servo/components/layout_2020/table/layout.rs
atbrakhi 8ba251c95f
layout: make padding and border use Au in pbm (#31289)
* use au for padding and border in pbm

* review fix
2024-02-12 22:49:50 +00:00

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
use std::ops::Add;
use app_units::{Au, MAX_AU};
use euclid::num::Zero;
use log::warn;
use style::computed_values::border_collapse::T as BorderCollapse;
use style::logical_geometry::WritingMode;
use style::values::computed::{CSSPixelLength, Length, LengthOrAuto, Percentage};
use style::values::generics::box_::{GenericVerticalAlign as VerticalAlign, VerticalAlignKeyword};
use style::values::generics::length::GenericLengthPercentageOrAuto::{Auto, LengthPercentage};
use super::{Table, TableSlot, TableSlotCell};
use crate::context::LayoutContext;
use crate::formatting_contexts::{Baselines, IndependentLayout};
use crate::fragment_tree::{AnonymousFragment, BoxFragment, CollapsedBlockMargins, Fragment};
use crate::geom::{LogicalRect, LogicalSides, LogicalVec2};
use crate::positioned::{PositioningContext, PositioningContextLength};
use crate::sizing::ContentSizes;
use crate::style_ext::{Clamp, ComputedValuesExt, PaddingBorderMargin};
use crate::table::TableSlotCoordinates;
use crate::ContainingBlock;
/// A result of a final or speculative layout of a single cell in
/// the table. Note that this is only done for slots that are not
/// covered by spans or empty.
struct CellLayout {
layout: IndependentLayout,
padding: LogicalSides<Length>,
border: LogicalSides<Length>,
positioning_context: PositioningContext,
}
impl CellLayout {
fn ascent(&self) -> Au {
self.layout
.baselines
.first
.unwrap_or(self.layout.content_block_size)
}
/// The block size of this laid out cell including its border and padding.
fn outer_block_size(&self) -> Au {
self.layout.content_block_size + (self.border.block_sum() + self.padding.block_sum()).into()
}
}
/// A helper struct that performs the layout of the box tree version
/// of a table into the fragment tree version. This implements
/// <https://drafts.csswg.org/css-tables/#table-layout-algorithm>
struct TableLayout<'a> {
table: &'a Table,
pbm: PaddingBorderMargin,
column_constrainedness: Vec<bool>,
column_has_originating_cell: Vec<bool>,
cell_measures: Vec<Vec<CellOrColumnMeasure>>,
assignable_width: Au,
column_measures: Vec<CellOrColumnMeasure>,
distributed_column_widths: Vec<Au>,
row_sizes: Vec<Au>,
row_baselines: Vec<Au>,
cells_laid_out: Vec<Vec<Option<CellLayout>>>,
}
#[derive(Clone, Debug)]
struct CellOrColumnMeasure {
content_sizes: ContentSizes,
percentage_width: Percentage,
}
impl CellOrColumnMeasure {
fn zero() -> Self {
Self {
content_sizes: ContentSizes::zero(),
percentage_width: Percentage(0.),
}
}
}
impl<'a> TableLayout<'a> {
fn new(table: &'a Table) -> TableLayout {
Self {
table,
pbm: PaddingBorderMargin::zero(),
column_constrainedness: Vec::new(),
column_has_originating_cell: Vec::new(),
cell_measures: Vec::new(),
assignable_width: Au::zero(),
column_measures: Vec::new(),
distributed_column_widths: Vec::new(),
row_sizes: Vec::new(),
row_baselines: Vec::new(),
cells_laid_out: Vec::new(),
}
}
/// Do the preparatory steps to table layout, measuring cells and distributing sizes
/// to all columns and rows.
fn compute_measures(
&mut self,
layout_context: &LayoutContext,
positioning_context: &mut PositioningContext,
containing_block: &ContainingBlock,
) {
let writing_mode = containing_block.style.writing_mode;
self.compute_column_constrainedness_and_has_originating_cells(writing_mode);
self.compute_cell_measures(layout_context, containing_block);
self.compute_column_measures();
self.compute_table_width(containing_block);
self.distributed_column_widths = self.distribute_width_to_columns();
self.do_row_layout_first_pass(layout_context, containing_block, positioning_context);
self.distribute_height_to_rows();
}
/// This is an implementation of *Computing Cell Measures* from
/// <https://drafts.csswg.org/css-tables/#computing-cell-measures>.
pub(crate) fn compute_cell_measures(
&mut self,
layout_context: &LayoutContext,
containing_block: &ContainingBlock,
) {
let writing_mode = containing_block.style.writing_mode;
for row_index in 0..self.table.size.height {
let mut row_measures = vec![CellOrColumnMeasure::zero(); self.table.size.width];
for column_index in 0..self.table.size.width {
let cell = match self.table.slots[row_index][column_index] {
TableSlot::Cell(ref cell) => cell,
_ => continue,
};
// TODO: Should `box_size` percentages be treated as zero here or resolved against
// the containing block?
let pbm = cell.style.padding_border_margin(containing_block);
let min_inline_size: Au = cell
.style
.min_box_size(writing_mode)
.inline
.percentage_relative_to(Length::zero())
.map(|value| value.into())
.auto_is(Au::zero);
let max_inline_size: Au = cell.style.max_box_size(writing_mode).inline.map_or_else(
|| MAX_AU,
|length_percentage| length_percentage.resolve(Length::zero()).into(),
);
let inline_size: Au = cell
.style
.box_size(writing_mode)
.inline
.percentage_relative_to(Length::zero())
.map(|value| value.into())
.auto_is(Au::zero);
let content_sizes = cell
.contents
.contents
.inline_content_sizes(layout_context, writing_mode);
// > The outer min-content width of a table-cell is max(min-width, min-content width)
// > adjusted by the cell intrinsic offsets.
let mut outer_min_content_width = content_sizes.min_content.max(min_inline_size);
let mut outer_max_content_width = if !self.column_constrainedness[column_index] {
// > The outer max-content width of a table-cell in a non-constrained column is
// > max(min-width, width, min-content width, min(max-width, max-content width))
// > adjusted by the cell intrinsic offsets.
min_inline_size
.max(inline_size)
.max(content_sizes.min_content)
.max(max_inline_size.min(content_sizes.max_content))
} else {
// > The outer max-content width of a table-cell in a constrained column is
// > max(min-width, width, min-content width, min(max-width, width)) adjusted by the
// > cell intrinsic offsets.
min_inline_size
.max(inline_size)
.max(content_sizes.min_content)
.max(max_inline_size.min(inline_size))
};
// > The percentage contribution of a table cell, column, or column group is defined
// > in terms of the computed values of width and max-width that have computed values
// > that are percentages:
// > min(percentage width, percentage max-width).
