mirror of
https://github.com/typst/typst
synced 2025-05-14 04:56:26 +08:00
1808 lines
77 KiB
Rust
1808 lines
77 KiB
Rust
use std::fmt::Debug;
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use typst_library::diag::{bail, SourceResult};
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use typst_library::engine::Engine;
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use typst_library::foundations::{Resolve, StyleChain};
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use typst_library::layout::grid::resolve::{
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Cell, CellGrid, Header, LinePosition, Repeatable,
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};
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use typst_library::layout::{
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Abs, Axes, Dir, Fr, Fragment, Frame, FrameItem, Length, Point, Region, Regions, Rel,
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Size, Sizing,
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};
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use typst_library::text::TextElem;
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use typst_library::visualize::Geometry;
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use typst_syntax::Span;
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use typst_utils::{MaybeReverseIter, Numeric};
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use super::{
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generate_line_segments, hline_stroke_at_column, layout_cell, vline_stroke_at_row,
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LineSegment, Rowspan, UnbreakableRowGroup,
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};
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/// Performs grid layout.
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pub struct GridLayouter<'a> {
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/// The grid of cells.
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pub(super) grid: &'a CellGrid<'a>,
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/// The regions to layout children into.
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pub(super) regions: Regions<'a>,
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/// The inherited styles.
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pub(super) styles: StyleChain<'a>,
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/// Resolved column sizes.
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pub(super) rcols: Vec<Abs>,
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/// The sum of `rcols`.
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pub(super) width: Abs,
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/// Resolved row sizes, by region.
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pub(super) rrows: Vec<Vec<RowPiece>>,
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/// The amount of unbreakable rows remaining to be laid out in the
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/// current unbreakable row group. While this is positive, no region breaks
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/// should occur.
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pub(super) unbreakable_rows_left: usize,
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/// Rowspans not yet laid out because not all of their spanned rows were
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/// laid out yet.
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pub(super) rowspans: Vec<Rowspan>,
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/// Grid layout state for the current region.
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pub(super) current: Current,
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/// Frames for finished regions.
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pub(super) finished: Vec<Frame>,
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/// The amount and height of header rows on each finished region.
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pub(super) finished_header_rows: Vec<FinishedHeaderRowInfo>,
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/// Whether this is an RTL grid.
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pub(super) is_rtl: bool,
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/// Currently repeating headers, one per level. Sorted by increasing
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/// levels.
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///
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/// Note that some levels may be absent, in particular level 0, which does
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/// not exist (so all levels are >= 1).
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pub(super) repeating_headers: Vec<&'a Header>,
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/// Headers, repeating or not, awaiting their first successful layout.
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/// Sorted by increasing levels.
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pub(super) pending_headers: &'a [Repeatable<Header>],
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/// Next headers to be processed.
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pub(super) upcoming_headers: &'a [Repeatable<Header>],
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/// State of the row being currently laid out.
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///
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/// This is kept as a field to avoid passing down too many parameters from
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/// `layout_row` into called functions, which would then have to pass them
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/// down to `push_row`, which reads these values.
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pub(super) row_state: RowState,
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/// The span of the grid element.
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pub(super) span: Span,
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}
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/// Grid layout state for the current region. This should be reset or updated
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/// on each region break.
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pub(super) struct Current {
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/// The initial size of the current region before we started subtracting.
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pub(super) initial: Size,
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/// Rows in the current region.
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pub(super) lrows: Vec<Row>,
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/// The amount of repeated header rows at the start of the current region.
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/// Thus, excludes rows from pending headers (which were placed for the
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/// first time).
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///
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/// Note that `repeating_headers` and `pending_headers` can change if we
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/// find a new header inside the region (not at the top), so this field
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/// is required to access information from the top of the region.
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///
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/// This information is used on finish region to calculate the total height
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/// of resolved header rows at the top of the region, which is used by
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/// multi-page rowspans so they can properly skip the header rows at the
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/// top of each region during layout.
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pub(super) repeated_header_rows: usize,
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/// The end bound of the row range of the last repeating header at the
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/// start of the region.
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///
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/// The last row might have disappeared from layout due to being empty, so
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/// this is how we can become aware of where the last header ends without
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/// having to check the vector of rows. Line layout uses this to determine
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/// when to prioritize the last lines under a header.
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///
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/// A value of zero indicates no repeated headers were placed.
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pub(super) last_repeated_header_end: usize,
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/// Stores the length of `lrows` before a sequence of rows equipped with
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/// orphan prevention was laid out. In this case, if no more rows without
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/// orphan prevention are laid out after those rows before the region ends,
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/// the rows will be removed, and there may be an attempt to place them
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/// again in the new region. Effectively, this is the mechanism used for
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/// orphan prevention of rows.
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///
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/// At the moment, this is only used by repeated headers (they aren't laid
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/// out if alone in the region) and by new headers, which are moved to the
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/// `pending_headers` vector and so will automatically be placed again
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/// until they fit and are not orphans in at least one region (or exactly
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/// one, for non-repeated headers).
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pub(super) lrows_orphan_snapshot: Option<usize>,
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/// The total simulated height for all headers currently in
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/// `repeating_headers` and `pending_headers`.
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///
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/// This field is reset on each new region and properly updated by
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/// `layout_auto_row` and `layout_relative_row`, and should not be read
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/// before all header rows are fully laid out. It is usually fine because
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/// header rows themselves are unbreakable, and unbreakable rows do not
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/// need to read this field at all.
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///
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/// This height is not only computed at the beginning of the region. It is
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/// updated whenever a new header is found, subtracting the height of
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/// headers which stopped repeating and adding the height of all new
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/// headers.
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pub(super) header_height: Abs,
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/// The height of effectively repeating headers, that is, ignoring
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/// non-repeating pending headers.
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///
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/// This is used by multi-page auto rows so they can inform cell layout on
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/// how much space should be taken by headers if they break across regions.
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/// In particular, non-repeating headers only occupy the initial region,
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/// but disappear on new regions, so they can be ignored.
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pub(super) repeating_header_height: Abs,
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/// The height for each repeating header that was placed in this region.
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/// Note that this includes headers not at the top of the region, before
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/// their first repetition (pending headers), and excludes headers removed
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/// by virtue of a new, conflicting header being found (short-lived
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/// headers).
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///
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/// This is used to know how much to update `repeating_header_height` by
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/// when finding a new header and causing existing repeating headers to
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/// stop.
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pub(super) repeating_header_heights: Vec<Abs>,
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/// The simulated footer height for this region.
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///
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/// The simulation occurs before any rows are laid out for a region.
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pub(super) footer_height: Abs,
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}
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/// Data about the row being laid out right now.
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#[derive(Debug, Default)]
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pub(super) struct RowState {
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/// If this is `Some`, this will be updated by the currently laid out row's
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/// height if it is auto or relative. This is used for header height
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/// calculation.
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pub(super) current_row_height: Option<Abs>,
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/// This is `true` when laying out non-short lived headers and footers.
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/// That is, headers and footers which are not immediately followed or
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/// preceded (respectively) by conflicting headers and footers of same or
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/// lower level, or the end or start of the table (respectively), which
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/// would cause them to never repeat, even once.
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///
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/// If this is `false`, the next row to be laid out will remove an active
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/// orphan snapshot and will flush pending headers, as there is no risk
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/// that they will be orphans anymore.
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pub(super) in_active_repeatable: bool,
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}
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/// Data about laid out repeated header rows for a specific finished region.
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#[derive(Debug, Default)]
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pub(super) struct FinishedHeaderRowInfo {
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/// The amount of repeated headers at the top of the region.
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pub(super) repeated_amount: usize,
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/// The end bound of the row range of the last repeated header at the top
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/// of the region.
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pub(super) last_repeated_header_end: usize,
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/// The total height of repeated headers at the top of the region.
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pub(super) repeated_height: Abs,
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}
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/// Details about a resulting row piece.
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#[derive(Debug)]
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pub struct RowPiece {
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/// The height of the segment.
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pub height: Abs,
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/// The index of the row.
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pub y: usize,
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}
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/// Produced by initial row layout, auto and relative rows are already finished,
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/// fractional rows not yet.
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pub(super) enum Row {
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/// Finished row frame of auto or relative row with y index.
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/// The last parameter indicates whether or not this is the last region
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/// where this row is laid out, and it can only be false when a row uses
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/// `layout_multi_row`, which in turn is only used by breakable auto rows.
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Frame(Frame, usize, bool),
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/// Fractional row with y index and disambiguator.
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Fr(Fr, usize, usize),
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}
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impl Row {
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/// Returns the `y` index of this row.
