Split crates

1 files changed, 56 insertions, 0 deletions

diff --git a/library/src/layout/place.rs b/library/src/layout/place.rs
new file mode 100644
index 00000000..7d760ab6
--- /dev/null
+++ b/library/src/layout/place.rs
@@ -0,0 +1,56 @@
+use super::AlignNode;
+use crate::prelude::*;
+
+/// Place content at an absolute position.
+#[derive(Debug, Hash)]
+pub struct PlaceNode(pub Content);
+
+#[node(LayoutBlock)]
+impl PlaceNode {
+    fn construct(_: &mut Vm, args: &mut Args) -> SourceResult<Content> {
+        let aligns = args.find()?.unwrap_or(Axes::with_x(Some(GenAlign::Start)));
+        let dx = args.named("dx")?.unwrap_or_default();
+        let dy = args.named("dy")?.unwrap_or_default();
+        let body = args.expect::<Content>("body")?;
+        Ok(Self(body.moved(Axes::new(dx, dy)).aligned(aligns)).pack())
+    }
+}
+
+impl LayoutBlock for PlaceNode {
+    fn layout_block(
+        &self,
+        world: Tracked<dyn World>,
+        regions: &Regions,
+        styles: StyleChain,
+    ) -> SourceResult<Vec<Frame>> {
+        let out_of_flow = self.out_of_flow();
+
+        // The pod is the base area of the region because for absolute
+        // placement we don't really care about the already used area.
+        let pod = {
+            let finite = regions.base.map(Abs::is_finite);
+            let expand = finite & (regions.expand | out_of_flow);
+            Regions::one(regions.base, regions.base, expand)
+        };
+
+        let mut frames = self.0.layout_block(world, &pod, styles)?;
+
+        // If expansion is off, zero all sizes so that we don't take up any
+        // space in our parent. Otherwise, respect the expand settings.
+        let target = regions.expand.select(regions.first, Size::zero());
+        frames[0].resize(target, Align::LEFT_TOP);
+
+        Ok(frames)
+    }
+}
+
+impl PlaceNode {
+    /// Whether this node wants to be placed relative to its its parent's base
+    /// origin. Instead of relative to the parent's current flow/cursor
+    /// position.
+    pub fn out_of_flow(&self) -> bool {
+        self.0
+            .downcast::<AlignNode>()
+            .map_or(false, |node| node.aligns.y.is_some())
+    }
+}