// > If the computed values are not percentages, then 0% is used for width, and an
// > infinite percentage is used for max-width.
let inline_size_percent = cell
.style
.box_size(writing_mode)
.inline
.non_auto()
.and_then(|length_percentage| length_percentage.to_percentage())
.unwrap_or(Percentage(0.));
let max_inline_size_percent = cell
.style
.max_box_size(writing_mode)
.inline
.and_then(|length_percentage| length_percentage.to_percentage())
.unwrap_or(Percentage(f32::INFINITY));
let percentage_contribution =
Percentage(inline_size_percent.0.min(max_inline_size_percent.0));
outer_min_content_width += pbm.padding_border_sums.inline;
outer_max_content_width += pbm.padding_border_sums.inline;
row_measures[column_index] = CellOrColumnMeasure {
content_sizes: ContentSizes {
min_content: outer_min_content_width,
max_content: outer_max_content_width,
},
percentage_width: percentage_contribution,
};
}
self.cell_measures.push(row_measures);
}
}
/// Compute the constrainedness of every column in the table.
///
/// > A column is constrained if its corresponding table-column-group (if any), its
/// > corresponding table-column (if any), or any of the cells spanning only that
/// > column has a computed width that is not "auto", and is not a percentage.
fn compute_column_constrainedness_and_has_originating_cells(
&mut self,
writing_mode: WritingMode,
) {
for column_index in 0..self.table.size.width {
let mut column_constrained = false;
let mut column_has_originating_cell = false;
for row_index in 0..self.table.size.height {
let coords = TableSlotCoordinates::new(column_index, row_index);
let cell_constrained = match self.table.resolve_first_cell(coords) {
Some(cell) if cell.colspan == 1 => cell
.style
.box_size(writing_mode)
.inline
.non_auto()
.map(|length_percentage| length_percentage.to_length().is_some())
.unwrap_or(false),
_ => false,
};
column_has_originating_cell = column_has_originating_cell ||
matches!(self.table.get_slot(coords), Some(TableSlot::Cell(_)));
column_constrained = column_constrained || cell_constrained;
}
self.column_constrainedness.push(column_constrained);
self.column_has_originating_cell
.push(column_has_originating_cell);
}
}
/// This is an implementation of *Computing Column Measures* from
/// <https://drafts.csswg.org/css-tables/#computing-column-measures>.
fn compute_column_measures(&mut self) {
let mut column_measures = Vec::new();
// Compute the column measures only taking into account cells with colspan == 1.
// This is the base case that will be used to iteratively account for cells with
// larger colspans afterward.
//
// > min-content width of a column based on cells of span up to 1
// > The largest of:
// > - the width specified for the column:
// > - the outer min-content width of its corresponding table-column,
// > if any (and not auto)
// > - the outer min-content width of its corresponding table-column-group, if any
// > - or 0, if there is none
// > - the outer min-content width of each cell that spans the column whose colSpan
// > is 1 (or just the one in the first row in fixed mode) or 0 if there is none
// >
// > max-content width of a column based on cells of span up to 1
// > The largest of:
// > - the outer max-content width of its corresponding
// > table-column-group, if any
// > - the outer max-content width of its corresponding table-column, if any
// > - the outer max-content width of each cell that spans the column
// > whose colSpan is 1 (or just the one in the first row if in fixed mode) or 0
// > if there is no such cell
// >
// > intrinsic percentage width of a column based on cells of span up to 1
// > The largest of the percentage contributions of each cell that spans the column whose colSpan is
// > 1, of its corresponding table-column (if any), and of its corresponding table-column-group (if
// > any)
//
// TODO: Take into account `table-column` and `table-column-group` lengths.
// TODO: Take into account changes to this computation for fixed table layout.
let mut next_span_n = usize::MAX;
for column_index in 0..self.table.size.width {
let mut column_measure = CellOrColumnMeasure::zero();
for row_index in 0..self.table.size.height {
let coords = TableSlotCoordinates::new(column_index, row_index);
match self.table.resolve_first_cell(coords) {
Some(cell) if cell.colspan == 1 => cell,
Some(cell) => {
next_span_n = next_span_n.min(cell.colspan);
continue;
},
_ => continue,
};
// This takes the max of `min_content`, `max_content`, and
// intrinsic percentage width as described above.
let cell_measure = &self.cell_measures[row_index][column_index];
column_measure
.content_sizes
.max_assign(cell_measure.content_sizes);
column_measure.percentage_width = Percentage(
column_measure
.percentage_width
.0
.max(cell_measure.percentage_width.0),
);
}
column_measures.push(column_measure);
}
// Now we have the base computation complete, so iteratively take into account cells
// with higher colspan. Using `next_span_n` we can skip over span counts that don't
// correspond to any cells.
