Simplify layout_inline's signature

3 files changed, 24 insertions, 29 deletions

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)
     }
 }