Simplify layout_inline's signature

9 files changed, 44 insertions, 53 deletions

diff --git a/library/src/graphics/hide.rs b/library/src/graphics/hide.rs
index 3affd809..0fdb8638 100644
--- a/library/src/graphics/hide.rs
+++ b/library/src/graphics/hide.rs
@@ -17,11 +17,9 @@ impl LayoutInline for HideNode {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
-        let mut frames = self.0.layout_inline(world, regions, styles)?;
-        for frame in &mut frames {
-            frame.clear();
-        }
-        Ok(frames)
+    ) -> SourceResult<Frame> {
+        let mut frame = self.0.layout_inline(world, regions, styles)?;
+        frame.clear();
+        Ok(frame)
     }
 }
diff --git a/library/src/graphics/image.rs b/library/src/graphics/image.rs
index 6bf02265..5524e1c0 100644
--- a/library/src/graphics/image.rs
+++ b/library/src/graphics/image.rs
@@ -43,7 +43,7 @@ impl LayoutInline for ImageNode {
         _: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
+    ) -> SourceResult<Frame> {
         let pxw = self.0.width() as f64;
         let pxh = self.0.height() as f64;
         let px_ratio = pxw / pxh;
@@ -94,7 +94,7 @@ impl LayoutInline for ImageNode {
             frame.link(url.clone());
         }
 
-        Ok(vec![frame])
+        Ok(frame)
     }
 }
 
diff --git a/library/src/graphics/line.rs b/library/src/graphics/line.rs
index df427171..112274d2 100644
--- a/library/src/graphics/line.rs
+++ b/library/src/graphics/line.rs
@@ -42,7 +42,7 @@ impl LayoutInline for LineNode {
         _: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
+    ) -> SourceResult<Frame> {
         let stroke = styles.get(Self::STROKE).unwrap_or_default();
 
         let origin = self
@@ -63,6 +63,6 @@ impl LayoutInline for LineNode {
         let shape = Geometry::Line(delta.to_point()).stroked(stroke);
         frame.push(origin.to_point(), Element::Shape(shape));
 
-        Ok(vec![frame])
+        Ok(frame)
     }
 }
diff --git a/library/src/graphics/shape.rs b/library/src/graphics/shape.rs
index be67532a..e336c3a3 100644
--- a/library/src/graphics/shape.rs
+++ b/library/src/graphics/shape.rs
@@ -78,8 +78,8 @@ impl<const S: ShapeKind> LayoutInline for ShapeNode<S> {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
-        let mut frames;
+    ) -> SourceResult<Frame> {
+        let mut frame;
         if let Some(child) = &self.0 {
             let mut inset = styles.get(Self::INSET);
             if is_round(S) {
@@ -90,7 +90,7 @@ impl<const S: ShapeKind> LayoutInline for ShapeNode<S> {
             let child = child.clone().padded(inset.map(|side| side.map(Length::from)));
 
             let mut pod = Regions::one(regions.first, regions.base, regions.expand);
-            frames = child.layout_inline(world, &pod, styles)?;
+            frame = child.layout_inline(world, &pod, styles)?;
 
             // Relayout with full expansion into square region to make sure
             // the result is really a square or circle.
@@ -99,14 +99,14 @@ impl<const S: ShapeKind> LayoutInline for ShapeNode<S> {
                     let target = regions.expand.select(regions.first, Size::zero());
                     target.x.max(target.y)
                 } else {
-                    let size = frames[0].size();
+                    let size = frame.size();
                     let desired = size.x.max(size.y);
                     desired.min(regions.first.x).min(regions.first.y)
                 };
 
                 pod.first = Size::splat(length);
                 pod.expand = Axes::splat(true);
-                frames = child.layout_inline(world, &pod, styles)?;
+                frame = child.layout_inline(world, &pod, styles)?;
             }
         } else {
             // The default size that a shape takes on if it has no child and
@@ -125,11 +125,9 @@ impl<const S: ShapeKind> LayoutInline for ShapeNode<S> {
                 size = regions.expand.select(regions.first, size);
             }
 
-            frames = vec![Frame::new(size)];
+            frame = Frame::new(size);
         }
 
-        let frame = &mut frames[0];
-
         // Add fill and/or stroke.
         let fill = styles.get(Self::FILL);
         let stroke = match styles.get(Self::STROKE) {
@@ -167,7 +165,7 @@ impl<const S: ShapeKind> LayoutInline for ShapeNode<S> {
             frame.link(url.clone());
         }
 
-        Ok(frames)
+        Ok(frame)
     }
 }
 
diff --git a/library/src/layout/container.rs b/library/src/layout/container.rs
index 20d80cba..eb899d54 100644
--- a/library/src/layout/container.rs
+++ b/library/src/layout/container.rs
@@ -26,7 +26,7 @@ impl LayoutInline for BoxNode {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
+    ) -> SourceResult<Frame> {
         // The "pod" is the region into which the child will be layouted.
         let pod = {
             // Resolve the sizing to a concrete size.
@@ -47,14 +47,13 @@ impl LayoutInline for BoxNode {
         };
 
         // Layout the child.
-        let mut frames = self.child.layout_inline(world, &pod, styles)?;
+        let mut frame = self.child.layout_inline(world, &pod, styles)?;
 
         // Ensure frame size matches regions size if expansion is on.
-        let frame = &mut frames[0];
         let target = regions.expand.select(regions.first, frame.size());
         frame.resize(target, Align::LEFT_TOP);
 
