layout/table/
layout.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5use core::cmp::Ordering;
6use std::mem;
7use std::ops::Range;
8
9use app_units::Au;
10use atomic_refcell::AtomicRef;
11use log::warn;
12use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};
13use servo_arc::Arc;
14use strum::{EnumIter, IntoEnumIterator};
15use style::Zero;
16use style::computed_values::border_collapse::T as BorderCollapse;
17use style::computed_values::box_sizing::T as BoxSizing;
18use style::computed_values::caption_side::T as CaptionSide;
19use style::computed_values::empty_cells::T as EmptyCells;
20use style::computed_values::position::T as Position;
21use style::computed_values::table_layout::T as TableLayoutMode;
22use style::computed_values::visibility::T as Visibility;
23use style::properties::ComputedValues;
24use style::values::computed::{
25    AlignmentBaseline, BaselineShift, BorderStyle, LengthPercentage as ComputedLengthPercentage,
26    Percentage,
27};
28use style::values::generics::box_::BaselineShiftKeyword;
29
30use super::{
31    ArcRefCell, CollapsedBorder, CollapsedBorderLine, SpecificTableGridInfo, Table, TableCaption,
32    TableLayoutStyle, TableSlot, TableSlotCell, TableSlotCoordinates, TableTrack, TableTrackGroup,
33};
34use crate::context::LayoutContext;
35use crate::dom::WeakLayoutBox;
36use crate::formatting_contexts::Baselines;
37use crate::fragment_tree::{
38    BoxFragment, CollapsedBlockMargins, ExtraBackground, Fragment, FragmentFlags,
39    PositioningFragment, SpecificLayoutInfo,
40};
41use crate::geom::{
42    LogicalRect, LogicalSides, LogicalSides1D, LogicalVec2, PhysicalPoint, PhysicalRect,
43    PhysicalSides, PhysicalVec, ToLogical, ToLogicalWithContainingBlock,
44};
45use crate::layout_box_base::CacheableLayoutResult;
46use crate::positioned::{PositioningContext, PositioningContextLength, relative_adjustement};
47use crate::sizing::{
48    ComputeInlineContentSizes, ContentSizes, InlineContentSizesResult, LazySize, Size,
49    SizeConstraint,
50};
51use crate::style_ext::{
52    BorderStyleColor, Clamp, ComputedValuesExt, LayoutStyle, PaddingBorderMargin,
53};
54use crate::table::WeakTableLevelBox;
55use crate::{
56    ConstraintSpace, ContainingBlock, ContainingBlockSize, IndefiniteContainingBlock, WritingMode,
57};
58
59#[derive(PartialEq)]
60enum CellContentAlignment {
61    Top,
62    Bottom,
63    Middle,
64    Baseline,
65}
66
67/// A result of a final or speculative layout of a single cell in
68/// the table. Note that this is only done for slots that are not
69/// covered by spans or empty.
70struct CellLayout {
71    layout: CacheableLayoutResult,
72    padding: LogicalSides<Au>,
73    border: LogicalSides<Au>,
74    positioning_context: PositioningContext,
75}
76
77impl CellLayout {
78    fn ascent(&self) -> Au {
79        self.layout
80            .baselines
81            .first
82            .unwrap_or(self.layout.content_block_size)
83    }
84
85    /// The block size of this laid out cell including its border and padding.
86    fn outer_block_size(&self) -> Au {
87        self.layout.content_block_size + self.border.block_sum() + self.padding.block_sum()
88    }
89
90    /// Whether the cell has no in-flow or out-of-flow contents, other than collapsed whitespace.
91    /// Note this logic differs from 'empty-cells', which counts abspos contents as empty.
92    fn is_empty(&self) -> bool {
93        self.layout.fragments.is_empty()
94    }
95
96    /// Whether the cell is considered empty for the purpose of the 'empty-cells' property.
97    fn is_empty_for_empty_cells(&self) -> bool {
98        self.layout
99            .fragments
100            .iter()
101            .all(|fragment| matches!(fragment, Fragment::AbsoluteOrFixedPositioned(_)))
102    }
103}
104
105/// Information stored during the layout of rows.
106#[derive(Clone, Debug, Default)]
107struct RowLayout {
108    constrained: bool,
109    has_cell_with_span_greater_than_one: bool,
110    percent: Percentage,
111}
112
113/// Information stored during the layout of columns.
114#[derive(Clone, Debug, Default)]
115struct ColumnLayout {
116    constrained: bool,
117    has_originating_cells: bool,
118    content_sizes: ContentSizes,
119    percentage: Option<Percentage>,
120}
121
122fn max_two_optional_percentages(
123    a: Option<Percentage>,
124    b: Option<Percentage>,
125) -> Option<Percentage> {
126    match (a, b) {
127        (Some(a), Some(b)) => Some(Percentage(a.0.max(b.0))),
128        _ => a.or(b),
129    }
130}
131
132impl ColumnLayout {
133    fn incorporate_cell_measure(&mut self, cell_measure: &CellOrTrackMeasure) {
134        self.content_sizes.max_assign(cell_measure.content_sizes);
135        self.percentage = max_two_optional_percentages(self.percentage, cell_measure.percentage);
136    }
137}
138
139impl CollapsedBorder {
140    fn new(style_color: BorderStyleColor, width: Au) -> Self {
141        Self { style_color, width }
142    }
143
144    fn from_layout_style(
145        layout_style: &LayoutStyle,
146        writing_mode: WritingMode,
147    ) -> LogicalSides<Self> {
148        let border_style_color = layout_style.style().border_style_color(writing_mode);
149        let border_width = layout_style.border_width(writing_mode);
150        LogicalSides {
151            inline_start: Self::new(border_style_color.inline_start, border_width.inline_start),
152            inline_end: Self::new(border_style_color.inline_end, border_width.inline_end),
153            block_start: Self::new(border_style_color.block_start, border_width.block_start),
154            block_end: Self::new(border_style_color.block_end, border_width.block_end),
155        }
156    }
157
158    fn max_assign(&mut self, other: &Self) {
159        if *self < *other {
160            *self = other.clone();
161        }
162    }
163
164    fn max_assign_to_slice(&self, slice: &mut [CollapsedBorder]) {
165        for collapsed_border in slice {
166            collapsed_border.max_assign(self)
167        }
168    }
169
170    fn hide(&mut self) {
171        self.style_color = BorderStyleColor::hidden();
172        self.width = Au::zero();
173    }
174}
175
176/// <https://drafts.csswg.org/css-tables/#border-specificity>
177/// > Given two borders styles, the border style having the most specificity is the border style which…
178/// > 1. … has the value "hidden" as border-style, if only one does
179/// > 2. … has the biggest border-width, once converted into css pixels
180/// > 3. … has the border-style which comes first in the following list:
181/// >    double, solid, dashed, dotted, ridge, outset, groove, inset, none
182impl PartialOrd for CollapsedBorder {
183    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
184        let is_hidden = |border: &Self| border.style_color.style == BorderStyle::Hidden;
185        let candidate = (is_hidden(self).cmp(&is_hidden(other)))
186            .then_with(|| self.width.cmp(&other.width))
187            .then_with(|| self.style_color.style.cmp(&other.style_color.style));
188        if !candidate.is_eq() || self.style_color.color == other.style_color.color {
189            Some(candidate)
190        } else {
191            None
192        }
193    }
194}
195
196impl Eq for CollapsedBorder {}
197
198type CollapsedBorders = LogicalVec2<Vec<CollapsedBorderLine>>;
199
200/// A helper struct that performs the layout of the box tree version
201/// of a table into the fragment tree version. This implements
202/// <https://drafts.csswg.org/css-tables/#table-layout-algorithm>
203pub(crate) struct TableLayout<'a> {
204    table: &'a Table,
205    pbm: PaddingBorderMargin,
206    rows: Vec<RowLayout>,
207    columns: Vec<ColumnLayout>,
208    cell_measures: Vec<Vec<LogicalVec2<CellOrTrackMeasure>>>,
209    /// The calculated width of the table, including space for the grid and also for any
210    /// captions.
211    table_width: Au,
212    /// The table width minus the total horizontal border spacing (if any). This is the
213    /// width that we will be able to allocate to the columns.
214    assignable_width: Au,
215    final_table_height: Au,
216    distributed_column_widths: Vec<Au>,
217    row_sizes: Vec<Au>,
218    /// The accumulated baseline of each row, relative to the top of the row.
219    row_baselines: Vec<Au>,
220    cells_laid_out: Vec<Vec<Option<CellLayout>>>,
221    basis_for_cell_padding_percentage: Au,
222    /// Information about collapsed borders.
223    collapsed_borders: Option<CollapsedBorders>,
224    is_in_fixed_mode: bool,
225}
226
227#[derive(Clone, Debug)]
228struct CellOrTrackMeasure {
229    content_sizes: ContentSizes,
230    percentage: Option<Percentage>,
231}
232
233impl Zero for CellOrTrackMeasure {
234    fn zero() -> Self {
235        Self {
236            content_sizes: ContentSizes::zero(),
237            percentage: None,
238        }
239    }
240
241    fn is_zero(&self) -> bool {
242        self.content_sizes.is_zero() && self.percentage.is_none()
243    }
244}
245
246impl<'a> TableLayout<'a> {
247    fn new(table: &'a Table) -> TableLayout<'a> {
248        // The CSSWG resolved that `auto` and `max-content` inline sizes prevent fixed table mode.
249        // <https://github.com/w3c/csswg-drafts/issues/10937>
250        let style = &table.style;
251        let is_in_fixed_mode = style.get_table().table_layout == TableLayoutMode::Fixed &&
252            !matches!(
253                style.box_size(style.writing_mode).inline,
254                Size::Initial | Size::MaxContent
255            );
256        Self {
257            table,
258            pbm: PaddingBorderMargin::zero(),
259            rows: Vec::new(),
260            columns: Vec::new(),
261            cell_measures: Vec::new(),
262            table_width: Au::zero(),
263            assignable_width: Au::zero(),
264            final_table_height: Au::zero(),
265            distributed_column_widths: Vec::new(),
266            row_sizes: Vec::new(),
267            row_baselines: Vec::new(),
268            cells_laid_out: Vec::new(),
269            basis_for_cell_padding_percentage: Au::zero(),
270            collapsed_borders: None,
271            is_in_fixed_mode,
272        }
273    }
274
275    /// This is an implementation of *Computing Cell Measures* from
276    /// <https://drafts.csswg.org/css-tables/#computing-cell-measures>.
277    pub(crate) fn compute_cell_measures(
278        &mut self,
279        layout_context: &LayoutContext,
280        writing_mode: WritingMode,
281    ) {
282        let row_measures = vec![LogicalVec2::zero(); self.table.size.width];
283        self.cell_measures = vec![row_measures; self.table.size.height];
284
285        for row_index in 0..self.table.size.height {
286            for column_index in 0..self.table.size.width {
287                let cell = match self.table.slots[row_index][column_index] {
288                    TableSlot::Cell(ref cell) => cell,
289                    _ => continue,
290                }
291                .borrow();
292
293                let layout_style = cell.context.layout_style();
294                let padding = layout_style
295                    .padding(writing_mode)
296                    .percentages_relative_to(Au::zero());
297                let border = self
298                    .get_collapsed_border_widths_for_area(LogicalSides {
299                        inline_start: column_index,
300                        inline_end: column_index + cell.colspan,
301                        block_start: row_index,
302                        block_end: row_index + cell.rowspan,
303                    })
304                    .unwrap_or_else(|| layout_style.border_width(writing_mode));
305
306                let padding_border_sums = LogicalVec2 {
307                    inline: padding.inline_sum() + border.inline_sum(),
308                    block: padding.block_sum() + border.block_sum(),
309                };
310
311                let CellOrColumnOuterSizes {
312                    preferred: preferred_size,
313                    min: min_size,
314                    max: max_size,
315                    percentage: percentage_size,
316                } = CellOrColumnOuterSizes::new(
317                    &cell.context.base.style,
318                    writing_mode,
319                    &padding_border_sums,
320                    self.is_in_fixed_mode,
321                );
322
323                // <https://drafts.csswg.org/css-tables/#in-fixed-mode>
324                // > When a table-root is laid out in fixed mode, the content of its table-cells is ignored
325                // > for the purpose of width computation, the aggregation algorithm for column sizing considers
326                // > only table-cells belonging to the first row track
327                let inline_measure = if self.is_in_fixed_mode {
328                    if row_index > 0 {
329                        CellOrTrackMeasure::zero()
330                    } else {
331                        CellOrTrackMeasure {
332                            content_sizes: preferred_size.inline.into(),
333                            percentage: percentage_size.inline,
334                        }
335                    }
336                } else {
337                    let constraint_space = ConstraintSpace::new(
338                        SizeConstraint::default(),
339                        &cell.context.base.style,
340                        cell.context.preferred_aspect_ratio(&padding_border_sums),
341                    );
342                    let inline_content_sizes = cell
343                        .context
344                        .inline_content_sizes(layout_context, &constraint_space)
345                        .sizes +
346                        padding_border_sums.inline.into();
347                    assert!(
348                        inline_content_sizes.max_content >= inline_content_sizes.min_content,
349                        "the max-content size should never be smaller than the min-content size"
350                    );
351
352                    // These formulas differ from the spec, but seem to match Gecko and Blink.
353                    let outer_min_content_width = inline_content_sizes
354                        .min_content
355                        .clamp_between_extremums(min_size.inline, max_size.inline);
356                    let outer_max_content_width = if self.columns[column_index].constrained {
357                        inline_content_sizes
358                            .min_content
359                            .max(preferred_size.inline)
360                            .clamp_between_extremums(min_size.inline, max_size.inline)
361                    } else {
362                        inline_content_sizes
363                            .max_content
364                            .max(preferred_size.inline)
365                            .clamp_between_extremums(min_size.inline, max_size.inline)
366                    };
367                    assert!(outer_min_content_width <= outer_max_content_width);
368
369                    CellOrTrackMeasure {
370                        content_sizes: ContentSizes {
371                            min_content: outer_min_content_width,
372                            max_content: outer_max_content_width,
373                        },
374                        percentage: percentage_size.inline,
375                    }
376                };
377
378                // This measure doesn't take into account the `min-content` and `max-content` sizes.
379                // These sizes are incorporated after the first row layout pass, when the block size
380                // of the layout is known.
381                let block_measure = CellOrTrackMeasure {
382                    content_sizes: preferred_size.block.into(),
383                    percentage: percentage_size.block,
384                };
385
386                self.cell_measures[row_index][column_index] = LogicalVec2 {
387                    inline: inline_measure,
388                    block: block_measure,
389                };
390            }
391        }
392    }
393
394    /// Compute the constrainedness of every column in the table.
395    ///
396    /// > A column is constrained if its corresponding table-column-group (if any), its
397    /// > corresponding table-column (if any), or any of the cells spanning only that
398    /// > column has a computed width that is not "auto", and is not a percentage.
