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66c4eee082
This improves #29874, but BlockContainer::inline_content_sizes will still need more changes in order to correctly handle sequences of floats.
827 lines
33 KiB
Rust
827 lines
33 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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//! Flow layout, also known as block-and-inline layout.
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use std::ops::DerefMut;
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use crate::cell::ArcRefCell;
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use crate::context::LayoutContext;
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use crate::flow::float::{ClearSide, ContainingBlockPositionInfo, FloatBox, SequentialLayoutState};
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use crate::flow::inline::InlineFormattingContext;
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use crate::formatting_contexts::{
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IndependentFormattingContext, IndependentLayout, NonReplacedFormattingContext,
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};
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use crate::fragment_tree::{
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BaseFragmentInfo, BoxFragment, CollapsedBlockMargins, CollapsedMargin, Fragment,
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};
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use crate::geom::flow_relative::{Rect, Sides, Vec2};
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use crate::positioned::{AbsolutelyPositionedBox, PositioningContext};
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use crate::replaced::ReplacedContent;
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use crate::sizing::{self, ContentSizes};
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use crate::style_ext::{ComputedValuesExt, PaddingBorderMargin};
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use crate::ContainingBlock;
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use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};
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use rayon_croissant::ParallelIteratorExt;
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use servo_arc::Arc;
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use style::logical_geometry::WritingMode;
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use style::properties::ComputedValues;
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use style::values::computed::{Length, LengthOrAuto};
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use style::Zero;
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mod construct;
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pub mod float;
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pub mod inline;
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mod root;
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pub use root::{BoxTree, CanvasBackground};
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#[derive(Debug, Serialize)]
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pub(crate) struct BlockFormattingContext {
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pub contents: BlockContainer,
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pub contains_floats: bool,
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}
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#[derive(Debug, Serialize)]
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pub(crate) enum BlockContainer {
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BlockLevelBoxes(Vec<ArcRefCell<BlockLevelBox>>),
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InlineFormattingContext(InlineFormattingContext),
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}
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#[derive(Debug, Serialize)]
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pub(crate) enum BlockLevelBox {
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SameFormattingContextBlock {
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base_fragment_info: BaseFragmentInfo,
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#[serde(skip_serializing)]
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style: Arc<ComputedValues>,
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contents: BlockContainer,
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},
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OutOfFlowAbsolutelyPositionedBox(ArcRefCell<AbsolutelyPositionedBox>),
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OutOfFlowFloatBox(FloatBox),
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Independent(IndependentFormattingContext),
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}
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struct FlowLayout {
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pub fragments: Vec<Fragment>,
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pub content_block_size: Length,
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pub collapsible_margins_in_children: CollapsedBlockMargins,
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}
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#[derive(Clone, Copy)]
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struct CollapsibleWithParentStartMargin(bool);
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impl BlockFormattingContext {
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pub(super) fn layout(
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&self,
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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containing_block: &ContainingBlock,
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tree_rank: usize,
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) -> IndependentLayout {
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let mut sequential_layout_state = if self.contains_floats || !layout_context.use_rayon {
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Some(SequentialLayoutState::new())
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} else {
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None
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};
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let flow_layout = self.contents.layout(
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layout_context,
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positioning_context,
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containing_block,
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tree_rank,
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sequential_layout_state.as_mut(),
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CollapsibleWithParentStartMargin(false),
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);
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debug_assert!(
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!flow_layout
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.collapsible_margins_in_children
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.collapsed_through
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);
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IndependentLayout {
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fragments: flow_layout.fragments,
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content_block_size: flow_layout.content_block_size +
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flow_layout.collapsible_margins_in_children.end.solve(),
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}
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}
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}
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impl BlockContainer {
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fn layout(
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&self,
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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containing_block: &ContainingBlock,
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tree_rank: usize,
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sequential_layout_state: Option<&mut SequentialLayoutState>,
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collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
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) -> FlowLayout {
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match self {
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BlockContainer::BlockLevelBoxes(child_boxes) => layout_block_level_children(
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layout_context,
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positioning_context,
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child_boxes,
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containing_block,
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tree_rank,
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sequential_layout_state,
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collapsible_with_parent_start_margin,
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),
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BlockContainer::InlineFormattingContext(ifc) => ifc.layout(
