Introduce `SizedNode`

7 files changed, 149 insertions, 97 deletions

diff --git a/src/geom/paint.rs b/src/geom/paint.rs
index 1d82966c..74d7d147 100644
--- a/src/geom/paint.rs
+++ b/src/geom/paint.rs
@@ -45,10 +45,15 @@ impl RgbaColor {
     /// White color.
     pub const WHITE: Self = Self { r: 255, g: 255, b: 255, a: 255 };
 
-    /// Constructs a new RGBA color.
+    /// Construct a new RGBA color.
     pub fn new(r: u8, g: u8, b: u8, a: u8) -> Self {
         Self { r, g, b, a }
     }
+
+    /// Construct a new, opaque gray color.
+    pub fn gray(luma: u8) -> Self {
+        Self::new(luma, luma, luma, 255)
+    }
 }
 
 impl FromStr for RgbaColor {
diff --git a/src/library/container.rs b/src/library/container.rs
deleted file mode 100644
index 2bcbbd19..00000000
--- a/src/library/container.rs
+++ /dev/null
@@ -1,26 +0,0 @@
-use super::prelude::*;
-use super::{ShapeKind, ShapeNode};
-
-/// `box`: Place content in a rectangular box.
-pub fn box_(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
-    let width = args.named("width")?;
-    let height = args.named("height")?;
-    let body: Template = args.find().unwrap_or_default();
-    Ok(Value::Template(Template::from_inline(move |style| {
-        ShapeNode {
-            shape: ShapeKind::Rect,
-            width,
-            height,
-            fill: None,
-            child: Some(body.to_flow(style).pack()),
-        }
-    })))
-}
-
-/// `block`: Place content in a block.
-pub fn block(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
-    let body: Template = args.expect("body")?;
-    Ok(Value::Template(Template::from_block(move |style| {
-        body.to_flow(style)
-    })))
-}
diff --git a/src/library/mod.rs b/src/library/mod.rs
index f11e05f3..fdede8bd 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -4,7 +4,6 @@
 //! definitions.
 
 mod align;
-mod container;
 mod deco;
 mod document;
 mod flow;
@@ -14,6 +13,7 @@ mod pad;
 mod page;
 mod par;
 mod shape;
+mod sized;
 mod spacing;
 mod stack;
 mod text;
@@ -35,7 +35,6 @@ mod prelude {
 
 pub use self::image::*;
 pub use align::*;
-pub use container::*;
 pub use deco::*;
 pub use document::*;
 pub use flow::*;
@@ -44,6 +43,7 @@ pub use pad::*;
 pub use page::*;
 pub use par::*;
 pub use shape::*;
+pub use sized::*;
 pub use spacing::*;
 pub use stack::*;
 pub use text::*;
diff --git a/src/library/par.rs b/src/library/par.rs
index c8befc2d..d0f31016 100644
--- a/src/library/par.rs
+++ b/src/library/par.rs
@@ -77,7 +77,7 @@ impl Layout for ParNode {
 
         // Prepare paragraph layout by building a representation on which we can
         // do line breaking without layouting each and every line from scratch.
-        let layouter = ParLayouter::new(self, ctx, regions.clone(), bidi);
+        let layouter = ParLayouter::new(self, ctx, regions, bidi);
 
         // Find suitable linebreaks.
         layouter.layout(ctx, regions.clone())
@@ -182,12 +182,9 @@ impl<'a> ParLayouter<'a> {
     fn new(
         par: &'a ParNode,
         ctx: &mut LayoutContext,
-        mut regions: Regions,
+        regions: &Regions,
         bidi: BidiInfo<'a>,
     ) -> Self {
-        // Disable expansion for children.
-        regions.expand = Spec::splat(false);
-
         let mut items = vec![];
         let mut ranges = vec![];
         let mut starts = vec![];
@@ -219,7 +216,10 @@ impl<'a> ParLayouter<'a> {
                     }
                 }
                 ParChild::Node(ref node, align) => {
-                    let frame = node.layout(ctx, &regions).remove(0);
+                    let size = Size::new(regions.current.w, regions.base.h);
+                    let expand = Spec::splat(false);
+                    let pod = Regions::one(size, regions.base, expand);
+                    let frame = node.layout(ctx, &pod).remove(0);
                     items.push(ParItem::Frame(Rc::take(frame.item), align));
                     ranges.push(range);
                 }
diff --git a/src/library/shape.rs b/src/library/shape.rs
index c64dedb3..112987ad 100644
--- a/src/library/shape.rs
+++ b/src/library/shape.rs
@@ -1,7 +1,7 @@
 use std::f64::consts::SQRT_2;
 
 use super::prelude::*;
-use super::PadNode;
+use super::{PadNode, SizedNode};
 use crate::util::RcExt;
 