399    fn compute_track_constrainedness_and_has_originating_cells(
400        &mut self,
401        writing_mode: WritingMode,
402    ) {
403        self.rows = vec![RowLayout::default(); self.table.size.height];
404        self.columns = vec![ColumnLayout::default(); self.table.size.width];
405
406        let is_length = |size: &Size<ComputedLengthPercentage>| {
407            size.to_numeric().is_some_and(|size| !size.has_percentage())
408        };
409
410        for column_index in 0..self.table.size.width {
411            if let Some(column) = self.table.columns.get(column_index) {
412                let column = column.borrow();
413                if is_length(&column.base.style.box_size(writing_mode).inline) {
414                    self.columns[column_index].constrained = true;
415                    continue;
416                }
417                if let Some(column_group_index) = column.group_index {
418                    let column_group = self.table.column_groups[column_group_index].borrow();
419                    if is_length(&column_group.base.style.box_size(writing_mode).inline) {
420                        self.columns[column_index].constrained = true;
421                        continue;
422                    }
423                }
424            }
425        }
426
427        for row_index in 0..self.table.size.height {
428            if let Some(row) = self.table.rows.get(row_index) {
429                let row = row.borrow();
430                if is_length(&row.base.style.box_size(writing_mode).block) {
431                    self.rows[row_index].constrained = true;
432                    continue;
433                }
434                if let Some(row_group_index) = row.group_index {
435                    let row_group = self.table.row_groups[row_group_index].borrow();
436                    if is_length(&row_group.base.style.box_size(writing_mode).block) {
437                        self.rows[row_index].constrained = true;
438                        continue;
439                    }
440                }
441            }
442        }
443
444        for column_index in 0..self.table.size.width {
445            for row_index in 0..self.table.size.height {
446                let coords = TableSlotCoordinates::new(column_index, row_index);
447                let cell_constrained = match self.table.resolve_first_cell(coords) {
448                    Some(cell) if cell.colspan == 1 => cell
449                        .context
450                        .base
451                        .style
452                        .box_size(writing_mode)
453                        .map(is_length),
454                    _ => LogicalVec2::default(),
455                };
456
457                let rowspan_greater_than_1 = match self.table.slots[row_index][column_index] {
458                    TableSlot::Cell(ref cell) => cell.borrow().rowspan > 1,
459                    _ => false,
460                };
461
462                self.rows[row_index].has_cell_with_span_greater_than_one |= rowspan_greater_than_1;
463                self.rows[row_index].constrained |= cell_constrained.block;
464
465                let has_originating_cell =
466                    matches!(self.table.get_slot(coords), Some(TableSlot::Cell(_)));
467                self.columns[column_index].has_originating_cells |= has_originating_cell;
468                self.columns[column_index].constrained |= cell_constrained.inline;
469            }
470        }
471    }
472
473    /// This is an implementation of *Computing Column Measures* from
474    /// <https://drafts.csswg.org/css-tables/#computing-column-measures>.
475    fn compute_column_measures(&mut self, writing_mode: WritingMode) {
476        // Compute the column measures only taking into account cells with colspan == 1.
477        // This is the base case that will be used to iteratively account for cells with
478        // larger colspans afterward.
479        //
480        // > min-content width of a column based on cells of span up to 1
481        // >     The largest of:
482        // >         - the width specified for the column:
483        // >               - the outer min-content width of its corresponding table-column,
484        // >                 if any (and not auto)
485        // >               - the outer min-content width of its corresponding table-column-group, if any
486        // >               - or 0, if there is none
487        // >         - the outer min-content width of each cell that spans the column whose colSpan
488        // >           is 1 (or just the one in the first row in fixed mode) or 0 if there is none
489        // >
490        // > max-content width of a column based on cells of span up to 1
491        // >     The largest of:
492        // >         - the outer max-content width of its corresponding
493        // >           table-column-group, if any
494        // >         - the outer max-content width of its corresponding table-column, if any
495        // >         - the outer max-content width of each cell that spans the column
496        // >           whose colSpan is 1 (or just the one in the first row if in fixed mode) or 0
497        // >           if there is no such cell
498        // >
499        // > intrinsic percentage width of a column based on cells of span up to 1
500        // >     The largest of the percentage contributions of each cell that spans the column whose colSpan is
501        // >     1, of its corresponding table-column (if any), and of its corresponding table-column-group (if
502        // >     any)
503        //
504        // TODO: Take into account `table-column` and `table-column-group` lengths.
505        // TODO: Take into account changes to this computation for fixed table layout.
506        let mut colspan_cell_constraints = Vec::new();
507        for column_index in 0..self.table.size.width {
508            let column = &mut self.columns[column_index];
509
510            let column_measure = self.table.get_column_measure_for_column_at_index(
511                writing_mode,
512                column_index,
513                self.is_in_fixed_mode,
514            );
515            column.content_sizes = column_measure.content_sizes;
516            column.percentage = column_measure.percentage;
517
518            for row_index in 0..self.table.size.height {
519                let coords = TableSlotCoordinates::new(column_index, row_index);
520                let cell_measure = &self.cell_measures[row_index][column_index].inline;
521
522                let cell = match self.table.get_slot(coords) {
523                    Some(TableSlot::Cell(cell)) => cell,
524                    _ => continue,
525                }
526                .borrow();
527
528                if cell.colspan != 1 {
529                    colspan_cell_constraints.push(ColspanToDistribute {
530                        starting_column: column_index,
531                        span: cell.colspan,
532                        content_sizes: cell_measure.content_sizes,
533                        percentage: cell_measure.percentage,
534                    });
535                    continue;
536                }
537
538                // This takes the max of `min_content`, `max_content`, and
539                // intrinsic percentage width as described above.
540                column.incorporate_cell_measure(cell_measure);
541            }
542        }
543
544        // Sort the colspanned cell constraints by their span and starting column.
545        colspan_cell_constraints.sort_by(ColspanToDistribute::comparison_for_sort);
546
547        // Distribute constraints from cells with colspan != 1 to their component columns.
548        self.distribute_colspanned_cells_to_columns(colspan_cell_constraints);
549
550        // > intrinsic percentage width of a column:
551        // > the smaller of:
552        // >   * the intrinsic percentage width of the column based on cells of span up to N,
553        // >     where N is the number of columns in the table
554        // >   * 100% minus the sum of the intrinsic percentage width of all prior columns in
555        // >     the table (further left when direction is "ltr" (right for "rtl"))
556        let mut total_intrinsic_percentage_width = 0.;
557        for column in self.columns.iter_mut() {
558            if let Some(ref mut percentage) = column.percentage {
559                let final_intrinsic_percentage_width =
560                    percentage.0.min(1. - total_intrinsic_percentage_width);
561                total_intrinsic_percentage_width += final_intrinsic_percentage_width;
562                *percentage = Percentage(final_intrinsic_percentage_width);
563            }
564        }
565    }
566
567    fn distribute_colspanned_cells_to_columns(
568        &mut self,
569        colspan_cell_constraints: Vec<ColspanToDistribute>,
570    ) {
571        for colspan_cell_constraints in colspan_cell_constraints {
572            self.distribute_colspanned_cell_to_columns(colspan_cell_constraints);
573        }
574    }
575
576    /// Distribute the inline size from a cell with colspan != 1 to the columns that it spans.
577    /// This is heavily inspired by the approach that Chromium takes in redistributing colspan
578    /// cells' inline size to columns (`DistributeColspanCellToColumnsAuto` in
579    /// `blink/renderer/core/layout/table/table_layout_utils.cc`).
580    fn distribute_colspanned_cell_to_columns(
581        &mut self,
582        colspan_cell_constraints: ColspanToDistribute,
583    ) {
584        let border_spacing = self.table.border_spacing().inline;
585        let column_range = colspan_cell_constraints.range();
586        let column_count = column_range.len();
587        let total_border_spacing =
588            border_spacing.scale_by((colspan_cell_constraints.span - 1) as f32);
589
590        let mut percent_columns_count = 0;
591        let mut columns_percent_sum = 0.;
592        let mut columns_non_percent_max_inline_size_sum = Au::zero();
593        for column in self.columns[column_range.clone()].iter() {
594            if let Some(percentage) = column.percentage {
595                percent_columns_count += 1;
596                columns_percent_sum += percentage.0;
597            } else {
598                columns_non_percent_max_inline_size_sum += column.content_sizes.max_content;
599            }
600        }
601
602        let colspan_percentage = colspan_cell_constraints.percentage.unwrap_or_default();
603        let surplus_percent = colspan_percentage.0 - columns_percent_sum;
604        if surplus_percent > 0. && column_count > percent_columns_count {
605            for column in self.columns[column_range.clone()].iter_mut() {
606                if column.percentage.is_some() {
607                    continue;
608                }
609
610                let ratio = if columns_non_percent_max_inline_size_sum.is_zero() {
611                    1. / ((column_count - percent_columns_count) as f32)
612                } else {
613                    column.content_sizes.max_content.to_f32_px() /
614                        columns_non_percent_max_inline_size_sum.to_f32_px()
615                };
616                column.percentage = Some(Percentage(surplus_percent * ratio));
617            }
618        }
619
620        let colspan_cell_min_size = (colspan_cell_constraints.content_sizes.min_content -
621            total_border_spacing)
622            .max(Au::zero());
623        let distributed_minimum = Self::distribute_width_to_columns(
624            colspan_cell_min_size,
625            &self.columns[column_range.clone()],
626        );
627        {
628            let column_span = &mut self.columns[colspan_cell_constraints.range()];
629            for (column, minimum_size) in column_span.iter_mut().zip(distributed_minimum) {
630                column.content_sizes.min_content.max_assign(minimum_size);
631            }
632        }
633
634        let colspan_cell_max_size = (colspan_cell_constraints.content_sizes.max_content -
635            total_border_spacing)
636            .max(Au::zero());
637        let distributed_maximum = Self::distribute_width_to_columns(
638            colspan_cell_max_size,
639            &self.columns[colspan_cell_constraints.range()],
640        );
641        {
642            let column_span = &mut self.columns[colspan_cell_constraints.range()];
643            for (column, maximum_size) in column_span.iter_mut().zip(distributed_maximum) {
644                column
645                    .content_sizes
646                    .max_content
647                    .max_assign(maximum_size.max(column.content_sizes.min_content));
648            }
649        }
650    }
651
652    fn compute_measures(&mut self, layout_context: &LayoutContext, writing_mode: WritingMode) {
653        self.compute_track_constrainedness_and_has_originating_cells(writing_mode);
654        self.compute_cell_measures(layout_context, writing_mode);
655        self.compute_column_measures(writing_mode);
656    }
657
658    /// Compute the GRIDMIN and GRIDMAX.
659    fn compute_grid_min_max(&self) -> ContentSizes {
660        // https://drafts.csswg.org/css-tables/#gridmin:
661        // > The row/column-grid width minimum (GRIDMIN) width is the sum of the min-content width of
662        // > all the columns plus cell spacing or borders.
663        // https://drafts.csswg.org/css-tables/#gridmax:
664        // > The row/column-grid width maximum (GRIDMAX) width is the sum of the max-content width of
665        // > all the columns plus cell spacing or borders.
666        //
667        // The specification doesn't say what to do with columns with percentages, so we follow the
668        // approach that LayoutNG takes here. We try to figure out the size contribution
669        // of the percentage columns, by working backward to find the calculated
670        // percentage of non-percent columns and using that to calculate the size of the
671        // percent columns.
672        let mut largest_percentage_column_max_size = Au::zero();
673        let mut percent_sum = 0.;
674        let mut non_percent_columns_max_sum = Au::zero();
675        let mut grid_min_max = ContentSizes::zero();
676        for column in self.columns.iter() {
677            match column.percentage {
678                Some(percentage) if !percentage.is_zero() => {
679                    largest_percentage_column_max_size.max_assign(
680                        column
681                            .content_sizes
682                            .max_content
683                            .scale_by(1.0 / percentage.0),
684                    );
685                    percent_sum += percentage.0;
686                },
687                _ => {
688                    non_percent_columns_max_sum += column.content_sizes.max_content;
689                },
690            }
691
692            grid_min_max += column.content_sizes;
693        }
694
695        grid_min_max
696            .max_content
697            .max_assign(largest_percentage_column_max_size);
698
699        // Do not take into account percentage of columns when this table is a descendant
700        // of a flex, grid, or table container. These modes with percentage columns can
701        // cause inline width to become infinitely wide.
702        if !percent_sum.is_zero() &&
703            self.table
704                .percentage_columns_allowed_for_inline_content_sizes
705        {
706            let total_inline_size =
707                non_percent_columns_max_sum.scale_by(1.0 / (1.0 - percent_sum.min(1.0)));
708            grid_min_max.max_content.max_assign(total_inline_size);
709        }
710
711        assert!(
712            grid_min_max.min_content <= grid_min_max.max_content,
713            "GRIDMAX should never be smaller than GRIDMIN {:?}",
714            grid_min_max
715        );
716
717        let inline_border_spacing = self.table.total_border_spacing().inline;
718        grid_min_max.min_content += inline_border_spacing;
719        grid_min_max.max_content += inline_border_spacing;
720        grid_min_max
721    }
722
723    /// Compute CAPMIN: <https://drafts.csswg.org/css-tables/#capmin>
724    fn compute_caption_minimum_inline_size(&self, layout_context: &LayoutContext) -> Au {
725        let containing_block = IndefiniteContainingBlock {
726            size: LogicalVec2::default(),
727            style: &self.table.style,
728        };
729        self.table
730            .captions
731            .iter()
732            .map(|caption| {
733                caption
734                    .borrow()
735                    .context
736                    .outer_inline_content_sizes(
737                        layout_context,
738                        &containing_block,
739                        &LogicalVec2::zero(),
740                        false, /* auto_block_size_stretches_to_containing_block */
741                    )
742                    .sizes
743                    .min_content
744            })
745            .max()
746            .unwrap_or_default()
747    }
748
749    fn compute_table_width(&mut self, containing_block_for_children: &ContainingBlock) {
750        // This assumes that the parent formatting context computed the correct inline size
751        // of the table, by enforcing its min-content size as a minimum.
752        // This should be roughly equivalent to what the spec calls "used width of a table".
753        // https://drafts.csswg.org/css-tables/#used-width-of-table
754        self.table_width = containing_block_for_children.size.inline;
755
756        // > The assignable table width is the used width of the table minus the total horizontal
757        // > border spacing (if any). This is the width that we will be able to allocate to the
758        // > columns.
759        self.assignable_width = self.table_width - self.table.total_border_spacing().inline;
760
761        // This is the amount that we will use to resolve percentages in the padding of cells.
762        // It matches what Gecko and Blink do, though they disagree when there is a big caption.
763        self.basis_for_cell_padding_percentage =
764            self.table_width - self.table.border_spacing().inline * 2;
765    }
766
767    /// Distribute width to columns, performing step 2.4 of table layout from
768    /// <https://drafts.csswg.org/css-tables/#table-layout-algorithm>.
769    fn distribute_width_to_columns(target_inline_size: Au, columns: &[ColumnLayout]) -> Vec<Au> {
770        // No need to do anything if there is no column.
771        // Note that tables without rows may still have columns.
772        if columns.is_empty() {
773            return Vec::new();
774        }
775
776        // > First, each column of the table is assigned a sizing type:
777        // >  * percent-column: a column whose any constraint is defined to use a percentage only
778        // >                    (with a value different from 0%)
779        // >  * pixel-column: column whose any constraint is defined to use a defined length only
780        // >                  (and is not a percent-column)
781        // >  * auto-column: any other column
782        // >
783        // > Then, valid sizing methods are to be assigned to the columns by sizing type, yielding
784        // > the following sizing-guesses:
785        // >
786        // > * The min-content sizing-guess is the set of column width assignments where
787        // >   each column is assigned its min-content width.
788        // > * The min-content-percentage sizing-guess is the set of column width assignments where:
789        // >       * each percent-column is assigned the larger of:
790        // >           * its intrinsic percentage width times the assignable width and
791        // >           * its min-content width.
792        // >       * all other columns are assigned their min-content width.
