Use line height based spacing model

typst · May 25, 2024 · 9052a0f · 9052a0f
1 parent 34f1a23
commit 9052a0f
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Showing 12 changed files with 66 additions and 41 deletions.
diff --git a/crates/typst/src/layout/flow.rs b/crates/typst/src/layout/flow.rs
@@ -280,7 +280,7 @@ impl<'a> FlowLayouter<'a> {
         styles: StyleChain,
     ) -> SourceResult<()> {
         let align = AlignElem::alignment_in(styles).resolve(styles);
-        let leading = ParElem::leading_in(styles);
+        let line_height = ParElem::line_height_in(styles);
         let consecutive = self.last_was_par;
         let lines = par
             .layout(
@@ -319,8 +319,14 @@ impl<'a> FlowLayouter<'a> {
             }
         }
 
-        for (i, mut frame) in lines.into_iter().enumerate() {
+        for (i, mut frame) in lines.clone().into_iter().enumerate() {
             if i > 0 {
+                let leading =
+                    if lines[i - 1].descent().abs() + frame.ascent() > line_height {
+                        Abs::pt(1.0)
+                    } else {
+                        line_height - lines[i - 1].descent().abs() - frame.ascent()
+                    };
                 self.layout_item(engine, FlowItem::Absolute(leading, true))?;
             }
 

diff --git a/crates/typst/src/layout/inline/mod.rs b/crates/typst/src/layout/inline/mod.rs
@@ -137,8 +137,9 @@ struct Preparation<'a> {
     cjk_latin_spacing: bool,
     /// Whether font fallback is enabled for this paragraph.
     fallback: bool,
-    /// The leading of the paragraph.
-    leading: Abs,
+    #[allow(unused)]
+    /// The line height of the paragraph.
+    line_height: Abs,
     /// How to determine line breaks.
     linebreaks: Smart<Linebreaks>,
     /// The text size.
@@ -678,7 +679,7 @@ fn prepare<'a>(
         hang: ParElem::hanging_indent_in(styles),
         cjk_latin_spacing,
         fallback: TextElem::fallback_in(styles),
-        leading: ParElem::leading_in(styles),
+        line_height: ParElem::line_height_in(styles),
         linebreaks: ParElem::linebreaks_in(styles),
         size: TextElem::size_in(styles),
     })
@@ -1283,29 +1284,36 @@ fn finalize(
         .collect::<SourceResult<_>>()?;
 
     // Positive ratios enable prevention, while zero and negative ratios disable it.
-    if p.costs.orphan().get() > 0.0 {
-        // Prevent orphans.
-        if frames.len() >= 2 && !frames[1].is_empty() {
-            let second = frames.remove(1);
-            let first = &mut frames[0];
-            merge(first, second, p.leading);
-        }
-    }
+    // if p.costs.orphan().get() > 0.0 {
+    //     // Prevent orphans.
+    //     if frames.len() >= 2 && !frames[1].is_empty() {
+    //         let second = frames.remove(1);
+    //         let first = &mut frames[0];
+    //         merge(first, second, p.line_height);
+    //     }
+    // }
+    // TODO: re-enable them
     if p.costs.widow().get() > 0.0 {
         // Prevent widows.
         let len = frames.len();
         if len >= 2 && !frames[len - 2].is_empty() {
             let second = frames.pop().unwrap();
             let first = frames.last_mut().unwrap();
-            merge(first, second, p.leading);
+            merge(first, second, p.line_height);
         }
     }
 
     Ok(Fragment::frames(frames))
 }
 
+#[allow(unused)]
 /// Merge two line frames
-fn merge(first: &mut Frame, second: Frame, leading: Abs) {
+fn merge(first: &mut Frame, second: Frame, line_height: Abs) {
+    let leading = if first.descent().abs() + second.ascent().abs() > line_height {
+        Abs::pt(1.0)
+    } else {
+        line_height - first.descent().abs() - second.ascent().abs()
+    };
     let offset = first.height() + leading;
     let total = offset + second.height();
     first.push_frame(Point::with_y(offset), second);