while next_span_n < usize::MAX {
(next_span_n, column_measures) = self
.compute_content_sizes_for_columns_with_span_up_to_n(next_span_n, &column_measures);
}
// > intrinsic percentage width of a column:
// > the smaller of:
// > * the intrinsic percentage width of the column based on cells of span up to N,
// > where N is the number of columns in the table
// > * 100% minus the sum of the intrinsic percentage width of all prior columns in
// > the table (further left when direction is "ltr" (right for "rtl"))
let mut total_intrinsic_percentage_width = 0.;
for column_index in 0..self.table.size.width {
let column_measure = &mut column_measures[column_index];
let final_intrinsic_percentage_width = column_measure
.percentage_width
.0
.min(100. - total_intrinsic_percentage_width);
total_intrinsic_percentage_width += final_intrinsic_percentage_width;
column_measure.percentage_width = Percentage(final_intrinsic_percentage_width);
}
self.column_measures = column_measures;
}
fn compute_content_sizes_for_columns_with_span_up_to_n(
&self,
n: usize,
old_column_measures: &[CellOrColumnMeasure],
) -> (usize, Vec<CellOrColumnMeasure>) {
let mut next_span_n = usize::MAX;
let mut new_content_sizes_for_columns = Vec::new();
let border_spacing = self.table.border_spacing();
for column_index in 0..self.table.size.width {
let old_column_measure = &old_column_measures[column_index];
let mut new_column_content_sizes = ContentSizes::zero();
let mut new_column_intrinsic_percentage_width = Percentage(0.);
for row_index in 0..self.table.size.height {
let coords = TableSlotCoordinates::new(column_index, row_index);
let resolved_coords = match self.table.resolve_first_cell_coords(coords) {
Some(resolved_coords) => resolved_coords,
None => continue,
};
let cell = match self.table.resolve_first_cell(resolved_coords) {
Some(cell) if cell.colspan <= n => cell,
Some(cell) => {
next_span_n = next_span_n.min(cell.colspan);
continue;
},
_ => continue,
};
let cell_measures = &self.cell_measures[resolved_coords.y][resolved_coords.x];
let cell_inline_content_sizes = cell_measures.content_sizes;
let columns_spanned = resolved_coords.x..resolved_coords.x + cell.colspan;
let baseline_content_sizes: ContentSizes = columns_spanned.clone().fold(
ContentSizes::zero(),
|total: ContentSizes, spanned_column_index| {
total + old_column_measures[spanned_column_index].content_sizes
},
);
let old_column_content_size = old_column_measure.content_sizes;
// > **min-content width of a column based on cells of span up to N (N > 1)**
// >
// > the largest of the min-content width of the column based on cells of span up to
// > N-1 and the contributions of the cells in the column whose colSpan is N, where
// > the contribution of a cell is the result of taking the following steps:
// >
// > 1. Define the baseline min-content width as the sum of the max-content
// > widths based on cells of span up to N-1 of all columns that the cell spans.
//
// Note: This definition is likely a typo, so we use the sum of the min-content
// widths here instead.
let baseline_min_content_width = baseline_content_sizes.min_content;
let baseline_max_content_width = baseline_content_sizes.max_content;
// > 2. Define the baseline border spacing as the sum of the horizontal
// > border-spacing for any columns spanned by the cell, other than the one in
// > which the cell originates.
let baseline_border_spacing = border_spacing.inline * (n as i32 - 1);
// > 3. The contribution of the cell is the sum of:
// > a. the min-content width of the column based on cells of span up to N-1
let a = old_column_content_size.min_content;
// > b. the product of:
// > - the ratio of:
// > - the max-content width of the column based on cells of span up
// > to N-1 of the column minus the min-content width of the
// > column based on cells of span up to N-1 of the column, to
// > - the baseline max-content width minus the baseline min-content
// > width
// > or zero if this ratio is undefined, and
// > - the outer min-content width of the cell minus the baseline
// > min-content width and the baseline border spacing, clamped to be
// > at least 0 and at most the difference between the baseline
// > max-content width and the baseline min-content width
let old_content_size_difference =
old_column_content_size.max_content - old_column_content_size.min_content;
let baseline_difference = baseline_min_content_width - baseline_max_content_width;
let mut b =
old_content_size_difference.to_f32_px() / baseline_difference.to_f32_px();
if !b.is_finite() {
b = 0.0;
}
let b = (cell_inline_content_sizes.min_content -
baseline_content_sizes.min_content -
baseline_border_spacing)
.clamp_between_extremums(Au::zero(), Some(baseline_difference))
.scale_by(b);
// > c. the product of:
// > - the ratio of the max-content width based on cells of span up to
// > N-1 of the column to the baseline max-content width
// > - the outer min-content width of the cell minus the baseline
// > max-content width and baseline border spacing, or 0 if this is
// > negative
let c = (cell_inline_content_sizes.min_content -
baseline_content_sizes.max_content -
baseline_border_spacing)
.min(Au::zero())
.scale_by(
old_column_content_size.max_content.to_f32_px() /
baseline_content_sizes.max_content.to_f32_px(),
);
let new_column_min_content_width = a + b + c;
// > **max-content width of a column based on cells of span up to N (N > 1)**
// >
// > The largest of the max-content width based on cells of span up to N-1 and the
// > contributions of the cells in the column whose colSpan is N, where the
// > contribution of a cell is the result of taking the following steps:
// > 1. Define the baseline max-content width as the sum of the max-content
// > widths based on cells of span up to N-1 of all columns that the cell spans.
//
// This is calculated above for the min-content width.
// > 2. Define the baseline border spacing as the sum of the horizontal
// > border-spacing for any columns spanned by the cell, other than the one in
// > which the cell originates.
//
// This is calculated above for min-content width.