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fn index(&self) -> usize {
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match self {
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Self::Frame(_, y, _) => *y,
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Self::Fr(_, y, _) => *y,
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}
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}
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}
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impl<'a> GridLayouter<'a> {
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/// Create a new grid layouter.
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///
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/// This prepares grid layout by unifying content and gutter tracks.
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pub fn new(
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grid: &'a CellGrid<'a>,
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regions: Regions<'a>,
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styles: StyleChain<'a>,
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span: Span,
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) -> Self {
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// We use these regions for auto row measurement. Since at that moment,
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// columns are already sized, we can enable horizontal expansion.
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let mut regions = regions;
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regions.expand = Axes::new(true, false);
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Self {
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grid,
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regions,
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styles,
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rcols: vec![Abs::zero(); grid.cols.len()],
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width: Abs::zero(),
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rrows: vec![],
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unbreakable_rows_left: 0,
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rowspans: vec![],
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finished: vec![],
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finished_header_rows: vec![],
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is_rtl: TextElem::dir_in(styles) == Dir::RTL,
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repeating_headers: vec![],
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upcoming_headers: &grid.headers,
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pending_headers: Default::default(),
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row_state: RowState::default(),
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current: Current {
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initial: regions.size,
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lrows: vec![],
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repeated_header_rows: 0,
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last_repeated_header_end: 0,
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lrows_orphan_snapshot: None,
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header_height: Abs::zero(),
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repeating_header_height: Abs::zero(),
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repeating_header_heights: vec![],
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footer_height: Abs::zero(),
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},
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span,
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}
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}
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/// Determines the columns sizes and then layouts the grid row-by-row.
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pub fn layout(mut self, engine: &mut Engine) -> SourceResult<Fragment> {
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self.measure_columns(engine)?;
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if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
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// Ensure rows in the first region will be aware of the possible
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// presence of the footer.
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self.prepare_footer(footer, engine, 0)?;
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self.regions.size.y -= self.current.footer_height;
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}
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let mut y = 0;
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let mut consecutive_header_count = 0;
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while y < self.grid.rows.len() {
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if let Some(next_header) = self.upcoming_headers.get(consecutive_header_count)
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{
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if next_header.range().contains(&y) {
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self.place_new_headers(&mut consecutive_header_count, engine)?;
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y = next_header.end;
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// Skip header rows during normal layout.
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continue;
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}
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}
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if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
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if y >= footer.start {
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if y == footer.start {
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self.layout_footer(footer, engine, self.finished.len())?;
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self.flush_orphans();
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}
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y = footer.end;
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continue;
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}
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}
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self.layout_row(y, engine, 0)?;
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// After the first non-header row is placed, pending headers are no
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// longer orphans and can repeat, so we move them to repeating
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// headers.
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//
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// Note that this is usually done in `push_row`, since the call to
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// `layout_row` above might trigger region breaks (for multi-page
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// auto rows), whereas this needs to be called as soon as any part
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// of a row is laid out. However, it's possible a row has no
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// visible output and thus does not push any rows even though it
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// was successfully laid out, in which case we additionally flush
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// here just in case.
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self.flush_orphans();
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y += 1;
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}
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self.finish_region(engine, true)?;
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// Layout any missing rowspans.
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// There are only two possibilities for rowspans not yet laid out
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// (usually, a rowspan is laid out as soon as its last row, or any row
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// after it, is laid out):
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// 1. The rowspan was fully empty and only spanned fully empty auto
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// rows, which were all prevented from being laid out. Those rowspans
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// are ignored by 'layout_rowspan', and are not of any concern.
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//
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// 2. The rowspan's last row was an auto row at the last region which
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// was not laid out, and no other rows were laid out after it. Those
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// might still need to be laid out, so we check for them.
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for rowspan in std::mem::take(&mut self.rowspans) {
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self.layout_rowspan(rowspan, None, engine)?;
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}
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self.render_fills_strokes()
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}
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/// Layout a row with a certain initial state, returning the final state.
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#[inline]
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pub(super) fn layout_row_with_state(
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&mut self,
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y: usize,
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engine: &mut Engine,
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disambiguator: usize,
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initial_state: RowState,
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) -> SourceResult<RowState> {
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// Keep a copy of the previous value in the stack, as this function can
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// call itself recursively (e.g. if a region break is triggered and a
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// header is placed), so we shouldn't outright overwrite it, but rather
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// save and later restore the state when back to this call.
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let previous = std::mem::replace(&mut self.row_state, initial_state);
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// Keep it as a separate function to allow inlining the return below,
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// as it's usually not needed.
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self.layout_row_internal(y, engine, disambiguator)?;
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Ok(std::mem::replace(&mut self.row_state, previous))
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}
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/// Layout the given row with the default row state.
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#[inline]
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pub(super) fn layout_row(
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&mut self,
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y: usize,
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engine: &mut Engine,
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disambiguator: usize,
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) -> SourceResult<()> {
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self.layout_row_with_state(y, engine, disambiguator, RowState::default())?;
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Ok(())
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}
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/// Layout the given row using the current state.
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pub(super) fn layout_row_internal(
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&mut self,
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y: usize,
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engine: &mut Engine,
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disambiguator: usize,
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) -> SourceResult<()> {
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// Skip to next region if current one is full, but only for content
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// rows, not for gutter rows, and only if we aren't laying out an
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// unbreakable group of rows.
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let is_content_row = !self.grid.is_gutter_track(y);
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if self.unbreakable_rows_left == 0 && self.regions.is_full() && is_content_row {
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self.finish_region(engine, false)?;
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}
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if is_content_row {
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// Gutter rows have no rowspans or possibly unbreakable cells.
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self.check_for_rowspans(disambiguator, y);
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self.check_for_unbreakable_rows(y, engine)?;
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}
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// Don't layout gutter rows at the top of a region.
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if is_content_row || !self.current.lrows.is_empty() {
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match self.grid.rows[y] {
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Sizing::Auto => self.layout_auto_row(engine, disambiguator, y)?,
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Sizing::Rel(v) => {
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self.layout_relative_row(engine, disambiguator, v, y)?
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}
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Sizing::Fr(v) => {
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if !self.row_state.in_active_repeatable {
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self.flush_orphans();
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}
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self.current.lrows.push(Row::Fr(v, y, disambiguator))
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}
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}
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}
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self.unbreakable_rows_left = self.unbreakable_rows_left.saturating_sub(1);
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Ok(())
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}
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/// Add lines and backgrounds.
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fn render_fills_strokes(mut self) -> SourceResult<Fragment> {
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let mut finished = std::mem::take(&mut self.finished);
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let frame_amount = finished.len();
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for (((frame_index, frame), rows), finished_header_rows) in
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finished.iter_mut().enumerate().zip(&self.rrows).zip(
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self.finished_header_rows
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.iter()
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.map(Some)
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.chain(std::iter::repeat(None)),
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)
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{
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if self.rcols.is_empty() || rows.is_empty() {
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continue;
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}
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// Render grid lines.
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// We collect lines into a vector before rendering so we can sort
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// them based on thickness, such that the lines with largest
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// thickness are drawn on top; and also so we can prepend all of
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// them at once in the frame, as calling prepend() for each line,
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// and thus pushing all frame items forward each time, would result
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// in quadratic complexity.
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let mut lines = vec![];
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// Which line position to look for in the list of lines for a
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// track, such that placing lines with those positions will
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// correspond to placing them before the given track index.
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//
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// If the index represents a gutter track, this means the list of
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// lines will actually correspond to the list of lines in the
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// previous index, so we must look for lines positioned after the
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// previous index, and not before, to determine which lines should
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// be placed before gutter.
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//
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// Note that the maximum index is always an odd number when
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// there's gutter, so we must check for it to ensure we don't give
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// it the same treatment as a line before a gutter track.
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let expected_line_position = |index, is_max_index: bool| {
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if self.grid.is_gutter_track(index) && !is_max_index {
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LinePosition::After
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} else {
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LinePosition::Before
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}
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};
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// Render vertical lines.
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// Render them first so horizontal lines have priority later.