793        // > * The min-content-specified sizing-guess is the set of column width assignments where:
794        // >       * each percent-column is assigned the larger of:
795        // >           * its intrinsic percentage width times the assignable width and
796        // >           * its min-content width
797        // >       * any other column that is constrained is assigned its max-content width
798        // >       * all other columns are assigned their min-content width.
799        // > * The max-content sizing-guess is the set of column width assignments where:
800        // >       * each percent-column is assigned the larger of:
801        // >           * its intrinsic percentage width times the assignable width and
802        // >           * its min-content width
803        // >       * all other columns are assigned their max-content width.
804        let mut min_content_sizing_guesses = Vec::new();
805        let mut min_content_percentage_sizing_guesses = Vec::new();
806        let mut min_content_specified_sizing_guesses = Vec::new();
807        let mut max_content_sizing_guesses = Vec::new();
808
809        for column in columns {
810            let min_content_width = column.content_sizes.min_content;
811            let max_content_width = column.content_sizes.max_content;
812            let constrained = column.constrained;
813
814            let (
815                min_content_percentage_sizing_guess,
816                min_content_specified_sizing_guess,
817                max_content_sizing_guess,
818            ) = if let Some(percentage) = column.percentage {
819                let resolved = target_inline_size.scale_by(percentage.0);
820                let percent_guess = min_content_width.max(resolved);
821                (percent_guess, percent_guess, percent_guess)
822            } else if constrained {
823                (min_content_width, max_content_width, max_content_width)
824            } else {
825                (min_content_width, min_content_width, max_content_width)
826            };
827
828            min_content_sizing_guesses.push(min_content_width);
829            min_content_percentage_sizing_guesses.push(min_content_percentage_sizing_guess);
830            min_content_specified_sizing_guesses.push(min_content_specified_sizing_guess);
831            max_content_sizing_guesses.push(max_content_sizing_guess);
832        }
833
834        // > If the assignable table width is less than or equal to the max-content sizing-guess, the
835        // > used widths of the columns must be the linear combination (with weights adding to 1) of
836        // > the two consecutive sizing-guesses whose width sums bound the available width.
837        //
838        // > Otherwise, the used widths of the columns are the result of starting from the max-content
839        // > sizing-guess and distributing the excess width to the columns of the table according to
840        // > the rules for distributing excess width to columns (for used width).
841        let max_content_sizing_sum = max_content_sizing_guesses.iter().sum();
842        if target_inline_size >= max_content_sizing_sum {
843            Self::distribute_extra_width_to_columns(
844                columns,
845                &mut max_content_sizing_guesses,
846                max_content_sizing_sum,
847                target_inline_size,
848            );
849            return max_content_sizing_guesses;
850        }
851        let min_content_specified_sizing_sum = min_content_specified_sizing_guesses.iter().sum();
852        if target_inline_size == min_content_specified_sizing_sum {
853            return min_content_specified_sizing_guesses;
854        }
855        let min_content_percentage_sizing_sum = min_content_percentage_sizing_guesses.iter().sum();
856        if target_inline_size == min_content_percentage_sizing_sum {
857            return min_content_percentage_sizing_guesses;
858        }
859        let min_content_sizes_sum = min_content_sizing_guesses.iter().sum();
860        if target_inline_size <= min_content_sizes_sum {
861            return min_content_sizing_guesses;
862        }
863
864        let bounds = |sum_a, sum_b| target_inline_size > sum_a && target_inline_size < sum_b;
865
866        let blend = |a: &[Au], sum_a: Au, b: &[Au], sum_b: Au| {
867            // First convert the Au units to f32 in order to do floating point division.
868            let weight_a = (target_inline_size - sum_b).to_f32_px() / (sum_a - sum_b).to_f32_px();
869            let weight_b = 1.0 - weight_a;
870
871            let mut remaining_assignable_width = target_inline_size;
872            let mut widths: Vec<Au> = a
873                .iter()
874                .zip(b.iter())
875                .map(|(guess_a, guess_b)| {
876                    let column_width = guess_a.scale_by(weight_a) + guess_b.scale_by(weight_b);
877                    // Clamp to avoid exceeding the assignable width. This could otherwise
878                    // happen when dealing with huge values whose sum is clamped to MAX_AU.
879                    let column_width = column_width.min(remaining_assignable_width);
880                    remaining_assignable_width -= column_width;
881                    column_width
882                })
883                .collect();
884
885            if !remaining_assignable_width.is_zero() {
886                // The computations above can introduce floating-point imprecisions.
887                // Since these errors are very small (1Au), it's fine to simply adjust
888                // the first column such that the total width matches the assignable width
889                debug_assert!(
890                    remaining_assignable_width >= Au::zero(),
891                    "Sum of columns shouldn't exceed the assignable table width"
892                );
893                debug_assert!(
894                    remaining_assignable_width <= Au::new(widths.len() as i32),
895                    "A deviation of more than one Au per column is unlikely to be caused by float imprecision"
896                );
897
898                // We checked if the table had columns at the top of the function, so there
899                // always is a first column
900                widths[0] += remaining_assignable_width;
901            }
902
903            debug_assert!(widths.iter().sum::<Au>() == target_inline_size);
904
905            widths
906        };
907
908        if bounds(min_content_sizes_sum, min_content_percentage_sizing_sum) {
909            return blend(
910                &min_content_sizing_guesses,
911                min_content_sizes_sum,
912                &min_content_percentage_sizing_guesses,
913                min_content_percentage_sizing_sum,
914            );
915        }
916
917        if bounds(
918            min_content_percentage_sizing_sum,
919            min_content_specified_sizing_sum,
920        ) {
921            return blend(
922                &min_content_percentage_sizing_guesses,
923                min_content_percentage_sizing_sum,
924                &min_content_specified_sizing_guesses,
925                min_content_specified_sizing_sum,
926            );
927        }
928
929        assert!(bounds(
930            min_content_specified_sizing_sum,
931            max_content_sizing_sum
932        ));
933        blend(
934            &min_content_specified_sizing_guesses,
935            min_content_specified_sizing_sum,
936            &max_content_sizing_guesses,
937            max_content_sizing_sum,
938        )
939    }
940
941    /// This is an implementation of *Distributing excess width to columns* from
942    /// <https://drafts.csswg.org/css-tables/#distributing-width-to-columns>.
943    fn distribute_extra_width_to_columns(
944        columns: &[ColumnLayout],
945        column_sizes: &mut [Au],
946        column_sizes_sum: Au,
947        assignable_width: Au,
948    ) {
949        let all_columns = 0..columns.len();
950        let extra_inline_size = assignable_width - column_sizes_sum;
951
952        let has_originating_cells =
953            |column_index: &usize| columns[*column_index].has_originating_cells;
954        let is_constrained = |column_index: &usize| columns[*column_index].constrained;
955        let is_unconstrained = |column_index: &usize| !is_constrained(column_index);
956        let has_percent_greater_than_zero = |column_index: &usize| {
957            columns[*column_index]
958                .percentage
959                .is_some_and(|percentage| percentage.0 > 0.)
960        };
961        let has_percent_zero = |column_index: &usize| !has_percent_greater_than_zero(column_index);
962        let has_max_content =
963            |column_index: &usize| !columns[*column_index].content_sizes.max_content.is_zero();
964
965        let max_content_sum = |column_index: usize| columns[column_index].content_sizes.max_content;
966
967        // > If there are non-constrained columns that have originating cells with intrinsic
968        // > percentage width of 0% and with nonzero max-content width (aka the columns allowed to
969        // > grow by this rule), the distributed widths of the columns allowed to grow by this rule
970        // > are increased in proportion to max-content width so the total increase adds to the
971        // > excess width.
972        let unconstrained_max_content_columns = all_columns
973            .clone()
974            .filter(is_unconstrained)
975            .filter(has_originating_cells)
976            .filter(has_percent_zero)
977            .filter(has_max_content);
978        let total_max_content_width: Au = unconstrained_max_content_columns
979            .clone()
980            .map(max_content_sum)
981            .sum();
982        if !total_max_content_width.is_zero() {
983            for column_index in unconstrained_max_content_columns {
984                column_sizes[column_index] += extra_inline_size.scale_by(
985                    columns[column_index].content_sizes.max_content.to_f32_px() /
986                        total_max_content_width.to_f32_px(),
987                );
988            }
989            return;
990        }
991
992        // > Otherwise, if there are non-constrained columns that have originating cells with intrinsic
993        // > percentage width of 0% (aka the columns allowed to grow by this rule, which thanks to the
994        // > previous rule must have zero max-content width), the distributed widths of the columns
995        // > allowed to grow by this rule are increased by equal amounts so the total increase adds to
996        // > the excess width.V
997        let unconstrained_no_percent_columns = all_columns
998            .clone()
999            .filter(is_unconstrained)
1000            .filter(has_originating_cells)
1001            .filter(has_percent_zero);
1002        let total_unconstrained_no_percent = unconstrained_no_percent_columns.clone().count();
1003        if total_unconstrained_no_percent > 0 {
1004            let extra_space_per_column =
1005                extra_inline_size.scale_by(1.0 / total_unconstrained_no_percent as f32);
1006            for column_index in unconstrained_no_percent_columns {
1007                column_sizes[column_index] += extra_space_per_column;
1008            }
1009            return;
1010        }
1011
1012        // > Otherwise, if there are constrained columns with intrinsic percentage width of 0% and
1013        // > with nonzero max-content width (aka the columns allowed to grow by this rule, which, due
1014        // > to other rules, must have originating cells), the distributed widths of the columns
1015        // > allowed to grow by this rule are increased in proportion to max-content width so the
1016        // > total increase adds to the excess width.
1017        let constrained_max_content_columns = all_columns
1018            .clone()
1019            .filter(is_constrained)
1020            .filter(has_originating_cells)
1021            .filter(has_percent_zero)
1022            .filter(has_max_content);
1023        let total_max_content_width: Au = constrained_max_content_columns
1024            .clone()
1025            .map(max_content_sum)
1026            .sum();
1027        if !total_max_content_width.is_zero() {
1028            for column_index in constrained_max_content_columns {
1029                column_sizes[column_index] += extra_inline_size.scale_by(
1030                    columns[column_index].content_sizes.max_content.to_f32_px() /
1031                        total_max_content_width.to_f32_px(),
1032                );
1033            }
1034            return;
1035        }
1036
1037        // > Otherwise, if there are columns with intrinsic percentage width greater than 0% (aka the
1038        // > columns allowed to grow by this rule, which, due to other rules, must have originating
1039        // > cells), the distributed widths of the columns allowed to grow by this rule are increased
1040        // > in proportion to intrinsic percentage width so the total increase adds to the excess
1041        // > width.
1042        let columns_with_percentage = all_columns.clone().filter(has_percent_greater_than_zero);
1043        let total_percent = columns_with_percentage
1044            .clone()
1045            .map(|column_index| columns[column_index].percentage.unwrap_or_default().0)
1046            .sum::<f32>();
1047        if total_percent > 0. {
1048            for column_index in columns_with_percentage {
1049                let column_percentage = columns[column_index].percentage.unwrap_or_default();
1050                column_sizes[column_index] +=
1051                    extra_inline_size.scale_by(column_percentage.0 / total_percent);
1052            }
1053            return;
1054        }
1055
1056        // > Otherwise, if there is any such column, the distributed widths of all columns that have
1057        // > originating cells are increased by equal amounts so the total increase adds to the excess
1058        // > width.
1059        let has_originating_cells_columns = all_columns.clone().filter(has_originating_cells);
1060        let total_has_originating_cells = has_originating_cells_columns.clone().count();
1061        if total_has_originating_cells > 0 {
1062            let extra_space_per_column =
1063                extra_inline_size.scale_by(1.0 / total_has_originating_cells as f32);
1064            for column_index in has_originating_cells_columns {
1065                column_sizes[column_index] += extra_space_per_column;
1066            }
1067            return;
1068        }
1069
1070        // > Otherwise, the distributed widths of all columns are increased by equal amounts so the
1071        // total increase adds to the excess width.
1072        let extra_space_for_all_columns = extra_inline_size.scale_by(1.0 / columns.len() as f32);
1073        for guess in column_sizes.iter_mut() {
1074            *guess += extra_space_for_all_columns;
1075        }
1076    }
1077
1078    /// This is an implementation of *Row layout (first pass)* from
1079    /// <https://drafts.csswg.org/css-tables/#row-layout>.
1080    fn layout_cells_in_row(
1081        &mut self,
1082        layout_context: &LayoutContext,
1083        containing_block_for_table: &ContainingBlock,
1084    ) {
1085        let layout_table_slot = |coordinate: TableSlotCoordinates, slot: &TableSlot| {
1086            let TableSlot::Cell(cell) = slot else {
1087                return None;
1088            };
1089
1090            let cell = cell.borrow();
1091            let area = LogicalSides {
1092                inline_start: coordinate.x,
1093                inline_end: coordinate.x + cell.colspan,
1094                block_start: coordinate.y,
1095                block_end: coordinate.y + cell.rowspan,
1096            };
1097            let layout_style = cell.context.layout_style();
1098            let border = self
1099                .get_collapsed_border_widths_for_area(area)
1100                .unwrap_or_else(|| {
1101                    layout_style.border_width(containing_block_for_table.style.writing_mode)
1102                });
1103            let padding: LogicalSides<Au> = layout_style
1104                .padding(containing_block_for_table.style.writing_mode)
1105                .percentages_relative_to(self.basis_for_cell_padding_percentage);
1106            let padding_border_sums = LogicalVec2 {
1107                inline: padding.inline_sum() + border.inline_sum(),
1108                block: padding.block_sum() + border.block_sum(),
1109            };
1110            let border_spacing_spanned =
1111                self.table.border_spacing().inline * (cell.colspan - 1) as i32;
1112
1113            let mut total_cell_width = (coordinate.x..coordinate.x + cell.colspan)
1114                .map(|column_index| self.distributed_column_widths[column_index])
1115                .sum::<Au>() -
1116                padding_border_sums.inline +
1117                border_spacing_spanned;
1118            total_cell_width = total_cell_width.max(Au::zero());
1119
1120            let preferred_aspect_ratio = cell.context.preferred_aspect_ratio(&padding_border_sums);
1121            let containing_block_for_children = ContainingBlock {
1122                size: ContainingBlockSize {
1123                    inline: total_cell_width,
1124                    block: SizeConstraint::default(),
1125                },
1126                style: &cell.context.base.style,
1127            };
1128
1129            let mut positioning_context = PositioningContext::default();
1130            let layout = cell.context.layout(
1131                layout_context,
1132                &mut positioning_context,
1133                &containing_block_for_children,
1134                containing_block_for_table,
1135                preferred_aspect_ratio,
1136                &LazySize::intrinsic(),
1137            );
1138
1139            Some(CellLayout {
1140                layout,
1141                padding,
1142                border,
1143                positioning_context,
1144            })
1145        };
1146
1147        self.cells_laid_out = if layout_context.use_rayon {
1148            self.table
1149                .slots
1150                .par_iter()
1151                .enumerate()
1152                .map(|(row_index, row_slots)| {
1153                    row_slots
1154                        .par_iter()
1155                        .enumerate()
1156                        .map(|(column_index, slot)| {
1157                            layout_table_slot(
1158                                TableSlotCoordinates::new(column_index, row_index),
1159                                slot,
1160                            )
1161                        })
1162                        .collect()
1163                })
1164                .collect()
1165        } else {
1166            self.table
1167                .slots
1168                .iter()
1169                .enumerate()
1170                .map(|(row_index, row_slots)| {
1171                    row_slots
1172                        .iter()
1173                        .enumerate()
1174                        .map(|(column_index, slot)| {
1175                            layout_table_slot(
1176                                TableSlotCoordinates::new(column_index, row_index),
1177                                slot,
1178                            )
1179                        })
1180                        .collect()
1181                })
1182                .collect()
1183        };
1184
1185        // Now go through all cells laid out and update the cell measure based on the size
1186        // determined during layout.
