More independent placed node

13 files changed, 126 insertions, 63 deletions

diff --git a/src/eval/template.rs b/src/eval/template.rs
index e9cbbfcf..d447161a 100644
--- a/src/eval/template.rs
+++ b/src/eval/template.rs
@@ -337,13 +337,24 @@ impl Builder {
 
     /// Push a block node into the active flow, finishing the active paragraph.
     fn block(&mut self, node: PackedNode) {
+        let mut is_placed = false;
+        if let Some(placed) = node.downcast::<PlacedNode>() {
+            is_placed = true;
+
+            // This prevents paragraph spacing after the placed node if it
+            // is completely out-of-flow.
+            if placed.out_of_flow() {
+                self.flow.last = Last::None;
+            }
+        }
+
         self.parbreak();
-        let in_flow = node.downcast::<PlacedNode>().is_none();
         self.flow.push(FlowChild::Node(node));
-        if in_flow {
-            self.parbreak();
-        } else {
-            // This prevents duplicate paragraph spacing around placed nodes.
+        self.parbreak();
+
+        // This prevents paragraph spacing between the placed node and
+        // the paragraph below it.
+        if is_placed {
             self.flow.last = Last::None;
         }
     }
diff --git a/src/frame.rs b/src/frame.rs
index 4eea0578..e02fdf46 100644
--- a/src/frame.rs
+++ b/src/frame.rs
@@ -57,13 +57,13 @@ impl Frame {
 
     /// Resize the frame to a new size, distributing new space according to the
     /// given alignments.
-    pub fn resize(&mut self, new: Size, aligns: Spec<Align>) {
-        if self.size != new {
+    pub fn resize(&mut self, target: Size, aligns: Spec<Align>) {
+        if self.size != target {
             let offset = Point::new(
-                aligns.x.resolve(new.x - self.size.x),
-                aligns.y.resolve(new.y - self.size.y),
+                aligns.x.resolve(target.x - self.size.x),
+                aligns.y.resolve(target.y - self.size.y),
             );
-            self.size = new;
+            self.size = target;
             self.baseline += offset.y;
             self.translate(offset);
         }
diff --git a/src/geom/align.rs b/src/geom/align.rs
index f068b821..be2eac96 100644
--- a/src/geom/align.rs
+++ b/src/geom/align.rs
@@ -18,6 +18,12 @@ pub enum Align {
 }
 
 impl Align {
+    /// Top-left alignment.
+    pub const LEFT_TOP: Spec<Self> = Spec { x: Align::Left, y: Align::Top };
+
+    /// Center-horizon alignment.
+    pub const CENTER_HORIZON: Spec<Self> = Spec { x: Align::Center, y: Align::Horizon };
+
     /// The axis this alignment belongs to.
     pub const fn axis(self) -> SpecAxis {
         match self {
diff --git a/src/geom/spec.rs b/src/geom/spec.rs
index 640d6231..16d63959 100644
--- a/src/geom/spec.rs
+++ b/src/geom/spec.rs
@@ -281,6 +281,14 @@ impl BitOr for Spec<bool> {
     }
 }
 
+impl BitOr<bool> for Spec<bool> {
+    type Output = Self;
+
+    fn bitor(self, rhs: bool) -> Self::Output {
+        Self { x: self.x | rhs, y: self.y | rhs }
+    }
+}
+
 impl BitAnd for Spec<bool> {
     type Output = Self;
 
@@ -289,6 +297,14 @@ impl BitAnd for Spec<bool> {
     }
 }
 
+impl BitAnd<bool> for Spec<bool> {
+    type Output = Self;
+
+    fn bitand(self, rhs: bool) -> Self::Output {
+        Self { x: self.x & rhs, y: self.y & rhs }
+    }
+}
+
 impl BitOrAssign for Spec<bool> {
     fn bitor_assign(&mut self, rhs: Self) {
         self.x |= rhs.x;
diff --git a/src/layout/mod.rs b/src/layout/mod.rs
index 405e4e83..9c57152a 100644
--- a/src/layout/mod.rs
+++ b/src/layout/mod.rs
@@ -136,10 +136,7 @@ impl PackedNode {
 