 /// `rect`: A rectangle with optional content.
@@ -55,7 +55,7 @@ pub fn circle(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 }
 
 fn shape_impl(
-    shape: ShapeKind,
+    kind: ShapeKind,
     mut width: Option<Linear>,
     mut height: Option<Linear>,
     fill: Option<Color>,
@@ -65,20 +65,30 @@ fn shape_impl(
     if body.is_none() {
         let v = Length::pt(30.0).into();
         height.get_or_insert(v);
-        width.get_or_insert(match shape {
+        width.get_or_insert(match kind {
             ShapeKind::Square | ShapeKind::Circle => v,
             ShapeKind::Rect | ShapeKind::Ellipse => 1.5 * v,
         });
     }
 
-    Value::Template(Template::from_inline(move |style| ShapeNode {
-        shape,
-        width,
-        height,
-        fill: Some(Paint::Color(
-            fill.unwrap_or(Color::Rgba(RgbaColor::new(175, 175, 175, 255))),
-        )),
-        child: body.as_ref().map(|template| template.to_flow(style).pack()),
+    // Set default fill if there's no fill.
+    let fill = fill.unwrap_or(Color::Rgba(RgbaColor::gray(175)));
+
+    Value::Template(Template::from_inline(move |style| {
+        let shape = Layout::pack(ShapeNode {
+            kind,
+            fill: Some(Paint::Color(fill)),
+            child: body.as_ref().map(|body| body.to_flow(style).pack()),
+        });
+
+        if width.is_some() || height.is_some() {
+            Layout::pack(SizedNode {
+                sizing: Spec::new(width, height),
+                child: shape,
+            })
+        } else {
+            shape
+        }
     }))
 }
 
@@ -86,11 +96,7 @@ fn shape_impl(
 #[derive(Debug, Hash)]
 pub struct ShapeNode {
     /// Which shape to place the child into.
-    pub shape: ShapeKind,
-    /// The width, if any.
-    pub width: Option<Linear>,
-    /// The height, if any.
-    pub height: Option<Linear>,
+    pub kind: ShapeKind,
     /// How to fill the shape, if at all.
     pub fill: Option<Paint>,
     /// The child node to place into the shape, if any.
@@ -116,33 +122,12 @@ impl Layout for ShapeNode {
         ctx: &mut LayoutContext,
         regions: &Regions,
     ) -> Vec<Constrained<Rc<Frame>>> {
-        // Resolve width and height relative to the region's base.
-        let width = self.width.map(|w| w.resolve(regions.base.w));
-        let height = self.height.map(|h| h.resolve(regions.base.h));
-
-        // Generate constraints.
-        let mut cts = Constraints::new(regions.expand);
-        cts.set_base_if_linear(regions.base, Spec::new(self.width, self.height));
-
-        // Set tight exact and base constraints if the child is
-        // automatically sized since we don't know what the child might do.
-        if self.width.is_none() {
-            cts.exact.x = Some(regions.current.w);
-            cts.base.x = Some(regions.base.w);
-        }
-
-        // Same here.
-        if self.height.is_none() {
-            cts.exact.y = Some(regions.current.h);
-            cts.base.y = Some(regions.base.h);
-        }
-
         // Layout.
         let mut frame = if let Some(child) = &self.child {
             let mut node: &dyn Layout = child;
 
             let padded;
-            if matches!(self.shape, ShapeKind::Circle | ShapeKind::Ellipse) {
+            if matches!(self.kind, ShapeKind::Circle | ShapeKind::Ellipse) {
                 // Padding with this ratio ensures that a rectangular child fits
                 // perfectly into a circle / an ellipse.
                 padded = PadNode {
@@ -152,29 +137,14 @@ impl Layout for ShapeNode {
                 node = &padded;
             }
 
-            // The "pod" is the region into which the child will be layouted.
-            let mut pod = {
-                let size = Size::new(
-                    width.unwrap_or(regions.current.w),
-                    height.unwrap_or(regions.base.h),
-                );
-
-                let base = Size::new(
-                    if width.is_some() { size.w } else { regions.base.w },
-                    if height.is_some() { size.h } else { regions.base.h },
-                );
-
-                let expand = Spec::new(width.is_some(), height.is_some());
-                Regions::one(size, base, expand)
-            };
-
             // Now, layout the child.
-            let mut frames = node.layout(ctx, &pod);
+            let mut frames = node.layout(ctx, regions);
 
-            if matches!(self.shape, ShapeKind::Square | ShapeKind::Circle) {
+            if matches!(self.kind, ShapeKind::Square | ShapeKind::Circle) {
                 // Relayout with full expansion into square region to make sure
                 // the result is really a square or circle.
                 let size = frames[0].item.size;
+                let mut pod = regions.clone();
                 pod.current.w = size.w.max(size.h).min(pod.current.w);
                 pod.current.h = pod.current.w;
                 pod.expand = Spec::splat(true);
@@ -185,14 +155,12 @@ impl Layout for ShapeNode {
             assert_eq!(frames.len(), 1);
             Rc::take(frames.into_iter().next().unwrap().item)
         } else {
-            // Resolve shape size.
-            let size = Size::new(width.unwrap_or_default(), height.unwrap_or_default());
-            Frame::new(size, size.h)
+            Frame::new(regions.current, regions.current.h)
         };
 