diff --git a/crates/typst/src/math/equation.rs b/crates/typst/src/math/equation.rs
@@ -16,7 +16,7 @@ use crate::layout::{
 use crate::math::{
     scaled_font_size, LayoutMath, MathContext, MathRunFrameBuilder, MathSize, MathVariant,
 };
-use crate::model::{Numbering, Outlinable, ParElem, Refable, Supplement};
+use crate::model::{Numbering, Outlinable, Refable, Supplement};
 use crate::syntax::Span;
 use crate::text::{
     families, variant, Font, FontFamily, FontList, FontWeight, LocalName, TextElem,
@@ -233,13 +233,12 @@ impl Packed<EquationElem> {
             let MathParItem::Frame(frame) = item else { continue };
 
             let font_size = scaled_font_size(&ctx, styles);
-            let slack = ParElem::leading_in(styles) * 0.7;
             let top_edge = TextElem::top_edge_in(styles).resolve(font_size, &font, None);
             let bottom_edge =
                 -TextElem::bottom_edge_in(styles).resolve(font_size, &font, None);
 
-            let ascent = top_edge.max(frame.ascent() - slack);
-            let descent = bottom_edge.max(frame.descent() - slack);
+            let ascent = top_edge.max(frame.ascent());
+            let descent = bottom_edge.max(frame.descent());
             frame.translate(Point::with_y(ascent - frame.baseline()));
             frame.size_mut().y = ascent + descent;
         }

diff --git a/crates/typst/src/math/row.rs b/crates/typst/src/math/row.rs
@@ -3,17 +3,14 @@ use std::iter::once;
 use unicode_math_class::MathClass;
 
 use crate::foundations::{Resolve, StyleChain};
-use crate::layout::{Abs, AlignElem, Em, Frame, Point, Size};
+use crate::layout::{Abs, AlignElem, Frame, Point, Size};
 use crate::math::{
-    alignments, scaled_font_size, spacing, EquationElem, FrameFragment, MathContext,
-    MathFragment, MathParItem, MathSize,
+    alignments, spacing, FrameFragment, MathContext, MathFragment, MathParItem,
 };
 use crate::model::ParElem;
 
 use super::fragment::SpacingFragment;
 
-pub const TIGHT_LEADING: Em = Em::new(0.25);
-
 /// A linear collection of [`MathFragment`]s.
 #[derive(Debug, Default, Clone)]
 pub struct MathRun(Vec<MathFragment>);
@@ -162,27 +159,31 @@ impl MathRun {
         ctx: &MathContext,
         styles: StyleChain,
     ) -> MathRunFrameBuilder {
+        let _ = ctx;
         let rows: Vec<_> = self.rows();
         let row_count = rows.len();
         let alignments = alignments(&rows);
 
-        let leading = if EquationElem::size_in(styles) >= MathSize::Text {
-            ParElem::leading_in(styles)
-        } else {
-            let font_size = scaled_font_size(ctx, styles);
-            TIGHT_LEADING.at(font_size)
-        };
+        let line_height = ParElem::line_height_in(styles);
 
         let align = AlignElem::alignment_in(styles).resolve(styles).x;
         let mut frames: Vec<(Frame, Point)> = vec![];
         let mut size = Size::zero();
-        for (i, row) in rows.into_iter().enumerate() {
+        for (i, row) in rows.clone().into_iter().enumerate() {
             if i == row_count - 1 && row.0.is_empty() {
                 continue;
             }
 
-            let sub = row.into_line_frame(&alignments.points, LeftRightAlternator::Right);
+            let sub = row
+                .clone()
+                .into_line_frame(&alignments.points, LeftRightAlternator::Right);
             if i > 0 {
+                let leading =
+                    if rows[i - 1].descent().abs() + row.ascent().abs() > line_height {
+                        Abs::pt(1.0)
+                    } else {
+                        line_height - rows[i - 1].descent().abs() - row.ascent().abs()
+                    };
                 size.y += leading;
             }
 