// > 3. The contribution of the cell is the sum of:
// > a. the max-content width of the column based on cells of span up to N-1
let a = old_column_content_size.max_content;
// > b. the product of:
// > 1. the ratio of the max-content width based on cells of span up to
// > N-1 of the column to the baseline max-content width
let b_1 = old_column_content_size.max_content.to_f32_px() /
baseline_content_sizes.max_content.to_f32_px();
// > 2. the outer max-content width of the cell minus the baseline
// > max-content width and the baseline border spacing, or 0 if this
// > is negative
let b_2 = (cell_inline_content_sizes.max_content -
baseline_content_sizes.max_content -
baseline_border_spacing)
.min(Au::zero());
let b = b_2.scale_by(b_1);
let new_column_max_content_width = a + b + c;
// The computed values for the column are always the largest of any processed cell
// in that column.
new_column_content_sizes.max_assign(ContentSizes {
min_content: new_column_min_content_width,
max_content: new_column_max_content_width,
});
// > If the intrinsic percentage width of a column based on cells of span up to N-1 is
// > greater than 0%, then the intrinsic percentage width of the column based on cells
// > of span up to N is the same as the intrinsic percentage width of the column based
// > on cells of span up to N-1.
// > Otherwise, it is the largest of the contributions of the cells in the column
// > whose colSpan is N, where the contribution of a cell is the result of taking
// > the following steps:
if old_column_measure.percentage_width.0 <= 0. &&
cell_measures.percentage_width.0 != 0.
{
// > 1. Start with the percentage contribution of the cell.
// > 2. Subtract the intrinsic percentage width of the column based on cells
// > of span up to N-1 of all columns that the cell spans. If this gives a
// > negative result, change it to 0%.
let mut spanned_columns_with_zero = 0;
let other_column_percentages_sum =
(columns_spanned).fold(0., |sum, spanned_column_index| {
let spanned_column_percentage =
old_column_measures[spanned_column_index].percentage_width;
if spanned_column_percentage.0 == 0. {
spanned_columns_with_zero += 1;
}
sum + spanned_column_percentage.0
});
let step_2 = (cell_measures.percentage_width -
Percentage(other_column_percentages_sum))
.clamp_to_non_negative();
// > Multiply by the ratio of:
// > 1. the columns non-spanning max-content width to
// > 2. the sum of the non-spanning max-content widths of all columns
// > spanned by the cell that have an intrinsic percentage width of the column
// > based on cells of span up to N-1 equal to 0%.
// > However, if this ratio is undefined because the denominator is zero,
// > instead use the 1 divided by the number of columns spanned by the cell
// > that have an intrinsic percentage width of the column based on cells of
// > span up to N-1 equal to zero.
let step_3 = step_2.0 * (1.0 / spanned_columns_with_zero as f32);
new_column_intrinsic_percentage_width =
Percentage(new_column_intrinsic_percentage_width.0.max(step_3));
}
}
new_content_sizes_for_columns.push(CellOrColumnMeasure {
content_sizes: new_column_content_sizes,
percentage_width: new_column_intrinsic_percentage_width,
});
}
(next_span_n, new_content_sizes_for_columns)
}
fn compute_table_width(&mut self, containing_block: &ContainingBlock) {
// https://drafts.csswg.org/css-tables/#gridmin:
// > The row/column-grid width minimum (GRIDMIN) width is the sum of the min-content width of
// > all the columns plus cell spacing or borders.
// https://drafts.csswg.org/css-tables/#gridmax:
// > The row/column-grid width maximum (GRIDMAX) width is the sum of the max-content width of
// > all the columns plus cell spacing or borders.
let mut grid_min_and_max = self
.column_measures
.iter()
.fold(ContentSizes::zero(), |result, measure| {
result + measure.content_sizes
});
let border_spacing = self.table.border_spacing();
let inline_border_spacing = border_spacing.inline * (self.table.size.width as i32 + 1);
grid_min_and_max.min_content += inline_border_spacing;
grid_min_and_max.max_content += inline_border_spacing;
self.pbm = self.table.style.padding_border_margin(containing_block);
let content_box_size = self
.table
.style
.content_box_size(containing_block, &self.pbm);
let min_content_sizes = self
.table
.style
.content_min_box_size(containing_block, &self.pbm)
.auto_is(Length::zero);
// https://drafts.csswg.org/css-tables/#used-min-width-of-table
// > The used min-width of a table is the greater of the resolved min-width, CAPMIN, and GRIDMIN.
let used_min_width_of_table = grid_min_and_max
.min_content
.max(min_content_sizes.inline.into());
// https://drafts.csswg.org/css-tables/#used-width-of-table
// > The used width of a table depends on the columns and captions widths as follows:
// > * If the table-roots width property has a computed value (resolving to
// > resolved-table-width) other than auto, the used width is the greater of
// > resolved-table-width, and the used min-width of the table.
// > * If the table-root has 'width: auto', the used width is the greater of min(GRIDMAX,
// > the tables containing block width), the used min-width of the table.
let used_width_of_table = match content_box_size.inline {
LengthPercentage(length_percentage) => {
Au::from(length_percentage).max(used_min_width_of_table)
},
Auto => grid_min_and_max
.max_content
.min(containing_block.inline_size.into())
.max(used_min_width_of_table),
};
// > The assignable table width is the used width of the table minus the total horizontal
// > border spacing (if any). This is the width that we will be able to allocate to the
// > columns.
self.assignable_width = used_width_of_table - inline_border_spacing;
}
/// Distribute width to columns, performing step 2.4 of table layout from
/// <https://drafts.csswg.org/css-tables/#table-layout-algorithm>.
fn distribute_width_to_columns(&self) -> Vec<Au> {
if self.table.slots.is_empty() {
return Vec::new();
}
// > First, each column of the table is assigned a sizing type:
// > * percent-column: a column whose any constraint is defined to use a percentage only
// > (with a value different from 0%)
// > * pixel-column: column whose any constraint is defined to use a defined length only
// > (and is not a percent-column)
// > * auto-column: any other column
// >
// > Then, valid sizing methods are to be assigned to the columns by sizing type, yielding
// > the following sizing-guesses:
// >
// > * The min-content sizing-guess is the set of column width assignments where
// > each column is assigned its min-content width.