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for (x, dx) in points(self.rcols.iter().copied()).enumerate() {
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let dx = if self.is_rtl { self.width - dx } else { dx };
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let is_end_border = x == self.grid.cols.len();
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let expected_vline_position = expected_line_position(x, is_end_border);
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let vlines_at_column = self
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.grid
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.vlines
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.get(if !self.grid.has_gutter {
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x
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} else if is_end_border {
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// The end border has its own vector of lines, but
|
|
// dividing it by 2 and flooring would give us the
|
|
// vector of lines with the index of the last column.
|
|
// Add 1 so we get the border's lines.
|
|
x / 2 + 1
|
|
} else {
|
|
// If x is a gutter column, this will round down to the
|
|
// index of the previous content column, which is
|
|
// intentional - the only lines which can appear before
|
|
// a gutter column are lines for the previous column
|
|
// marked with "LinePosition::After". Therefore, we get
|
|
// the previous column's lines. Worry not, as
|
|
// 'generate_line_segments' will correctly filter lines
|
|
// based on their LinePosition for us.
|
|
//
|
|
// If x is a content column, this will correctly return
|
|
// its index before applying gutters, so nothing
|
|
// special here (lines with "LinePosition::After" would
|
|
// then be ignored for this column, as we are drawing
|
|
// lines before it, not after).
|
|
x / 2
|
|
})
|
|
.into_iter()
|
|
.flatten()
|
|
.filter(|line| line.position == expected_vline_position);
|
|
|
|
let tracks = rows.iter().map(|row| (row.y, row.height));
|
|
|
|
// Determine all different line segments we have to draw in
|
|
// this column, and convert them to points and shapes.
|
|
//
|
|
// Even a single, uniform line might generate more than one
|
|
// segment, if it happens to cross a colspan (over which it
|
|
// must not be drawn).
|
|
let segments = generate_line_segments(
|
|
self.grid,
|
|
tracks,
|
|
x,
|
|
vlines_at_column,
|
|
vline_stroke_at_row,
|
|
)
|
|
.map(|segment| {
|
|
let LineSegment { stroke, offset: dy, length, priority } = segment;
|
|
let stroke = (*stroke).clone().unwrap_or_default();
|
|
let thickness = stroke.thickness;
|
|
let half = thickness / 2.0;
|
|
let target = Point::with_y(length + thickness);
|
|
let vline = Geometry::Line(target).stroked(stroke);
|
|
(
|
|
thickness,
|
|
priority,
|
|
Point::new(dx, dy - half),
|
|
FrameItem::Shape(vline, self.span),
|
|
)
|
|
});
|
|
|
|
lines.extend(segments);
|
|
}
|
|
|
|
// Render horizontal lines.
|
|
// They are rendered second as they default to appearing on top.
|
|
// First, calculate their offsets from the top of the frame.
|
|
let hline_offsets = points(rows.iter().map(|piece| piece.height));
|
|
|
|
// Additionally, determine their indices (the indices of the
|
|
// rows they are drawn on top of). In principle, this will
|
|
// correspond to the rows' indices directly, except for the
|
|
// last hline index, which must be (amount of rows) in order to
|
|
// draw the table's bottom border.
|
|
let hline_indices = rows
|
|
.iter()
|
|
.map(|piece| piece.y)
|
|
.chain(std::iter::once(self.grid.rows.len()))
|
|
.enumerate();
|
|
|
|
// Converts a row to the corresponding index in the vector of
|
|
// hlines.
|
|
let hline_index_of_row = |y: usize| {
|
|
if !self.grid.has_gutter {
|
|
y
|
|
} else if y == self.grid.rows.len() {
|
|
y / 2 + 1
|
|
} else {
|
|
// Check the vlines loop for an explanation regarding
|
|
// these index operations.
|
|
y / 2
|
|
}
|
|
};
|
|
|
|
let get_hlines_at = |y| {
|
|
self.grid
|
|
.hlines
|
|
.get(hline_index_of_row(y))
|
|
.map(Vec::as_slice)
|
|
.unwrap_or(&[])
|
|
};
|
|
|
|
let mut prev_y = None;
|
|
for ((i, y), dy) in hline_indices.zip(hline_offsets) {
|
|
// Position of lines below the row index in the previous iteration.
|
|
let expected_prev_line_position = prev_y
|
|
.map(|prev_y| {
|
|
expected_line_position(
|
|
prev_y + 1,
|
|
prev_y + 1 == self.grid.rows.len(),
|
|
)
|
|
})
|
|
.unwrap_or(LinePosition::Before);
|
|
|
|
// Header's lines at the bottom have priority when repeated.
|
|
// This will store the end bound of the last header if the
|
|
// current iteration is calculating lines under it.
|
|
let last_repeated_header_end_above = finished_header_rows
|
|
.filter(|info| prev_y.is_some() && i == info.repeated_amount)
|
|
.map(|info| info.last_repeated_header_end);
|
|
|
|
// If some grid rows were omitted between the previous resolved
|
|
// row and the current one, we ensure lines below the previous
|
|
// row don't "disappear" and are considered, albeit with less
|
|
// priority. However, don't do this when we're below a header,
|
|
// as it must have more priority instead of less, so it is
|
|
// chained later instead of before (stored in the
|
|
// 'header_hlines' variable below). The exception is when the
|
|
// last row in the header is removed, in which case we append
|
|
// both the lines under the row above us and also (later) the
|
|
// lines under the header's (removed) last row.
|
|
let prev_lines = prev_y
|
|
.filter(|prev_y| {
|
|
prev_y + 1 != y
|
|
&& last_repeated_header_end_above.is_none_or(
|
|
|last_repeated_header_end| {
|
|
prev_y + 1 != last_repeated_header_end
|
|
},
|
|
)
|
|
})
|
|
.map(|prev_y| get_hlines_at(prev_y + 1))
|
|
.unwrap_or(&[]);
|
|
|
|
let expected_hline_position =
|
|
expected_line_position(y, y == self.grid.rows.len());
|
|
|
|
let hlines_at_y = get_hlines_at(y)
|
|
.iter()
|
|
.filter(|line| line.position == expected_hline_position);
|
|
|
|
let top_border_hlines = if prev_y.is_none() && y != 0 {
|
|
// For lines at the top of the region, give priority to
|
|
// the lines at the top border.
|
|
get_hlines_at(0)
|
|
} else {
|
|
&[]
|
|
};
|
|
|
|
let mut expected_header_line_position = LinePosition::Before;
|
|
let header_hlines = if let Some((header_end_above, prev_y)) =
|
|
last_repeated_header_end_above.zip(prev_y)
|
|
{
|
|
if !self.grid.has_gutter
|
|
|| matches!(
|
|
self.grid.rows[prev_y],
|
|
Sizing::Rel(length) if length.is_zero()
|
|
)
|
|
{
|
|
// For lines below a header, give priority to the
|
|
// lines originally below the header rather than
|
|
// the lines of what's below the repeated header.
|
|
// However, no need to do that when we're laying
|
|
// out the header for the first time, since the
|
|
// lines being normally laid out then will be
|
|
// precisely the lines below the header.
|
|
//
|
|
// Additionally, we don't repeat lines above the row
|
|
// below the header when gutter is enabled, since, in
|
|
// that case, there will be a gutter row between header
|
|
// and content, so no lines should overlap. The
|
|
// exception is when the gutter at the end of the
|
|
// header has a size of zero, which happens when only
|
|
// column-gutter is specified, for example. In that
|
|
// case, we still repeat the line under the gutter.
|
|
expected_header_line_position = expected_line_position(
|
|
header_end_above,
|
|
header_end_above == self.grid.rows.len(),
|
|
);
|
|
get_hlines_at(header_end_above)
|
|
} else {
|
|
&[]
|
|
}
|
|
} else {
|
|
&[]
|
|
};
|
|
|
|
// The effective hlines to be considered at this row index are
|
|
// chained in order of increasing priority:
|
|
// 1. Lines from the row right above us, if needed;
|
|
// 2. Lines from the current row (usually, only those are
|
|
// present);
|
|
// 3. Lines from the top border (above the top cells, hence
|
|
// 'before' position only);
|
|
// 4. Lines from the header above us, if present.
|
|
let hlines_at_row =
|
|
prev_lines
|
|
.iter()
|
|
.filter(|line| line.position == expected_prev_line_position)
|
|
.chain(hlines_at_y)
|
|
.chain(
|
|
top_border_hlines
|
|
.iter()
|
|
.filter(|line| line.position == LinePosition::Before),
|
|
)
|
|
.chain(header_hlines.iter().filter(|line| {
|
|
line.position == expected_header_line_position
|
|
}));
|
|
|
|
let tracks = self.rcols.iter().copied().enumerate();
|
|
|
|
// Normally, given an hline above row y, the row above it is
|
|
// 'y - 1' (if y > 0). However, sometimes that's not true, for
|
|
// example if 'y - 1' is in a previous region, or if 'y - 1'
|
|
// was an empty auto row which was removed. Therefore, we tell
|
|
// the hlines at this index which row is actually above them in
|
|
// the laid out region so they can include that row's bottom
|
|
// strokes in the folding process.
|
|
let local_top_y = prev_y;
|
|
|
|
// When we're in the last region, the bottom border stroke
|
|
// doesn't necessarily gain priority like it does in previous
|
|
// regions.
