Move everything into `crates/` directory

1 files changed, 708 insertions, 0 deletions

diff --git a/crates/typst-library/src/layout/grid.rs b/crates/typst-library/src/layout/grid.rs
new file mode 100644
index 00000000..4f5175e9
--- /dev/null
+++ b/crates/typst-library/src/layout/grid.rs
@@ -0,0 +1,708 @@
+use crate::prelude::*;
+use crate::text::TextElem;
+
+use super::Sizing;
+
+/// Arranges content in a grid.
+///
+/// The grid element allows you to arrange content in a grid. You can define the
+/// number of rows and columns, as well as the size of the gutters between them.
+/// There are multiple sizing modes for columns and rows that can be used to
+/// create complex layouts.
+///
+/// The sizing of the grid is determined by the track sizes specified in the
+/// arguments. Because each of the sizing parameters accepts the same values, we
+/// will explain them just once, here. Each sizing argument accepts an array of
+/// individual track sizes. A track size is either:
+///
+/// - `{auto}`: The track will be sized to fit its contents. It will be at most
+///   as large as the remaining space. If there is more than one `{auto}` track
+///   which, and together they claim more than the available space, the `{auto}`
+///   tracks will fairly distribute the available space among themselves.
+///
+/// - A fixed or relative length (e.g. `{10pt}` or `{20% - 1cm}`): The track
+///   will be exactly of this size.
+///
+/// - A fractional length (e.g. `{1fr}`): Once all other tracks have been sized,
+///   the remaining space will be divided among the fractional tracks according
+///   to their fractions. For example, if there are two fractional tracks, each
+///   with a fraction of `{1fr}`, they will each take up half of the remaining
+///   space.
+///
+/// To specify a single track, the array can be omitted in favor of a single
+/// value. To specify multiple `{auto}` tracks, enter the number of tracks
+/// instead of an array. For example, `columns:` `{3}` is equivalent to
+/// `columns:` `{(auto, auto, auto)}`.
+///
+/// ## Example { #example }
+/// ```example
+/// #set text(10pt, style: "italic")
+/// #let cell = rect.with(
+///   inset: 8pt,
+///   fill: rgb("e4e5ea"),
+///   width: 100%,
+///   radius: 6pt
+/// )
+/// #grid(
+///   columns: (60pt, 1fr, 60pt),
+///   rows: (60pt, auto),
+///   gutter: 3pt,
+///   cell(height: 100%)[Easy to learn],
+///   cell(height: 100%)[Great output],
+///   cell(height: 100%)[Intuitive],
+///   cell[Our best Typst yet],
+///   cell[
+///     Responsive design in print
+///     for everyone
+///   ],
+///   cell[One more thing...],
+/// )
+/// ```
+///
+/// Display: Grid
+/// Category: layout
+#[element(Layout)]
+pub struct GridElem {
+    /// The column sizes.
+    ///
+    /// Either specify a track size array or provide an integer to create a grid
+    /// with that many `{auto}`-sized columns. Note that opposed to rows and
+    /// gutters, providing a single track size will only ever create a single
+    /// column.
+    pub columns: TrackSizings,
+
+    /// The row sizes.
+    ///
+    /// If there are more cells than fit the defined rows, the last row is
+    /// repeated until there are no more cells.
+    pub rows: TrackSizings,
+
+    /// The gaps between rows & columns.
+    ///
+    /// If there are more gutters than defined sizes, the last gutter is repeated.
+    #[external]
+    pub gutter: TrackSizings,
+
+    /// The gaps between columns. Takes precedence over `gutter`.
+    #[parse(
+        let gutter = args.named("gutter")?;
+        args.named("column-gutter")?.or_else(|| gutter.clone())
+    )]
+    pub column_gutter: TrackSizings,
+
+    /// The gaps between rows. Takes precedence over `gutter`.
+    #[parse(args.named("row-gutter")?.or_else(|| gutter.clone()))]
+    pub row_gutter: TrackSizings,
+
+    /// The contents of the grid cells.
+    ///
+    /// The cells are populated in row-major order.
+    #[variadic]
+    pub children: Vec<Content>,
+}
+
+impl Layout for GridElem {
+    #[tracing::instrument(name = "GridElem::layout", skip_all)]
+    fn layout(
+        &self,
+        vt: &mut Vt,
+        styles: StyleChain,
+        regions: Regions,
+    ) -> SourceResult<Fragment> {
+        // Prepare grid layout by unifying content and gutter tracks.
+        let cells = self.children();
+        let layouter = GridLayouter::new(
+            Axes::new(&self.columns(styles).0, &self.rows(styles).0),
+            Axes::new(&self.column_gutter(styles).0, &self.row_gutter(styles).0),
+            &cells,
+            regions,
+            styles,
+        );
+
+        // Measure the columns and layout the grid row-by-row.