     /// Transform this node's contents without affecting layout.
     pub fn moved(self, offset: Point) -> Self {
-        self.transformed(
-            Transform::translation(offset.x, offset.y),
-            Spec::new(Align::Left, Align::Top),
-        )
+        self.transformed(Transform::translation(offset.x, offset.y), Align::LEFT_TOP)
     }
 
     /// Transform this node's contents without affecting layout.
diff --git a/src/library/align.rs b/src/library/align.rs
index 7ad5a2d4..a2881cce 100644
--- a/src/library/align.rs
+++ b/src/library/align.rs
@@ -2,6 +2,18 @@ use super::prelude::*;
 
 /// `align`: Configure the alignment along the layouting axes.
 pub fn align(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    castable! {
+        Spec<Option<Align>>,
+        Expected: "1d or 2d alignment",
+        @align: Align => {
+            let mut aligns = Spec::default();
+            aligns.set(align.axis(), Some(*align));
+            aligns
+        },
+        @aligns: Spec<Align> => aligns.map(Some),
+
+    }
+
     let aligns = args.expect::<Spec<_>>("alignment")?;
     let body = args.expect::<Template>("body")?;
     Ok(Value::Template(Template::from_block(move |style| {
@@ -36,8 +48,8 @@ impl Layout for AlignNode {
         // Layout the child.
         let mut frames = self.child.layout(ctx, &pod);
 
-        for (Constrained { item: frame, cts }, (current, base)) in
-            frames.iter_mut().zip(regions.iter())
+        for ((current, base), Constrained { item: frame, cts }) in
+            regions.iter().zip(&mut frames)
         {
             // Align in the target size. The target size depends on whether we
             // should expand.
diff --git a/src/library/flow.rs b/src/library/flow.rs
index e105c596..587b5a80 100644
--- a/src/library/flow.rs
+++ b/src/library/flow.rs
@@ -101,10 +101,10 @@ enum FlowItem {
     Absolute(Length),
     /// Fractional spacing between other items.
     Fractional(Fractional),
-    /// A frame to be placed directly at the origin.
-    Placed(Rc<Frame>),
     /// A frame for a layouted child node and how to align it.
     Frame(Rc<Frame>, Spec<Align>),
+    /// An absolutely placed frame.
+    Placed(Rc<Frame>),
 }
 
 impl<'a> FlowLayouter<'a> {
@@ -166,17 +166,11 @@ impl<'a> FlowLayouter<'a> {
 
     /// Layout a node.
     fn layout_node(&mut self, ctx: &mut LayoutContext, node: &PackedNode) {
-        // Placed nodes with vertical alignment are handled separately
-        // because their position shouldn't depend on other flow elements.
         if let Some(placed) = node.downcast::<PlacedNode>() {
-            if let Some(aligned) = placed.child.downcast::<AlignNode>() {
-                if aligned.aligns.y.is_some() {
-                    let base = self.regions.base;
-                    let pod = Regions::one(base, base, Spec::splat(true));
-                    let frame = placed.layout(ctx, &pod).remove(0);
-                    self.items.push(FlowItem::Placed(frame.item));
-                    return;
-                }
+            let frame = node.layout(ctx, &self.regions).remove(0);
+            if placed.out_of_flow() {
+                self.items.push(FlowItem::Placed(frame.item));
+                return;
             }
         }
 
@@ -233,9 +227,6 @@ impl<'a> FlowLayouter<'a> {
                 FlowItem::Fractional(v) => {
                     before += v.resolve(self.fr, remaining);
                 }
-                FlowItem::Placed(frame) => {
-                    output.push_frame(Point::zero(), frame);
-                }
                 FlowItem::Frame(frame, aligns) => {
                     ruler = ruler.max(aligns.y);
 