|
|
let in_last_region = frame_index + 1 == frame_amount;
|
|
|
|
// Determine all different line segments we have to draw in
|
|
// this row, and convert them to points and shapes.
|
|
let segments = generate_line_segments(
|
|
self.grid,
|
|
tracks,
|
|
y,
|
|
hlines_at_row,
|
|
|grid, y, x, stroke| {
|
|
hline_stroke_at_column(
|
|
grid,
|
|
rows,
|
|
local_top_y,
|
|
last_repeated_header_end_above,
|
|
in_last_region,
|
|
y,
|
|
x,
|
|
stroke,
|
|
)
|
|
},
|
|
)
|
|
.map(|segment| {
|
|
let LineSegment { stroke, offset: dx, length, priority } = segment;
|
|
let stroke = (*stroke).clone().unwrap_or_default();
|
|
let thickness = stroke.thickness;
|
|
let half = thickness / 2.0;
|
|
let dx = if self.is_rtl { self.width - dx - length } else { dx };
|
|
let target = Point::with_x(length + thickness);
|
|
let hline = Geometry::Line(target).stroked(stroke);
|
|
(
|
|
thickness,
|
|
priority,
|
|
Point::new(dx - half, dy),
|
|
FrameItem::Shape(hline, self.span),
|
|
)
|
|
});
|
|
|
|
// Draw later (after we sort all lines below.)
|
|
lines.extend(segments);
|
|
|
|
prev_y = Some(y);
|
|
}
|
|
|
|
// Sort by increasing thickness, so that we draw larger strokes
|
|
// on top. When the thickness is the same, sort by priority.
|
|
//
|
|
// Sorting by thickness avoids layering problems where a smaller
|
|
// hline appears "inside" a larger vline. When both have the same
|
|
// size, hlines are drawn on top (since the sort is stable, and
|
|
// they are pushed later).
|
|
lines.sort_by_key(|(thickness, priority, ..)| (*thickness, *priority));
|
|
|
|
// Render cell backgrounds.
|
|
// We collect them into a vector so they can all be prepended at
|
|
// once to the frame, together with lines.
|
|
let mut fills = vec![];
|
|
|
|
// Reverse with RTL so that later columns start first.
|
|
let mut dx = Abs::zero();
|
|
for (x, &col) in self.rcols.iter().enumerate().rev_if(self.is_rtl) {
|
|
let mut dy = Abs::zero();
|
|
for row in rows {
|
|
// We want to only draw the fill starting at the parent
|
|
// positions of cells. However, sometimes the parent
|
|
// position is absent from the current region, either
|
|
// because the first few rows of a rowspan were empty auto
|
|
// rows and thus removed from layout, or because the parent
|
|
// cell was in a previous region (in which case we'd want
|
|
// to draw its fill again, in the current region).
|
|
// Therefore, we first analyze the parent position to see
|
|
// if the current row would be the first row spanned by the
|
|
// parent cell in this region. If so, this means we have to
|
|
// start drawing the cell's fill here. If not, we ignore
|
|
// the position `(x, row.y)`, as its fill will already have
|
|
// been rendered before.
|
|
//
|
|
// Note: In the case of gutter rows, we have to check the
|
|
// row below before discarding them fully, because a
|
|
// gutter row might be the first row spanned by a rowspan
|
|
// in this region (e.g. if the first row was empty and
|
|
// therefore removed), so its fill could start in that
|
|
// gutter row. That's why we use
|
|
// 'effective_parent_cell_position'.
|
|
let parent = self
|
|
.grid
|
|
.effective_parent_cell_position(x, row.y)
|
|
.filter(|parent| {
|
|
// Ensure this is the first column spanned by the
|
|
// cell before drawing its fill, otherwise we
|
|
// already rendered its fill in a previous
|
|
// iteration of the outer loop (and/or this is a
|
|
// gutter column, which we ignore).
|
|
//
|
|
// Additionally, we should only draw the fill when
|
|
// this row is the local parent Y for this cell,
|
|
// that is, the first row spanned by the cell's
|
|
// parent in this region, because if the parent
|
|
// cell's fill was already drawn in a previous
|
|
// region, we must render it again in later regions
|
|
// spanned by that cell. Note that said condition
|
|
// always holds when the current cell has a rowspan
|
|
// of 1 and we're not currently at a gutter row.
|
|
parent.x == x
|
|
&& (parent.y == row.y
|
|
|| rows
|
|
.iter()
|
|
.find(|row| row.y >= parent.y)
|
|
.is_some_and(|first_spanned_row| {
|
|
first_spanned_row.y == row.y
|
|
}))
|
|
});
|
|
|
|
if let Some(parent) = parent {
|
|
let cell = self.grid.cell(parent.x, parent.y).unwrap();
|
|
let fill = cell.fill.clone();
|
|
if let Some(fill) = fill {
|
|
let rowspan = self.grid.effective_rowspan_of_cell(cell);
|
|
let height = if rowspan == 1 {
|
|
row.height
|
|
} else {
|
|
rows.iter()
|
|
.filter(|row| {
|
|
(parent.y..parent.y + rowspan).contains(&row.y)
|
|
})
|
|
.map(|row| row.height)
|
|
.sum()
|
|
};
|
|
let width = self.cell_spanned_width(cell, x);
|
|
// In the grid, cell colspans expand to the right,
|
|
// so we're at the leftmost (lowest 'x') column
|
|
// spanned by the cell. However, in RTL, cells
|
|
// expand to the left. Therefore, without the
|
|
// offset below, cell fills would start at the
|
|
// rightmost visual position of a cell and extend
|
|
// over to unrelated columns to the right in RTL.
|
|
// We avoid this by ensuring the fill starts at the
|
|
// very left of the cell, even with colspan > 1.
|
|
let offset =
|
|
if self.is_rtl { -width + col } else { Abs::zero() };
|
|
let pos = Point::new(dx + offset, dy);
|
|
let size = Size::new(width, height);
|
|
let rect = Geometry::Rect(size).filled(fill);
|
|
fills.push((pos, FrameItem::Shape(rect, self.span)));
|
|
}
|
|
}
|
|
dy += row.height;
|
|
}
|
|
dx += col;
|
|
}
|
|
|
|
// Now we render each fill and stroke by prepending to the frame,
|
|
// such that both appear below cell contents. Fills come first so
|
|
// that they appear below lines.
|
|
frame.prepend_multiple(
|
|
fills
|
|
.into_iter()
|
|
.chain(lines.into_iter().map(|(_, _, point, shape)| (point, shape))),
|
|
);
|
|
}
|
|
|
|
Ok(Fragment::frames(finished))
|
|
}
|
|
|
|
/// Determine all column sizes.
|
|
fn measure_columns(&mut self, engine: &mut Engine) -> SourceResult<()> {
|
|
// Sum of sizes of resolved relative tracks.
|
|
let mut rel = Abs::zero();
|
|
|
|
// Sum of fractions of all fractional tracks.
|
|
let mut fr = Fr::zero();
|
|
|
|
// Resolve the size of all relative columns and compute the sum of all
|
|
// fractional tracks.
|
|
for (&col, rcol) in self.grid.cols.iter().zip(&mut self.rcols) {
|
|
match col {
|
|
Sizing::Auto => {}
|
|
Sizing::Rel(v) => {
|
|
let resolved =
|
|
v.resolve(self.styles).relative_to(self.regions.base().x);
|
|
*rcol = resolved;
|
|
rel += resolved;
|
|
}
|
|
Sizing::Fr(v) => fr += v,
|
|
}
|
|
}
|
|
|
|
// Size that is not used by fixed-size columns.
|
|
let available = self.regions.size.x - rel;
|
|
if available >= Abs::zero() {
|
|
// Determine size of auto columns.
|
|
let (auto, count) = self.measure_auto_columns(engine, available)?;
|
|
|
|
// If there is remaining space, distribute it to fractional columns,
|
|
// otherwise shrink auto columns.
|
|
let remaining = available - auto;
|
|
if remaining >= Abs::zero() {
|
|
self.grow_fractional_columns(remaining, fr);
|
|
} else {
|
|
self.shrink_auto_columns(available, count);
|
|
}
|
|
}
|
|
|
|
// Sum up the resolved column sizes once here.
|
|
self.width = self.rcols.iter().sum();
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Total width spanned by the cell (among resolved columns).
|
|
/// Includes spanned gutter columns.
|
|
pub(super) fn cell_spanned_width(&self, cell: &Cell, x: usize) -> Abs {
|
|
let colspan = self.grid.effective_colspan_of_cell(cell);
|
|
self.rcols.iter().skip(x).take(colspan).sum()
|
|
}
|
|
|
|
/// Measure the size that is available to auto columns.