1187        for row_index in 0..self.table.size.height {
1188            for column_index in 0..self.table.size.width {
1189                let Some(layout) = &self.cells_laid_out[row_index][column_index] else {
1190                    continue;
1191                };
1192
1193                self.cell_measures[row_index][column_index]
1194                    .block
1195                    .content_sizes
1196                    .max_assign(layout.outer_block_size().into());
1197            }
1198        }
1199    }
1200
1201    /// Do the first layout of a table row, after laying out the cells themselves. This is
1202    /// more or less and implementation of <https://drafts.csswg.org/css-tables/#row-layout>.
1203    fn do_first_row_layout(&mut self, writing_mode: WritingMode) -> Vec<Au> {
1204        let mut row_sizes = (0..self.table.size.height)
1205            .map(|row_index| {
1206                let (mut max_ascent, mut max_descent, mut max_row_height) =
1207                    (Au::zero(), Au::zero(), Au::zero());
1208
1209                for column_index in 0..self.table.size.width {
1210                    let cell = match self.table.slots[row_index][column_index] {
1211                        TableSlot::Cell(ref cell) => cell,
1212                        _ => continue,
1213                    };
1214
1215                    let layout = match self.cells_laid_out[row_index][column_index] {
1216                        Some(ref layout) => layout,
1217                        None => {
1218                            warn!(
1219                                "Did not find a layout at a slot index with an originating cell."
1220                            );
1221                            continue;
1222                        },
1223                    };
1224
1225                    let cell = cell.borrow();
1226                    let outer_block_size = layout.outer_block_size();
1227                    if cell.rowspan == 1 {
1228                        max_row_height.max_assign(outer_block_size);
1229                    }
1230
1231                    if cell.content_alignment() == CellContentAlignment::Baseline {
1232                        let ascent = layout.ascent();
1233                        let border_padding_start =
1234                            layout.border.block_start + layout.padding.block_start;
1235                        let border_padding_end = layout.border.block_end + layout.padding.block_end;
1236                        max_ascent.max_assign(ascent + border_padding_start);
1237
1238                        // Only take into account the descent of this cell if doesn't span
1239                        // rows. The descent portion of the cell in cells that do span rows
1240                        // may extend into other rows.
1241                        if cell.rowspan == 1 {
1242                            max_descent.max_assign(
1243                                layout.layout.content_block_size - ascent + border_padding_end,
1244                            );
1245                        }
1246                    }
1247                }
1248                self.row_baselines.push(max_ascent);
1249                max_row_height.max(max_ascent + max_descent)
1250            })
1251            .collect();
1252        self.calculate_row_sizes_after_first_layout(&mut row_sizes, writing_mode);
1253        row_sizes
1254    }
1255
1256    #[allow(clippy::ptr_arg)] // Needs to be a vec because of the function above
1257    /// After doing layout of table rows, calculate final row size and distribute space across
1258    /// rowspanned cells. This follows the implementation of LayoutNG and the priority
1259    /// agorithm described at <https://github.com/w3c/csswg-drafts/issues/4418>.
1260    fn calculate_row_sizes_after_first_layout(
1261        &mut self,
1262        row_sizes: &mut Vec<Au>,
1263        writing_mode: WritingMode,
1264    ) {
1265        let mut cells_to_distribute = Vec::new();
1266        let mut total_percentage = 0.;
1267        #[allow(clippy::needless_range_loop)] // It makes sense to use it here
1268        for row_index in 0..self.table.size.height {
1269            let row_measure = self
1270                .table
1271                .get_row_measure_for_row_at_index(writing_mode, row_index);
1272            row_sizes[row_index].max_assign(row_measure.content_sizes.min_content);
1273
1274            let mut percentage = row_measure.percentage.unwrap_or_default().0;
1275            for column_index in 0..self.table.size.width {
1276                let cell_percentage = self.cell_measures[row_index][column_index]
1277                    .block
1278                    .percentage
1279                    .unwrap_or_default()
1280                    .0;
1281                percentage = percentage.max(cell_percentage);
1282
1283                let cell_measure = &self.cell_measures[row_index][column_index].block;
1284                let cell = match self.table.slots[row_index][column_index] {
1285                    TableSlot::Cell(ref cell) if cell.borrow().rowspan > 1 => cell,
1286                    TableSlot::Cell(_) => {
1287                        // If this is an originating cell, that isn't spanning, then we make sure the row is
1288                        // at least big enough to hold the cell.
1289                        row_sizes[row_index].max_assign(cell_measure.content_sizes.max_content);
1290                        continue;
1291                    },
1292                    _ => continue,
1293                };
1294
1295                cells_to_distribute.push(RowspanToDistribute {
1296                    coordinates: TableSlotCoordinates::new(column_index, row_index),
1297                    cell: cell.borrow(),
1298                    measure: cell_measure,
1299                });
1300            }
1301
1302            self.rows[row_index].percent = Percentage(percentage.min(1. - total_percentage));
1303            total_percentage += self.rows[row_index].percent.0;
1304        }
1305
1306        cells_to_distribute.sort_by(|a, b| {
1307            if a.range() == b.range() {
1308                return a
1309                    .measure
1310                    .content_sizes
1311                    .min_content
1312                    .cmp(&b.measure.content_sizes.min_content);
1313            }
1314            if a.fully_encloses(b) {
1315                return std::cmp::Ordering::Greater;
1316            }
1317            if b.fully_encloses(a) {
1318                return std::cmp::Ordering::Less;
1319            }
1320            a.coordinates.y.cmp(&b.coordinates.y)
1321        });
1322
1323        for rowspan_to_distribute in cells_to_distribute {
1324            let rows_spanned = rowspan_to_distribute.range();
1325            let current_rows_size = rows_spanned.clone().map(|index| row_sizes[index]).sum();
1326            let border_spacing_spanned =
1327                self.table.border_spacing().block * (rows_spanned.len() - 1) as i32;
1328            let excess_size = (rowspan_to_distribute.measure.content_sizes.min_content -
1329                current_rows_size -
1330                border_spacing_spanned)
1331                .max(Au::zero());
1332
1333            self.distribute_extra_size_to_rows(
1334                excess_size,
1335                rows_spanned,
1336                row_sizes,
1337                None,
1338                true, /* rowspan_distribution */
1339            );
1340        }
1341    }
1342
1343    /// An implementation of the same extra block size distribution algorithm used in
1344    /// LayoutNG and described at <https://github.com/w3c/csswg-drafts/issues/4418>.
1345    fn distribute_extra_size_to_rows(
1346        &self,
1347        mut excess_size: Au,
1348        track_range: Range<usize>,
1349        track_sizes: &mut [Au],
1350        percentage_resolution_size: Option<Au>,
1351        rowspan_distribution: bool,
1352    ) {
1353        if excess_size.is_zero() {
1354            return;
1355        }
1356
1357        let is_constrained = |track_index: &usize| self.rows[*track_index].constrained;
1358        let is_unconstrained = |track_index: &usize| !is_constrained(track_index);
1359        let is_empty: Vec<bool> = track_sizes.iter().map(|size| size.is_zero()).collect();
1360        let is_not_empty = |track_index: &usize| !is_empty[*track_index];
1361        let other_row_that_starts_a_rowspan = |track_index: &usize| {
1362            *track_index != track_range.start &&
1363                self.rows[*track_index].has_cell_with_span_greater_than_one
1364        };
1365
1366        // If we have a table height (not during rowspan distribution), first distribute to rows
1367        // that have percentage sizes proportionally to the size missing to reach the percentage
1368        // of table height required.
1369        if let Some(percentage_resolution_size) = percentage_resolution_size {
1370            let get_percent_block_size_deficit = |row_index: usize, track_size: Au| {
1371                let size_needed_for_percent =
1372                    percentage_resolution_size.scale_by(self.rows[row_index].percent.0);
1373                (size_needed_for_percent - track_size).max(Au::zero())
1374            };
1375            let percent_block_size_deficit: Au = track_range
1376                .clone()
1377                .map(|index| get_percent_block_size_deficit(index, track_sizes[index]))
1378                .sum();
1379            let percent_distributable_block_size = percent_block_size_deficit.min(excess_size);
1380            if percent_distributable_block_size > Au::zero() {
1381                for track_index in track_range.clone() {
1382                    let row_deficit =
1383                        get_percent_block_size_deficit(track_index, track_sizes[track_index]);
1384                    if row_deficit > Au::zero() {
1385                        let ratio =
1386                            row_deficit.to_f32_px() / percent_block_size_deficit.to_f32_px();
1387                        let size = percent_distributable_block_size.scale_by(ratio);
1388                        track_sizes[track_index] += size;
1389                        excess_size -= size;
1390                    }
1391                }
1392            }
1393        }
1394
1395        // If this is rowspan distribution and there are rows other than the first row that have a
1396        // cell with rowspan > 1, distribute the extra space equally to those rows.
1397        if rowspan_distribution {
1398            let rows_that_start_rowspan: Vec<usize> = track_range
1399                .clone()
1400                .filter(other_row_that_starts_a_rowspan)
1401                .collect();
1402            if !rows_that_start_rowspan.is_empty() {
1403                let scale = 1.0 / rows_that_start_rowspan.len() as f32;
1404                for track_index in rows_that_start_rowspan.iter() {
1405                    track_sizes[*track_index] += excess_size.scale_by(scale);
1406                }
1407                return;
1408            }
1409        }
1410
1411        // If there are unconstrained non-empty rows, grow them all proportionally to their current size.
1412        let unconstrained_non_empty_rows: Vec<usize> = track_range
1413            .clone()
1414            .filter(is_unconstrained)
1415            .filter(is_not_empty)
1416            .collect();
1417        if !unconstrained_non_empty_rows.is_empty() {
1418            let total_size: Au = unconstrained_non_empty_rows
1419                .iter()
1420                .map(|index| track_sizes[*index])
1421                .sum();
1422            for track_index in unconstrained_non_empty_rows.iter() {
1423                let scale = track_sizes[*track_index].to_f32_px() / total_size.to_f32_px();
1424                track_sizes[*track_index] += excess_size.scale_by(scale);
1425            }
1426            return;
1427        }
1428
1429        let (non_empty_rows, empty_rows): (Vec<usize>, Vec<usize>) =
1430            track_range.clone().partition(is_not_empty);
1431        let only_have_empty_rows = empty_rows.len() == track_range.len();
1432        if !empty_rows.is_empty() {
1433            // If this is rowspan distribution and there are only empty rows, just grow the
1434            // last one.
1435            if rowspan_distribution && only_have_empty_rows {
1436                track_sizes[*empty_rows.last().unwrap()] += excess_size;
1437                return;
1438            }
1439
1440            // Otherwise, if we only have empty rows or if all the non-empty rows are constrained,
1441            // then grow the empty rows.
1442            let non_empty_rows_all_constrained = !non_empty_rows.iter().any(is_unconstrained);
1443            if only_have_empty_rows || non_empty_rows_all_constrained {
1444                // If there are both unconstrained and constrained empty rows, only increase the
1445                // size of the unconstrained ones, otherwise increase the size of all empty rows.
1446                let mut rows_to_grow = &empty_rows;
1447                let unconstrained_empty_rows: Vec<usize> = rows_to_grow
1448                    .iter()
1449                    .copied()
1450                    .filter(is_unconstrained)
1451                    .collect();
1452                if !unconstrained_empty_rows.is_empty() {
1453                    rows_to_grow = &unconstrained_empty_rows;
1454                }
1455
1456                // All empty rows that will grow equally.
1457                let scale = 1.0 / rows_to_grow.len() as f32;
1458                for track_index in rows_to_grow.iter() {
1459                    track_sizes[*track_index] += excess_size.scale_by(scale);
1460                }
1461                return;
1462            }
1463        }
1464
1465        // If there are non-empty rows, they all grow in proportion to their current size,
1466        // whether or not they are constrained.
1467        if !non_empty_rows.is_empty() {
1468            let total_size: Au = non_empty_rows.iter().map(|index| track_sizes[*index]).sum();
1469            for track_index in non_empty_rows.iter() {
1470                let scale = track_sizes[*track_index].to_f32_px() / total_size.to_f32_px();
1471                track_sizes[*track_index] += excess_size.scale_by(scale);
1472            }
1473        }
1474    }
1475
1476    /// Given computed row sizes, compute the final block size of the table and distribute extra
1477    /// block size to table rows.
1478    fn compute_table_height_and_final_row_heights(
1479        &mut self,
1480        mut row_sizes: Vec<Au>,
1481        containing_block_for_children: &ContainingBlock,
1482    ) {
1483        // The table content height is the maximum of the computed table height from style and the
1484        // sum of computed row heights from row layout plus size from borders and spacing.
1485        // TODO: for `height: stretch`, the block size of the containing block is the available
1486        // space for the entire table wrapper, but here we are using that amount for the table grid.
1487        // Therefore, if there is a caption, this will cause overflow. Gecko and WebKit have the
1488        // same problem, but not Blink.
1489        let table_height_from_style = containing_block_for_children.size.block.definite_or_min();
1490
1491        let block_border_spacing = self.table.total_border_spacing().block;
1492        let table_height_from_rows = row_sizes.iter().sum::<Au>() + block_border_spacing;
1493        self.final_table_height = table_height_from_rows.max(table_height_from_style);
1494
1495        // If the table height is defined by the rows sizes, there is no extra space to distribute
1496        // to rows.
1497        if self.final_table_height == table_height_from_rows {
1498            self.row_sizes = row_sizes;
1499            return;
1500        }
1501
1502        // There was extra block size added to the table from the table style, so distribute this
1503        // extra space to rows using the same distribution algorithm used for distributing rowspan
1504        // space.
1505        // TODO: This should first distribute space to row groups and then to rows.
1506        self.distribute_extra_size_to_rows(
1507            self.final_table_height - table_height_from_rows,
1508            0..self.table.size.height,
1509            &mut row_sizes,
1510            Some(self.final_table_height),
1511            false, /* rowspan_distribution */
1512        );
1513        self.row_sizes = row_sizes;
1514    }
1515
1516    fn layout_caption(
1517        &self,
1518        caption: &TableCaption,
1519        layout_context: &LayoutContext,
1520        parent_positioning_context: &mut PositioningContext,
1521    ) -> BoxFragment {
1522        let containing_block = &ContainingBlock {
1523            size: ContainingBlockSize {
1524                inline: self.table_width + self.pbm.padding_border_sums.inline,
1525                block: SizeConstraint::default(),
1526            },
1527            style: &self.table.style,
1528        };
1529
1530        // The parent of a caption is the table wrapper, which establishes an independent
1531        // formatting context. Therefore, we don't ignore block margins when resolving a
1532        // stretch block size. https://drafts.csswg.org/css-sizing-4/#stretch-fit-sizing
1533        let ignore_block_margins_for_stretch = LogicalSides1D::new(false, false);
1534
1535        let mut positioning_context =
1536            PositioningContext::new_for_layout_box_base(&caption.context.base);
1537        let mut box_fragment = caption.context.layout_in_flow_block_level(
1538            layout_context,
1539            positioning_context
1540                .as_mut()
1541                .unwrap_or(parent_positioning_context),
1542            containing_block,
1543            None, /* sequential_layout_state */
1544            ignore_block_margins_for_stretch,
1545        );
1546
1547        if let Some(mut positioning_context) = positioning_context.take() {
1548            positioning_context.layout_collected_children(layout_context, &mut box_fragment);
1549            parent_positioning_context.append(positioning_context);
1550        }
1551
1552        box_fragment
1553    }
1554
1555    /// Lay out the table (grid and captions) of this [`TableLayout`] into fragments. This should
1556    /// only be be called after calling [`TableLayout.compute_measures`].
