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