|
|
fn measure_auto_columns(
|
|
&mut self,
|
|
engine: &mut Engine,
|
|
available: Abs,
|
|
) -> SourceResult<(Abs, usize)> {
|
|
let mut auto = Abs::zero();
|
|
let mut count = 0;
|
|
let all_frac_cols = self
|
|
.grid
|
|
.cols
|
|
.iter()
|
|
.enumerate()
|
|
.filter(|(_, col)| col.is_fractional())
|
|
.map(|(x, _)| x)
|
|
.collect::<Vec<_>>();
|
|
|
|
// Determine size of auto columns by laying out all cells in those
|
|
// columns, measuring them and finding the largest one.
|
|
for (x, &col) in self.grid.cols.iter().enumerate() {
|
|
if col != Sizing::Auto {
|
|
continue;
|
|
}
|
|
|
|
let mut resolved = Abs::zero();
|
|
for y in 0..self.grid.rows.len() {
|
|
// We get the parent cell in case this is a merged position.
|
|
let Some(parent) = self.grid.parent_cell_position(x, y) else {
|
|
continue;
|
|
};
|
|
if parent.y != y {
|
|
// Don't check the width of rowspans more than once.
|
|
continue;
|
|
}
|
|
let cell = self.grid.cell(parent.x, parent.y).unwrap();
|
|
let colspan = self.grid.effective_colspan_of_cell(cell);
|
|
if colspan > 1 {
|
|
let last_spanned_auto_col = self
|
|
.grid
|
|
.cols
|
|
.iter()
|
|
.enumerate()
|
|
.skip(parent.x)
|
|
.take(colspan)
|
|
.rev()
|
|
.find(|(_, col)| **col == Sizing::Auto)
|
|
.map(|(x, _)| x);
|
|
|
|
if last_spanned_auto_col != Some(x) {
|
|
// A colspan only affects the size of the last spanned
|
|
// auto column.
|
|
continue;
|
|
}
|
|
}
|
|
|
|
if colspan > 1
|
|
&& self.regions.size.x.is_finite()
|
|
&& !all_frac_cols.is_empty()
|
|
&& all_frac_cols
|
|
.iter()
|
|
.all(|x| (parent.x..parent.x + colspan).contains(x))
|
|
{
|
|
// Additionally, as a heuristic, a colspan won't affect the
|
|
// size of auto columns if it already spans all fractional
|
|
// columns, since those would already expand to provide all
|
|
// remaining available after auto column sizing to that
|
|
// cell. However, this heuristic is only valid in finite
|
|
// regions (pages without 'auto' width), since otherwise
|
|
// the fractional columns don't expand at all.
|
|
continue;
|
|
}
|
|
|
|
// Sum the heights of spanned rows to find the expected
|
|
// available height for the cell, unless it spans a fractional
|
|
// or auto column.
|
|
let rowspan = self.grid.effective_rowspan_of_cell(cell);
|
|
let height = self
|
|
.grid
|
|
.rows
|
|
.iter()
|
|
.skip(y)
|
|
.take(rowspan)
|
|
.try_fold(Abs::zero(), |acc, col| {
|
|
// For relative rows, we can already resolve the correct
|
|
// base and for auto and fr we could only guess anyway.
|
|
match col {
|
|
Sizing::Rel(v) => Some(
|
|
acc + v
|
|
.resolve(self.styles)
|
|
.relative_to(self.regions.base().y),
|
|
),
|
|
_ => None,
|
|
}
|
|
})
|
|
.unwrap_or_else(|| self.regions.base().y);
|
|
|
|
// Don't expand this auto column more than the cell actually
|
|
// needs. To do this, we check how much the other, previously
|
|
// resolved columns provide to the cell in terms of width
|
|
// (if it is a colspan), and subtract this from its expected
|
|
// width when comparing with other cells in this column. Note
|
|
// that, since this is the last auto column spanned by this
|
|
// cell, all other auto columns will already have been resolved
|
|
// and will be considered.
|
|
// Only fractional columns will be excluded from this
|
|
// calculation, which can lead to auto columns being expanded
|
|
// unnecessarily when cells span both a fractional column and
|
|
// an auto column. One mitigation for this is the heuristic
|
|
// used above to not expand the last auto column spanned by a
|
|
// cell if it spans all fractional columns in a finite region.
|
|
let already_covered_width = self.cell_spanned_width(cell, parent.x);
|
|
|
|
let size = Size::new(available, height);
|
|
let pod = Region::new(size, Axes::splat(false));
|
|
let frame =
|
|
layout_cell(cell, engine, 0, self.styles, pod.into())?.into_frame();
|
|
resolved.set_max(frame.width() - already_covered_width);
|
|
}
|
|
|
|
self.rcols[x] = resolved;
|
|
auto += resolved;
|
|
count += 1;
|
|
}
|
|
|
|
Ok((auto, count))
|
|
}
|
|
|
|
/// Distribute remaining space to fractional columns.
|
|
fn grow_fractional_columns(&mut self, remaining: Abs, fr: Fr) {
|
|
if fr.is_zero() {
|
|
return;
|
|
}
|
|
|
|
for (&col, rcol) in self.grid.cols.iter().zip(&mut self.rcols) {
|
|
if let Sizing::Fr(v) = col {
|
|
*rcol = v.share(fr, remaining);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Redistribute space to auto columns so that each gets a fair share.
|
|
fn shrink_auto_columns(&mut self, available: Abs, count: usize) {
|
|
let mut last;
|
|
let mut fair = -Abs::inf();
|
|
let mut redistribute = available;
|
|
let mut overlarge = count;
|
|
let mut changed = true;
|
|
|
|
// Iteratively remove columns that don't need to be shrunk.
|
|
while changed && overlarge > 0 {
|
|
changed = false;
|
|
last = fair;
|
|
fair = redistribute / (overlarge as f64);
|
|
|
|
for (&col, &rcol) in self.grid.cols.iter().zip(&self.rcols) {
|
|
// Remove an auto column if it is not overlarge (rcol <= fair),
|
|
// but also hasn't already been removed (rcol > last).
|
|
if col == Sizing::Auto && rcol <= fair && rcol > last {
|
|
redistribute -= rcol;
|
|
overlarge -= 1;
|
|
changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Redistribute space fairly among overlarge columns.
|
|
for (&col, rcol) in self.grid.cols.iter().zip(&mut self.rcols) {
|
|
if col == Sizing::Auto && *rcol > fair {
|
|
*rcol = fair;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Layout a row with automatic height. Such a row may break across multiple
|
|
/// regions.
|
|
fn layout_auto_row(
|
|
&mut self,
|
|
engine: &mut Engine,
|
|
disambiguator: usize,
|
|
y: usize,
|
|
) -> SourceResult<()> {
|
|
// Determine the size for each region of the row. If the first region
|
|
// ends up empty for some column, skip the region and remeasure.
|
|
let mut resolved = match self.measure_auto_row(
|
|
engine,
|
|
disambiguator,
|
|
y,
|
|
true,
|
|
self.unbreakable_rows_left,
|
|
None,
|
|
)? {
|
|
Some(resolved) => resolved,
|
|
None => {
|
|
self.finish_region(engine, false)?;
|
|
self.measure_auto_row(
|
|
engine,
|
|
disambiguator,
|
|
y,
|
|
false,
|
|
self.unbreakable_rows_left,
|
|
None,
|
|
)?
|
|
.unwrap()
|
|
}
|
|
};
|
|
|
|
// Nothing to layout.
|
|
if resolved.is_empty() {
|
|
return Ok(());
|
|
}
|
|
|
|
// Layout into a single region.
|
|
if let &[first] = resolved.as_slice() {
|
|
let frame = self.layout_single_row(engine, disambiguator, first, y)?;
|
|
self.push_row(frame, y, true);
|
|
|
|
if let Some(row_height) = &mut self.row_state.current_row_height {
|
|
// Add to header height, as we are in a header row.
|
|
*row_height += first;
|
|
}
|
|
|
|
return Ok(());
|
|
}
|
|
|
|
// Expand all but the last region.
|
|
// Skip the first region if the space is eaten up by an fr row.
|
|
let len = resolved.len();
|
|
for ((i, region), target) in
|
|
self.regions
|
|
.iter()
|
|
.enumerate()
|
|
.zip(&mut resolved[..len - 1])
|
|
.skip(self.current.lrows.iter().any(|row| matches!(row, Row::Fr(..)))
|
|
as usize)
|
|
{
|
|
// Subtract header and footer heights from the region height when
|
|
// it's not the first. Ignore non-repeating headers as they only
|
|
// appear on the first region by definition.