1557    #[servo_tracing::instrument(name = "Table::layout", skip_all)]
1558    fn layout(
1559        mut self,
1560        layout_context: &LayoutContext,
1561        positioning_context: &mut PositioningContext,
1562        containing_block_for_children: &ContainingBlock,
1563        containing_block_for_table: &ContainingBlock,
1564    ) -> CacheableLayoutResult {
1565        let table_writing_mode = containing_block_for_children.style.writing_mode;
1566        self.compute_border_collapse(table_writing_mode);
1567        let layout_style = self.table.layout_style(Some(&self));
1568
1569        self.pbm = layout_style
1570            .padding_border_margin_with_writing_mode_and_containing_block_inline_size(
1571                table_writing_mode,
1572                containing_block_for_table.size.inline,
1573            );
1574        self.compute_measures(layout_context, table_writing_mode);
1575        self.compute_table_width(containing_block_for_children);
1576
1577        // The table wrapper is the one that has the CSS properties for the grid's border and padding. This
1578        // weirdness is difficult to express in Servo's layout system. We have the wrapper size itself as if
1579        // those properties applied to it and then just account for the discrepency in sizing here. In reality,
1580        // the wrapper does not draw borders / backgrounds and all of its content (grid and captions) are
1581        // placed with a negative offset in the table wrapper's content box so that they overlap the undrawn
1582        // border / padding area.
1583        //
1584        // TODO: This is a pretty large hack. It would be nicer to actually have the grid sized properly,
1585        // but it works for now.
1586        //
1587        // Get the padding, border, and margin of the table using the inline size of the table's containing
1588        // block but in the writing of the table itself.
1589        // TODO: This is broken for orthoganol flows, because the inline size of the parent isn't necessarily
1590        // the inline size of the table.
1591        let containing_block_for_logical_conversion = ContainingBlock {
1592            size: ContainingBlockSize {
1593                inline: self.table_width,
1594                block: containing_block_for_table.size.block,
1595            },
1596            style: containing_block_for_children.style,
1597        };
1598        let offset_from_wrapper = -self.pbm.padding - self.pbm.border;
1599        let mut current_block_offset = offset_from_wrapper.block_start;
1600
1601        let mut table_layout = CacheableLayoutResult {
1602            fragments: Vec::new(),
1603            content_block_size: Zero::zero(),
1604            content_inline_size_for_table: None,
1605            baselines: Baselines::default(),
1606            depends_on_block_constraints: true,
1607            specific_layout_info: Some(SpecificLayoutInfo::TableWrapper),
1608            collapsible_margins_in_children: CollapsedBlockMargins::zero(),
1609        };
1610
1611        #[derive(EnumIter, PartialEq)]
1612        enum TableWrapperSection {
1613            TopCaptions,
1614            Grid,
1615            BottomCaptions,
1616        }
1617        impl TableWrapperSection {
1618            fn accepts_caption(&self, caption: &TableCaption) -> bool {
1619                match caption.context.style().clone_caption_side() {
1620                    CaptionSide::Top => *self == TableWrapperSection::TopCaptions,
1621                    CaptionSide::Bottom => *self == TableWrapperSection::BottomCaptions,
1622                }
1623            }
1624        }
1625
1626        for section in TableWrapperSection::iter() {
1627            if section == TableWrapperSection::Grid {
1628                let original_positioning_context_length = positioning_context.len();
1629                let mut grid_fragment = self.layout_grid(
1630                    layout_context,
1631                    positioning_context,
1632                    &containing_block_for_logical_conversion,
1633                    containing_block_for_children,
1634                );
1635
1636                // Take the baseline of the grid fragment, after adjusting it to be in the coordinate system
1637                // of the table wrapper.
1638                let logical_grid_content_rect = grid_fragment
1639                    .content_rect()
1640                    .to_logical(&containing_block_for_logical_conversion);
1641                let grid_pbm = grid_fragment
1642                    .padding_border_margin()
1643                    .to_logical(table_writing_mode);
1644                table_layout.baselines = grid_fragment.baselines(table_writing_mode).offset(
1645                    current_block_offset +
1646                        logical_grid_content_rect.start_corner.block +
1647                        grid_pbm.block_start,
1648                );
1649
1650                grid_fragment.base.rect = LogicalRect {
1651                    start_corner: LogicalVec2 {
1652                        inline: offset_from_wrapper.inline_start + grid_pbm.inline_start,
1653                        block: current_block_offset + grid_pbm.block_start,
1654                    },
1655                    size: grid_fragment.base.rect.size.to_logical(table_writing_mode),
1656                }
1657                .as_physical(Some(&containing_block_for_logical_conversion));
1658
1659                current_block_offset += grid_fragment
1660                    .border_rect()
1661                    .size
1662                    .to_logical(table_writing_mode)
1663                    .block;
1664                if logical_grid_content_rect.size.inline < self.table_width {
1665                    // This can happen when collapsing columns
1666                    table_layout.content_inline_size_for_table =
1667                        Some(logical_grid_content_rect.size.inline);
1668                }
1669
1670                let grid_fragment = Fragment::Box(ArcRefCell::new(grid_fragment));
1671                positioning_context.adjust_static_position_of_hoisted_fragments(
1672                    &grid_fragment,
1673                    original_positioning_context_length,
1674                );
1675                table_layout.fragments.push(grid_fragment);
1676            } else {
1677                let caption_fragments = self.table.captions.iter().filter_map(|caption| {
1678                    let caption = caption.borrow();
1679                    if !section.accepts_caption(&caption) {
1680                        return None;
1681                    }
1682
1683                    let original_positioning_context_length = positioning_context.len();
1684                    let mut caption_fragment =
1685                        self.layout_caption(&caption, layout_context, positioning_context);
1686
1687                    // The caption is not placed yet. Construct a rectangle for it in the adjusted containing block
1688                    // for the table children and only then convert the result to physical geometry.
1689                    let caption_pbm = caption_fragment
1690                        .padding_border_margin()
1691                        .to_logical(table_writing_mode);
1692
1693                    let caption_style = caption_fragment.style().clone();
1694                    let caption_relative_offset = match caption_style.clone_position() {
1695                        Position::Relative => {
1696                            relative_adjustement(&caption_style, containing_block_for_children)
1697                        },
1698                        _ => LogicalVec2::zero(),
1699                    };
1700
1701                    caption_fragment.base.rect = LogicalRect {
1702                        start_corner: LogicalVec2 {
1703                            inline: offset_from_wrapper.inline_start + caption_pbm.inline_start,
1704                            block: current_block_offset + caption_pbm.block_start,
1705                        } + caption_relative_offset,
1706                        size: caption_fragment
1707                            .content_rect()
1708                            .size
1709                            .to_logical(table_writing_mode),
1710                    }
1711                    .as_physical(Some(&containing_block_for_logical_conversion));
1712
1713                    current_block_offset += caption_fragment
1714                        .margin_rect()
1715                        .size
1716                        .to_logical(table_writing_mode)
1717                        .block;
1718
1719                    let caption_fragment = Fragment::Box(ArcRefCell::new(caption_fragment));
1720                    positioning_context.adjust_static_position_of_hoisted_fragments(
1721                        &caption_fragment,
1722                        original_positioning_context_length,
1723                    );
1724
1725                    caption.context.base.set_fragment(caption_fragment.clone());
1726                    Some(caption_fragment)
1727                });
1728                table_layout.fragments.extend(caption_fragments);
1729            }
1730        }
1731
1732        table_layout.content_block_size = current_block_offset + offset_from_wrapper.block_end;
1733        table_layout
1734    }
1735
1736    /// Lay out the grid portion of this [`TableLayout`] into fragments. This should only be be
1737    /// called after calling [`TableLayout.compute_measures`].
1738    fn layout_grid(
1739        &mut self,
1740        layout_context: &LayoutContext,
1741        positioning_context: &mut PositioningContext,
1742        containing_block_for_logical_conversion: &ContainingBlock,
1743        containing_block_for_children: &ContainingBlock,
1744    ) -> BoxFragment {
1745        self.distributed_column_widths =
1746            Self::distribute_width_to_columns(self.assignable_width, &self.columns);
1747        self.layout_cells_in_row(layout_context, containing_block_for_children);
1748        let table_writing_mode = containing_block_for_children.style.writing_mode;
1749        let first_layout_row_heights = self.do_first_row_layout(table_writing_mode);
1750        self.compute_table_height_and_final_row_heights(
1751            first_layout_row_heights,
1752            containing_block_for_children,
1753        );
1754
1755        assert_eq!(self.table.size.height, self.row_sizes.len());
1756        assert_eq!(self.table.size.width, self.distributed_column_widths.len());
1757
1758        if self.table.size.width == 0 && self.table.size.height == 0 {
1759            let content_rect = LogicalRect {
1760                start_corner: LogicalVec2::zero(),
1761                size: LogicalVec2 {
1762                    inline: self.table_width,
1763                    block: self.final_table_height,
1764                },
1765            }
1766            .as_physical(Some(containing_block_for_logical_conversion));
1767            return BoxFragment::new(
1768                self.table.grid_base_fragment_info,
1769                self.table.grid_style.clone(),
1770                Vec::new(),
1771                content_rect,
1772                self.pbm.padding.to_physical(table_writing_mode),
1773                self.pbm.border.to_physical(table_writing_mode),
1774                PhysicalSides::zero(),
1775                self.specific_layout_info_for_grid(),
1776            );
1777        }
1778
1779        let mut table_fragments = Vec::new();
1780        let table_and_track_dimensions = TableAndTrackDimensions::new(self);
1781        self.make_fragments_for_columns_and_column_groups(
1782            &table_and_track_dimensions,
1783            &mut table_fragments,
1784        );
1785
1786        let mut baselines = Baselines::default();
1787        let mut row_group_fragment_layout = None;
1788        for row_index in 0..self.table.size.height {
1789            // From <https://drafts.csswg.org/css-align-3/#baseline-export>
1790            // > If any cells in the row participate in first baseline/last baseline alignment along
1791            // > the inline axis, the first/last baseline set of the row is generated from their
1792            // > shared alignment baseline and the row’s first available font, after alignment has
1793            // > been performed. Otherwise, the first/last baseline set of the row is synthesized from
1794            // > the lowest and highest content edges of the cells in the row. [CSS2]
1795            //
1796            // If any cell below has baseline alignment, these values will be overwritten,
1797            // but they are initialized to the content edge of the first row.
1798            if row_index == 0 {
1799                let row_end = table_and_track_dimensions
1800                    .get_row_rect(0)
1801                    .max_block_position();
1802                baselines.first = Some(row_end);
1803                baselines.last = Some(row_end);
1804            }
1805
1806            let row_is_collapsed = self.is_row_collapsed(row_index);
1807            let table_row = self.table.rows[row_index].borrow();
1808            let mut row_fragment_layout = RowFragmentLayout::new(
1809                &table_row,
1810                row_index,
1811                &table_and_track_dimensions,
1812                &self.table.style,
1813            );
1814
1815            let old_row_group_index = row_group_fragment_layout
1816                .as_ref()
1817                .map(|layout: &RowGroupFragmentLayout| layout.index);
1818            if table_row.group_index != old_row_group_index {
1819                // First create the Fragment for any existing RowGroupFragmentLayout.
1820                if let Some(old_row_group_layout) = row_group_fragment_layout.take() {
1821                    table_fragments.push(old_row_group_layout.finish(
1822                        layout_context,
1823                        positioning_context,
1824                        containing_block_for_logical_conversion,
1825                        containing_block_for_children,
1826                    ));
1827                }
1828
1829                // Then, create a new RowGroupFragmentLayout for the current and potentially subsequent rows.
1830                if let Some(new_group_index) = table_row.group_index {
1831                    row_group_fragment_layout = Some(RowGroupFragmentLayout::new(
1832                        self.table.row_groups[new_group_index].clone(),
1833                        new_group_index,
1834                        &table_and_track_dimensions,
1835                    ));
1836                }
1837            }
1838
1839            let column_indices = 0..self.table.size.width;
1840            row_fragment_layout.fragments.reserve(self.table.size.width);
1841            for column_index in column_indices {
1842                self.do_final_cell_layout(
1843                    row_index,
1844                    column_index,
1845                    &table_and_track_dimensions,
1846                    &mut baselines,
1847                    &mut row_fragment_layout,
1848                    row_group_fragment_layout.as_mut(),
1849                    positioning_context,
1850                    self.is_column_collapsed(column_index) || row_is_collapsed,
1851                );
1852            }
1853
1854            let row_fragment = row_fragment_layout.finish(
1855                layout_context,
1856                positioning_context,
1857                containing_block_for_logical_conversion,
1858                containing_block_for_children,
1859                &mut row_group_fragment_layout,
1860            );
1861
1862            match row_group_fragment_layout.as_mut() {
1863                Some(layout) => layout.fragments.push(row_fragment),
1864                None => table_fragments.push(row_fragment),
1865            }
1866        }
1867
1868        if let Some(row_group_layout) = row_group_fragment_layout.take() {
1869            table_fragments.push(row_group_layout.finish(
1870                layout_context,
1871                positioning_context,
1872                containing_block_for_logical_conversion,
1873                containing_block_for_children,
1874            ));
1875        }
1876
1877        let content_rect = LogicalRect {
1878            start_corner: LogicalVec2::zero(),
1879            size: LogicalVec2 {
1880                inline: table_and_track_dimensions.table_rect.max_inline_position(),
1881                block: table_and_track_dimensions.table_rect.max_block_position(),
1882            },
1883        }
1884        .as_physical(Some(containing_block_for_logical_conversion));
1885        BoxFragment::new(
1886            self.table.grid_base_fragment_info,
1887            self.table.grid_style.clone(),
1888            table_fragments,
1889            content_rect,
1890            self.pbm.padding.to_physical(table_writing_mode),
1891            self.pbm.border.to_physical(table_writing_mode),
1892            PhysicalSides::zero(),
1893            self.specific_layout_info_for_grid(),
1894        )
1895        .with_baselines(baselines)
1896    }
1897
1898    fn specific_layout_info_for_grid(&mut self) -> Option<SpecificLayoutInfo> {
1899        mem::take(&mut self.collapsed_borders).map(|mut collapsed_borders| {
1900            // TODO: It would probably be better to use `TableAndTrackDimensions`, since that
1901            // has already taken care of collapsed tracks and knows the final track positions.