// > * The min-content-percentage sizing-guess is the set of column width assignments where:
// > * each percent-column is assigned the larger of:
// > * its intrinsic percentage width times the assignable width and
// > * its min-content width.
// > * all other columns are assigned their min-content width.
// > * The min-content-specified sizing-guess is the set of column width assignments where:
// > * each percent-column is assigned the larger of:
// > * its intrinsic percentage width times the assignable width and
// > * its min-content width
// > * any other column that is constrained is assigned its max-content width
// > * all other columns are assigned their min-content width.
// > * The max-content sizing-guess is the set of column width assignments where:
// > * each percent-column is assigned the larger of:
// > * its intrinsic percentage width times the assignable width and
// > * its min-content width
// > * all other columns are assigned their max-content width.
let mut min_content_sizing_guesses = Vec::new();
let mut min_content_percentage_sizing_guesses = Vec::new();
let mut min_content_specified_sizing_guesses = Vec::new();
let mut max_content_sizing_guesses = Vec::new();
for column_idx in 0..self.table.size.width {
use style::Zero;
let column_measure = &self.column_measures[column_idx];
let min_content_width = column_measure.content_sizes.min_content;
let max_content_width = column_measure.content_sizes.max_content;
let constrained = self.column_constrainedness[column_idx];
let (
min_content_percentage_sizing_guess,
min_content_specified_sizing_guess,
max_content_sizing_guess,
) = if !column_measure.percentage_width.is_zero() {
let resolved = self
.assignable_width
.scale_by(column_measure.percentage_width.0);
let percent_guess = min_content_width.max(resolved);
(percent_guess, percent_guess, percent_guess)
} else if constrained {
(min_content_width, max_content_width, max_content_width)
} else {
(min_content_width, min_content_width, max_content_width)
};
min_content_sizing_guesses.push(min_content_width);
min_content_percentage_sizing_guesses.push(min_content_percentage_sizing_guess);
min_content_specified_sizing_guesses.push(min_content_specified_sizing_guess);
max_content_sizing_guesses.push(max_content_sizing_guess);
}
// > If the assignable table width is less than or equal to the max-content sizing-guess, the
// > used widths of the columns must be the linear combination (with weights adding to 1) of
// > the two consecutive sizing-guesses whose width sums bound the available width.
//
// > Otherwise, the used widths of the columns are the result of starting from the max-content
// > sizing-guess and distributing the excess width to the columns of the table according to
// > the rules for distributing excess width to columns (for used width).
fn sum(guesses: &[Au]) -> Au {
guesses.iter().fold(Au::zero(), |sum, guess| sum + *guess)
}
let max_content_sizing_sum = sum(&max_content_sizing_guesses);
if self.assignable_width >= max_content_sizing_sum {
self.distribute_extra_width_to_columns(
&mut max_content_sizing_guesses,
max_content_sizing_sum,
);
return max_content_sizing_guesses;
}
let min_content_specified_sizing_sum = sum(&min_content_specified_sizing_guesses);
if self.assignable_width == min_content_specified_sizing_sum {
return min_content_specified_sizing_guesses;
}
let min_content_percentage_sizing_sum = sum(&min_content_percentage_sizing_guesses);
if self.assignable_width == min_content_percentage_sizing_sum {
return min_content_percentage_sizing_guesses;
}
let min_content_sizes_sum = sum(&min_content_sizing_guesses);
if self.assignable_width <= min_content_sizes_sum {
return min_content_sizing_guesses;
}
let bounds = |sum_a, sum_b| self.assignable_width > sum_a && self.assignable_width < sum_b;
let blend = |a: &[Au], sum_a: Au, b: &[Au], sum_b: Au| {
// First convert the Au units to f32 in order to do floating point division.
let weight_a =
(self.assignable_width - sum_b).to_f32_px() / (sum_a - sum_b).to_f32_px();
let weight_b = 1.0 - weight_a;
a.iter()
.zip(b.iter())
.map(|(guess_a, guess_b)| {
(guess_a.scale_by(weight_a)) + (guess_b.scale_by(weight_b))
})
.collect()
};
if bounds(min_content_sizes_sum, min_content_percentage_sizing_sum) {
return blend(
&min_content_sizing_guesses,
min_content_sizes_sum,
&min_content_percentage_sizing_guesses,
min_content_percentage_sizing_sum,
);
}
if bounds(
min_content_percentage_sizing_sum,
min_content_specified_sizing_sum,
) {
return blend(
&min_content_percentage_sizing_guesses,
min_content_percentage_sizing_sum,
&min_content_specified_sizing_guesses,
min_content_specified_sizing_sum,
);
}
assert!(bounds(
min_content_specified_sizing_sum,
max_content_sizing_sum
));
blend(
&min_content_specified_sizing_guesses,
min_content_specified_sizing_sum,
&max_content_sizing_guesses,
max_content_sizing_sum,
)
}
/// This is an implementation of *Distributing excess width to columns* from
/// <https://drafts.csswg.org/css-tables/#distributing-width-to-columns>.
fn distribute_extra_width_to_columns(&self, column_sizes: &mut Vec<Au>, column_sizes_sum: Au) {
let all_columns = 0..self.table.size.width;
let extra_inline_size = self.assignable_width - column_sizes_sum;
let has_originating_cells =
|column_index: &usize| self.column_has_originating_cell[*column_index];
let is_constrained = |column_index: &usize| self.column_constrainedness[*column_index];
let is_unconstrained = |column_index: &usize| !is_constrained(column_index);
let has_percent_greater_than_zero =
|column_index: &usize| self.column_measures[*column_index].percentage_width.0 > 0.;
let has_percent_zero = |column_index: &usize| !has_percent_greater_than_zero(column_index);
let has_max_content = |column_index: &usize| {
self.column_measures[*column_index]
.content_sizes
.max_content !=
Au(0)
};
let max_content_sum =
|column_index: usize| self.column_measures[column_index].content_sizes.max_content;
// > If there are non-constrained columns that have originating cells with intrinsic
// > percentage width of 0% and with nonzero max-content width (aka the columns allowed to
// > grow by this rule), the distributed widths of the columns allowed to grow by this rule
// > are increased in proportion to max-content width so the total increase adds to the
// > excess width.