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layout_context,
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positioning_context,
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containing_block,
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tree_rank,
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sequential_layout_state,
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),
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}
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}
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pub(super) fn inline_content_sizes(
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&self,
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layout_context: &LayoutContext,
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writing_mode: WritingMode,
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) -> ContentSizes {
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match &self {
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Self::BlockLevelBoxes(boxes) if layout_context.use_rayon => boxes
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.par_iter()
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.map(|box_| {
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box_.borrow_mut()
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.inline_content_sizes(layout_context, writing_mode)
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})
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.reduce(ContentSizes::zero, ContentSizes::max),
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Self::BlockLevelBoxes(boxes) => boxes
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.iter()
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.map(|box_| {
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box_.borrow_mut()
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.inline_content_sizes(layout_context, writing_mode)
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})
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.reduce(ContentSizes::max)
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.unwrap_or_else(ContentSizes::zero),
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Self::InlineFormattingContext(context) => {
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context.inline_content_sizes(layout_context, writing_mode)
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},
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}
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}
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}
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fn layout_block_level_children(
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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child_boxes: &[ArcRefCell<BlockLevelBox>],
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containing_block: &ContainingBlock,
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tree_rank: usize,
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mut sequential_layout_state: Option<&mut SequentialLayoutState>,
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collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
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) -> FlowLayout {
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match sequential_layout_state {
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Some(ref mut sequential_layout_state) => layout_block_level_children_sequentially(
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layout_context,
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positioning_context,
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child_boxes,
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containing_block,
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tree_rank,
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sequential_layout_state,
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collapsible_with_parent_start_margin,
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),
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None => layout_block_level_children_in_parallel(
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layout_context,
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positioning_context,
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child_boxes,
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containing_block,
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tree_rank,
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collapsible_with_parent_start_margin,
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),
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}
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}
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fn layout_block_level_children_in_parallel(
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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child_boxes: &[ArcRefCell<BlockLevelBox>],
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containing_block: &ContainingBlock,
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tree_rank: usize,
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collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
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) -> FlowLayout {
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let mut placement_state = PlacementState::new(collapsible_with_parent_start_margin);
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let fragments = positioning_context.adjust_static_positions(tree_rank, |positioning_context| {
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let collects_for_nearest_positioned_ancestor =
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positioning_context.collects_for_nearest_positioned_ancestor();
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let mut fragments: Vec<Fragment> = child_boxes
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.par_iter()
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.enumerate()
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.mapfold_reduce_into(
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positioning_context,
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|positioning_context, (tree_rank, box_)| {
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box_.borrow_mut().layout(
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layout_context,
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positioning_context,
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containing_block,
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tree_rank,
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/* sequential_layout_state = */ None,
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)
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},
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|| PositioningContext::new_for_rayon(collects_for_nearest_positioned_ancestor),
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PositioningContext::append,
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)
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.collect();
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for fragment in fragments.iter_mut() {
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placement_state.place_fragment(fragment);
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}
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fragments
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});
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FlowLayout {
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fragments,
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content_block_size: placement_state.current_block_direction_position,
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collapsible_margins_in_children: placement_state.collapsible_margins_in_children(),
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}
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}
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fn layout_block_level_children_sequentially(
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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child_boxes: &[ArcRefCell<BlockLevelBox>],
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containing_block: &ContainingBlock,
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tree_rank: usize,
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sequential_layout_state: &mut SequentialLayoutState,
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collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
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) -> FlowLayout {
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let mut placement_state = PlacementState::new(collapsible_with_parent_start_margin);
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let fragments = positioning_context.adjust_static_positions(tree_rank, |positioning_context| {
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// Because floats are involved, we do layout for this block formatting context in tree
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// order without parallelism. This enables mutable access to a `SequentialLayoutState` that
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// tracks every float encountered so far (again in tree order).