|
|
target.set_max(
|
|
region.y
|
|
- if i > 0 {
|
|
self.current.repeating_header_height + self.current.footer_height
|
|
} else {
|
|
Abs::zero()
|
|
},
|
|
);
|
|
}
|
|
|
|
// Layout into multiple regions.
|
|
let fragment = self.layout_multi_row(engine, disambiguator, &resolved, y)?;
|
|
let len = fragment.len();
|
|
for (i, frame) in fragment.into_iter().enumerate() {
|
|
self.push_row(frame, y, i + 1 == len);
|
|
if i + 1 < len {
|
|
self.finish_region(engine, false)?;
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Measure the regions sizes of an auto row. The option is always `Some(_)`
|
|
/// if `can_skip` is false.
|
|
/// If `unbreakable_rows_left` is positive, this function shall only return
|
|
/// a single frame. Useful when an unbreakable rowspan crosses this auto
|
|
/// row.
|
|
/// The `row_group_data` option is used within the unbreakable row group
|
|
/// simulator to predict the height of the auto row if previous rows in the
|
|
/// group were placed in the same region.
|
|
pub(super) fn measure_auto_row(
|
|
&self,
|
|
engine: &mut Engine,
|
|
disambiguator: usize,
|
|
y: usize,
|
|
can_skip: bool,
|
|
unbreakable_rows_left: usize,
|
|
row_group_data: Option<&UnbreakableRowGroup>,
|
|
) -> SourceResult<Option<Vec<Abs>>> {
|
|
let breakable = unbreakable_rows_left == 0;
|
|
let mut resolved: Vec<Abs> = vec![];
|
|
let mut pending_rowspans: Vec<(usize, usize, Vec<Abs>)> = vec![];
|
|
|
|
for x in 0..self.rcols.len() {
|
|
// Get the parent cell in case this is a merged position.
|
|
let Some(parent) = self.grid.parent_cell_position(x, y) else {
|
|
// Skip gutter columns.
|
|
continue;
|
|
};
|
|
if parent.x != x {
|
|
// Only check the height of a colspan once.
|
|
continue;
|
|
}
|
|
// The parent cell is never a gutter or merged position.
|
|
let cell = self.grid.cell(parent.x, parent.y).unwrap();
|
|
let rowspan = self.grid.effective_rowspan_of_cell(cell);
|
|
|
|
if rowspan > 1 {
|
|
let last_spanned_auto_row = self
|
|
.grid
|
|
.rows
|
|
.iter()
|
|
.enumerate()
|
|
.skip(parent.y)
|
|
.take(rowspan)
|
|
.rev()
|
|
.find(|(_, &row)| row == Sizing::Auto)
|
|
.map(|(y, _)| y);
|
|
|
|
if last_spanned_auto_row != Some(y) {
|
|
// A rowspan should only affect the height of its last
|
|
// spanned auto row.
|
|
continue;
|
|
}
|
|
}
|
|
|
|
let measurement_data = self.prepare_auto_row_cell_measurement(
|
|
parent,
|
|
cell,
|
|
breakable,
|
|
row_group_data,
|
|
);
|
|
let size = Axes::new(measurement_data.width, measurement_data.height);
|
|
let backlog =
|
|
measurement_data.backlog.unwrap_or(&measurement_data.custom_backlog);
|
|
|
|
let pod = if !breakable {
|
|
// Force cell to fit into a single region when the row is
|
|
// unbreakable, even when it is a breakable rowspan, as a best
|
|
// effort.
|
|
let mut pod: Regions = Region::new(size, self.regions.expand).into();
|
|
pod.full = measurement_data.full;
|
|
|
|
if measurement_data.frames_in_previous_regions > 0 {
|
|
// Best effort to conciliate a breakable rowspan which
|
|
// started at a previous region going through an
|
|
// unbreakable auto row. Ensure it goes through previously
|
|
// laid out regions, but stops at this one when measuring.
|
|
pod.backlog = backlog;
|
|
}
|
|
|
|
pod
|
|
} else {
|
|
// This row is breakable, so measure the cell normally, with
|
|
// the initial height and backlog determined previously.
|
|
let mut pod = self.regions;
|
|
pod.size = size;
|
|
pod.backlog = backlog;
|
|
pod.full = measurement_data.full;
|
|
pod.last = measurement_data.last;
|
|
|
|
pod
|
|
};
|
|
|
|
let frames =
|
|
layout_cell(cell, engine, disambiguator, self.styles, pod)?.into_frames();
|
|
|
|
// Skip the first region if one cell in it is empty. Then,
|
|
// remeasure.
|
|
if let Some([first, rest @ ..]) =
|
|
frames.get(measurement_data.frames_in_previous_regions..)
|
|
{
|
|
if can_skip
|
|
&& breakable
|
|
&& first.is_empty()
|
|
&& rest.iter().any(|frame| !frame.is_empty())
|
|
{
|
|
return Ok(None);
|
|
}
|
|
}
|
|
|
|
// Skip frames from previous regions if applicable.
|
|
let mut sizes = frames
|
|
.iter()
|
|
.skip(measurement_data.frames_in_previous_regions)
|
|
.map(|frame| frame.height())
|
|
.collect::<Vec<_>>();
|
|
|
|
// Don't expand this row more than the cell needs.
|
|
// To figure out how much height the cell needs, we must first
|
|
// subtract, from the cell's expected height, the already resolved
|
|
// heights of its spanned rows. Note that this is the last spanned
|
|
// auto row, so all previous auto rows were already resolved, as
|
|
// well as fractional rows in previous regions.
|
|
// Additionally, we subtract the heights of fixed-size rows which
|
|
// weren't laid out yet, since those heights won't change in
|
|
// principle.
|
|
// Upcoming fractional rows are ignored.
|
|
// Upcoming gutter rows might be removed, so we need to simulate
|
|
// them.
|
|
if rowspan > 1 {
|
|
let should_simulate = self.prepare_rowspan_sizes(
|
|
y,
|
|
&mut sizes,
|
|
cell,
|
|
parent.y,
|
|
rowspan,
|
|
unbreakable_rows_left,
|
|
&measurement_data,
|
|
);
|
|
|
|
if should_simulate {
|
|
// Rowspan spans gutter and is breakable. We'll need to
|
|
// run a simulation to predict how much this auto row needs
|
|
// to expand so that the rowspan's contents fit into the
|
|
// table.
|
|
pending_rowspans.push((parent.y, rowspan, sizes));
|
|
continue;
|
|
}
|
|
}
|
|
|
|
let mut sizes = sizes.into_iter();
|
|
|
|
for (target, size) in resolved.iter_mut().zip(&mut sizes) {
|
|
target.set_max(size);
|
|
}
|
|
|
|
// New heights are maximal by virtue of being new. Note that
|
|
// this extend only uses the rest of the sizes iterator.
|
|
resolved.extend(sizes);
|
|
}
|
|
|
|
// Simulate the upcoming regions in order to predict how much we need
|
|
// to expand this auto row for rowspans which span gutter.
|
|
if !pending_rowspans.is_empty() {
|
|
self.simulate_and_measure_rowspans_in_auto_row(
|
|
y,
|
|
&mut resolved,
|
|
&pending_rowspans,
|
|
unbreakable_rows_left,
|
|
row_group_data,
|
|
disambiguator,
|
|
engine,
|
|
)?;
|
|
}
|
|
|
|
debug_assert!(breakable || resolved.len() <= 1);
|
|
|
|
Ok(Some(resolved))
|
|
}
|
|
|
|
/// Layout a row with relative height. Such a row cannot break across
|
|
/// multiple regions, but it may force a region break.
|
|
fn layout_relative_row(
|
|
&mut self,
|
|
engine: &mut Engine,
|
|
disambiguator: usize,
|
|
v: Rel<Length>,
|
|
y: usize,
|
|
) -> SourceResult<()> {
|
|
let resolved = v.resolve(self.styles).relative_to(self.regions.base().y);
|
|
let frame = self.layout_single_row(engine, disambiguator, resolved, y)?;
|
|
|
|
if let Some(row_height) = &mut self.row_state.current_row_height {
|
|
// Add to header height, as we are in a header row.
|
|
*row_height += resolved;
|
|
}
|
|
|
|
// Skip to fitting region, but only if we aren't part of an unbreakable
|
|
// row group. We use 'may_progress_with_offset' so our 'may_progress'
|
|
// call properly considers that a header and a footer would be added
|
|
// on each region break, so we only keep skipping regions until we
|
|
// reach one with the same height of the 'last' region (which can be
|
|
// endlessly repeated) when subtracting header and footer height.
