Split crates

1 files changed, 62 insertions, 0 deletions

diff --git a/library/src/layout/align.rs b/library/src/layout/align.rs
new file mode 100644
index 00000000..5e1b3555
--- /dev/null
+++ b/library/src/layout/align.rs
@@ -0,0 +1,62 @@
+use crate::prelude::*;
+use crate::text::{HorizontalAlign, ParNode};
+
+/// Align content along the layouting axes.
+#[derive(Debug, Hash)]
+pub struct AlignNode {
+    /// How to align the content horizontally and vertically.
+    pub aligns: Axes<Option<GenAlign>>,
+    /// The content to be aligned.
+    pub child: Content,
+}
+
+#[node(LayoutBlock)]
+impl AlignNode {
+    fn construct(_: &mut Vm, args: &mut Args) -> SourceResult<Content> {
+        let aligns: Axes<Option<GenAlign>> = args.find()?.unwrap_or_default();
+        let body: Content = args.expect("body")?;
+
+        if let Axes { x: Some(x), y: None } = aligns {
+            if !body.has::<dyn LayoutBlock>() {
+                return Ok(body.styled(ParNode::ALIGN, HorizontalAlign(x)));
+            }
+        }
+
+        Ok(body.aligned(aligns))
+    }
+}
+
+impl LayoutBlock for AlignNode {
+    fn layout_block(
+        &self,
+        world: Tracked<dyn World>,
+        regions: &Regions,
+        styles: StyleChain,
+    ) -> SourceResult<Vec<Frame>> {
+        // The child only needs to expand along an axis if there's no alignment.
+        let mut pod = regions.clone();
+        pod.expand &= self.aligns.as_ref().map(Option::is_none);
+
+        // Align paragraphs inside the child.
+        let mut passed = StyleMap::new();
+        if let Some(align) = self.aligns.x {
+            passed.set(ParNode::ALIGN, HorizontalAlign(align));
+        }
+
+        // Layout the child.
+        let mut frames = self.child.layout_block(world, &pod, passed.chain(&styles))?;
+        for (region, frame) in regions.iter().zip(&mut frames) {
+            // Align in the target size. The target size depends on whether we
+            // should expand.
+            let target = regions.expand.select(region, frame.size());
+            let aligns = self
+                .aligns
+                .map(|align| align.resolve(styles))
+                .unwrap_or(Axes::new(Align::Left, Align::Top));
+
+            frame.resize(target, aligns);
+        }
+
+        Ok(frames)
+    }
+}