From 3a08d63b4b9d43b0fd250104ac98df5f53f579b8 Mon Sep 17 00:00:00 2001
From: Malo <57839069+MDLC01@users.noreply.github.com>
Date: Sat, 19 Apr 2025 17:57:47 +0200
Subject: [PATCH] Apply baseline shift and italic compensation to non-textual
 elements

---
 crates/typst-layout/src/inline/collect.rs |  4 +--
 crates/typst-layout/src/inline/line.rs    | 31 +++++++++++++++++++----
 crates/typst-layout/src/inline/mod.rs     |  2 +-
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/crates/typst-layout/src/inline/collect.rs b/crates/typst-layout/src/inline/collect.rs
index 5a1b7b4fc..829f64b66 100644
--- a/crates/typst-layout/src/inline/collect.rs
+++ b/crates/typst-layout/src/inline/collect.rs
@@ -206,7 +206,7 @@ pub fn collect<'a>(
                     }
                     InlineItem::Frame(mut frame) => {
                         frame.modify(&FrameModifiers::get_in(styles));
-                        apply_baseline_shift(&mut frame, styles);
+                        apply_shift(&engine.world, &mut frame, styles);
                         collector.push_item(Item::Frame(frame));
                     }
                 }
@@ -221,7 +221,7 @@ pub fn collect<'a>(
                 let mut frame = layout_and_modify(styles, |styles| {
                     layout_box(elem, engine, loc, styles, region)
                 })?;
-                apply_baseline_shift(&mut frame, styles);
+                apply_shift(&engine.world, &mut frame, styles);
                 collector.push_item(Item::Frame(frame));
             }
         } else if let Some(elem) = child.to_packed::<TagElem>() {
diff --git a/crates/typst-layout/src/inline/line.rs b/crates/typst-layout/src/inline/line.rs
index 659d33f4a..3782f7034 100644
--- a/crates/typst-layout/src/inline/line.rs
+++ b/crates/typst-layout/src/inline/line.rs
@@ -5,7 +5,7 @@ use typst_library::engine::Engine;
 use typst_library::introspection::{SplitLocator, Tag};
 use typst_library::layout::{Abs, Dir, Em, Fr, Frame, FrameItem, Point};
 use typst_library::model::ParLineMarker;
-use typst_library::text::{Lang, TextElem};
+use typst_library::text::{variant, Lang, TextElem};
 use typst_utils::Numeric;
 
 use super::*;
@@ -412,9 +412,30 @@ fn should_repeat_hyphen(pred_line: &Line, text: &str) -> bool {
     }
 }
 
-/// Apply the current baseline shift to a frame.
-pub fn apply_baseline_shift(frame: &mut Frame, styles: StyleChain) {
-    frame.translate(Point::with_y(TextElem::baseline_in(styles)));
+/// Apply the current baseline shift and italic compensation to a frame.
+pub fn apply_shift<'a>(
+    world: &Tracked<'a, dyn World + 'a>,
+    frame: &mut Frame,
+    styles: StyleChain,
+) {
+    let mut baseline = TextElem::baseline_in(styles);
+    let mut compensation = Abs::zero();
+    if let Some(scripts) = TextElem::subperscript_in(styles) {
+        let font_metrics = TextElem::font_in(styles)
+            .into_iter()
+            .find_map(|family| {
+                world
+                    .book()
+                    .select(family.as_str(), variant(styles))
+                    .and_then(|id| world.font(id))
+            })
+            .map_or(scripts.kind.default_metrics(), |f| {
+                scripts.kind.read_metrics(f.metrics())
+            });
+        baseline -= scripts.shift.unwrap_or(font_metrics.vertical_offset).resolve(styles);
+        compensation += font_metrics.horizontal_offset.resolve(styles);
+    }
+    frame.translate(Point::new(compensation, baseline));
 }
 
 /// Commit to a line and build its frame.
@@ -519,7 +540,7 @@ pub fn commit(
                     let mut frame = layout_and_modify(*styles, |styles| {
                         layout_box(elem, engine, loc.relayout(), styles, region)
                     })?;
-                    apply_baseline_shift(&mut frame, *styles);
+                    apply_shift(&engine.world, &mut frame, *styles);
                     push(&mut offset, frame);
                 } else {
                     offset += amount;
diff --git a/crates/typst-layout/src/inline/mod.rs b/crates/typst-layout/src/inline/mod.rs
index 5ef820d07..f5033b170 100644
--- a/crates/typst-layout/src/inline/mod.rs
+++ b/crates/typst-layout/src/inline/mod.rs
@@ -28,7 +28,7 @@ use typst_utils::{Numeric, SliceExt};
 use self::collect::{collect, Item, Segment, SpanMapper};
 use self::deco::decorate;
 use self::finalize::finalize;
-use self::line::{apply_baseline_shift, commit, line, Line};
+use self::line::{apply_shift, commit, line, Line};
 use self::linebreak::{linebreak, Breakpoint};
 use self::prepare::{prepare, Preparation};
 use self::shaping::{