+        Ok(layouter.layout(vt)?.fragment)
+    }
+}
+
+/// Track sizing definitions.
+#[derive(Debug, Default, Clone, Eq, PartialEq, Hash)]
+pub struct TrackSizings(pub Vec<Sizing>);
+
+cast! {
+    TrackSizings,
+    self => self.0.into_value(),
+    sizing: Sizing => Self(vec![sizing]),
+    count: NonZeroUsize => Self(vec![Sizing::Auto; count.get()]),
+    values: Array => Self(values.into_iter().map(Value::cast).collect::<StrResult<_>>()?),
+}
+
+/// Performs grid layout.
+pub struct GridLayouter<'a> {
+    /// The grid cells.
+    cells: &'a [Content],
+    /// Whether this is an RTL grid.
+    is_rtl: bool,
+    /// Whether this grid has gutters.
+    has_gutter: bool,
+    /// The column tracks including gutter tracks.
+    cols: Vec<Sizing>,
+    /// The row tracks including gutter tracks.
+    rows: Vec<Sizing>,
+    /// The regions to layout children into.
+    regions: Regions<'a>,
+    /// The inherited styles.
+    styles: StyleChain<'a>,
+    /// Resolved column sizes.
+    rcols: Vec<Abs>,
+    /// The sum of `rcols`.
+    width: Abs,
+    /// Resolve row sizes, by region.
+    rrows: Vec<Vec<RowPiece>>,
+    /// Rows in the current region.
+    lrows: Vec<Row>,
+    /// The initial size of the current region before we started subtracting.
+    initial: Size,
+    /// Frames for finished regions.
+    finished: Vec<Frame>,
+}
+
+/// The resulting sizes of columns and rows in a grid.
+#[derive(Debug)]
+pub struct GridLayout {
+    /// The fragment.
+    pub fragment: Fragment,
+    /// The column widths.
+    pub cols: Vec<Abs>,
+    /// The heights of the resulting rows segments, by region.
+    pub rows: Vec<Vec<RowPiece>>,
+}
+
+/// Details about a resulting row piece.
+#[derive(Debug)]
+pub struct RowPiece {
+    /// The height of the segment.
+    pub height: Abs,
+    /// The index of the row.
+    pub y: usize,
+}
+
+/// Produced by initial row layout, auto and relative rows are already finished,
+/// fractional rows not yet.
+enum Row {
+    /// Finished row frame of auto or relative row with y index.
+    Frame(Frame, usize),
+    /// Fractional row with y index.
+    Fr(Fr, usize),
+}
+
+impl<'a> GridLayouter<'a> {
+    /// Create a new grid layouter.
+    ///
+    /// This prepares grid layout by unifying content and gutter tracks.
+    pub fn new(
+        tracks: Axes<&[Sizing]>,
+        gutter: Axes<&[Sizing]>,
+        cells: &'a [Content],
+        regions: Regions<'a>,
+        styles: StyleChain<'a>,
+    ) -> Self {
+        let mut cols = vec![];
+        let mut rows = vec![];
+
+        // Number of content columns: Always at least one.
+        let c = tracks.x.len().max(1);
+
+        // Number of content rows: At least as many as given, but also at least
+        // as many as needed to place each item.
+        let r = {
+            let len = cells.len();
+            let given = tracks.y.len();
+            let needed = len / c + (len % c).clamp(0, 1);
+            given.max(needed)
+        };
+
+        let has_gutter = gutter.any(|tracks| !tracks.is_empty());
+        let auto = Sizing::Auto;
+        let zero = Sizing::Rel(Rel::zero());
+        let get_or = |tracks: &[_], idx, default| {
+            tracks.get(idx).or(tracks.last()).copied().unwrap_or(default)
+        };
+
+        // Collect content and gutter columns.
+        for x in 0..c {
+            cols.push(get_or(tracks.x, x, auto));
+            if has_gutter {
+                cols.push(get_or(gutter.x, x, zero));
+            }
+        }
+
+        // Collect content and gutter rows.
+        for y in 0..r {
+            rows.push(get_or(tracks.y, y, auto));
+            if has_gutter {
+                rows.push(get_or(gutter.y, y, zero));
+            }
+        }
+
+        // Remove superfluous gutter tracks.
+        if has_gutter {
+            cols.pop();
+            rows.pop();
+        }
+
+        // Reverse for RTL.
+        let is_rtl = TextElem::dir_in(styles) == Dir::RTL;
+        if is_rtl {
+            cols.reverse();
+        }
+
+        // We use these regions for auto row measurement. Since at that moment,
+        // columns are already sized, we can enable horizontal expansion.