-        Ok(frames)
+        Ok(frame)
     }
 }
 
diff --git a/library/src/layout/mod.rs b/library/src/layout/mod.rs
index f79da71c..605da3b2 100644
--- a/library/src/layout/mod.rs
+++ b/library/src/layout/mod.rs
@@ -112,7 +112,7 @@ pub trait LayoutInline: 'static + Sync + Send {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>>;
+    ) -> SourceResult<Frame>;
 }
 
 impl LayoutInline for Content {
@@ -122,7 +122,10 @@ impl LayoutInline for Content {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
+    ) -> SourceResult<Frame> {
+        assert!(regions.backlog.is_empty());
+        assert!(regions.last.is_none());
+
         if !self.has::<dyn Show>() || !styles.applicable(self) {
             if let Some(node) = self.to::<dyn LayoutInline>() {
                 let barrier = StyleEntry::Barrier(self.id());
@@ -133,7 +136,7 @@ impl LayoutInline for Content {
             if let Some(node) = self.to::<dyn LayoutBlock>() {
                 let barrier = StyleEntry::Barrier(self.id());
                 let styles = barrier.chain(&styles);
-                return node.layout_block(world, regions, styles);
+                return Ok(node.layout_block(world, regions, styles)?.remove(0));
             }
         }
 
@@ -141,7 +144,7 @@ impl LayoutInline for Content {
         let mut builder = Builder::new(world, &scratch, false);
         builder.accept(self, styles)?;
         let (flow, shared) = builder.into_flow(styles)?;
-        flow.layout_block(world, regions, shared)
+        Ok(flow.layout_block(world, regions, shared)?.remove(0))
     }
 }
 
diff --git a/library/src/layout/transform.rs b/library/src/layout/transform.rs
index 4e0b8ac2..c45aa165 100644
--- a/library/src/layout/transform.rs
+++ b/library/src/layout/transform.rs
@@ -30,16 +30,12 @@ impl LayoutInline for MoveNode {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
-        let mut frames = self.child.layout_inline(world, regions, styles)?;
-
+    ) -> SourceResult<Frame> {
+        let mut frame = self.child.layout_inline(world, regions, styles)?;
         let delta = self.delta.resolve(styles);
-        for frame in &mut frames {
-            let delta = delta.zip(frame.size()).map(|(d, s)| d.relative_to(s));
-            frame.translate(delta.to_point());
-        }
-
-        Ok(frames)
+        let delta = delta.zip(frame.size()).map(|(d, s)| d.relative_to(s));
+        frame.translate(delta.to_point());
+        Ok(frame)
     }
 }
 
@@ -88,20 +84,17 @@ impl<const T: TransformKind> LayoutInline for TransformNode<T> {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
-        let origin = styles.get(Self::ORIGIN).unwrap_or(Align::CENTER_HORIZON);
-        let mut frames = self.child.layout_inline(world, regions, styles)?;
+    ) -> SourceResult<Frame> {
+        let mut frame = self.child.layout_inline(world, regions, styles)?;
 
-        for frame in &mut frames {
-            let Axes { x, y } = origin.zip(frame.size()).map(|(o, s)| o.position(s));
-            let transform = Transform::translate(x, y)
-                .pre_concat(self.transform)
-                .pre_concat(Transform::translate(-x, -y));
-
-            frame.transform(transform);
-        }
+        let origin = styles.get(Self::ORIGIN).unwrap_or(Align::CENTER_HORIZON);
+        let Axes { x, y } = origin.zip(frame.size()).map(|(o, s)| o.position(s));
+        let transform = Transform::translate(x, y)
+            .pre_concat(self.transform)
+            .pre_concat(Transform::translate(-x, -y));
+        frame.transform(transform);
 
-        Ok(frames)
+        Ok(frame)
     }
 }
 
diff --git a/library/src/math/mod.rs b/library/src/math/mod.rs
index bcf09c04..7772c0af 100644
--- a/library/src/math/mod.rs
+++ b/library/src/math/mod.rs
@@ -51,8 +51,8 @@ impl LayoutInline for MathNode {
         world: Tracked<dyn World>,
         _: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
-        Ok(vec![layout_tex(&self.texify(), self.display, world, styles)?])
+    ) -> SourceResult<Frame> {
+        layout_tex(&self.texify(), self.display, world, styles)
     }
 }
 
diff --git a/library/src/text/par.rs b/library/src/text/par.rs
index df02bc3c..1d01071d 100644
--- a/library/src/text/par.rs
+++ b/library/src/text/par.rs
@@ -141,7 +141,7 @@ impl LayoutInline for RepeatNode {
         world: Tracked<dyn World>,
         regions: &Regions,
         styles: StyleChain,
-    ) -> SourceResult<Vec<Frame>> {
+    ) -> SourceResult<Frame> {
         self.0.layout_inline(world, regions, styles)
     }
 }
@@ -526,7 +526,7 @@ fn prepare<'a>(
                 } else {
                     let size = Size::new(regions.first.x, regions.base.y);
                     let pod = Regions::one(size, regions.base, Axes::splat(false));
-                    let mut frame = inline.layout_inline(world, &pod, styles)?.remove(0);
+                    let mut frame = inline.layout_inline(world, &pod, styles)?;
                     frame.translate(Point::with_y(styles.get(TextNode::BASELINE)));
                     items.push(Item::Frame(frame));
                 }
@@ -1151,7 +1151,7 @@ fn commit(
                 let fill = Fr::one().share(fr, remaining);
                 let size = Size::new(fill, regions.base.y);
                 let pod = Regions::one(size, regions.base, Axes::new(false, false));
-                let frame = repeat.layout_inline(world, &pod, *styles)?.remove(0);
+                let frame = repeat.layout_inline(world, &pod, *styles)?;
                 let width = frame.width();
                 let count = (fill / width).floor();
                 let remaining = fill % width;