let unconstrained_max_content_columns = all_columns
.clone()
.filter(is_unconstrained)
.filter(has_originating_cells)
.filter(has_percent_zero)
.filter(has_max_content);
let total_max_content_width = unconstrained_max_content_columns
.clone()
.map(max_content_sum)
.fold(Au::zero(), |a, b| a + b);
if total_max_content_width != Au::zero() {
for column_index in unconstrained_max_content_columns {
column_sizes[column_index] += extra_inline_size.scale_by(
self.column_measures[column_index]
.content_sizes
.max_content
.to_f32_px() /
total_max_content_width.to_f32_px(),
);
}
return;
}
// > Otherwise, if there are non-constrained columns that have originating cells with intrinsic
// > percentage width of 0% (aka the columns allowed to grow by this rule, which thanks to the
// > previous rule must have zero max-content width), the distributed widths of the columns
// > allowed to grow by this rule are increased by equal amounts so the total increase adds to
// > the excess width.V
let unconstrained_no_percent_columns = all_columns
.clone()
.filter(is_unconstrained)
.filter(has_originating_cells)
.filter(has_percent_zero);
let total_unconstrained_no_percent = unconstrained_no_percent_columns.clone().count();
if total_unconstrained_no_percent > 0 {
let extra_space_per_column =
extra_inline_size.scale_by(1.0 / total_unconstrained_no_percent as f32);
for column_index in unconstrained_no_percent_columns {
column_sizes[column_index] += extra_space_per_column;
}
return;
}
// > Otherwise, if there are constrained columns with intrinsic percentage width of 0% and
// > with nonzero max-content width (aka the columns allowed to grow by this rule, which, due
// > to other rules, must have originating cells), the distributed widths of the columns
// > allowed to grow by this rule are increased in proportion to max-content width so the
// > total increase adds to the excess width.
let constrained_max_content_columns = all_columns
.clone()
.filter(is_constrained)
.filter(has_originating_cells)
.filter(has_percent_zero)
.filter(has_max_content);
let total_max_content_width = constrained_max_content_columns
.clone()
.map(max_content_sum)
.fold(Au::zero(), |a, b| a + b);
if total_max_content_width != Au::zero() {
for column_index in constrained_max_content_columns {
column_sizes[column_index] += extra_inline_size.scale_by(
self.column_measures[column_index]
.content_sizes
.max_content
.to_f32_px() /
total_max_content_width.to_f32_px(),
);
}
return;
}
// > Otherwise, if there are columns with intrinsic percentage width greater than 0% (aka the
// > columns allowed to grow by this rule, which, due to other rules, must have originating
// > cells), the distributed widths of the columns allowed to grow by this rule are increased
// > in proportion to intrinsic percentage width so the total increase adds to the excess
// > width.
let columns_with_percentage = all_columns.clone().filter(has_percent_greater_than_zero);
let total_percent = columns_with_percentage
.clone()
.map(|column_index| self.column_measures[column_index].percentage_width.0)
.sum::<f32>();
if total_percent > 0. {
for column_index in columns_with_percentage {
column_sizes[column_index] += extra_inline_size.scale_by(
self.column_measures[column_index].percentage_width.0 / total_percent,
);
}
return;
}
// > Otherwise, if there is any such column, the distributed widths of all columns that have
// > originating cells are increased by equal amounts so the total increase adds to the excess
// > width.
let has_originating_cells_columns = all_columns.clone().filter(has_originating_cells);
let total_has_originating_cells = has_originating_cells_columns.clone().count();
if total_has_originating_cells > 0 {
let extra_space_per_column =
extra_inline_size.scale_by(1.0 / total_has_originating_cells as f32);
for column_index in has_originating_cells_columns {
column_sizes[column_index] += extra_space_per_column;
}
return;
}
// > Otherwise, the distributed widths of all columns are increased by equal amounts so the
// total increase adds to the excess width.
let extra_space_for_all_columns =
extra_inline_size.scale_by(1.0 / self.table.size.width as f32);
for guess in column_sizes.iter_mut() {
*guess += extra_space_for_all_columns;
}
}
/// This is an implementation of *Row layout (first pass)* from
/// <https://drafts.csswg.org/css-tables/#row-layout>.
fn do_row_layout_first_pass(
&mut self,
layout_context: &LayoutContext,
containing_block: &ContainingBlock,
parent_positioning_context: &mut PositioningContext,
) {
for row_index in 0..self.table.slots.len() {
let row = &self.table.slots[row_index];
let mut cells_laid_out_row = Vec::new();
for column_index in 0..row.len() {
let cell = match &row[column_index] {
TableSlot::Cell(cell) => cell,
_ => {
cells_laid_out_row.push(None);
continue;
},
};
let mut total_width = Au::zero();
for width_index in column_index..column_index + cell.colspan {
total_width += self.distributed_column_widths[width_index];
}
let border = cell.style.border_width(containing_block.style.writing_mode);
let padding = cell
.style
.padding(containing_block.style.writing_mode)
.percentages_relative_to(Length::zero());
let inline_border_padding_sum = border.inline_sum() + padding.inline_sum();
let mut total_width: CSSPixelLength =
Length::from(total_width) - inline_border_padding_sum;
total_width = total_width.max(Length::zero());
let containing_block_for_children = ContainingBlock {
inline_size: total_width,
block_size: LengthOrAuto::Auto,
style: &cell.style,
};
let collect_for_nearest_positioned_ancestor =
parent_positioning_context.collects_for_nearest_positioned_ancestor();
let mut positioning_context =
PositioningContext::new_for_subtree(collect_for_nearest_positioned_ancestor);
let layout = cell.contents.layout(
layout_context,
&mut positioning_context,
&containing_block_for_children,
);
cells_laid_out_row.push(Some(CellLayout {
layout,
padding,
border,
positioning_context,
}))
}
self.cells_laid_out.push(cells_laid_out_row);
}
}
fn distribute_height_to_rows(&mut self) {
for row_index in 0..self.table.size.height {
let (mut max_ascent, mut max_descent, mut max_row_height) =
(Au::zero(), Au::zero(), Au::zero());
for column_index in 0..self.table.size.width {
let coords = TableSlotCoordinates::new(column_index, row_index);
let cell = match self.table.slots[row_index][column_index] {
TableSlot::Cell(ref cell) => cell,
TableSlot::Spanned(ref spanned_cells) if spanned_cells[0].y != 0 => {
let offset = spanned_cells[0];
let origin = coords - offset;
// We only allocate the remaining space for the last row of the rowspanned cell.