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child_boxes
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.iter()
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.enumerate()
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.map(|(tree_rank, child_box)| {
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let mut fragment = child_box.borrow_mut().layout(
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layout_context,
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positioning_context,
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containing_block,
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tree_rank,
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Some(&mut *sequential_layout_state),
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);
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placement_state.place_fragment(&mut fragment);
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placement_state
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.adjust_positions_of_float_children(&mut fragment, sequential_layout_state);
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fragment
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})
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.collect()
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});
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FlowLayout {
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fragments,
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content_block_size: placement_state.current_block_direction_position,
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collapsible_margins_in_children: placement_state.collapsible_margins_in_children(),
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}
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}
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impl BlockLevelBox {
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fn layout(
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&mut self,
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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containing_block: &ContainingBlock,
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tree_rank: usize,
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sequential_layout_state: Option<&mut SequentialLayoutState>,
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) -> Fragment {
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match self {
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BlockLevelBox::SameFormattingContextBlock {
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base_fragment_info: tag,
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style,
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contents,
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} => Fragment::Box(positioning_context.layout_maybe_position_relative_fragment(
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layout_context,
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containing_block,
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style,
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|positioning_context| {
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layout_in_flow_non_replaced_block_level(
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layout_context,
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positioning_context,
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containing_block,
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*tag,
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style,
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NonReplacedContents::SameFormattingContextBlock(contents),
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tree_rank,
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sequential_layout_state,
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)
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},
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)),
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BlockLevelBox::Independent(independent) => match independent {
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IndependentFormattingContext::Replaced(replaced) => {
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Fragment::Box(positioning_context.layout_maybe_position_relative_fragment(
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layout_context,
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containing_block,
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&replaced.style,
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|_positioning_context| {
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layout_in_flow_replaced_block_level(
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containing_block,
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replaced.base_fragment_info,
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&replaced.style,
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&replaced.contents,
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sequential_layout_state,
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)
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},
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))
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},
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IndependentFormattingContext::NonReplaced(non_replaced) => {
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Fragment::Box(positioning_context.layout_maybe_position_relative_fragment(
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layout_context,
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containing_block,
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&non_replaced.style,
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|positioning_context| {
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layout_in_flow_non_replaced_block_level(
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layout_context,
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positioning_context,
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containing_block,
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non_replaced.base_fragment_info,
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&non_replaced.style,
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NonReplacedContents::EstablishesAnIndependentFormattingContext(
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non_replaced,
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),
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tree_rank,
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sequential_layout_state,
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)
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},
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))
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},
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},
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BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(box_) => {
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let hoisted_box = AbsolutelyPositionedBox::to_hoisted(
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box_.clone(),
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// This is incorrect, however we do not know the
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// correct positioning until later, in place_block_level_fragment,
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// and this value will be adjusted there
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Vec2::zero(),
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tree_rank,
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containing_block,
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);
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let hoisted_fragment = hoisted_box.fragment.clone();
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positioning_context.push(hoisted_box);
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Fragment::AbsoluteOrFixedPositioned(hoisted_fragment)
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},
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BlockLevelBox::OutOfFlowFloatBox(box_) => box_.layout(
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layout_context,
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positioning_context,
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containing_block,
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sequential_layout_state,
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),
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}
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}
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fn inline_content_sizes(
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&mut self,
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layout_context: &LayoutContext,
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containing_block_writing_mode: WritingMode,
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) -> ContentSizes {
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match self {
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Self::SameFormattingContextBlock {
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style, contents, ..
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} => sizing::outer_inline(style, containing_block_writing_mode, || {
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contents.inline_content_sizes(layout_context, style.writing_mode)
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}),
