.block.percentage_relative_to(cbbs),
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};
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replaced_used_size = None;
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},
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}
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let padding = style.padding().percentages_relative_to(cbis);
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let border = style.border_width();
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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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let inline_axis = 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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/* avoid_negative_margin_start */ true,
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self.box_offsets.inline,
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size.inline,
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);
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let block_axis = 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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/* avoid_negative_margin_start */ false,
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self.box_offsets.block,
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size.block,
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);
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let margin = Sides {
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inline_start: inline_axis.margin_start,
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inline_end: inline_axis.margin_end,
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block_start: block_axis.margin_start,
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block_end: block_axis.margin_end,
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};
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let for_icb = for_initial_containing_block;
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PositioningContext::for_positioned(layout_context, for_icb, |positioning_context| {
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let size;
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let fragments;
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match self.absolutely_positioned_box.contents.as_replaced() {
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Ok(replaced) => {
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// https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
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// https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
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let style = &self.absolutely_positioned_box.contents.style;
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size = replaced_used_size.unwrap();
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fragments = replaced.make_fragments(style, size.clone());
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},
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Err(non_replaced) => {
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// https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-width
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// https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-height
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let inline_size = inline_axis.size.auto_is(|| {
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let available_size = match inline_axis.anchor {
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Anchor::Start(start) => {
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cbis - start - pb.inline_sum() - margin.inline_sum()
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},
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Anchor::End(end) => cbis - end - pb.inline_sum() - margin.inline_sum(),
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};
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self.absolutely_positioned_box
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.contents
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.content_sizes
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.shrink_to_fit(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: block_axis.size,
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style,
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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.style.writing_mode,
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containing_block_for_children.style.writing_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 independent_layout = non_replaced.layout(
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layout_context,
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positioning_context,
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&containing_block_for_children,
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dummy_tree_rank,
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);
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size = Vec2 {
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inline: inline_size,
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block: block_axis
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.size
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.auto_is(|| independent_layout.content_block_size),
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};
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fragments = independent_layout.fragments
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},
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};
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let inline_start = match inline_axis.anchor {
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Anchor::Start(start) => start + pb.inline_start + margin.inline_start,
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Anchor::End(end) => cbis - end - pb.inline_end - margin.inline_end - size.inline,
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};
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let block_start = match block_axis.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 - size.block,
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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,
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};
