Sort line items by logical order when constructing frame (#5887)

Co-authored-by: Laurenz <laurmaedje@gmail.com>

1 files changed, 34 insertions, 24 deletions

diff --git a/crates/typst-layout/src/inline/line.rs b/crates/typst-layout/src/inline/line.rs
index f0518927..7bf4d4c7 100644
--- a/crates/typst-layout/src/inline/line.rs
+++ b/crates/typst-layout/src/inline/line.rs
@@ -219,7 +219,7 @@ fn collect_items<'a>(
     // Add fallback text to expand the line height, if necessary.
     if !items.iter().any(|item| matches!(item, Item::Text(_))) {
         if let Some(fallback) = fallback {
-            items.push(fallback);
+            items.push(fallback, usize::MAX);
         }
     }
 
@@ -270,10 +270,10 @@ fn collect_range<'a>(
     items: &mut Items<'a>,
     fallback: &mut Option<ItemEntry<'a>>,
 ) {
-    for (subrange, item) in p.slice(range.clone()) {
+    for (idx, (subrange, item)) in p.slice(range.clone()).enumerate() {
         // All non-text items are just kept, they can't be split.
         let Item::Text(shaped) = item else {
-            items.push(item);
+            items.push(item, idx);
             continue;
         };
 
@@ -293,10 +293,10 @@ fn collect_range<'a>(
         } else if split {
             // When the item is split in half, reshape it.
             let reshaped = shaped.reshape(engine, sliced);
-            items.push(Item::Text(reshaped));
+            items.push(Item::Text(reshaped), idx);
         } else {
             // When the item is fully contained, just keep it.
-            items.push(item);
+            items.push(item, idx);
         }
     }
 }
@@ -499,16 +499,16 @@ pub fn commit(
 
     // Build the frames and determine the height and baseline.
     let mut frames = vec![];
-    for item in line.items.iter() {
-        let mut push = |offset: &mut Abs, frame: Frame| {
+    for &(idx, ref item) in line.items.indexed_iter() {
+        let mut push = |offset: &mut Abs, frame: Frame, idx: usize| {
             let width = frame.width();
             top.set_max(frame.baseline());
             bottom.set_max(frame.size().y - frame.baseline());
-            frames.push((*offset, frame));
+            frames.push((*offset, frame, idx));
             *offset += width;
         };
 
-        match item {
+        match &**item {
             Item::Absolute(v, _) => {
                 offset += *v;
             }
@@ -520,7 +520,7 @@ pub fn commit(
                         layout_box(elem, engine, loc.relayout(), styles, region)
                     })?;
                     apply_baseline_shift(&mut frame, *styles);
-                    push(&mut offset, frame);
+                    push(&mut offset, frame, idx);
                 } else {
                     offset += amount;
                 }
@@ -532,15 +532,15 @@ pub fn commit(
                     justification_ratio,
                     extra_justification,
                 );
-                push(&mut offset, frame);
+                push(&mut offset, frame, idx);
             }
             Item::Frame(frame) => {
-                push(&mut offset, frame.clone());
+                push(&mut offset, frame.clone(), idx);
             }
             Item::Tag(tag) => {
                 let mut frame = Frame::soft(Size::zero());
                 frame.push(Point::zero(), FrameItem::Tag((*tag).clone()));
-                frames.push((offset, frame));
+                frames.push((offset, frame, idx));
             }
             Item::Skip(_) => {}
         }
@@ -559,8 +559,13 @@ pub fn commit(
         add_par_line_marker(&mut output, marker, engine, locator, top);
     }
 
+    // Ensure that the final frame's items are in logical order rather than in
+    // visual order. This is important because it affects the order of elements
+    // during introspection and thus things like counters.
+    frames.sort_unstable_by_key(|(_, _, idx)| *idx);
+
     // Construct the line's frame.
-    for (offset, frame) in frames {
+    for (offset, frame, _) in frames {
         let x = offset + p.config.align.position(remaining);
         let y = top - frame.baseline();
         output.push_frame(Point::new(x, y), frame);
@@ -627,7 +632,7 @@ fn overhang(c: char) -> f64 {
 }
 
 /// A collection of owned or borrowed inline items.
-pub struct Items<'a>(Vec<ItemEntry<'a>>);
+pub struct Items<'a>(Vec<(usize, ItemEntry<'a>)>);
 
 impl<'a> Items<'a> {
     /// Create empty items.
@@ -636,33 +641,38 @@ impl<'a> Items<'a> {
     }
 
     /// Push a new item.
-    pub fn push(&mut self, entry: impl Into<ItemEntry<'a>>) {
-        self.0.push(entry.into());
+    pub fn push(&mut self, entry: impl Into<ItemEntry<'a>>, idx: usize) {
+        self.0.push((idx, entry.into()));
     }
 
     /// Iterate over the items.
     pub fn iter(&self) -> impl Iterator<Item = &Item<'a>> {
-        self.0.iter().map(|item| &**item)
+        self.0.iter().map(|(_, item)| &**item)
+    }
+
+    /// Iterate over the items with indices
+    pub fn indexed_iter(&self) -> impl Iterator<Item = &(usize, ItemEntry<'a>)> {
+        self.0.iter()
     }
 
     /// Access the first item.
     pub fn first(&self) -> Option<&Item<'a>> {
-        self.0.first().map(|item| &**item)
+        self.0.first().map(|(_, item)| &**item)
     }
 
     /// Access the last item.
     pub fn last(&self) -> Option<&Item<'a>> {
-        self.0.last().map(|item| &**item)
+        self.0.last().map(|(_, item)| &**item)
     }
 
     /// Access the first item mutably, if it is text.
     pub fn first_text_mut(&mut self) -> Option<&mut ShapedText<'a>> {
-        self.0.first_mut()?.text_mut()
+        self.0.first_mut()?.1.text_mut()
     }
 
     /// Access the last item mutably, if it is text.
     pub fn last_text_mut(&mut self) -> Option<&mut ShapedText<'a>> {
-        self.0.last_mut()?.text_mut()
+        self.0.last_mut()?.1.text_mut()
     }
 
     /// Reorder the items starting at the given index to RTL.
@@ -673,12 +683,12 @@ impl<'a> Items<'a> {
 
 impl<'a> FromIterator<ItemEntry<'a>> for Items<'a> {
     fn from_iter<I: IntoIterator<Item = ItemEntry<'a>>>(iter: I) -> Self {
-        Self(iter.into_iter().collect())
+        Self(iter.into_iter().enumerate().collect())
     }
 }
 
 impl<'a> Deref for Items<'a> {
-    type Target = Vec<ItemEntry<'a>>;
+    type Target = Vec<(usize, ItemEntry<'a>)>;
 
     fn deref(&self) -> &Self::Target {
         &self.0