1902            let mut track_sizes = LogicalVec2 {
1903                inline: mem::take(&mut self.distributed_column_widths),
1904                block: mem::take(&mut self.row_sizes),
1905            };
1906            for (column_index, column_size) in track_sizes.inline.iter_mut().enumerate() {
1907                if self.is_column_collapsed(column_index) {
1908                    mem::take(column_size);
1909                }
1910            }
1911            for (row_index, row_size) in track_sizes.block.iter_mut().enumerate() {
1912                if self.is_row_collapsed(row_index) {
1913                    mem::take(row_size);
1914                }
1915            }
1916            let writing_mode = self.table.style.writing_mode;
1917            if !writing_mode.is_bidi_ltr() {
1918                track_sizes.inline.reverse();
1919                collapsed_borders.inline.reverse();
1920                for border_line in &mut collapsed_borders.block {
1921                    border_line.reverse();
1922                }
1923            }
1924            SpecificLayoutInfo::TableGridWithCollapsedBorders(Box::new(SpecificTableGridInfo {
1925                collapsed_borders: if writing_mode.is_horizontal() {
1926                    PhysicalVec::new(collapsed_borders.inline, collapsed_borders.block)
1927                } else {
1928                    PhysicalVec::new(collapsed_borders.block, collapsed_borders.inline)
1929                },
1930                track_sizes: if writing_mode.is_horizontal() {
1931                    PhysicalVec::new(track_sizes.inline, track_sizes.block)
1932                } else {
1933                    PhysicalVec::new(track_sizes.block, track_sizes.inline)
1934                },
1935            }))
1936        })
1937    }
1938
1939    fn is_row_collapsed(&self, row_index: usize) -> bool {
1940        let Some(row) = &self.table.rows.get(row_index) else {
1941            return false;
1942        };
1943
1944        let row = row.borrow();
1945        if row.base.style.get_inherited_box().visibility == Visibility::Collapse {
1946            return true;
1947        }
1948        let row_group = match row.group_index {
1949            Some(group_index) => self.table.row_groups[group_index].borrow(),
1950            None => return false,
1951        };
1952        row_group.base.style.get_inherited_box().visibility == Visibility::Collapse
1953    }
1954
1955    fn is_column_collapsed(&self, column_index: usize) -> bool {
1956        let Some(column) = &self.table.columns.get(column_index) else {
1957            return false;
1958        };
1959        let column = column.borrow();
1960        if column.base.style.get_inherited_box().visibility == Visibility::Collapse {
1961            return true;
1962        }
1963        let col_group = match column.group_index {
1964            Some(group_index) => self.table.column_groups[group_index].borrow(),
1965            None => return false,
1966        };
1967        col_group.base.style.get_inherited_box().visibility == Visibility::Collapse
1968    }
1969
1970    #[allow(clippy::too_many_arguments)]
1971    fn do_final_cell_layout(
1972        &mut self,
1973        row_index: usize,
1974        column_index: usize,
1975        dimensions: &TableAndTrackDimensions,
1976        baselines: &mut Baselines,
1977        row_fragment_layout: &mut RowFragmentLayout,
1978        row_group_fragment_layout: Option<&mut RowGroupFragmentLayout>,
1979        positioning_context_for_table: &mut PositioningContext,
1980        is_collapsed: bool,
1981    ) {
1982        // The PositioningContext for cells is, in order or preference, the PositioningContext of the row,
1983        // the PositioningContext of the row group, or the PositioningContext of the table.
1984        let row_group_positioning_context =
1985            row_group_fragment_layout.and_then(|layout| layout.positioning_context.as_mut());
1986        let positioning_context = row_fragment_layout
1987            .positioning_context
1988            .as_mut()
1989            .or(row_group_positioning_context)
1990            .unwrap_or(positioning_context_for_table);
1991
1992        let layout = match self.cells_laid_out[row_index][column_index].take() {
1993            Some(layout) => layout,
1994            None => {
1995                return;
1996            },
1997        };
1998        let cell = match self.table.slots[row_index][column_index] {
1999            TableSlot::Cell(ref cell) => cell,
2000            _ => {
2001                warn!("Did not find a non-spanned cell at index with layout.");
2002                return;
2003            },
2004        }
2005        .borrow();
2006
2007        // If this cell has baseline alignment, it can adjust the table's overall baseline.
2008        let row_block_offset = row_fragment_layout.rect.start_corner.block;
2009        let row_baseline = self.row_baselines[row_index];
2010        if cell.content_alignment() == CellContentAlignment::Baseline && !layout.is_empty() {
2011            let baseline = row_block_offset + row_baseline;
2012            if row_index == 0 {
2013                baselines.first = Some(baseline);
2014            }
2015            baselines.last = Some(baseline);
2016        }
2017        let mut row_relative_cell_rect = dimensions.get_cell_rect(
2018            TableSlotCoordinates::new(column_index, row_index),
2019            cell.rowspan,
2020            cell.colspan,
2021        );
2022        row_relative_cell_rect.start_corner -= row_fragment_layout.rect.start_corner;
2023        let mut fragment = cell.create_fragment(
2024            layout,
2025            row_relative_cell_rect,
2026            row_baseline,
2027            positioning_context,
2028            &self.table.style,
2029            &row_fragment_layout.containing_block,
2030            is_collapsed,
2031        );
2032
2033        // Make a table part rectangle relative to the row fragment for the purposes of
2034        // drawing extra backgrounds.
2035        //
2036        // This rectangle is an offset between the row fragment and the other table
2037        // part rectangle (row group, column, column group). Everything between them
2038        // is laid out in a left-to-right fashion, but respecting the verticality of
2039        // the writing mode. This is why below, only the axes are flipped, but the
2040        // rectangle is not flipped for RTL.
2041        let make_relative_to_row_start = |mut rect: LogicalRect<Au>| {
2042            rect.start_corner -= row_fragment_layout.rect.start_corner;
2043            let writing_mode = self.table.style.writing_mode;
2044            PhysicalRect::new(
2045                if writing_mode.is_horizontal() {
2046                    PhysicalPoint::new(rect.start_corner.inline, rect.start_corner.block)
2047                } else {
2048                    PhysicalPoint::new(rect.start_corner.block, rect.start_corner.inline)
2049                },
2050                rect.size.to_physical_size(writing_mode),
2051            )
2052        };
2053
2054        let column = self.table.columns.get(column_index);
2055        let column_group = column
2056            .and_then(|column| column.borrow().group_index)
2057            .and_then(|index| self.table.column_groups.get(index));
2058        if let Some(column_group) = column_group {
2059            let column_group = column_group.borrow();
2060            let rect = make_relative_to_row_start(dimensions.get_column_group_rect(&column_group));
2061            fragment.add_extra_background(ExtraBackground {
2062                style: column_group.shared_background_style.clone(),
2063                rect,
2064            })
2065        }
2066        if let Some(column) = column {
2067            let column = column.borrow();
2068            if !column.is_anonymous {
2069                let rect = make_relative_to_row_start(dimensions.get_column_rect(column_index));
2070                fragment.add_extra_background(ExtraBackground {
2071                    style: column.shared_background_style.clone(),
2072                    rect,
2073                })
2074            }
2075        }
2076        let row = self.table.rows.get(row_index);
2077        let row_group = row
2078            .and_then(|row| row.borrow().group_index)
2079            .and_then(|index| self.table.row_groups.get(index));
2080        if let Some(row_group) = row_group {
2081            let rect =
2082                make_relative_to_row_start(dimensions.get_row_group_rect(&row_group.borrow()));
2083            fragment.add_extra_background(ExtraBackground {
2084                style: row_group.borrow().shared_background_style.clone(),
2085                rect,
2086            })
2087        }
2088        if let Some(row) = row {
2089            let row = row.borrow();
2090            let rect = make_relative_to_row_start(row_fragment_layout.rect);
2091            fragment.add_extra_background(ExtraBackground {
2092                style: row.shared_background_style.clone(),
2093                rect,
2094            })
2095        }
2096
2097        let fragment = Fragment::Box(ArcRefCell::new(fragment));
2098        cell.context.base.set_fragment(fragment.clone());
2099        row_fragment_layout.fragments.push(fragment);
2100    }
2101
2102    fn make_fragments_for_columns_and_column_groups(
2103        &self,
2104        dimensions: &TableAndTrackDimensions,
2105        fragments: &mut Vec<Fragment>,
2106    ) {
2107        for column_group in self.table.column_groups.iter() {
2108            let column_group = column_group.borrow();
2109            if !column_group.is_empty() {
2110                let fragment = Fragment::Positioning(PositioningFragment::new_empty(
2111                    column_group.base.base_fragment_info,
2112                    dimensions
2113                        .get_column_group_rect(&column_group)
2114                        .as_physical(None),
2115                    column_group.base.style.clone(),
2116                ));
2117                column_group.base.set_fragment(fragment.clone());
2118                fragments.push(fragment);
2119            }
2120        }
2121
2122        for (column_index, column) in self.table.columns.iter().enumerate() {
2123            let column = column.borrow();
2124            let fragment = Fragment::Positioning(PositioningFragment::new_empty(
2125                column.base.base_fragment_info,
2126                dimensions.get_column_rect(column_index).as_physical(None),
2127                column.base.style.clone(),
2128            ));
2129            column.base.set_fragment(fragment.clone());
2130            fragments.push(fragment);
2131        }
2132    }
2133
2134    fn compute_border_collapse(&mut self, writing_mode: WritingMode) {
2135        if self.table.style.get_inherited_table().border_collapse != BorderCollapse::Collapse {
2136            self.collapsed_borders = None;
2137            return;
2138        }
2139
2140        let mut collapsed_borders = LogicalVec2 {
2141            block: vec![
2142                vec![Default::default(); self.table.size.width];
2143                self.table.size.height + 1
2144            ],
2145            inline: vec![
2146                vec![Default::default(); self.table.size.height];
2147                self.table.size.width + 1
2148            ],
2149        };
2150
2151        let apply_border = |collapsed_borders: &mut CollapsedBorders,
2152                            layout_style: &LayoutStyle,
2153                            block: &Range<usize>,
2154                            inline: &Range<usize>| {
2155            let border = CollapsedBorder::from_layout_style(layout_style, writing_mode);
2156            border
2157                .block_start
2158                .max_assign_to_slice(&mut collapsed_borders.block[block.start][inline.clone()]);
2159            border
2160                .block_end
2161                .max_assign_to_slice(&mut collapsed_borders.block[block.end][inline.clone()]);
2162            border
2163                .inline_start
2164                .max_assign_to_slice(&mut collapsed_borders.inline[inline.start][block.clone()]);
2165            border
2166                .inline_end
2167                .max_assign_to_slice(&mut collapsed_borders.inline[inline.end][block.clone()]);
2168        };
2169        let hide_inner_borders = |collapsed_borders: &mut CollapsedBorders,
2170                                  block: &Range<usize>,
2171                                  inline: &Range<usize>| {
2172            for x in inline.clone() {
2173                for y in block.clone() {
2174                    if x != inline.start {
2175                        collapsed_borders.inline[x][y].hide();
2176                    }
2177                    if y != block.start {
2178                        collapsed_borders.block[y][x].hide();
2179                    }
2180                }
2181            }
2182        };
2183        let all_rows = 0..self.table.size.height;
2184        let all_columns = 0..self.table.size.width;
2185        for row_index in all_rows.clone() {
2186            for column_index in all_columns.clone() {
2187                let cell = match self.table.slots[row_index][column_index] {
2188                    TableSlot::Cell(ref cell) => cell,
2189                    _ => continue,
2190                }
2191                .borrow();
2192                let block_range = row_index..row_index + cell.rowspan;
2193                let inline_range = column_index..column_index + cell.colspan;
2194                hide_inner_borders(&mut collapsed_borders, &block_range, &inline_range);
2195                apply_border(
2196                    &mut collapsed_borders,
2197                    &cell.context.layout_style(),
2198                    &block_range,
2199                    &inline_range,
2200                );
2201            }
2202        }
2203        for (row_index, row) in self.table.rows.iter().enumerate() {
2204            let row = row.borrow();
2205            apply_border(
2206                &mut collapsed_borders,
2207                &row.layout_style(),
2208                &(row_index..row_index + 1),
2209                &all_columns,
2210            );
2211        }
2212        for row_group in &self.table.row_groups {
2213            let row_group = row_group.borrow();
2214            apply_border(
2215                &mut collapsed_borders,
2216                &row_group.layout_style(),
2217                &row_group.track_range,
2218                &all_columns,
2219            );
2220        }
2221        for (column_index, column) in self.table.columns.iter().enumerate() {
2222            let column = column.borrow();
2223            apply_border(
2224                &mut collapsed_borders,
2225                &column.layout_style(),
2226                &all_rows,
2227                &(column_index..column_index + 1),
2228            );
2229        }
2230        for column_group in &self.table.column_groups {
2231            let column_group = column_group.borrow();
2232            apply_border(
2233                &mut collapsed_borders,
2234                &column_group.layout_style(),
2235                &all_rows,
2236                &column_group.track_range,
2237            );
2238        }
2239        apply_border(
2240            &mut collapsed_borders,
2241            &self.table.layout_style_for_grid(),
2242            &all_rows,
2243            &all_columns,
2244        );
2245
2246        self.collapsed_borders = Some(collapsed_borders);
2247    }
2248
2249    fn get_collapsed_border_widths_for_area(
2250        &self,
2251        area: LogicalSides<usize>,
2252    ) -> Option<LogicalSides<Au>> {
2253        let collapsed_borders = self.collapsed_borders.as_ref()?;
2254        let columns = || area.inline_start..area.inline_end;
2255        let rows = || area.block_start..area.block_end;
2256        let max_width = |slice: &[CollapsedBorder]| {
2257            let slice_widths = slice.iter().map(|collapsed_border| collapsed_border.width);
2258            slice_widths.max().unwrap_or_default()
2259        };
2260        Some(area.map_inline_and_block_axes(
2261            |column| max_width(&collapsed_borders.inline[*column][rows()]) / 2,
2262            |row| max_width(&collapsed_borders.block[*row][columns()]) / 2,
2263        ))
2264    }
2265}
2266
2267struct RowFragmentLayout<'a> {
2268    row: &'a TableTrack,
2269    rect: LogicalRect<Au>,
2270    containing_block: ContainingBlock<'a>,
2271    positioning_context: Option<PositioningContext>,
2272    fragments: Vec<Fragment>,
2273}
2274
2275impl<'a> RowFragmentLayout<'a> {
2276    fn new(
2277        table_row: &'a TableTrack,
2278        index: usize,
2279        dimensions: &TableAndTrackDimensions,
2280        table_style: &'a ComputedValues,
2281    ) -> Self {
2282        let rect = dimensions.get_row_rect(index);
2283        let containing_block = ContainingBlock {
2284            size: ContainingBlockSize {
2285                inline: rect.size.inline,
2286                block: SizeConstraint::Definite(rect.size.block),
2287            },
2288            style: table_style,
2289        };
2290        Self {
2291            row: table_row,
2292            rect,
2293            positioning_context: PositioningContext::new_for_layout_box_base(&table_row.base),
2294            containing_block,
2295            fragments: Vec::new(),
2296        }
2297    }
2298    fn finish(
2299        mut self,
2300        layout_context: &LayoutContext,
2301        table_positioning_context: &mut PositioningContext,
2302        containing_block_for_logical_conversion: &ContainingBlock,
2303        containing_block_for_children: &ContainingBlock,
2304        row_group_fragment_layout: &mut Option<RowGroupFragmentLayout>,
2305    ) -> Fragment {
2306        if self.positioning_context.is_some() {
2307            self.rect.start_corner +=
2308                relative_adjustement(&self.row.base.style, containing_block_for_children);
2309        }
2310
2311        let (inline_size, block_size) = if let Some(row_group_layout) = row_group_fragment_layout {
2312            self.rect.start_corner -= row_group_layout.rect.start_corner;
2313            (
2314                row_group_layout.rect.size.inline,
2315                SizeConstraint::Definite(row_group_layout.rect.size.block),
2316            )
2317        } else {
2318            (
2319                containing_block_for_logical_conversion.size.inline,
2320                containing_block_for_logical_conversion.size.block,
2321            )
2322        };
2323
2324        let row_group_containing_block = ContainingBlock {
2325            size: ContainingBlockSize {
2326                inline: inline_size,
2327                block: block_size,
2328            },
2329            style: containing_block_for_logical_conversion.style,
2330        };
2331
2332        let mut row_fragment = BoxFragment::new(
2333            self.row.base.base_fragment_info,
2334            self.row.base.style.clone(),
2335            self.fragments,
2336            self.rect.as_physical(Some(&row_group_containing_block)),
2337            PhysicalSides::zero(), /* padding */
2338            PhysicalSides::zero(), /* border */
2339            PhysicalSides::zero(), /* margin */
2340            None,                  /* specific_layout_info */
2341        );
2342        row_fragment.set_does_not_paint_background();
2343
2344        if let Some(mut row_positioning_context) = self.positioning_context.take() {
2345            row_positioning_context.layout_collected_children(layout_context, &mut row_fragment);
2346
2347            let parent_positioning_context = row_group_fragment_layout
2348                .as_mut()
2349                .and_then(|layout| layout.positioning_context.as_mut())
2350                .unwrap_or(table_positioning_context);
2351            parent_positioning_context.append(row_positioning_context);
2352        }
2353
2354        let fragment = Fragment::Box(ArcRefCell::new(row_fragment));
2355        self.row.base.set_fragment(fragment.clone());
2356        fragment
2357    }
2358}
2359
2360struct RowGroupFragmentLayout {
2361    row_group: ArcRefCell<TableTrackGroup>,
2362    rect: LogicalRect<Au>,
2363    positioning_context: Option<PositioningContext>,
2364    index: usize,
2365    fragments: Vec<Fragment>,
2366}
2367
2368impl RowGroupFragmentLayout {
2369    fn new(
2370        row_group: ArcRefCell<TableTrackGroup>,
2371        index: usize,
2372        dimensions: &TableAndTrackDimensions,
2373    ) -> Self {
2374        let (rect, positioning_context) = {
2375            let row_group = row_group.borrow();
2376            (
2377                dimensions.get_row_group_rect(&row_group),
2378                PositioningContext::new_for_layout_box_base(&row_group.base),
2379            )
2380        };
2381        Self {
2382            row_group,
2383            rect,
2384            positioning_context,
2385            index,
2386            fragments: Vec::new(),
2387        }
2388    }
2389
2390    fn finish(
2391        mut self,
2392        layout_context: &LayoutContext,
2393        table_positioning_context: &mut PositioningContext,
2394        containing_block_for_logical_conversion: &ContainingBlock,
2395        containing_block_for_children: &ContainingBlock,
2396    ) -> Fragment {
2397        let row_group = self.row_group.borrow();
2398        if self.positioning_context.is_some() {
2399            self.rect.start_corner +=
2400                relative_adjustement(&row_group.base.style, containing_block_for_children);
2401        }
2402
2403        let mut row_group_fragment = BoxFragment::new(
2404            row_group.base.base_fragment_info,
2405            row_group.base.style.clone(),
2406            self.fragments,
2407            self.rect
2408                .as_physical(Some(containing_block_for_logical_conversion)),
2409            PhysicalSides::zero(), /* padding */
2410            PhysicalSides::zero(), /* border */
2411            PhysicalSides::zero(), /* margin */
2412            None,                  /* specific_layout_info */
2413        );
2414        row_group_fragment.set_does_not_paint_background();
2415
2416        if let Some(mut row_positioning_context) = self.positioning_context.take() {
2417            row_positioning_context
2418                .layout_collected_children(layout_context, &mut row_group_fragment);
2419            table_positioning_context.append(row_positioning_context);
2420        }
2421
2422        let fragment = Fragment::Box(ArcRefCell::new(row_group_fragment));
2423        row_group.base.set_fragment(fragment.clone());
2424        fragment
2425    }
2426}
2427
2428struct TableAndTrackDimensions {
2429    /// The rect of the full table, not counting for borders, padding, and margin.