if let Some(TableSlot::Cell(origin_cell)) = self.table.get_slot(origin) {
if origin_cell.rowspan != offset.y + 1 {
continue;
}
}
// This is all of the rows that are spanned except this one.
let used_block_size = (origin.y..coords.y)
.map(|row_index| self.row_sizes[row_index])
.fold(Au::zero(), |sum, size| sum + size);
if let Some(layout) = &self.cells_laid_out[origin.y][origin.x] {
max_row_height =
max_row_height.max(layout.outer_block_size() - used_block_size);
}
continue;
},
_ => continue,
};
let layout = match self.cells_laid_out[row_index][column_index] {
Some(ref layout) => layout,
None => {
warn!("Did not find a layout at a slot index with an originating cell.");
continue;
},
};
let outer_block_size = layout.outer_block_size();
if cell.rowspan == 1 {
max_row_height = max_row_height.max(outer_block_size);
}
if cell.effective_vertical_align() == VerticalAlignKeyword::Baseline {
let ascent = layout.ascent();
let border_padding_start =
layout.border.block_start + layout.padding.block_start;
let border_padding_end = layout.border.block_end + layout.padding.block_end;
max_ascent = max_ascent.max(ascent + border_padding_start.into());
// Only take into account the descent of this cell if doesn't span
// rows. The descent portion of the cell in cells that do span rows
// will be allocated to the other rows that it spans.
if cell.rowspan == 1 {
max_descent = max_descent.max(
layout.layout.content_block_size - ascent + border_padding_end.into(),
);
}
}
}
self.row_baselines.push(max_ascent);
self.row_sizes
.push(max_row_height.max(max_ascent + max_descent));
}
}
/// Lay out the table of this [`TableLayout`] into fragments. This should only be be called
/// after calling [`TableLayout.compute_measures`].
fn layout(mut self, positioning_context: &mut PositioningContext) -> IndependentLayout {
assert_eq!(self.table.size.height, self.row_sizes.len());
assert_eq!(self.table.size.width, self.distributed_column_widths.len());
let mut baselines = Baselines::default();
let border_spacing = self.table.border_spacing();
let mut fragments = Vec::new();
let mut row_offset = border_spacing.block;
for row_index in 0..self.table.size.height {
let mut column_offset = border_spacing.inline;
let row_size = self.row_sizes[row_index];
let row_baseline = self.row_baselines[row_index];
// From <https://drafts.csswg.org/css-align-3/#baseline-export>
// > If any cells in the row participate in first baseline/last baseline alignment along
// > the inline axis, the first/last baseline set of the row is generated from their
// > shared alignment baseline and the rows first available font, after alignment has
// > been performed. Otherwise, the first/last baseline set of the row is synthesized from
// > the lowest and highest content edges of the cells in the row. [CSS2]
//
// If any cell below has baseline alignment, these values will be overwritten,
// but they are initialized to the content edge of the first row.
if row_index == 0 {
baselines.first = Some(row_offset + row_size);
baselines.last = Some(row_offset + row_size);
}
for column_index in 0..self.table.size.width {
let layout = match self.cells_laid_out[row_index][column_index].take() {
Some(layout) => layout,
None => {
continue;
},
};
let cell = match self.table.slots[row_index][column_index] {
TableSlot::Cell(ref cell) => cell,
_ => {
warn!("Did not find a non-spanned cell at index with layout.");
continue;
},
};
// If this cell has baseline alignment, it can adjust the table's overall baseline.
if cell.effective_vertical_align() == VerticalAlignKeyword::Baseline {
if row_index == 0 {
baselines.first = Some(row_offset + row_baseline);
}
baselines.last = Some(row_offset + row_baseline);
}
// Calculate the inline and block size of all rows and columns that this cell spans.