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Self::Independent(independent) => independent
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.outer_inline_content_sizes(layout_context, containing_block_writing_mode),
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BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(_) => ContentSizes::zero(),
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BlockLevelBox::OutOfFlowFloatBox(float_box) => float_box
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.contents
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.outer_inline_content_sizes(layout_context, containing_block_writing_mode),
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}
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}
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}
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enum NonReplacedContents<'a> {
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SameFormattingContextBlock(&'a BlockContainer),
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EstablishesAnIndependentFormattingContext(&'a NonReplacedFormattingContext),
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}
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/// https://drafts.csswg.org/css2/visudet.html#blockwidth
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/// https://drafts.csswg.org/css2/visudet.html#normal-block
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fn layout_in_flow_non_replaced_block_level(
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layout_context: &LayoutContext,
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positioning_context: &mut PositioningContext,
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containing_block: &ContainingBlock,
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base_fragment_info: BaseFragmentInfo,
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style: &Arc<ComputedValues>,
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block_level_kind: NonReplacedContents,
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tree_rank: usize,
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mut sequential_layout_state: Option<&mut SequentialLayoutState>,
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) -> BoxFragment {
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let pbm = style.padding_border_margin(containing_block);
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let box_size = style.content_box_size(containing_block, &pbm);
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let max_box_size = style.content_max_box_size(containing_block, &pbm);
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let min_box_size = style
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.content_min_box_size(containing_block, &pbm)
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.auto_is(Length::zero);
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// https://drafts.csswg.org/css2/visudet.html#min-max-widths
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let solve_inline_margins = |inline_size| {
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solve_inline_margins_for_in_flow_block_level(containing_block, &pbm, inline_size)
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};
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let (mut inline_size, mut inline_margins) =
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if let Some(inline_size) = box_size.inline.non_auto() {
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(inline_size, solve_inline_margins(inline_size))
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} else {
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let margin_inline_start = pbm.margin.inline_start.auto_is(Length::zero);
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let margin_inline_end = pbm.margin.inline_end.auto_is(Length::zero);
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let inline_size = containing_block.inline_size -
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pbm.padding_border_sums.inline -
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margin_inline_start -
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margin_inline_end;
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(inline_size, (margin_inline_start, margin_inline_end))
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};
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if let Some(max_inline_size) = max_box_size.inline {
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if inline_size > max_inline_size {
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inline_size = max_inline_size;
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inline_margins = solve_inline_margins(inline_size);
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}
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}
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if inline_size < min_box_size.inline {
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inline_size = min_box_size.inline;
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inline_margins = solve_inline_margins(inline_size);
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}
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let margin = Sides {
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inline_start: inline_margins.0,
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inline_end: inline_margins.1,
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block_start: pbm.margin.block_start.auto_is(Length::zero),
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block_end: pbm.margin.block_end.auto_is(Length::zero),
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};
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|
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// https://drafts.csswg.org/css2/visudet.html#min-max-heights
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let mut block_size = box_size.block;
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if let LengthOrAuto::LengthPercentage(ref mut block_size) = block_size {
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*block_size = block_size.clamp_between_extremums(min_box_size.block, max_box_size.block);
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}
|
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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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style,
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};
|
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|
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// https://drafts.csswg.org/css-writing-modes/#orthogonal-flows
|
|
assert_eq!(
|
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containing_block.style.writing_mode, 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 block_is_same_formatting_context = match block_level_kind {
|
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NonReplacedContents::SameFormattingContextBlock(_) => true,
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NonReplacedContents::EstablishesAnIndependentFormattingContext(_) => false,
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};
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|
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let start_margin_can_collapse_with_children = block_is_same_formatting_context &&
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pbm.padding.block_start == Length::zero() &&
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pbm.border.block_start == Length::zero();
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let end_margin_can_collapse_with_children = block_is_same_formatting_context &&
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pbm.padding.block_end == Length::zero() &&
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pbm.border.block_end == Length::zero() &&
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block_size == LengthOrAuto::Auto;
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|
|
let mut clearance = Length::zero();
|
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let parent_containing_block_position_info;
|
|
match sequential_layout_state {
|
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None => parent_containing_block_position_info = None,
|
|
Some(ref mut sequential_layout_state) => {
|
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sequential_layout_state.adjoin_assign(&CollapsedMargin::new(margin.block_start));
|
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if !start_margin_can_collapse_with_children {
|
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sequential_layout_state.collapse_margins();
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}
|
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|
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// Introduce clearance if necessary.
|
|
let clear_side = ClearSide::from_style(style);
|
|
clearance = sequential_layout_state.calculate_clearance(clear_side);
|
|
|
|
// NB: This will be a no-op if we're collapsing margins with our children since that
|
|
// can only happen if we have no block-start padding and border.
|
|
sequential_layout_state.advance_block_position(
|
|
pbm.padding.block_start + pbm.border.block_start + clearance,
|
|
);
|
|
|
|
// We are about to lay out children. Update the offset between the block formatting
|
|
// context and the containing block that we create for them. This offset is used to
|
|
// ajust BFC relative coordinates to coordinates that are relative to our content box.
|
|
// Our content box establishes the containing block for non-abspos children, including
|
|
// floats.