2430    table_rect: LogicalRect<Au>,
2431    /// The rect of the full table, not counting for borders, padding, and margin
2432    /// and offset by any border spacing and caption.
2433    table_cells_rect: LogicalRect<Au>,
2434    /// The min and max block offsets of each table row.
2435    row_dimensions: Vec<(Au, Au)>,
2436    /// The min and max inline offsets of each table column
2437    column_dimensions: Vec<(Au, Au)>,
2438}
2439
2440impl TableAndTrackDimensions {
2441    fn new(table_layout: &TableLayout) -> Self {
2442        let border_spacing = table_layout.table.border_spacing();
2443
2444        // The sizes used for a dimension when that dimension has no table tracks.
2445        let fallback_inline_size = table_layout.assignable_width;
2446        let fallback_block_size = table_layout.final_table_height;
2447
2448        let mut column_dimensions = Vec::new();
2449        let mut column_offset = Au::zero();
2450        for column_index in 0..table_layout.table.size.width {
2451            if table_layout.is_column_collapsed(column_index) {
2452                column_dimensions.push((column_offset, column_offset));
2453                continue;
2454            }
2455            let start_offset = column_offset + border_spacing.inline;
2456            let end_offset = start_offset + table_layout.distributed_column_widths[column_index];
2457            column_dimensions.push((start_offset, end_offset));
2458            column_offset = end_offset;
2459        }
2460        column_offset += if table_layout.table.size.width == 0 {
2461            fallback_inline_size
2462        } else {
2463            border_spacing.inline
2464        };
2465
2466        let mut row_dimensions = Vec::new();
2467        let mut row_offset = Au::zero();
2468        for row_index in 0..table_layout.table.size.height {
2469            if table_layout.is_row_collapsed(row_index) {
2470                row_dimensions.push((row_offset, row_offset));
2471                continue;
2472            }
2473            let start_offset = row_offset + border_spacing.block;
2474            let end_offset = start_offset + table_layout.row_sizes[row_index];
2475            row_dimensions.push((start_offset, end_offset));
2476            row_offset = end_offset;
2477        }
2478        row_offset += if table_layout.table.size.height == 0 {
2479            fallback_block_size
2480        } else {
2481            border_spacing.block
2482        };
2483
2484        let table_start_corner = LogicalVec2 {
2485            inline: column_dimensions.first().map_or_else(Au::zero, |v| v.0),
2486            block: row_dimensions.first().map_or_else(Au::zero, |v| v.0),
2487        };
2488        let table_size = LogicalVec2 {
2489            inline: column_dimensions
2490                .last()
2491                .map_or(fallback_inline_size, |v| v.1),
2492            block: row_dimensions.last().map_or(fallback_block_size, |v| v.1),
2493        } - table_start_corner;
2494        let table_cells_rect = LogicalRect {
2495            start_corner: table_start_corner,
2496            size: table_size,
2497        };
2498
2499        let table_rect = LogicalRect {
2500            start_corner: LogicalVec2::zero(),
2501            size: LogicalVec2 {
2502                inline: column_offset,
2503                block: row_offset,
2504            },
2505        };
2506
2507        Self {
2508            table_rect,
2509            table_cells_rect,
2510            row_dimensions,
2511            column_dimensions,
2512        }
2513    }
2514
2515    fn get_row_rect(&self, row_index: usize) -> LogicalRect<Au> {
2516        let mut row_rect = self.table_cells_rect;
2517        let row_dimensions = self.row_dimensions[row_index];
2518        row_rect.start_corner.block = row_dimensions.0;
2519        row_rect.size.block = row_dimensions.1 - row_dimensions.0;
2520        row_rect
2521    }
2522
2523    fn get_column_rect(&self, column_index: usize) -> LogicalRect<Au> {
2524        let mut row_rect = self.table_cells_rect;
2525        let column_dimensions = self.column_dimensions[column_index];
2526        row_rect.start_corner.inline = column_dimensions.0;
2527        row_rect.size.inline = column_dimensions.1 - column_dimensions.0;
2528        row_rect
2529    }
2530
2531    fn get_row_group_rect(&self, row_group: &TableTrackGroup) -> LogicalRect<Au> {
2532        if row_group.is_empty() {
2533            return LogicalRect::zero();
2534        }
2535
2536        let mut row_group_rect = self.table_cells_rect;
2537        let block_start = self.row_dimensions[row_group.track_range.start].0;
2538        let block_end = self.row_dimensions[row_group.track_range.end - 1].1;
2539        row_group_rect.start_corner.block = block_start;
2540        row_group_rect.size.block = block_end - block_start;
2541        row_group_rect
2542    }
2543
2544    fn get_column_group_rect(&self, column_group: &TableTrackGroup) -> LogicalRect<Au> {
2545        if column_group.is_empty() {
2546            return LogicalRect::zero();
2547        }
2548
2549        let mut column_group_rect = self.table_cells_rect;
2550        let inline_start = self.column_dimensions[column_group.track_range.start].0;
2551        let inline_end = self.column_dimensions[column_group.track_range.end - 1].1;
2552        column_group_rect.start_corner.inline = inline_start;
2553        column_group_rect.size.inline = inline_end - inline_start;
2554        column_group_rect
2555    }
2556
2557    fn get_cell_rect(
2558        &self,
2559        coordinates: TableSlotCoordinates,
2560        rowspan: usize,
2561        colspan: usize,
2562    ) -> LogicalRect<Au> {
2563        let start_corner = LogicalVec2 {
2564            inline: self.column_dimensions[coordinates.x].0,
2565            block: self.row_dimensions[coordinates.y].0,
2566        };
2567        let size = LogicalVec2 {
2568            inline: self.column_dimensions[coordinates.x + colspan - 1].1,
2569            block: self.row_dimensions[coordinates.y + rowspan - 1].1,
2570        } - start_corner;
2571        LogicalRect { start_corner, size }
2572    }
2573}
2574
2575impl Table {
2576    fn border_spacing(&self) -> LogicalVec2<Au> {
2577        if self.style.clone_border_collapse() == BorderCollapse::Collapse {
2578            LogicalVec2::zero()
2579        } else {
2580            let border_spacing = self.style.clone_border_spacing();
2581            LogicalVec2 {
2582                inline: border_spacing.horizontal(),
2583                block: border_spacing.vertical(),
2584            }
2585        }
2586    }
2587
2588    fn total_border_spacing(&self) -> LogicalVec2<Au> {
2589        let border_spacing = self.border_spacing();
2590        LogicalVec2 {
2591            inline: if self.size.width > 0 {
2592                border_spacing.inline * (self.size.width as i32 + 1)
2593            } else {
2594                Au::zero()
2595            },
2596            block: if self.size.height > 0 {
2597                border_spacing.block * (self.size.height as i32 + 1)
2598            } else {
2599                Au::zero()
2600            },
2601        }
2602    }
2603
2604    fn get_column_measure_for_column_at_index(
2605        &self,
2606        writing_mode: WritingMode,
2607        column_index: usize,
2608        is_in_fixed_mode: bool,
2609    ) -> CellOrTrackMeasure {
2610        let column = match self.columns.get(column_index) {
2611            Some(column) => column,
2612            None => return CellOrTrackMeasure::zero(),
2613        }
2614        .borrow();
2615
2616        let CellOrColumnOuterSizes {
2617            preferred: preferred_size,
2618            min: min_size,
2619            max: max_size,
2620            percentage: percentage_size,
2621        } = CellOrColumnOuterSizes::new(
2622            &column.base.style,
2623            writing_mode,
2624            &Default::default(),
2625            is_in_fixed_mode,
2626        );
2627
2628        CellOrTrackMeasure {
2629            content_sizes: ContentSizes {
2630                // > The outer min-content width of a table-column or table-column-group is
2631                // > max(min-width, width).
2632                // But that's clearly wrong, since it would be equal to or greater than
2633                // the outer max-content width. So we match other browsers instead.
2634                min_content: min_size.inline,
2635                // > The outer max-content width of a table-column or table-column-group is
2636                // > max(min-width, min(max-width, width)).
2637                // This matches Gecko, but Blink and WebKit ignore max_size.
2638                max_content: preferred_size
2639                    .inline
2640                    .clamp_between_extremums(min_size.inline, max_size.inline),
2641            },
2642            percentage: percentage_size.inline,
2643        }
2644    }
2645
2646    fn get_row_measure_for_row_at_index(
2647        &self,
2648        writing_mode: WritingMode,
2649        row_index: usize,
2650    ) -> CellOrTrackMeasure {
2651        let row = match self.rows.get(row_index) {
2652            Some(row) => row,
2653            None => return CellOrTrackMeasure::zero(),
2654        };
2655
2656        // In the block axis, the min-content and max-content sizes are the same
2657        // (except for new layout boxes like grid and flex containers). Note that
2658        // other browsers don't seem to use the min and max sizing properties here.
2659        let row = row.borrow();
2660        let size = row.base.style.box_size(writing_mode);
2661        let max_size = row.base.style.max_box_size(writing_mode);
2662        let percentage_contribution = get_size_percentage_contribution(&size, &max_size);
2663
2664        CellOrTrackMeasure {
2665            content_sizes: size
2666                .block
2667                .to_numeric()
2668                .and_then(|size| size.to_length())
2669                .map_or_else(Au::zero, Au::from)
2670                .into(),
2671            percentage: percentage_contribution.block,
2672        }
2673    }
2674
2675    pub(crate) fn layout(
2676        &self,
2677        layout_context: &LayoutContext,
2678        positioning_context: &mut PositioningContext,
2679        containing_block_for_children: &ContainingBlock,
2680        containing_block_for_table: &ContainingBlock,
2681    ) -> CacheableLayoutResult {
2682        TableLayout::new(self).layout(
2683            layout_context,
2684            positioning_context,
2685            containing_block_for_children,
2686            containing_block_for_table,
2687        )
2688    }
2689
2690    pub(crate) fn attached_to_tree(&self, layout_box: WeakLayoutBox) {
2691        for caption in &self.captions {
2692            caption
2693                .borrow_mut()
2694                .context
2695                .base
2696                .parent_box
2697                .replace(layout_box.clone());
2698        }
2699        for row_group in &self.row_groups {
2700            row_group
2701                .borrow_mut()
2702                .base
2703                .parent_box
2704                .replace(layout_box.clone());
2705        }
2706        for column_group in &self.column_groups {
2707            column_group
2708                .borrow_mut()
2709                .base
2710                .parent_box
2711                .replace(layout_box.clone());
2712        }
2713        for row in &self.rows {
2714            let row = &mut *row.borrow_mut();
2715            if let Some(group_index) = row.group_index {
2716                row.base.parent_box.replace(WeakLayoutBox::TableLevelBox(
2717                    WeakTableLevelBox::TrackGroup(self.row_groups[group_index].downgrade()),
2718                ));
2719            } else {
2720                row.base.parent_box.replace(layout_box.clone());
2721            }
2722        }
2723        for column in &self.columns {
2724            let column = &mut *column.borrow_mut();
2725            if let Some(group_index) = column.group_index {
2726                column.base.parent_box.replace(WeakLayoutBox::TableLevelBox(
2727                    WeakTableLevelBox::TrackGroup(self.column_groups[group_index].downgrade()),
2728                ));
2729            } else {
2730                column.base.parent_box.replace(layout_box.clone());
2731            }
2732        }
2733        for row_index in 0..self.size.height {
2734            let row = WeakLayoutBox::TableLevelBox(WeakTableLevelBox::Track(
2735                self.rows[row_index].downgrade(),
2736            ));
2737            for column_index in 0..self.size.width {
2738                if let TableSlot::Cell(ref cell) = self.slots[row_index][column_index] {
2739                    cell.borrow_mut()
2740                        .context
2741                        .base
2742                        .parent_box
2743                        .replace(row.clone());
2744                }
2745            }
2746        }
2747    }
2748}
2749
2750impl ComputeInlineContentSizes for Table {
2751    #[servo_tracing::instrument(name = "Table::compute_inline_content_sizes", skip_all)]
2752    fn compute_inline_content_sizes(
2753        &self,
2754        layout_context: &LayoutContext,
2755        constraint_space: &ConstraintSpace,
2756    ) -> InlineContentSizesResult {
2757        let writing_mode = constraint_space.style.writing_mode;
2758        let mut layout = TableLayout::new(self);
2759        layout.compute_border_collapse(writing_mode);
2760        layout.pbm = self
2761            .layout_style(Some(&layout))
2762            .padding_border_margin_with_writing_mode_and_containing_block_inline_size(
2763                writing_mode,
2764                Au::zero(),
2765            );
2766        layout.compute_measures(layout_context, writing_mode);
2767
2768        let grid_content_sizes = layout.compute_grid_min_max();
2769
2770        // Padding and border should apply to the table grid, but they will be taken into
2771        // account when computing the inline content sizes of the table wrapper (our parent), so
2772        // this code removes their contribution from the inline content size of the caption.
