Minor changes to columns

src/library/columns.rs

@@ -43,18 +43,19 @@ impl Layout for ColumnsNode {
             return self.child.layout(ctx, regions);
         }
 
-        // All gutters in the document. (Can be different because the relative
+        // Gutter width for each region. (Can be different because the relative
         // component is calculated seperately for each region.)
         let mut gutters = vec![];
-        // Sizes of all columns resulting from `region.current` and
-        // `region.backlog`.
+
+        // Sizes of all columns resulting from `region.current`,
+        // `region.backlog` and `regions.last`.
         let mut sizes = vec![];
 
         let columns = self.columns.get();
 
-        for (current, base) in std::iter::once((regions.current, regions.base))
-            .chain(regions.backlog.as_slice().iter().map(|&s| (s, s)))
-            .chain(regions.last.iter().map(|&s| (s, s)))
+        for (current, base) in regions
+            .iter()
+            .take(1 + regions.backlog.len() + if regions.last.is_some() { 1 } else { 0 })
         {
             let gutter = self.gutter.resolve(base.x);
             gutters.push(gutter);
@@ -68,9 +69,11 @@ impl Layout for ColumnsNode {
         }
 
         let first = sizes.remove(0);
-        let mut pod =
-            Regions::one(first, Size::new(first.x, regions.base.y), regions.expand);
-        pod.expand.x = true;
+        let mut pod = Regions::one(
+            first,
+            Size::new(first.x, regions.base.y),
+            Spec::new(true, regions.expand.y),
+        );
 
         // Retrieve elements for the last region from the vectors.
         let last_gutter = if regions.last.is_some() {
@@ -84,24 +87,18 @@ impl Layout for ColumnsNode {
 
         pod.backlog = sizes.into_iter();
 
-        let frames = self.child.layout(ctx, &pod);
+        let mut frames = self.child.layout(ctx, &pod).into_iter();
 
         let dir = ctx.styles.get(ParNode::DIR);
 
-        let to = |cursor: Length, width: Length, regions: &Regions| {
-            if dir.is_positive() {
-                cursor
-            } else {
-                regions.current.x - cursor - width
-            }
-        };
-        let mut cursor = Length::zero();
-
-        let mut frames = frames.into_iter();
-        let mut res = vec![];
+        let mut finished = vec![];
         let total_regions = (frames.len() as f32 / columns as f32).ceil() as usize;
 
-        for (i, (current, base)) in regions.iter().take(total_regions).enumerate() {
+        for ((current, base), gutter) in regions
+            .iter()
+            .take(total_regions)
+            .zip(gutters.into_iter().chain(last_gutter.into_iter().cycle()))
+        {
             // The height should be the parent height if the node shall expand.
             // Otherwise its the maximum column height for the frame. In that
             // case, the frame is first created with zero height and then
@@ -109,6 +106,8 @@ impl Layout for ColumnsNode {
             let mut height = if regions.expand.y { current.y } else { Length::zero() };
             let mut frame = Frame::new(Spec::new(regions.current.x, height));
 
+            let mut cursor = Length::zero();
+
             for _ in 0 .. columns {
                 let child_frame = match frames.next() {
                     Some(frame) => frame.item,
@@ -118,16 +117,19 @@ impl Layout for ColumnsNode {
                 let width = child_frame.size.x;
 
                 if !regions.expand.y {
-                    height = height.max(child_frame.size.y);
+                    height.set_max(child_frame.size.y);
                 }
 
                 frame.push_frame(
-                    Point::new(to(cursor, width, &regions), Length::zero()),
+                    Point::with_x(if dir.is_positive() {
+                        cursor
+                    } else {
+                        regions.current.x - cursor - width
+                    }),
                     child_frame,
                 );
 
-                cursor += width
-                    + gutters.get(i).copied().unwrap_or_else(|| last_gutter.unwrap());
+                cursor += width + gutter;
             }
 
             frame.size.y = height;
@@ -135,10 +137,9 @@ impl Layout for ColumnsNode {
             let mut cts = Constraints::new(regions.expand);
             cts.base = base.map(Some);
             cts.exact = current.map(Some);
-            res.push(frame.constrain(cts));
-            cursor = Length::zero();
+            finished.push(frame.constrain(cts));
         }
 
-        res
+        finished
     }
 }

tests/typ/layout/columns.typ

@@ -81,7 +81,7 @@ D
 Arbitrary horizontal growth.
 
 ---
-// Test columns in an infinitely wide frame.
+// Test columns in an infinitely high frame.
 #set page(width: 7.05cm, columns: 2)
 
 There can be as much content as you want in the left column
@@ -102,7 +102,3 @@ This is a normal page. Very normal.
 // Test a page with zero columns.
 // Error: 49-50 must be positive
 #set page(height: auto, width: 7.05cm, columns: 0)
-
-This makes less sense.
-
-// colbreak in auto stroke box on sized page that should be higher than box