Support first-line-indent for every paragraph (#5768)

5 files changed, 60 insertions, 27 deletions

diff --git a/crates/typst-layout/src/flow/collect.rs b/crates/typst-layout/src/flow/collect.rs
index f2c7ebd1..34362a6c 100644
--- a/crates/typst-layout/src/flow/collect.rs
+++ b/crates/typst-layout/src/flow/collect.rs
@@ -23,6 +23,7 @@ use typst_library::World;
 use typst_utils::SliceExt;
 
 use super::{layout_multi_block, layout_single_block, FlowMode};
+use crate::inline::ParSituation;
 use crate::modifiers::layout_and_modify;
 
 /// Collects all elements of the flow into prepared children. These are much
@@ -46,7 +47,7 @@ pub fn collect<'a>(
         base,
         expand,
         output: Vec::with_capacity(children.len()),
-        last_was_par: false,
+        par_situation: ParSituation::First,
     }
     .run(mode)
 }
@@ -60,7 +61,7 @@ struct Collector<'a, 'x, 'y> {
     expand: bool,
     locator: SplitLocator<'a>,
     output: Vec<Child<'a>>,
-    last_was_par: bool,
+    par_situation: ParSituation,
 }
 
 impl<'a> Collector<'a, '_, '_> {
@@ -123,8 +124,7 @@ impl<'a> Collector<'a, '_, '_> {
             styles,
             self.base,
             self.expand,
-            false,
-            false,
+            None,
         )?
         .into_frames();
 
@@ -165,7 +165,7 @@ impl<'a> Collector<'a, '_, '_> {
             styles,
             self.base,
             self.expand,
-            self.last_was_par,
+            self.par_situation,
         )?
         .into_frames();
 
@@ -175,7 +175,7 @@ impl<'a> Collector<'a, '_, '_> {
         self.lines(lines, styles);
 
         self.output.push(Child::Rel(spacing.into(), 4));
-        self.last_was_par = true;
+        self.par_situation = ParSituation::Consecutive;
 
         Ok(())
     }
@@ -272,7 +272,7 @@ impl<'a> Collector<'a, '_, '_> {
         };
 
         self.output.push(spacing(elem.below(styles)));
-        self.last_was_par = false;
+        self.par_situation = ParSituation::Other;
     }
 
     /// Collects a placed element into a [`PlacedChild`].
diff --git a/crates/typst-layout/src/inline/collect.rs b/crates/typst-layout/src/inline/collect.rs
index cbc490ba..14cf2e3b 100644
--- a/crates/typst-layout/src/inline/collect.rs
+++ b/crates/typst-layout/src/inline/collect.rs
@@ -5,6 +5,7 @@ use typst_library::layout::{
     Abs, AlignElem, BoxElem, Dir, Fr, Frame, HElem, InlineElem, InlineItem, Sizing,
     Spacing,
 };
+use typst_library::model::{EnumElem, ListElem, TermsElem};
 use typst_library::routines::Pair;
 use typst_library::text::{
     is_default_ignorable, LinebreakElem, SmartQuoteElem, SmartQuoter, SmartQuotes,
@@ -124,26 +125,33 @@ pub fn collect<'a>(
     locator: &mut SplitLocator<'a>,
     styles: StyleChain<'a>,
     region: Size,
-    consecutive: bool,
-    paragraph: bool,
+    situation: Option<ParSituation>,
 ) -> SourceResult<(String, Vec<Segment<'a>>, SpanMapper)> {
     let mut collector = Collector::new(2 + children.len());
     let mut quoter = SmartQuoter::new();
 
     let outer_dir = TextElem::dir_in(styles);
 
-    if paragraph && consecutive {
+    if let Some(situation) = situation {
         let first_line_indent = ParElem::first_line_indent_in(styles);
-        if !first_line_indent.is_zero()
+        if !first_line_indent.amount.is_zero()
+            && match situation {
+                // First-line indent for the first paragraph after a list bullet
+                // just looks bad.
+                ParSituation::First => first_line_indent.all && !in_list(styles),
+                ParSituation::Consecutive => true,
+                ParSituation::Other => first_line_indent.all,
+            }
             && AlignElem::alignment_in(styles).resolve(styles).x
                 == outer_dir.start().into()
         {
-            collector.push_item(Item::Absolute(first_line_indent.resolve(styles), false));
+            collector.push_item(Item::Absolute(
+                first_line_indent.amount.resolve(styles),
+                false,
+            ));
             collector.spans.push(1, Span::detached());
         }
-    }
 
-    if paragraph {
         let hang = ParElem::hanging_indent_in(styles);
         if !hang.is_zero() {
             collector.push_item(Item::Absolute(-hang, false));
@@ -257,6 +265,16 @@ pub fn collect<'a>(
     Ok((collector.full, collector.segments, collector.spans))
 }
 