let inline_size: Au = (column_index..column_index + cell.colspan)
.map(|index| self.distributed_column_widths[index])
.fold(Au::zero(), Au::add) +
((cell.colspan - 1) as i32 * border_spacing.inline);
let block_size: Au = (row_index..row_index + cell.rowspan)
.map(|index| self.row_sizes[index])
.fold(Au::zero(), Au::add) +
((cell.rowspan - 1) as i32 * border_spacing.block);
let cell_rect: LogicalRect<Length> = LogicalRect {
start_corner: LogicalVec2 {
inline: column_offset.into(),
block: row_offset.into(),
},
size: LogicalVec2 {
inline: inline_size.into(),
block: block_size.into(),
},
};
fragments.push(Fragment::Box(cell.create_fragment(
layout,
cell_rect,
row_baseline,
positioning_context,
)));
column_offset += inline_size + border_spacing.inline;
}
row_offset += row_size + border_spacing.block;
}
if self.table.anonymous {
baselines.first = None;
baselines.last = None;
}
IndependentLayout {
fragments,
content_block_size: row_offset,
baselines,
}
}
}
impl Table {
fn border_spacing(&self) -> LogicalVec2<Au> {
if self.style.clone_border_collapse() == BorderCollapse::Collapse {
LogicalVec2::zero()
} else {
let border_spacing = self.style.clone_border_spacing();
LogicalVec2 {
inline: border_spacing.horizontal(),
block: border_spacing.vertical(),
}
}
}
fn inline_content_sizes_for_cell_at(
&self,
coords: TableSlotCoordinates,
layout_context: &LayoutContext,
writing_mode: WritingMode,
) -> ContentSizes {
let cell = match self.resolve_first_cell(coords) {
Some(cell) => cell,
None => return ContentSizes::zero(),
};
let sizes = cell.inline_content_sizes(layout_context, writing_mode);
sizes.map(|size| size.scale_by(1.0 / cell.colspan as f32))
}
pub(crate) fn compute_inline_content_sizes(
&self,
layout_context: &LayoutContext,
writing_mode: WritingMode,
) -> (ContentSizes, Vec<Vec<ContentSizes>>) {
let mut total_size = ContentSizes::zero();
let mut inline_content_sizes = Vec::new();
for column_index in 0..self.size.width {
let mut row_inline_content_sizes = Vec::new();
let mut max_content_sizes_in_column = ContentSizes::zero();
for row_index in 0..self.size.width {
// TODO: Take into account padding and border here.
let coords = TableSlotCoordinates::new(column_index, row_index);
let content_sizes =
self.inline_content_sizes_for_cell_at(coords, layout_context, writing_mode);
max_content_sizes_in_column.max_assign(content_sizes);
row_inline_content_sizes.push(content_sizes);
}
inline_content_sizes.push(row_inline_content_sizes);
total_size += max_content_sizes_in_column;
}
(total_size, inline_content_sizes)
}
pub(crate) fn inline_content_sizes(
&mut self,
layout_context: &LayoutContext,
writing_mode: WritingMode,
) -> ContentSizes {
self.compute_inline_content_sizes(layout_context, writing_mode)
.0
}
pub(crate) fn layout(
&self,
layout_context: &LayoutContext,
positioning_context: &mut PositioningContext,
containing_block: &ContainingBlock,
) -> IndependentLayout {
let mut table_layout = TableLayout::new(self);
table_layout.compute_measures(layout_context, positioning_context, containing_block);
table_layout.layout(positioning_context)
}
}
impl TableSlotCell {
pub(crate) fn inline_content_sizes(
&self,
layout_context: &LayoutContext,
writing_mode: WritingMode,
) -> ContentSizes {
let border = self.style.border_width(writing_mode);
let padding = self.style.padding(writing_mode);
// For padding, a cyclic percentage is resolved against zero for determining intrinsic size
// contributions.
// https://drafts.csswg.org/css-sizing-3/#min-percentage-contribution
let zero = Length::zero();
let border_padding_sum = border.inline_sum() +
padding.inline_start.resolve(zero) +
padding.inline_end.resolve(zero);
let mut sizes = self
.contents
.contents
.inline_content_sizes(layout_context, writing_mode);
sizes.min_content += border_padding_sum.into();
sizes.max_content += border_padding_sum.into();
sizes
}
fn effective_vertical_align(&self) -> VerticalAlignKeyword {
match self.style.clone_vertical_align() {
VerticalAlign::Keyword(VerticalAlignKeyword::Top) => VerticalAlignKeyword::Top,
VerticalAlign::Keyword(VerticalAlignKeyword::Bottom) => VerticalAlignKeyword::Bottom,
VerticalAlign::Keyword(VerticalAlignKeyword::Middle) => VerticalAlignKeyword::Middle,
_ => VerticalAlignKeyword::Baseline,
}
}
fn create_fragment(
&self,
mut layout: CellLayout,
cell_rect: LogicalRect<Length>,
cell_baseline: Au,
positioning_context: &mut PositioningContext,
) -> BoxFragment {
// This must be scoped to this function because it conflicts with euclid's Zero.
use style::Zero as StyleZero;
let cell_content_rect = cell_rect.deflate(&(&layout.padding + &layout.border));
let content_block_size = layout.layout.content_block_size.into();
let vertical_align_offset = match self.effective_vertical_align() {
VerticalAlignKeyword::Top => Length::new(0.),
VerticalAlignKeyword::Bottom => cell_content_rect.size.block - content_block_size,
VerticalAlignKeyword::Middle => {
(cell_content_rect.size.block - content_block_size).scale_by(0.5)
},
_ => {
Length::from(cell_baseline) -
(layout.padding.block_start + layout.border.block_start) -
Length::from(layout.ascent())
},
};
// Create an `AnonymousFragment` to move the cell contents to the cell baseline.
let mut vertical_align_fragment_rect = cell_content_rect.clone();
vertical_align_fragment_rect.start_corner = LogicalVec2 {
inline: Length::new(0.),
block: vertical_align_offset,
};
let vertical_align_fragment = AnonymousFragment::new(
vertical_align_fragment_rect,
layout.layout.fragments,
self.style.writing_mode,
);
// Adjust the static position of all absolute children based on the
// final content rect of this fragment. Note that we are not shifting by the position of the
// Anonymous fragment we use to shift content to the baseline.
//
// TODO(mrobinson): This is correct for absolutes that are direct children of the table
// cell, but wrong for absolute fragments that are more deeply nested in the hierarchy of
// fragments.
layout
.positioning_context
.adjust_static_position_of_hoisted_fragments_with_offset(
&cell_content_rect.start_corner,
PositioningContextLength::zero(),
);
positioning_context.append(layout.positioning_context);
BoxFragment::new(
self.base_fragment_info,
self.style.clone(),
vec![Fragment::Anonymous(vertical_align_fragment)],
cell_content_rect,
layout.padding,
layout.border,
LogicalSides::zero(), /* margin */
None, /* clearance */
CollapsedBlockMargins::zero(),
)
.with_baselines(layout.layout.baselines)
}
}