|
|
//
|
|
// See 'check_for_unbreakable_rows' as for why we're using
|
|
// 'header_height' to predict header height and not
|
|
// 'repeating_header_height'.
|
|
let height = frame.height();
|
|
while self.unbreakable_rows_left == 0
|
|
&& !self.regions.size.y.fits(height)
|
|
&& may_progress_with_offset(
|
|
self.regions,
|
|
self.current.header_height + self.current.footer_height,
|
|
)
|
|
{
|
|
self.finish_region(engine, false)?;
|
|
|
|
// Don't skip multiple regions for gutter and don't push a row.
|
|
if self.grid.is_gutter_track(y) {
|
|
return Ok(());
|
|
}
|
|
}
|
|
|
|
self.push_row(frame, y, true);
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Layout a row with fixed height and return its frame.
|
|
fn layout_single_row(
|
|
&mut self,
|
|
engine: &mut Engine,
|
|
disambiguator: usize,
|
|
height: Abs,
|
|
y: usize,
|
|
) -> SourceResult<Frame> {
|
|
if !self.width.is_finite() {
|
|
bail!(self.span, "cannot create grid with infinite width");
|
|
}
|
|
|
|
if !height.is_finite() {
|
|
bail!(self.span, "cannot create grid with infinite height");
|
|
}
|
|
|
|
let mut output = Frame::soft(Size::new(self.width, height));
|
|
let mut pos = Point::zero();
|
|
|
|
// Reverse the column order when using RTL.
|
|
for (x, &rcol) in self.rcols.iter().enumerate().rev_if(self.is_rtl) {
|
|
if let Some(cell) = self.grid.cell(x, y) {
|
|
// Rowspans have a separate layout step
|
|
if cell.rowspan.get() == 1 {
|
|
let width = self.cell_spanned_width(cell, x);
|
|
let size = Size::new(width, height);
|
|
let mut pod: Regions = Region::new(size, Axes::splat(true)).into();
|
|
if self.grid.rows[y] == Sizing::Auto
|
|
&& self.unbreakable_rows_left == 0
|
|
{
|
|
// Cells at breakable auto rows have lengths relative
|
|
// to the entire page, unlike cells in unbreakable auto
|
|
// rows.
|
|
pod.full = self.regions.full;
|
|
}
|
|
let frame =
|
|
layout_cell(cell, engine, disambiguator, self.styles, pod)?
|
|
.into_frame();
|
|
let mut pos = pos;
|
|
if self.is_rtl {
|
|
// In the grid, cell colspans expand to the right,
|
|
// so we're at the leftmost (lowest 'x') column
|
|
// spanned by the cell. However, in RTL, cells
|
|
// expand to the left. Therefore, without the
|
|
// offset below, the cell's contents would be laid out
|
|
// starting at its rightmost visual position and extend
|
|
// over to unrelated cells to its right in RTL.
|
|
// We avoid this by ensuring the rendered cell starts at
|
|
// the very left of the cell, even with colspan > 1.
|
|
let offset = -width + rcol;
|
|
pos.x += offset;
|
|
}
|
|
output.push_frame(pos, frame);
|
|
}
|
|
}
|
|
|
|
pos.x += rcol;
|
|
}
|
|
|
|
Ok(output)
|
|
}
|
|
|
|
/// Layout a row spanning multiple regions.
|
|
fn layout_multi_row(
|
|
&mut self,
|
|
engine: &mut Engine,
|
|
disambiguator: usize,
|
|
heights: &[Abs],
|
|
y: usize,
|
|
) -> SourceResult<Fragment> {
|
|
// Prepare frames.
|
|
let mut outputs: Vec<_> = heights
|
|
.iter()
|
|
.map(|&h| Frame::soft(Size::new(self.width, h)))
|
|
.collect();
|
|
|
|
// Prepare regions.
|
|
let size = Size::new(self.width, heights[0]);
|
|
let mut pod: Regions = Region::new(size, Axes::splat(true)).into();
|
|
pod.full = self.regions.full;
|
|
pod.backlog = &heights[1..];
|
|
|
|
// Layout the row.
|
|
let mut pos = Point::zero();
|
|
for (x, &rcol) in self.rcols.iter().enumerate().rev_if(self.is_rtl) {
|
|
if let Some(cell) = self.grid.cell(x, y) {
|
|
// Rowspans have a separate layout step
|
|
if cell.rowspan.get() == 1 {
|
|
let width = self.cell_spanned_width(cell, x);
|
|
pod.size.x = width;
|
|
|
|
// Push the layouted frames into the individual output frames.
|
|
let fragment =
|
|
layout_cell(cell, engine, disambiguator, self.styles, pod)?;
|
|
for (output, frame) in outputs.iter_mut().zip(fragment) {
|
|
let mut pos = pos;
|
|
if self.is_rtl {
|
|
let offset = -width + rcol;
|
|
pos.x += offset;
|
|
}
|
|
output.push_frame(pos, frame);
|
|
}
|
|
}
|
|
}
|
|
|
|
pos.x += rcol;
|
|
}
|
|
|
|
Ok(Fragment::frames(outputs))
|
|
}
|
|
|
|
/// Push a row frame into the current region.
|
|
/// The `is_last` parameter must be `true` if this is the last frame which
|
|
/// will be pushed for this particular row. It can be `false` for rows
|
|
/// spanning multiple regions.
|
|
fn push_row(&mut self, frame: Frame, y: usize, is_last: bool) {
|
|
if !self.row_state.in_active_repeatable {
|
|
// There is now a row after the rows equipped with orphan
|
|
// prevention, so no need to keep moving them anymore.
|
|
self.flush_orphans();
|
|
}
|
|
self.regions.size.y -= frame.height();
|
|
self.current.lrows.push(Row::Frame(frame, y, is_last));
|
|
}
|
|
|
|
/// Finish rows for one region.
|
|
pub(super) fn finish_region(
|
|
&mut self,
|
|
engine: &mut Engine,
|
|
last: bool,
|
|
) -> SourceResult<()> {
|
|
if let Some(orphan_snapshot) = self.current.lrows_orphan_snapshot.take() {
|
|
if !last {
|
|
self.current.lrows.truncate(orphan_snapshot);
|
|
self.current.repeated_header_rows =
|
|
self.current.repeated_header_rows.min(orphan_snapshot);
|
|
|
|
if orphan_snapshot == 0 {
|
|
// Removed all repeated headers.
|
|
self.current.last_repeated_header_end = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
if self
|
|
.current
|
|
.lrows
|
|
.last()
|
|
.is_some_and(|row| self.grid.is_gutter_track(row.index()))
|
|
{
|
|
// Remove the last row in the region if it is a gutter row.
|
|
self.current.lrows.pop().unwrap();
|
|
self.current.repeated_header_rows =
|
|
self.current.repeated_header_rows.min(self.current.lrows.len());
|
|
}
|
|
|
|
// If no rows other than the footer have been laid out so far
|
|
// (e.g. due to header orphan prevention), and there are rows
|
|
// beside the footer, then don't lay it out at all.
|
|
//
|
|
// It is worth noting that the footer is made non-repeatable at
|
|
// the grid resolving stage if it is short-lived, that is, if
|
|
// it is at the start of the table (or right after headers at
|
|
// the start of the table).
|
|
// TODO(subfooters): explicitly check for short-lived footers.
|
|
// TODO(subfooters): widow prevention for non-repeated footers with a
|
|
// similar mechanism / when implementing multiple footers.
|
|
let footer_would_be_widow =
|
|
matches!(self.grid.footer, Some(Repeatable::Repeated(_)))
|
|
&& self.current.lrows.is_empty()
|
|
&& may_progress_with_offset(
|
|
self.regions,
|
|
// This header height isn't doing much as we just
|
|
// confirmed that there are no headers in this region,
|
|
// but let's keep it here for correctness. It will add
|
|
// zero anyway.
|
|
self.current.header_height + self.current.footer_height,
|
|
);
|
|
|
|
let mut laid_out_footer_start = None;
|
|
if !footer_would_be_widow {
|
|
if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
|
|
// Don't layout the footer if it would be alone with the header
|
|
// in the page (hence the widow check), and don't layout it
|
|
// twice.
|
|
// TODO: this check can be replaced by a vector of repeating
|
|
// footers in the future.
|
|
if self.current.lrows.iter().all(|row| row.index() < footer.start) {
|
|
laid_out_footer_start = Some(footer.start);
|
|
self.layout_footer(footer, engine, self.finished.len())?;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Determine the height of existing rows in the region.