         // Add background shape if desired.
         if let Some(fill) = self.fill {
-            let (pos, geometry) = match self.shape {
+            let (pos, geometry) = match self.kind {
                 ShapeKind::Square | ShapeKind::Rect => {
                     (Point::zero(), Geometry::Rect(frame.size))
                 }
@@ -204,6 +172,11 @@ impl Layout for ShapeNode {
             frame.prepend(pos, Element::Geometry(geometry, fill));
         }
 
+        // Generate tight constraints for now.
+        let mut cts = Constraints::new(regions.expand);
+        cts.exact = regions.current.to_spec().map(Some);
+        cts.base = regions.base.to_spec().map(Some);
+
         vec![frame.constrain(cts)]
     }
 }
diff --git a/src/library/sized.rs b/src/library/sized.rs
new file mode 100644
index 00000000..631f9e6f
--- /dev/null
+++ b/src/library/sized.rs
@@ -0,0 +1,100 @@
+use super::prelude::*;
+
+/// `box`: Size content and place it into a paragraph.
+pub fn box_(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    let width = args.named("width")?;
+    let height = args.named("height")?;
+    let body: Template = args.find().unwrap_or_default();
+    Ok(Value::Template(Template::from_inline(move |style| {
+        let flow = body.to_flow(style).pack();
+        if width.is_some() || height.is_some() {
+            Layout::pack(SizedNode {
+                sizing: Spec::new(width, height),
+                child: flow,
+            })
+        } else {
+            flow
+        }
+    })))
+}
+
+/// `block`: Size content and place it into the flow.
+pub fn block(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    let width = args.named("width")?;
+    let height = args.named("height")?;
+    let body: Template = args.find().unwrap_or_default();
+    Ok(Value::Template(Template::from_block(move |style| {
+        let flow = body.to_flow(style).pack();
+        if width.is_some() || height.is_some() {
+            Layout::pack(SizedNode {
+                sizing: Spec::new(width, height),
+                child: flow,
+            })
+        } else {
+            flow
+        }
+    })))
+}
+
+/// A node that sizes its child.
+#[derive(Debug, Hash)]
+pub struct SizedNode {
+    /// The node to-be-sized.
+    pub child: PackedNode,
+    /// How to size the node horizontally and vertically.
+    pub sizing: Spec<Option<Linear>>,
+}
+
+impl Layout for SizedNode {
+    fn layout(
+        &self,
+        ctx: &mut LayoutContext,
+        regions: &Regions,
+    ) -> Vec<Constrained<Rc<Frame>>> {
+        // Resolve width and height relative to the region's base.
+        let width = self.sizing.x.map(|w| w.resolve(regions.base.w));
+        let height = self.sizing.y.map(|h| h.resolve(regions.base.h));
+
+        // Generate constraints.
+        let mut cts = Constraints::new(regions.expand);
+        cts.set_base_if_linear(regions.base, self.sizing);
+
+        // Set tight exact and base constraints if the child is
+        // automatically sized since we don't know what the child might do.
+        if self.sizing.x.is_none() {
+            cts.exact.x = Some(regions.current.w);
+            cts.base.x = Some(regions.base.w);
+        }
+
+        // Same here.
+        if self.sizing.y.is_none() {
+            cts.exact.y = Some(regions.current.h);
+            cts.base.y = Some(regions.base.h);
+        }
+
+        // The "pod" is the region into which the child will be layouted.
+        let pod = {
+            let size = Size::new(
+                width.unwrap_or(regions.current.w),
+                height.unwrap_or(regions.current.h),
+            );
+
+            let base = Size::new(
+                if width.is_some() { size.w } else { regions.base.w },
+                if height.is_some() { size.h } else { regions.base.h },
+            );
+
+            let expand = Spec::new(
+                width.is_some() || regions.expand.x,
+                height.is_some() || regions.expand.y,
+            );
+
+            // TODO: Allow multiple regions if only width is set.
+            Regions::one(size, base, expand)
+        };
+
+        let mut frames = self.child.layout(ctx, &pod);
+        frames[0].cts = cts;
+        frames
+    }
+}
diff --git a/src/library/stack.rs b/src/library/stack.rs
index 46825939..dec5ec2d 100644
--- a/src/library/stack.rs
+++ b/src/library/stack.rs
@@ -35,12 +35,12 @@ pub fn stack(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
                     children.push(StackChild::Spacing(*v));
                     delayed = None;
                 }
-                Child::Any(template) => {
+                Child::Any(child) => {
                     if let Some(v) = delayed {
                         children.push(StackChild::Spacing(v));
                     }
 
-                    let node = template.to_flow(style).pack();
+                    let node = child.to_flow(style).pack();
                     children.push(StackChild::Node(node));
                     delayed = spacing;
                 }