|
|
let inline_start = sequential_layout_state
|
|
.floats
|
|
.containing_block_info
|
|
.inline_start +
|
|
pbm.padding.inline_start +
|
|
pbm.border.inline_start +
|
|
margin.inline_start;
|
|
let new_cb_offsets = ContainingBlockPositionInfo {
|
|
block_start: sequential_layout_state.bfc_relative_block_position,
|
|
block_start_margins_not_collapsed: sequential_layout_state.current_margin,
|
|
inline_start,
|
|
inline_end: inline_start + inline_size,
|
|
};
|
|
parent_containing_block_position_info =
|
|
Some(sequential_layout_state.update_all_containing_block_offsets(new_cb_offsets));
|
|
},
|
|
};
|
|
|
|
let mut block_margins_collapsed_with_children = CollapsedBlockMargins::from_margin(&margin);
|
|
|
|
let fragments;
|
|
let mut content_block_size;
|
|
match block_level_kind {
|
|
NonReplacedContents::SameFormattingContextBlock(contents) => {
|
|
let flow_layout = contents.layout(
|
|
layout_context,
|
|
positioning_context,
|
|
&containing_block_for_children,
|
|
tree_rank,
|
|
sequential_layout_state.as_mut().map(|x| &mut **x),
|
|
CollapsibleWithParentStartMargin(start_margin_can_collapse_with_children),
|
|
);
|
|
|
|
fragments = flow_layout.fragments;
|
|
content_block_size = flow_layout.content_block_size;
|
|
|
|
// Update margins.
|
|
let mut collapsible_margins_in_children = flow_layout.collapsible_margins_in_children;
|
|
if start_margin_can_collapse_with_children {
|
|
block_margins_collapsed_with_children
|
|
.start
|
|
.adjoin_assign(&collapsible_margins_in_children.start);
|
|
if collapsible_margins_in_children.collapsed_through {
|
|
block_margins_collapsed_with_children
|
|
.start
|
|
.adjoin_assign(&std::mem::replace(
|
|
&mut collapsible_margins_in_children.end,
|
|
CollapsedMargin::zero(),
|
|
));
|
|
}
|
|
}
|
|
if end_margin_can_collapse_with_children {
|
|
block_margins_collapsed_with_children
|
|
.end
|
|
.adjoin_assign(&collapsible_margins_in_children.end);
|
|
} else {
|
|
content_block_size += collapsible_margins_in_children.end.solve();
|
|
}
|
|
block_margins_collapsed_with_children.collapsed_through =
|
|
collapsible_margins_in_children.collapsed_through &&
|
|
block_is_same_formatting_context &&
|
|
pbm.padding_border_sums.block == Length::zero() &&
|
|
block_size.auto_is(|| Length::zero()) == Length::zero() &&
|
|
min_box_size.block == Length::zero();
|
|
},
|
|
NonReplacedContents::EstablishesAnIndependentFormattingContext(non_replaced) => {
|
|
let independent_layout = non_replaced.layout(
|
|
layout_context,
|
|
positioning_context,
|
|
&containing_block_for_children,
|
|
tree_rank,
|
|
);
|
|
fragments = independent_layout.fragments;
|
|
content_block_size = independent_layout.content_block_size;
|
|
},
|
|
};
|
|
|
|
let block_size = block_size.auto_is(|| {
|
|
content_block_size.clamp_between_extremums(min_box_size.block, max_box_size.block)
|
|
});
|
|
|
|
if let Some(ref mut sequential_layout_state) = sequential_layout_state {
|
|
// Now that we're done laying out our children, we can restore the
|
|
// parent's containing block position information.
|
|
sequential_layout_state
|
|
.update_all_containing_block_offsets(parent_containing_block_position_info.unwrap());
|
|
|
|
// Account for padding and border. We also might have to readjust the
|
|
// `bfc_relative_block_position` if it was different from the content size (i.e. was
|
|
// non-`auto` and/or was affected by min/max block size).