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BoxFragment {
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style: style.clone(),
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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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}
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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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struct AxisResult {
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anchor: Anchor,
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size: LengthOrAuto,
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margin_start: Length,
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margin_end: Length,
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}
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|
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/// This unifies some of the parts in common in:
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///
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/// * https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-width
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/// * https://drafts.csswg.org/css2/visudet.html#abs-non-replaced-height
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///
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/// … and:
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///
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/// * https://drafts.csswg.org/css2/visudet.html#abs-replaced-width
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/// * https://drafts.csswg.org/css2/visudet.html#abs-replaced-height
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///
|
||
/// In the replaced case, `size` is never `Auto`.
|
||
fn solve_axis(
|
||
containing_size: Length,
|
||
padding_border_sum: Length,
|
||
computed_margin_start: LengthOrAuto,
|
||
computed_margin_end: LengthOrAuto,
|
||
avoid_negative_margin_start: bool,
|
||
box_offsets: AbsoluteBoxOffsets,
|
||
size: LengthOrAuto,
|
||
) -> AxisResult {
|
||
match box_offsets {
|
||
AbsoluteBoxOffsets::StaticStart { start } => AxisResult {
|
||
anchor: Anchor::Start(start),
|
||
size,
|
||
margin_start: computed_margin_start.auto_is(Length::zero),
|
||
margin_end: computed_margin_end.auto_is(Length::zero),
|
||
},
|
||
AbsoluteBoxOffsets::Start { start } => AxisResult {
|
||
anchor: Anchor::Start(start.percentage_relative_to(containing_size)),
|
||
size,
|
||
margin_start: computed_margin_start.auto_is(Length::zero),
|
||
margin_end: computed_margin_end.auto_is(Length::zero),
|
||
},
|
||
AbsoluteBoxOffsets::End { end } => AxisResult {
|
||
anchor: Anchor::End(end.percentage_relative_to(containing_size)),
|
||
size,
|
||
margin_start: computed_margin_start.auto_is(Length::zero),
|
||
margin_end: computed_margin_end.auto_is(Length::zero),
|
||
},
|
||
AbsoluteBoxOffsets::Both { start, end } => {
|
||
let start = start.percentage_relative_to(containing_size);
|
||
let end = end.percentage_relative_to(containing_size);
|
||
|
||
let margin_start;
|
||
let margin_end;
|
||
let used_size;
|
||
if let LengthOrAuto::LengthPercentage(s) = size {
|
||
used_size = s;
|
||
let margins = containing_size - start - end - padding_border_sum - s;
|
||
match (computed_margin_start, computed_margin_end) {
|
||
(LengthOrAuto::Auto, LengthOrAuto::Auto) => {
|
||
if avoid_negative_margin_start && margins < Length::zero() {
|
||
margin_start = Length::zero();
|
||
margin_end = margins;
|
||
} else {
|
||
margin_start = margins / 2.;
|
||
margin_end = margins / 2.;
|
||
}
|
||
},
|
||
(LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => {
|
||
margin_start = margins - end;
|
||
margin_end = end;
|
||
},
|
||
(LengthOrAuto::LengthPercentage(start), LengthOrAuto::Auto) => {
|
||
margin_start = start;
|
||
margin_end = margins - start;
|
||
},
|
||
(
|
||
LengthOrAuto::LengthPercentage(start),
|
||
LengthOrAuto::LengthPercentage(end),
|
||
) => {
|
||
margin_start = start;
|
||
margin_end = end;
|
||
},
|
||
}
|
||
} else {
|
||
margin_start = computed_margin_start.auto_is(Length::zero);
|
||
margin_end = computed_margin_end.auto_is(Length::zero);
|
||
// FIXME(nox): What happens if that is negative?
|
||
used_size =
|
||
containing_size - start - end - padding_border_sum - margin_start - margin_end
|
||
};
|
||
AxisResult {
|
||
anchor: Anchor::Start(start),
|
||
size: LengthOrAuto::LengthPercentage(used_size),
|
||
margin_start,
|
||
margin_end,
|
||
}
|
||
},
|
||
}
|
||
}
|
||
|
||
fn adjust_static_positions(
|
||
absolutely_positioned_fragments: &mut [HoistedAbsolutelyPositionedBox],
|
||
child_fragments: &[Fragment],
|
||
tree_rank_in_parent: usize,
|
||
) {
|
||
for abspos_fragment in absolutely_positioned_fragments {
|
||
let child_fragment_rect = match &child_fragments[abspos_fragment.tree_rank] {
|
||
Fragment::Box(b) => &b.content_rect,
|
||
Fragment::Anonymous(a) => &a.rect,
|
||
_ => unreachable!(),
|
||
};
|
||
|
||
abspos_fragment.tree_rank = tree_rank_in_parent;
|
||
|
||
if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.box_offsets.inline {
|
||
*start += child_fragment_rect.start_corner.inline;
|
||
}
|
||
|
||
if let AbsoluteBoxOffsets::StaticStart { start } = &mut abspos_fragment.box_offsets.block {
|
||
*start += child_fragment_rect.start_corner.block;
|
||
}
|
||
}
|
||
}
|
||
|
||
fn vec_append_owned<T>(a: &mut Vec<T>, mut b: Vec<T>) {
|
||
if a.is_empty() {
|
||
*a = b
|
||
} else {
|
||
a.append(&mut b)
|
||
}
|
||
}
|
||
|
||
/// https://drafts.csswg.org/css2/visuren.html#relative-positioning
|
||
pub(crate) fn relative_adjustement(
|
||
style: &ComputedValues,
|
||
containing_block: &ContainingBlock,
|
||
) -> Vec2<Length> {
|
||
let cbis = containing_block.inline_size;
|
||
let cbbs = containing_block.block_size.auto_is(Length::zero);
|
||
let box_offsets = style.box_offsets().map_inline_and_block_axes(
|
||
|v| v.percentage_relative_to(cbis),
|
||
|v| v.percentage_relative_to(cbbs),
|
||
);
|
||
fn adjust(start: LengthOrAuto, end: LengthOrAuto) -> Length {
|
||
match (start, end) {
|
||
(LengthOrAuto::Auto, LengthOrAuto::Auto) => Length::zero(),
|
||
(LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => -end,
|
||
(LengthOrAuto::LengthPercentage(start), _) => start,
|
||
}
|
||
}
|
||
Vec2 {
|
||
inline: adjust(box_offsets.inline_start, box_offsets.inline_end),
|
||
block: adjust(box_offsets.block_start, box_offsets.block_end),
|
||
}
|
||
}
|