+        let mut regions = regions;
+        regions.expand = Axes::new(true, false);
+
+        Self {
+            cells,
+            is_rtl,
+            has_gutter,
+            rows,
+            regions,
+            styles,
+            rcols: vec![Abs::zero(); cols.len()],
+            cols,
+            width: Abs::zero(),
+            rrows: vec![],
+            lrows: vec![],
+            initial: regions.size,
+            finished: vec![],
+        }
+    }
+
+    /// Determines the columns sizes and then layouts the grid row-by-row.
+    pub fn layout(mut self, vt: &mut Vt) -> SourceResult<GridLayout> {
+        self.measure_columns(vt)?;
+
+        for y in 0..self.rows.len() {
+            // Skip to next region if current one is full, but only for content
+            // rows, not for gutter rows.
+            if self.regions.is_full() && (!self.has_gutter || y % 2 == 0) {
+                self.finish_region(vt)?;
+            }
+
+            match self.rows[y] {
+                Sizing::Auto => self.layout_auto_row(vt, y)?,
+                Sizing::Rel(v) => self.layout_relative_row(vt, v, y)?,
+                Sizing::Fr(v) => self.lrows.push(Row::Fr(v, y)),
+            }
+        }
+
+        self.finish_region(vt)?;
+
+        Ok(GridLayout {
+            fragment: Fragment::frames(self.finished),
+            cols: self.rcols,
+            rows: self.rrows,
+        })
+    }
+
+    /// Determine all column sizes.
+    #[tracing::instrument(name = "GridLayouter::measure_columns", skip_all)]
+    fn measure_columns(&mut self, vt: &mut Vt) -> 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.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(vt, 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(())
+    }
+
+    /// Measure the size that is available to auto columns.
+    fn measure_auto_columns(
+        &mut self,
+        vt: &mut Vt,
+        available: Abs,
+    ) -> SourceResult<(Abs, usize)> {
+        let mut auto = Abs::zero();
+        let mut count = 0;
+
+        // 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.cols.iter().enumerate() {
+            if col != Sizing::Auto {
+                continue;
+            }
+
+            let mut resolved = Abs::zero();
+            for y in 0..self.rows.len() {
+                if let Some(cell) = self.cell(x, y) {
+                    // For relative rows, we can already resolve the correct
+                    // base and for auto and fr we could only guess anyway.
+                    let height = match self.rows[y] {
+                        Sizing::Rel(v) => {
+                            v.resolve(self.styles).relative_to(self.regions.base().y)
+                        }
+                        _ => self.regions.base().y,
+                    };
+
+                    let size = Size::new(available, height);
+                    let pod = Regions::one(size, Axes::splat(false));
+                    let frame = cell.measure(vt, self.styles, pod)?.into_frame();
+                    resolved.set_max(frame.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.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.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.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, vt: &mut Vt, 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(vt, y, true)? {
+            Some(resolved) => resolved,
+            None => {
+                self.finish_region(vt)?;
+                self.measure_auto_row(vt, y, false)?.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(vt, first, y)?;
+            self.push_row(frame, y);
+            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 (region, target) in self
+            .regions
+            .iter()
+            .zip(&mut resolved[..len - 1])
+            .skip(self.lrows.iter().any(|row| matches!(row, Row::Fr(..))) as usize)
+        {
+            target.set_max(region.y);
+        }
+
+        // Layout into multiple regions.
+        let fragment = self.layout_multi_row(vt, &resolved, y)?;
+        let len = fragment.len();
+        for (i, frame) in fragment.into_iter().enumerate() {
+            self.push_row(frame, y);
+            if i + 1 < len {
+                self.finish_region(vt)?;
+            }
+        }
+
+        Ok(())
+    }
+
+    /// Measure the regions sizes of an auto row. The option is always `Some(_)`
+    /// if `can_skip` is false.
+    fn measure_auto_row(
+        &mut self,
+        vt: &mut Vt,
+        y: usize,
+        can_skip: bool,
+    ) -> SourceResult<Option<Vec<Abs>>> {
+        let mut resolved: Vec<Abs> = vec![];
+
+        for (x, &rcol) in self.rcols.iter().enumerate() {
+            if let Some(cell) = self.cell(x, y) {
+                let mut pod = self.regions;
+                pod.size.x = rcol;
+
+                let frames = cell.measure(vt, self.styles, pod)?.into_frames();
+
+                // Skip the first region if one cell in it is empty. Then,
+                // remeasure.
+                if let [first, rest @ ..] = frames.as_slice() {
+                    if can_skip
+                        && first.is_empty()
+                        && rest.iter().any(|frame| !frame.is_empty())
+                    {
+                        return Ok(None);
+                    }
+                }
+
+                let mut sizes = frames.iter().map(|frame| frame.height());
+                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);
+            }
+        }
+
+        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,
+        vt: &mut Vt,
+        v: Rel<Length>,
+        y: usize,
+    ) -> SourceResult<()> {
+        let resolved = v.resolve(self.styles).relative_to(self.regions.base().y);
+        let frame = self.layout_single_row(vt, resolved, y)?;
+
+        // Skip to fitting region.