|
|
sequential_layout_state.advance_block_position(
|
|
(block_size - content_block_size) + pbm.padding.block_end + pbm.border.block_end,
|
|
);
|
|
|
|
if !end_margin_can_collapse_with_children {
|
|
sequential_layout_state.collapse_margins();
|
|
}
|
|
sequential_layout_state.adjoin_assign(&CollapsedMargin::new(margin.block_end));
|
|
}
|
|
|
|
let content_rect = Rect {
|
|
start_corner: Vec2 {
|
|
block: pbm.padding.block_start + pbm.border.block_start + clearance,
|
|
inline: pbm.padding.inline_start + pbm.border.inline_start + margin.inline_start,
|
|
},
|
|
size: Vec2 {
|
|
block: block_size,
|
|
inline: inline_size,
|
|
},
|
|
};
|
|
|
|
BoxFragment::new(
|
|
base_fragment_info,
|
|
style.clone(),
|
|
fragments,
|
|
content_rect,
|
|
pbm.padding,
|
|
pbm.border,
|
|
margin,
|
|
clearance,
|
|
block_margins_collapsed_with_children,
|
|
)
|
|
}
|
|
|
|
/// https://drafts.csswg.org/css2/visudet.html#block-replaced-width
|
|
/// https://drafts.csswg.org/css2/visudet.html#inline-replaced-width
|
|
/// https://drafts.csswg.org/css2/visudet.html#inline-replaced-height
|
|
fn layout_in_flow_replaced_block_level<'a>(
|
|
containing_block: &ContainingBlock,
|
|
base_fragment_info: BaseFragmentInfo,
|
|
style: &Arc<ComputedValues>,
|
|
replaced: &ReplacedContent,
|
|
mut sequential_layout_state: Option<&mut SequentialLayoutState>,
|
|
) -> BoxFragment {
|
|
let pbm = style.padding_border_margin(containing_block);
|
|
let size = replaced.used_size_as_if_inline_element(containing_block, style, None, &pbm);
|
|
|
|
let (margin_inline_start, margin_inline_end) =
|
|
solve_inline_margins_for_in_flow_block_level(containing_block, &pbm, size.inline);
|
|
let margin = Sides {
|
|
inline_start: margin_inline_start,
|
|
inline_end: margin_inline_end,
|
|
block_start: pbm.margin.block_start.auto_is(Length::zero),
|
|
block_end: pbm.margin.block_end.auto_is(Length::zero),
|
|
};
|
|
let fragments = replaced.make_fragments(style, size.clone());
|
|
|
|
let mut clearance = Length::zero();
|
|
if let Some(ref mut sequential_layout_state) = sequential_layout_state {
|
|
sequential_layout_state.collapse_margins();
|
|
clearance = sequential_layout_state.calculate_clearance(ClearSide::from_style(style));
|
|
sequential_layout_state
|
|
.advance_block_position(pbm.border.block_sum() + pbm.padding.block_sum() + size.block);
|
|
};
|
|
|
|
let content_rect = Rect {
|
|
start_corner: Vec2 {
|
|
block: pbm.padding.block_start + pbm.border.block_start + clearance,
|
|
inline: pbm.padding.inline_start + pbm.border.inline_start + margin.inline_start,
|
|
},
|
|
size,
|
|
};
|
|
let block_margins_collapsed_with_children = CollapsedBlockMargins::from_margin(&margin);
|
|
|
|
BoxFragment::new(
|
|
base_fragment_info,
|
|
style.clone(),
|
|
fragments,
|
|
content_rect,
|
|
pbm.padding,
|
|
pbm.border,
|
|
margin,
|
|
Length::zero(),
|
|
block_margins_collapsed_with_children,
|
|
)
|
|
}
|
|
|
|
fn solve_inline_margins_for_in_flow_block_level(
|
|
containing_block: &ContainingBlock,
|
|
pbm: &PaddingBorderMargin,
|
|
inline_size: Length,
|
|
) -> (Length, Length) {
|
|
let available = containing_block.inline_size - pbm.padding_border_sums.inline - inline_size;
|
|
match (pbm.margin.inline_start, pbm.margin.inline_end) {
|
|
(LengthOrAuto::Auto, LengthOrAuto::Auto) => (available / 2., available / 2.),
|
|
(LengthOrAuto::Auto, LengthOrAuto::LengthPercentage(end)) => (available - end, end),
|
|
(LengthOrAuto::LengthPercentage(start), _) => (start, available - start),
|
|
}
|
|
}
|
|
|
|
// State that we maintain when placing blocks.
|
|
//
|
|
// In parallel mode, this placement is done after all child blocks are laid out. In sequential
|
|
// mode, this is done right after each block is laid out.
