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use may_progress_with_repeats

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This commit is contained in:
PgBiel 2025-05-12 20:03:36 -03:00
parent 2127a9e044
commit 3ec699541a
2 changed files with 35 additions and 37 deletions
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20
crates/typst-layout/src/grid/layouter.rs
View File

@ -81,6 +81,9 @@ pub(super) struct Current {
/// This is used to quickly tell if any additional space in the region has
/// been occupied since then.
pub(super) initial_after_repeats: Abs,
/// Whether `layouter.regions.may_progress()` was `true` at the top of the
/// region.
pub(super) could_progress_at_top: bool,
/// Rows in the current region.
pub(super) lrows: Vec<Row>,
/// The amount of repeated header rows at the start of the current region.
@ -253,6 +256,7 @@ impl<'a> GridLayouter<'a> {
current: Current {
initial: regions.size,
initial_after_repeats: regions.size.y,
could_progress_at_top: regions.may_progress(),
lrows: vec![],
repeated_header_rows: 0,
last_repeated_header_end: 0,
@ -1383,10 +1387,7 @@ impl<'a> GridLayouter<'a> {
let height = frame.height();
while self.unbreakable_rows_left == 0
&& !self.regions.size.y.fits(height)
&& may_progress_with_offset(
self.regions,
self.current.repeating_header_height + self.current.footer_height,
)
&& self.may_progress_with_repeats()
{
self.finish_region(engine, false)?;
@ -1569,12 +1570,7 @@ impl<'a> GridLayouter<'a> {
let footer_would_be_widow =
matches!(self.grid.footer, Some(Repeatable::Repeated(_)))
&& self.current.lrows.is_empty()
&& may_progress_with_offset(
self.regions,
// Don't sum header height as we just confirmed that there
// are no headers in this region.
self.current.footer_height,
);
&& self.may_progress_with_repeats();
let mut laid_out_footer_start = None;
if !footer_would_be_widow {
@ -1773,6 +1769,10 @@ impl<'a> GridLayouter<'a> {
self.rrows.push(resolved_rows);
self.regions.next();
self.current.initial = self.regions.size;
// Repeats haven't been laid out yet, so in the meantime, this will
// represent the initial height after repeats laid out so far, and will
// be gradually updated when preparing footers and repeating headers.
self.current.initial_after_repeats = self.current.initial.y;
if !self.grid.headers.is_empty() {

52
crates/typst-layout/src/grid/repeated.rs
View File

@ -3,10 +3,30 @@ use typst_library::engine::Engine;
use typst_library::layout::grid::resolve::{Footer, Header, Repeatable};
use typst_library::layout::{Abs, Axes, Frame, Regions};
use super::layouter::{may_progress_with_offset, GridLayouter, RowState};
use super::layouter::{GridLayouter, RowState};
use super::rowspans::UnbreakableRowGroup;
impl<'a> GridLayouter<'a> {
/// Checks whether a region break could help a situation where we're out of
/// space for the next row. The criteria are:
///
/// 1. If we could progress at the top of the region, that indicates the
/// region has a backlog, or (if we're at the first region) a region break
/// is at all possible (`regions.last` is `Some()`), so that's sufficient.
///
/// 2. Otherwise, we may progress if another region break is possible
/// (`regions.last` is still `Some()`) and non-repeating rows have been
/// placed, since that means the space they occupy will be available in the
/// next region.
pub fn may_progress_with_repeats(&self) -> bool {
// TODO(subfooters): check below isn't enough to detect non-repeating
// footers... we can also change 'initial_after_repeats' to stop being
// calculated if there were any non-repeating footers.
self.current.could_progress_at_top
|| self.regions.last.is_some()
&& self.regions.size.y != self.current.initial_after_repeats
}
pub fn place_new_headers(
&mut self,
consecutive_header_count: &mut usize,
@ -213,16 +233,7 @@ impl<'a> GridLayouter<'a> {
let mut skipped_region = false;
while self.unbreakable_rows_left == 0
&& !self.regions.size.y.fits(header_height)
&& may_progress_with_offset(
self.regions,
// - Assume footer height already starts subtracted from the
// first region's size;
// - On each iteration, we subtract footer height from the
// available size for consistency with the first region, so we
// need to consider the footer when evaluating if skipping yet
// another region would make a difference.
self.current.footer_height,
)
&& self.may_progress_with_repeats()
{
// Advance regions without any output until we can place the
// header and the footer.
@ -275,8 +286,7 @@ impl<'a> GridLayouter<'a> {
debug_assert!(self.current.lrows.is_empty());
debug_assert!(self.current.lrows_orphan_snapshot.is_none());
let may_progress =
may_progress_with_offset(self.regions, self.current.footer_height);
let may_progress = self.may_progress_with_repeats();
if may_progress {
// Enable orphan prevention for headers at the top of the region.
@ -372,16 +382,7 @@ impl<'a> GridLayouter<'a> {
// consider if we can already be in an unbreakable row group?
while self.unbreakable_rows_left == 0
&& !self.regions.size.y.fits(header_height)
&& may_progress_with_offset(
self.regions,
// 'finish_region' will place currently active headers and
// footers again. We assume previous pending headers have
// already been flushed, so in principle
// 'header_height == repeating_header_height' here
// (there won't be any pending headers at this point, other
// than the ones we are about to place).
self.current.repeating_header_height + self.current.footer_height,
)
&& self.may_progress_with_repeats()
{
// Note that, after the first region skip, the new headers will go
// at the top of the region, but after the repeating headers that
@ -394,10 +395,7 @@ impl<'a> GridLayouter<'a> {
// TODO(subfooters): what if there is a footer right after it?
let should_snapshot = !short_lived
&& self.current.lrows_orphan_snapshot.is_none()
&& may_progress_with_offset(
self.regions,
self.current.repeating_header_height + self.current.footer_height,
);
&& self.may_progress_with_repeats();
if should_snapshot {
// If we don't enter this branch while laying out non-short lived