diff --git a/crates/typst/src/model/enum.rs b/crates/typst/src/model/enum.rs
@@ -224,7 +224,8 @@ impl LayoutMultiple for Packed<EnumElem> {
         let indent = self.indent(styles);
         let body_indent = self.body_indent(styles);
         let gutter = if self.tight(styles) {
-            ParElem::leading_in(styles).into()
+            // TODO(mgt): fix this
+            ParElem::line_height_in(styles).into()
         } else {
             self.spacing(styles)
                 .unwrap_or_else(|| *BlockElem::below_in(styles).amount())

diff --git a/crates/typst/src/model/footnote.rs b/crates/typst/src/model/footnote.rs
@@ -299,9 +299,9 @@ impl Show for Packed<FootnoteEntry> {
 impl ShowSet for Packed<FootnoteEntry> {
     fn show_set(&self, _: StyleChain) -> Styles {
         let text_size = Em::new(0.85);
-        let leading = Em::new(0.5);
+        let line_height = Em::new(1.158203125);
         let mut out = Styles::new();
-        out.set(ParElem::set_leading(leading.into()));
+        out.set(ParElem::set_line_height(line_height.into()));
         out.set(TextElem::set_size(TextSize(text_size.into())));
         out
     }

diff --git a/crates/typst/src/model/list.rs b/crates/typst/src/model/list.rs
@@ -148,7 +148,8 @@ impl LayoutMultiple for Packed<ListElem> {
         let indent = self.indent(styles);
         let body_indent = self.body_indent(styles);
         let gutter = if self.tight(styles) {
-            ParElem::leading_in(styles).into()
+            // TODO(mgt): fix this
+            ParElem::line_height_in(styles).into()
         } else {
             self.spacing(styles)
                 .unwrap_or_else(|| *BlockElem::below_in(styles).amount())

diff --git a/crates/typst/src/model/par.rs b/crates/typst/src/model/par.rs
@@ -35,11 +35,11 @@ use crate::layout::{Em, Fragment, Length, Size};
 /// ```
 #[elem(title = "Paragraph", Debug, Construct)]
 pub struct ParElem {
-    /// The spacing between lines.
+    /// The spacing between baselines.
     #[resolve]
     #[ghost]
-    #[default(Em::new(0.65).into())]
-    pub leading: Length,
+    #[default(Em::new(1.308203125).into())]
+    pub line_height: Length,
 
     /// Whether to justify text in its line.
     ///

diff --git a/crates/typst/src/model/terms.rs b/crates/typst/src/model/terms.rs
@@ -121,7 +121,8 @@ impl LayoutMultiple for Packed<TermsElem> {
         let indent = self.indent(styles);
         let hanging_indent = self.hanging_indent(styles);
         let gutter = if self.tight(styles) {
-            ParElem::leading_in(styles).into()
+            // TODO(mgt): fix this
+            ParElem::line_height_in(styles).into()
         } else {
             self.spacing(styles)
                 .unwrap_or_else(|| *BlockElem::below_in(styles).amount())

diff --git a/crates/typst/src/realize/mod.rs b/crates/typst/src/realize/mod.rs
@@ -401,7 +401,8 @@ impl<'a> FlowBuilder<'a> {
             };
 
             if !last_was_parbreak && is_tight_list {
-                let leading = ParElem::leading_in(styles);
+                // TODO(mgt): fix this
+                let leading = ParElem::line_height_in(styles);
                 let spacing = VElem::list_attach(leading.into());
                 self.0.push(arenas.store(spacing.pack()), styles);
             }

diff --git a/tests/ref/par-inline-math-overlap.png b/tests/ref/par-inline-math-overlap.png
diff --git a/tests/suite/model/par.typ b/tests/suite/model/par.typ
@@ -76,3 +76,10 @@ Welcome \ here. Does this work well?
 #set text(dir: rtl)
 لآن وقد أظلم الليل وبدأت النجوم
 تنضخ وجه الطبيعة التي أعْيَتْ من طول ما انبعثت في النهار
+
+--- par-inline-math-overlap ---
+#lorem(1) $1/123456$ #lorem(2) $12345667/1/1$
+
+#lorem(3) $sum_(x=0)^n$ #lorem(3)
+
+#lorem(3) $display((a+b)/(c+d))$ #lorem(2) $display((a/b+1)/c+1)$ #lorem(7)