|
|
pub(crate) struct PlacementState {
|
|
next_in_flow_margin_collapses_with_parent_start_margin: bool,
|
|
start_margin: CollapsedMargin,
|
|
current_margin: CollapsedMargin,
|
|
current_block_direction_position: Length,
|
|
}
|
|
|
|
impl PlacementState {
|
|
fn new(
|
|
collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
|
|
) -> PlacementState {
|
|
PlacementState {
|
|
next_in_flow_margin_collapses_with_parent_start_margin:
|
|
collapsible_with_parent_start_margin.0,
|
|
start_margin: CollapsedMargin::zero(),
|
|
current_margin: CollapsedMargin::zero(),
|
|
current_block_direction_position: Length::zero(),
|
|
}
|
|
}
|
|
|
|
fn place_fragment(&mut self, fragment: &mut Fragment) {
|
|
match fragment {
|
|
Fragment::Box(fragment) => {
|
|
let fragment_block_margins = &fragment.block_margins_collapsed_with_children;
|
|
let fragment_block_size = fragment.clearance +
|
|
fragment.padding.block_sum() +
|
|
fragment.border.block_sum() +
|
|
fragment.content_rect.size.block;
|
|
|
|
if self.next_in_flow_margin_collapses_with_parent_start_margin {
|
|
debug_assert_eq!(self.current_margin.solve(), Length::zero());
|
|
self.start_margin
|
|
.adjoin_assign(&fragment_block_margins.start);
|
|
if fragment_block_margins.collapsed_through {
|
|
self.start_margin.adjoin_assign(&fragment_block_margins.end);
|
|
return;
|
|
}
|
|
self.next_in_flow_margin_collapses_with_parent_start_margin = false;
|
|
} else {
|
|
self.current_margin
|
|
.adjoin_assign(&fragment_block_margins.start);
|
|
}
|
|
fragment.content_rect.start_corner.block +=
|
|
self.current_margin.solve() + self.current_block_direction_position;
|
|
if fragment_block_margins.collapsed_through {
|
|
self.current_margin
|
|
.adjoin_assign(&fragment_block_margins.end);
|
|
return;
|
|
}
|
|
self.current_block_direction_position +=
|
|
self.current_margin.solve() + fragment_block_size;
|
|
self.current_margin = fragment_block_margins.end;
|
|
},
|
|
Fragment::AbsoluteOrFixedPositioned(fragment) => {
|
|
let offset = Vec2 {
|
|
block: self.current_margin.solve() + self.current_block_direction_position,
|
|
inline: Length::new(0.),
|
|
};
|
|
fragment.borrow_mut().adjust_offsets(offset);
|
|
},
|
|
Fragment::Anonymous(_) | Fragment::Float(_) => {},
|
|
_ => unreachable!(),
|
|
}
|
|
}
|
|
|
|
fn collapsible_margins_in_children(&self) -> CollapsedBlockMargins {
|
|
CollapsedBlockMargins {
|
|
collapsed_through: self.next_in_flow_margin_collapses_with_parent_start_margin,
|
|
start: self.start_margin,
|
|
end: self.current_margin,
|
|
}
|
|
}
|
|
|
|
/// When Float fragments are created in block flows, they are positioned
|
|
/// relative to the float containing independent block formatting context.
|
|
/// Once we place a float's containing block, this function can be used to
|
|
/// fix up the float position to be relative to the containing block.
|
|
fn adjust_positions_of_float_children(
|
|
&self,
|
|
fragment: &mut Fragment,
|
|
sequential_layout_state: &mut SequentialLayoutState,
|
|
) {
|
|
let fragment = match fragment {
|
|
Fragment::Box(ref mut fragment) => fragment,
|
|
_ => return,
|
|
};
|
|
|
|
// TODO(mrobinson): Will these margins be accurate if this fragment
|
|
// collapses through. Can a fragment collapse through when it has a
|
|
// non-zero sized float inside? The float won't be positioned correctly
|
|
// anyway (see the comment in `floats.rs` about margin collapse), but
|
|
// this might make the result even worse.
|
|
let collapsed_margins = self.collapsible_margins_in_children().start.adjoin(
|
|
&sequential_layout_state
|
|
.floats
|
|
.containing_block_info
|
|
.block_start_margins_not_collapsed,
|
|
);
|
|
|
|
let parent_fragment_offset_in_cb = &fragment.content_rect.start_corner;
|
|
let parent_fragment_offset_in_formatting_context = Vec2 {
|
|
inline: sequential_layout_state
|
|
.floats
|
|
.containing_block_info
|
|
.inline_start +
|
|
parent_fragment_offset_in_cb.inline,
|
|
block: sequential_layout_state
|
|
.floats
|
|
.containing_block_info
|
|
.block_start +
|
|
collapsed_margins.solve() +
|
|
parent_fragment_offset_in_cb.block,
|
|
};
|
|
|
|
for child_fragment in fragment.children.iter_mut() {
|
|
if let Fragment::Float(box_fragment) = child_fragment.borrow_mut().deref_mut() {
|
|
box_fragment.content_rect.start_corner = &box_fragment.content_rect.start_corner -
|
|
&parent_fragment_offset_in_formatting_context;
|
|
}
|
|
}
|
|
}
|
|
}
|