|
|
let mut used = Abs::zero();
|
|
let mut fr = Fr::zero();
|
|
for row in &self.current.lrows {
|
|
match row {
|
|
Row::Frame(frame, _, _) => used += frame.height(),
|
|
Row::Fr(v, _, _) => fr += *v,
|
|
}
|
|
}
|
|
|
|
// Determine the size of the grid in this region, expanding fully if
|
|
// there are fr rows.
|
|
let mut size = Size::new(self.width, used).min(self.current.initial);
|
|
if fr.get() > 0.0 && self.current.initial.y.is_finite() {
|
|
size.y = self.current.initial.y;
|
|
}
|
|
|
|
// The frame for the region.
|
|
let mut output = Frame::soft(size);
|
|
let mut pos = Point::zero();
|
|
let mut rrows = vec![];
|
|
let current_region = self.finished.len();
|
|
let mut repeated_header_row_height = Abs::zero();
|
|
|
|
// Place finished rows and layout fractional rows.
|
|
for (i, row) in std::mem::take(&mut self.current.lrows).into_iter().enumerate() {
|
|
let (frame, y, is_last) = match row {
|
|
Row::Frame(frame, y, is_last) => (frame, y, is_last),
|
|
Row::Fr(v, y, disambiguator) => {
|
|
let remaining = self.regions.full - used;
|
|
let height = v.share(fr, remaining);
|
|
(self.layout_single_row(engine, disambiguator, height, y)?, y, true)
|
|
}
|
|
};
|
|
|
|
let height = frame.height();
|
|
if i < self.current.repeated_header_rows {
|
|
repeated_header_row_height += height;
|
|
}
|
|
|
|
// Ensure rowspans which span this row will have enough space to
|
|
// be laid out over it later.
|
|
for rowspan in self
|
|
.rowspans
|
|
.iter_mut()
|
|
.filter(|rowspan| (rowspan.y..rowspan.y + rowspan.rowspan).contains(&y))
|
|
.filter(|rowspan| {
|
|
rowspan.max_resolved_row.is_none_or(|max_row| y > max_row)
|
|
})
|
|
{
|
|
// If the first region wasn't defined yet, it will have the
|
|
// initial value of usize::MAX, so we can set it to the current
|
|
// region's index.
|
|
if rowspan.first_region > current_region {
|
|
rowspan.first_region = current_region;
|
|
// The rowspan starts at this region, precisely at this
|
|
// row. In other regions, it will start at dy = 0.
|
|
rowspan.dy = pos.y;
|
|
// When we layout the rowspan later, the full size of the
|
|
// pod must be equal to the full size of the first region
|
|
// it appears in.
|
|
rowspan.region_full = self.regions.full;
|
|
}
|
|
let amount_missing_heights = (current_region + 1)
|
|
.saturating_sub(rowspan.heights.len() + rowspan.first_region);
|
|
|
|
// Ensure the vector of heights is long enough such that the
|
|
// last height is the one for the current region.
|
|
rowspan
|
|
.heights
|
|
.extend(std::iter::repeat_n(Abs::zero(), amount_missing_heights));
|
|
|
|
// Ensure that, in this region, the rowspan will span at least
|
|
// this row.
|
|
*rowspan.heights.last_mut().unwrap() += height;
|
|
|
|
if is_last {
|
|
// Do not extend the rowspan through this row again, even
|
|
// if it is repeated in a future region.
|
|
rowspan.max_resolved_row = Some(y);
|
|
}
|
|
}
|
|
|
|
// We use a for loop over indices to avoid borrow checking
|
|
// problems (we need to mutate the rowspans vector, so we can't
|
|
// have an iterator actively borrowing it). We keep a separate
|
|
// 'i' variable so we can step the counter back after removing
|
|
// a rowspan (see explanation below).
|
|
let mut i = 0;
|
|
while let Some(rowspan) = self.rowspans.get(i) {
|
|
// Layout any rowspans which end at this row, but only if this is
|
|
// this row's last frame (to avoid having the rowspan stop being
|
|
// laid out at the first frame of the row).
|
|
// Any rowspans ending before this row are laid out even
|
|
// on this row's first frame.
|
|
if laid_out_footer_start.is_none_or(|footer_start| {
|
|
// If this is a footer row, then only lay out this rowspan
|
|
// if the rowspan is contained within the footer.
|
|
y < footer_start || rowspan.y >= footer_start
|
|
}) && (rowspan.y + rowspan.rowspan < y + 1
|
|
|| rowspan.y + rowspan.rowspan == y + 1 && is_last)
|
|
{
|
|
// Rowspan ends at this or an earlier row, so we take
|
|
// it from the rowspans vector and lay it out.
|
|
// It's safe to pass the current region as a possible
|
|
// region for the rowspan to be laid out in, even if
|
|
// the rowspan's last row was at an earlier region,
|
|
// because the rowspan won't have an entry for this
|
|
// region in its 'heights' vector if it doesn't span
|
|
// any rows in this region.
|
|
//
|
|
// Here we don't advance the index counter ('i') because
|
|
// a new element we haven't checked yet in this loop
|
|
// will take the index of the now removed element, so
|
|
// we have to check the same index again in the next
|
|
// iteration.
|
|
let rowspan = self.rowspans.remove(i);
|
|
self.layout_rowspan(
|
|
rowspan,
|
|
Some((&mut output, repeated_header_row_height)),
|
|
engine,
|
|
)?;
|
|
} else {
|
|
i += 1;
|
|
}
|
|
}
|
|
|
|
output.push_frame(pos, frame);
|
|
rrows.push(RowPiece { height, y });
|
|
pos.y += height;
|
|
}
|
|
|
|
self.finish_region_internal(
|
|
output,
|
|
rrows,
|
|
FinishedHeaderRowInfo {
|
|
repeated_amount: self.current.repeated_header_rows,
|
|
last_repeated_header_end: self.current.last_repeated_header_end,
|
|
repeated_height: repeated_header_row_height,
|
|
},
|
|
);
|
|
|
|
if !last {
|
|
self.current.repeated_header_rows = 0;
|
|
self.current.last_repeated_header_end = 0;
|
|
self.current.header_height = Abs::zero();
|
|
self.current.repeating_header_height = Abs::zero();
|
|
self.current.repeating_header_heights.clear();
|
|
|
|
let disambiguator = self.finished.len();
|
|
if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
|
|
self.prepare_footer(footer, engine, disambiguator)?;
|
|
}
|
|
|
|
// Ensure rows don't try to overrun the footer.
|
|
// Note that header layout will only subtract this again if it has
|
|
// to skip regions to fit headers, so there is no risk of
|
|
// subtracting this twice.
|
|
self.regions.size.y -= self.current.footer_height;
|
|
|
|
if !self.repeating_headers.is_empty() || !self.pending_headers.is_empty() {
|
|
// Add headers to the new region.
|
|
self.layout_active_headers(engine)?;
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Advances to the next region, registering the finished output and
|
|
/// resolved rows for the current region in the appropriate vectors.
|
|
pub(super) fn finish_region_internal(
|
|
&mut self,
|
|
output: Frame,
|
|
resolved_rows: Vec<RowPiece>,
|
|
header_row_info: FinishedHeaderRowInfo,
|
|
) {
|
|
self.finished.push(output);
|
|
self.rrows.push(resolved_rows);
|
|
self.regions.next();
|
|
self.current.initial = self.regions.size;
|
|
|
|
if !self.grid.headers.is_empty() {
|
|
self.finished_header_rows.push(header_row_info);
|
|
}
|
|
|
|
// Ensure orphan prevention is handled before resolving rows.
|
|
debug_assert!(self.current.lrows_orphan_snapshot.is_none());
|
|
}
|
|
}
|
|
|
|
/// Turn an iterator of extents into an iterator of offsets before, in between,
|
|
/// and after the extents, e.g. [10mm, 5mm] -> [0mm, 10mm, 15mm].
|
|
pub(super) fn points(
|
|
extents: impl IntoIterator<Item = Abs>,
|
|
) -> impl Iterator<Item = Abs> {
|
|
let mut offset = Abs::zero();
|
|
std::iter::once(Abs::zero()).chain(extents).map(move |extent| {
|
|
offset += extent;
|
|
offset
|
|
})
|
|
}
|
|
|
|
/// Checks if the first region of a sequence of regions is not the last usable
|
|
/// region, assuming that the last region will always be occupied by some
|
|
/// specific offset height, even after calling `.next()`, due to some
|
|
/// additional logic which adds content automatically on each region turn (in
|
|
/// our case, headers).
|
|
pub(super) fn may_progress_with_offset(regions: Regions<'_>, offset: Abs) -> bool {
|
|
!regions.backlog.is_empty()
|
|
|| regions.last.is_some_and(|height| regions.size.y + offset != height)
|
|
}
|