+/// Whether we have a list ancestor.
+///
+/// When we support some kind of more general ancestry mechanism, this can
+/// become more elegant.
+fn in_list(styles: StyleChain) -> bool {
+    ListElem::depth_in(styles).0 > 0
+        || !EnumElem::parents_in(styles).is_empty()
+        || TermsElem::within_in(styles)
+}
+
 /// Collects segments.
 struct Collector<'a> {
     full: String,
diff --git a/crates/typst-layout/src/inline/mod.rs b/crates/typst-layout/src/inline/mod.rs
index 83ca82bf..f8a36368 100644
--- a/crates/typst-layout/src/inline/mod.rs
+++ b/crates/typst-layout/src/inline/mod.rs
@@ -42,7 +42,7 @@ pub fn layout_par(
     styles: StyleChain,
     region: Size,
     expand: bool,
-    consecutive: bool,
+    situation: ParSituation,
 ) -> SourceResult<Fragment> {
     layout_par_impl(
         elem,
@@ -56,7 +56,7 @@ pub fn layout_par(
         styles,
         region,
         expand,
-        consecutive,
+        situation,
     )
 }
 
@@ -75,7 +75,7 @@ fn layout_par_impl(
     styles: StyleChain,
     region: Size,
     expand: bool,
-    consecutive: bool,
+    situation: ParSituation,
 ) -> SourceResult<Fragment> {
     let link = LocatorLink::new(locator);
     let mut locator = Locator::link(&link).split();
@@ -105,8 +105,7 @@ fn layout_par_impl(
         styles,
         region,
         expand,
-        true,
-        consecutive,
+        Some(situation),
     )
 }
 
@@ -119,16 +118,15 @@ pub fn layout_inline<'a>(
     styles: StyleChain<'a>,
     region: Size,
     expand: bool,
-    paragraph: bool,
-    consecutive: bool,
+    par: Option<ParSituation>,
 ) -> SourceResult<Fragment> {
     // Collect all text into one string for BiDi analysis.
     let (text, segments, spans) =
-        collect(children, engine, locator, styles, region, consecutive, paragraph)?;
+        collect(children, engine, locator, styles, region, par)?;
 
     // Perform BiDi analysis and performs some preparation steps before we
     // proceed to line breaking.
-    let p = prepare(engine, children, &text, segments, spans, styles, paragraph)?;
+    let p = prepare(engine, children, &text, segments, spans, styles, par)?;
 
     // Break the text into lines.
     let lines = linebreak(engine, &p, region.x - p.hang);
@@ -136,3 +134,17 @@ pub fn layout_inline<'a>(
     // Turn the selected lines into frames.
     finalize(engine, &p, &lines, styles, region, expand, locator)
 }
+
+/// Distinguishes between a few different kinds of paragraphs.
+///
+/// In the form `Option<ParSituation>`, `None` implies that we are creating an
+/// inline layout that isn't a semantic paragraph.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum ParSituation {
+    /// The paragraph is the first thing in the flow.
+    First,
+    /// The paragraph follows another paragraph.
+    Consecutive,
+    /// Any other kind of paragraph.
+    Other,
+}
diff --git a/crates/typst-layout/src/inline/prepare.rs b/crates/typst-layout/src/inline/prepare.rs
index e26c9b14..0344d433 100644
--- a/crates/typst-layout/src/inline/prepare.rs
+++ b/crates/typst-layout/src/inline/prepare.rs
@@ -85,7 +85,7 @@ pub fn prepare<'a>(
     segments: Vec<Segment<'a>>,
     spans: SpanMapper,
     styles: StyleChain<'a>,
-    paragraph: bool,
+    situation: Option<ParSituation>,
 ) -> SourceResult<Preparation<'a>> {
     let dir = TextElem::dir_in(styles);
     let default_level = match dir {
@@ -130,7 +130,11 @@ pub fn prepare<'a>(
     }
 
     // Only apply hanging indent to real paragraphs.
-    let hang = if paragraph { ParElem::hanging_indent_in(styles) } else { Abs::zero() };
+    let hang = if situation.is_some() {
+        ParElem::hanging_indent_in(styles)
+    } else {
+        Abs::zero()
+    };
 
     Ok(Preparation {
         text,
diff --git a/crates/typst-layout/src/math/text.rs b/crates/typst-layout/src/math/text.rs
index 5897c3c0..9a64992a 100644
--- a/crates/typst-layout/src/math/text.rs
+++ b/crates/typst-layout/src/math/text.rs
@@ -107,8 +107,7 @@ fn layout_inline_text(
             styles,
             Size::splat(Abs::inf()),
             false,
-            false,
-            false,
+            None,
         )?
         .into_frame();