2773        let caption_content_sizes = ContentSizes::from(
2774            layout.compute_caption_minimum_inline_size(layout_context) -
2775                layout.pbm.padding_border_sums.inline,
2776        );
2777
2778        InlineContentSizesResult {
2779            sizes: grid_content_sizes.max(caption_content_sizes),
2780            depends_on_block_constraints: false,
2781        }
2782    }
2783}
2784
2785impl Table {
2786    #[inline]
2787    pub(crate) fn layout_style<'a>(
2788        &'a self,
2789        layout: Option<&'a TableLayout<'a>>,
2790    ) -> LayoutStyle<'a> {
2791        LayoutStyle::Table(TableLayoutStyle {
2792            table: self,
2793            layout,
2794        })
2795    }
2796
2797    #[inline]
2798    pub(crate) fn layout_style_for_grid(&self) -> LayoutStyle<'_> {
2799        LayoutStyle::Default(&self.grid_style)
2800    }
2801}
2802
2803impl TableTrack {
2804    #[inline]
2805    pub(crate) fn layout_style(&self) -> LayoutStyle<'_> {
2806        LayoutStyle::Default(&self.base.style)
2807    }
2808}
2809
2810impl TableTrackGroup {
2811    #[inline]
2812    pub(crate) fn layout_style(&self) -> LayoutStyle<'_> {
2813        LayoutStyle::Default(&self.base.style)
2814    }
2815}
2816
2817impl TableLayoutStyle<'_> {
2818    #[inline]
2819    pub(crate) fn style(&self) -> &ComputedValues {
2820        &self.table.style
2821    }
2822
2823    #[inline]
2824    pub(crate) fn collapses_borders(&self) -> bool {
2825        self.style().get_inherited_table().border_collapse == BorderCollapse::Collapse
2826    }
2827
2828    pub(crate) fn halved_collapsed_border_widths(&self) -> LogicalSides<Au> {
2829        debug_assert!(self.collapses_borders());
2830        let area = LogicalSides {
2831            inline_start: 0,
2832            inline_end: self.table.size.width,
2833            block_start: 0,
2834            block_end: self.table.size.height,
2835        };
2836        if let Some(layout) = self.layout {
2837            layout.get_collapsed_border_widths_for_area(area)
2838        } else {
2839            // TODO: this should be cached.
2840            let mut layout = TableLayout::new(self.table);
2841            layout.compute_border_collapse(self.style().writing_mode);
2842            layout.get_collapsed_border_widths_for_area(area)
2843        }
2844        .expect("Collapsed borders should be computed")
2845    }
2846}
2847
2848impl TableSlotCell {
2849    fn content_alignment(&self) -> CellContentAlignment {
2850        // The spec still assumes that `vertical-align` is a longhand, so it's not very clear
2851        // if this logic is completely correct, but it seems to match Firefox.
2852        // <https://github.com/w3c/csswg-drafts/issues/13458>
2853        let style_box = self.context.base.style.get_box();
2854        match style_box.baseline_shift {
2855            BaselineShift::Keyword(BaselineShiftKeyword::Top) => CellContentAlignment::Top,
2856            BaselineShift::Keyword(BaselineShiftKeyword::Bottom) => CellContentAlignment::Bottom,
2857            _ => match style_box.alignment_baseline {
2858                AlignmentBaseline::Middle => CellContentAlignment::Middle,
2859                _ => CellContentAlignment::Baseline,
2860            },
2861        }
2862    }
2863
2864    #[allow(clippy::too_many_arguments)]
2865    fn create_fragment(
2866        &self,
2867        mut layout: CellLayout,
2868        cell_rect: LogicalRect<Au>,
2869        cell_baseline: Au,
2870        positioning_context: &mut PositioningContext,
2871        table_style: &ComputedValues,
2872        containing_block: &ContainingBlock,
2873        is_collapsed: bool,
2874    ) -> BoxFragment {
2875        // This must be scoped to this function because it conflicts with euclid's Zero.
2876        use style::Zero as StyleZero;
2877
2878        let cell_content_rect = cell_rect.deflate(&(layout.padding + layout.border));
2879        let content_block_size = layout.layout.content_block_size;
2880        let free_space = || Au::zero().max(cell_content_rect.size.block - content_block_size);
2881        let vertical_align_offset = match self.content_alignment() {
2882            CellContentAlignment::Top => Au::zero(),
2883            CellContentAlignment::Bottom => free_space(),
2884            CellContentAlignment::Middle => free_space().scale_by(0.5),
2885            CellContentAlignment::Baseline => {
2886                cell_baseline -
2887                    (layout.padding.block_start + layout.border.block_start) -
2888                    layout.ascent()
2889            },
2890        };
2891
2892        let mut base_fragment_info = self.context.base.base_fragment_info;
2893        if self.context.base.style.get_inherited_table().empty_cells == EmptyCells::Hide &&
2894            table_style.get_inherited_table().border_collapse != BorderCollapse::Collapse &&
2895            layout.is_empty_for_empty_cells()
2896        {
2897            base_fragment_info.flags.insert(FragmentFlags::DO_NOT_PAINT);
2898        }
2899
2900        if is_collapsed {
2901            base_fragment_info.flags.insert(FragmentFlags::IS_COLLAPSED);
2902        }
2903
2904        // Create an `AnonymousFragment` to move the cell contents to the cell baseline.
2905        let mut vertical_align_fragment_rect = cell_content_rect;
2906        vertical_align_fragment_rect.start_corner = LogicalVec2 {
2907            inline: Au::zero(),
2908            block: vertical_align_offset,
2909        };
2910        let vertical_align_fragment = PositioningFragment::new_anonymous(
2911            self.context.base.style.clone(),
2912            vertical_align_fragment_rect.as_physical(None),
2913            layout.layout.fragments,
2914        );
2915
2916        // Adjust the static position of all absolute children based on the
2917        // final content rect of this fragment. Note that we are not shifting by the position of the
2918        // Anonymous fragment we use to shift content to the baseline.
2919        //
2920        // TODO(mrobinson): This is correct for absolutes that are direct children of the table
2921        // cell, but wrong for absolute fragments that are more deeply nested in the hierarchy of
2922        // fragments.
2923        let physical_cell_rect = cell_content_rect.as_physical(Some(containing_block));
2924        layout
2925            .positioning_context
2926            .adjust_static_position_of_hoisted_fragments_with_offset(
2927                &physical_cell_rect.origin.to_vector(),
2928                PositioningContextLength::zero(),
2929            );
2930        positioning_context.append(layout.positioning_context);
2931
2932        let specific_layout_info = (table_style.get_inherited_table().border_collapse ==
2933            BorderCollapse::Collapse)
2934            .then_some(SpecificLayoutInfo::TableCellWithCollapsedBorders);
2935
2936        BoxFragment::new(
2937            base_fragment_info,
2938            self.context.base.style.clone(),
2939            vec![Fragment::Positioning(vertical_align_fragment)],
2940            physical_cell_rect,
2941            layout.padding.to_physical(table_style.writing_mode),
2942            layout.border.to_physical(table_style.writing_mode),
2943            PhysicalSides::zero(), /* margin */
2944            specific_layout_info,
2945        )
2946        .with_baselines(layout.layout.baselines)
2947    }
2948}
2949
2950fn get_size_percentage_contribution(
2951    size: &LogicalVec2<Size<ComputedLengthPercentage>>,
2952    max_size: &LogicalVec2<Size<ComputedLengthPercentage>>,
2953) -> LogicalVec2<Option<Percentage>> {
2954    // From <https://drafts.csswg.org/css-tables/#percentage-contribution>
2955    // > The percentage contribution of a table cell, column, or column group is defined
2956    // > in terms of the computed values of width and max-width that have computed values
2957    // > that are percentages:
2958    // >    min(percentage width, percentage max-width).
2959    // > If the computed values are not percentages, then 0% is used for width, and an
2960    // > infinite percentage is used for max-width.
2961    LogicalVec2 {
2962        inline: max_two_optional_percentages(
2963            size.inline.to_percentage(),
2964            max_size.inline.to_percentage(),
2965        ),
2966        block: max_two_optional_percentages(
2967            size.block.to_percentage(),
2968            max_size.block.to_percentage(),
2969        ),
2970    }
2971}
2972
2973struct CellOrColumnOuterSizes {
2974    min: LogicalVec2<Au>,
2975    preferred: LogicalVec2<Au>,
2976    max: LogicalVec2<Option<Au>>,
2977    percentage: LogicalVec2<Option<Percentage>>,
2978}
2979
2980impl CellOrColumnOuterSizes {
2981    fn new(
2982        style: &Arc<ComputedValues>,
2983        writing_mode: WritingMode,
2984        padding_border_sums: &LogicalVec2<Au>,
2985        is_in_fixed_mode: bool,
2986    ) -> Self {
2987        let box_sizing = style.get_position().box_sizing;
2988        let outer_size = |size: LogicalVec2<Au>| match box_sizing {
2989            BoxSizing::ContentBox => size + *padding_border_sums,
2990            BoxSizing::BorderBox => LogicalVec2 {
2991                inline: size.inline.max(padding_border_sums.inline),
2992                block: size.block.max(padding_border_sums.block),
2993            },
2994        };
2995
2996        let outer_option_size = |size: LogicalVec2<Option<Au>>| match box_sizing {
2997            BoxSizing::ContentBox => size.map_inline_and_block_axes(
2998                |inline| inline.map(|inline| inline + padding_border_sums.inline),
2999                |block| block.map(|block| block + padding_border_sums.block),
3000            ),
3001            BoxSizing::BorderBox => size.map_inline_and_block_axes(
3002                |inline| inline.map(|inline| inline.max(padding_border_sums.inline)),
3003                |block| block.map(|block| block.max(padding_border_sums.block)),
3004            ),
3005        };
3006
3007        let get_size_for_axis = |size: &Size<ComputedLengthPercentage>| {
3008            // Note that measures treat all size values other than <length>
3009            // as the initial value of the property.
3010            size.to_numeric()
3011                .and_then(|length_percentage| length_percentage.to_length())
3012                .map(Au::from)
3013        };
3014
3015        let size = style.box_size(writing_mode);
3016        if is_in_fixed_mode {
3017            return Self {
3018                percentage: size.map(|v| v.to_percentage()),
3019                preferred: outer_option_size(size.map(get_size_for_axis))
3020                    .map(|v| v.unwrap_or_default()),
3021                min: LogicalVec2::default(),
3022                max: LogicalVec2::default(),
3023            };
3024        }
3025
3026        let min_size = style.min_box_size(writing_mode);
3027        let max_size = style.max_box_size(writing_mode);
3028
3029        Self {
3030            min: outer_size(min_size.map(|v| get_size_for_axis(v).unwrap_or_default())),
3031            preferred: outer_size(size.map(|v| get_size_for_axis(v).unwrap_or_default())),
3032            max: outer_option_size(max_size.map(get_size_for_axis)),
3033            percentage: get_size_percentage_contribution(&size, &max_size),
3034        }
3035    }
3036}
3037
3038struct RowspanToDistribute<'a> {
3039    coordinates: TableSlotCoordinates,
3040    cell: AtomicRef<'a, TableSlotCell>,
3041    measure: &'a CellOrTrackMeasure,
3042}
3043
3044impl RowspanToDistribute<'_> {
3045    fn range(&self) -> Range<usize> {
3046        self.coordinates.y..self.coordinates.y + self.cell.rowspan
3047    }
3048
3049    fn fully_encloses(&self, other: &RowspanToDistribute) -> bool {
3050        other.coordinates.y > self.coordinates.y && other.range().end < self.range().end
3051    }
3052}
3053
3054/// The inline size constraints provided by a cell that span multiple columns (`colspan` > 1).
3055/// These constraints are distributed to the individual columns that make up this cell's span.
3056#[derive(Debug)]
3057struct ColspanToDistribute {
3058    starting_column: usize,
3059    span: usize,
3060    content_sizes: ContentSizes,
3061    percentage: Option<Percentage>,
3062}
3063
3064impl ColspanToDistribute {
3065    /// A comparison function to sort the colspan cell constraints primarily by their span
3066    /// width and secondarily by their starting column. This is not an implementation of
3067    /// `PartialOrd` because we want to return [`Ordering::Equal`] even if `self != other`.
3068    fn comparison_for_sort(a: &Self, b: &Self) -> Ordering {
3069        a.span
3070            .cmp(&b.span)
3071            .then_with(|| a.starting_column.cmp(&b.starting_column))
3072    }
3073
3074    fn range(&self) -> Range<usize> {
3075        self.starting_column..self.starting_column + self.span
3076    }
3077}
3078
3079#[cfg(test)]
3080mod test {
3081    use app_units::MIN_AU;
3082
3083    use super::*;
3084    use crate::sizing::ContentSizes;
3085
3086    #[test]
3087    fn test_colspan_to_distribute_first_sort_by_span() {
3088        let a = ColspanToDistribute {
3089            starting_column: 0,
3090            span: 0,
3091            content_sizes: ContentSizes {
3092                min_content: MIN_AU,
3093                max_content: MIN_AU,
3094            },
3095            percentage: None,
3096        };
3097
3098        let b = ColspanToDistribute {
3099            starting_column: 0,
3100            span: 1,
3101            content_sizes: ContentSizes {
3102                min_content: MIN_AU,
3103                max_content: MIN_AU,
3104            },
3105            percentage: None,
3106        };
3107
3108        let ordering = ColspanToDistribute::comparison_for_sort(&a, &b);
3109        assert_eq!(ordering, Ordering::Less);
3110    }
3111
3112    #[test]
3113    fn test_colspan_to_distribute_if_spans_are_equal_sort_by_starting_column() {
3114        let a = ColspanToDistribute {
3115            starting_column: 0,
3116            span: 0,
3117            content_sizes: ContentSizes {
3118                min_content: MIN_AU,
3119                max_content: MIN_AU,
3120            },
3121            percentage: None,
3122        };
3123
3124        let b = ColspanToDistribute {
3125            starting_column: 1,
3126            span: 0,
3127            content_sizes: ContentSizes {
3128                min_content: MIN_AU,
3129                max_content: MIN_AU,
3130            },
3131            percentage: None,
3132        };
3133
3134        let ordering = ColspanToDistribute::comparison_for_sort(&a, &b);
3135        assert_eq!(ordering, Ordering::Less);
3136    }
3137}