+        let height = frame.height();
+        while !self.regions.size.y.fits(height) && !self.regions.in_last() {
+            self.finish_region(vt)?;
+
+            // Don't skip multiple regions for gutter and don't push a row.
+            if self.has_gutter && y % 2 == 1 {
+                return Ok(());
+            }
+        }
+
+        self.push_row(frame, y);
+
+        Ok(())
+    }
+
+    /// Layout a row with fixed height and return its frame.
+    fn layout_single_row(
+        &mut self,
+        vt: &mut Vt,
+        height: Abs,
+        y: usize,
+    ) -> SourceResult<Frame> {
+        let mut output = Frame::new(Size::new(self.width, height));
+        let mut pos = Point::zero();
+
+        for (x, &rcol) in self.rcols.iter().enumerate() {
+            if let Some(cell) = self.cell(x, y) {
+                let size = Size::new(rcol, height);
+                let mut pod = Regions::one(size, Axes::splat(true));
+                if self.rows[y] == Sizing::Auto {
+                    pod.full = self.regions.full;
+                }
+                let frame = cell.layout(vt, self.styles, pod)?.into_frame();
+                output.push_frame(pos, frame);
+            }
+
+            pos.x += rcol;
+        }
+
+        Ok(output)
+    }
+
+    /// Layout a row spanning multiple regions.
+    fn layout_multi_row(
+        &mut self,
+        vt: &mut Vt,
+        heights: &[Abs],
+        y: usize,
+    ) -> SourceResult<Fragment> {
+        // Prepare frames.
+        let mut outputs: Vec<_> = heights
+            .iter()
+            .map(|&h| Frame::new(Size::new(self.width, h)))
+            .collect();
+
+        // Prepare regions.
+        let size = Size::new(self.width, heights[0]);
+        let mut pod = Regions::one(size, Axes::splat(true));
+        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() {
+            if let Some(cell) = self.cell(x, y) {
+                pod.size.x = rcol;
+
+                // Push the layouted frames into the individual output frames.
+                let fragment = cell.layout(vt, self.styles, pod)?;
+                for (output, frame) in outputs.iter_mut().zip(fragment) {
+                    output.push_frame(pos, frame);
+                }
+            }
+
+            pos.x += rcol;
+        }
+
+        Ok(Fragment::frames(outputs))
+    }
+
+    /// Push a row frame into the current region.
+    fn push_row(&mut self, frame: Frame, y: usize) {
+        self.regions.size.y -= frame.height();
+        self.lrows.push(Row::Frame(frame, y));
+    }
+
+    /// Finish rows for one region.
+    fn finish_region(&mut self, vt: &mut Vt) -> SourceResult<()> {
+        // Determine the height of existing rows in the region.
+        let mut used = Abs::zero();
+        let mut fr = Fr::zero();
+        for row in &self.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.initial);
+        if fr.get() > 0.0 && self.initial.y.is_finite() {
+            size.y = self.initial.y;
+        }
+
+        // The frame for the region.
+        let mut output = Frame::new(size);
+        let mut pos = Point::zero();
+        let mut rrows = vec![];
+
+        // Place finished rows and layout fractional rows.
+        for row in std::mem::take(&mut self.lrows) {
+            let (frame, y) = match row {
+                Row::Frame(frame, y) => (frame, y),
+                Row::Fr(v, y) => {
+                    let remaining = self.regions.full - used;
+                    let height = v.share(fr, remaining);
+                    (self.layout_single_row(vt, height, y)?, y)
+                }
+            };
+
+            let height = frame.height();
+            output.push_frame(pos, frame);
+            rrows.push(RowPiece { height, y });
+            pos.y += height;
+        }
+
+        self.finished.push(output);
+        self.rrows.push(rrows);
+        self.regions.next();
+        self.initial = self.regions.size;
+
+        Ok(())
+    }
+
+    /// Get the content of the cell in column `x` and row `y`.
+    ///
+    /// Returns `None` if it's a gutter cell.
+    #[track_caller]
+    fn cell(&self, mut x: usize, y: usize) -> Option<&'a Content> {
+        assert!(x < self.cols.len());
+        assert!(y < self.rows.len());
+
+        // Columns are reorder, but the cell slice is not.
+        if self.is_rtl {
+            x = self.cols.len() - 1 - x;
+        }
+
+        if self.has_gutter {
+            // Even columns and rows are children, odd ones are gutter.
+            if x % 2 == 0 && y % 2 == 0 {
+                let c = 1 + self.cols.len() / 2;
+                self.cells.get((y / 2) * c + x / 2)
+            } else {
+                None
+            }
+        } else {
+            let c = self.cols.len();
+            self.cells.get(y * c + x)
+        }
+    }
+}