@@ -253,6 +244,9 @@ impl<'a> FlowLayouter<'a> {
 
                     output.push_frame(pos, frame);
                 }
+                FlowItem::Placed(frame) => {
+                    output.push_frame(Point::with_y(before), frame);
+                }
             }
         }
 
diff --git a/src/library/image.rs b/src/library/image.rs
index 92580f6e..a20f3856 100644
--- a/src/library/image.rs
+++ b/src/library/image.rs
@@ -51,7 +51,7 @@ impl Layout for ImageNode {
         let wide = pixel_ratio > current_ratio;
 
         // The space into which the image will be placed according to its fit.
-        let canvas = if expand.x && expand.y {
+        let target = if expand.x && expand.y {
             current
         } else if expand.x || (wide && current.x.is_finite()) {
             Size::new(current.x, current.y.min(current.x.safe_div(pixel_ratio)))
@@ -65,20 +65,20 @@ impl Layout for ImageNode {
         let size = match self.fit {
             ImageFit::Contain | ImageFit::Cover => {
                 if wide == (self.fit == ImageFit::Contain) {
-                    Size::new(canvas.x, canvas.x / pixel_ratio)
+                    Size::new(target.x, target.x / pixel_ratio)
                 } else {
-                    Size::new(canvas.y * pixel_ratio, canvas.y)
+                    Size::new(target.y * pixel_ratio, target.y)
                 }
             }
-            ImageFit::Stretch => canvas,
+            ImageFit::Stretch => target,
         };
 
         // First, place the image in a frame of exactly its size and then resize
-        // the frame to the canvas size, center aligning the image in the
+        // the frame to the target size, center aligning the image in the
         // process.
         let mut frame = Frame::new(size);
         frame.push(Point::zero(), Element::Image(self.id, size));
-        frame.resize(canvas, Spec::new(Align::Center, Align::Horizon));
+        frame.resize(target, Align::CENTER_HORIZON);
 
         // Create a clipping group if the fit mode is "cover".
         if self.fit == ImageFit::Cover {
diff --git a/src/library/mod.rs b/src/library/mod.rs
index c953a76e..d60a13ea 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -153,15 +153,3 @@ castable! {
     Expected: "color",
     Value::Color(color) => Paint::Solid(color),
 }
-
-castable! {
-    Spec<Option<Align>>,
-    Expected: "1d or 2d alignment",
-    @align: Align => {
-        let mut aligns = Spec::default();
-        aligns.set(align.axis(), Some(*align));
-        aligns
-    },
-    @aligns: Spec<Align> => aligns.map(Some),
-
-}
diff --git a/src/library/pad.rs b/src/library/pad.rs
index ce7f4150..4bd7fd64 100644
--- a/src/library/pad.rs
+++ b/src/library/pad.rs
@@ -39,8 +39,8 @@ impl Layout for PadNode {
         let pod = regions.map(|size| shrink(size, self.padding));
         let mut frames = self.child.layout(ctx, &pod);
 
-        for (Constrained { item: frame, cts }, (current, base)) in
-            frames.iter_mut().zip(regions.iter())
+        for ((current, base), Constrained { item: frame, cts }) in
+            regions.iter().zip(&mut frames)
         {
             // Apply the padding inversely such that the grown size padded
             // yields the frame's size.
diff --git a/src/library/placed.rs b/src/library/placed.rs
index 4f1c5b85..1ae51530 100644
--- a/src/library/placed.rs
+++ b/src/library/placed.rs
@@ -1,4 +1,5 @@
 use super::prelude::*;
+use super::AlignNode;
 
 /// `place`: Place content at an absolute position.
 pub fn place(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
@@ -13,23 +14,60 @@ pub fn place(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     })))
 }
 
-/// A node that places its child out-of-flow.
+/// A node that places its child absolutely.
 #[derive(Debug, Hash)]
 pub struct PlacedNode {
     /// The node to be placed.
     pub child: PackedNode,
 }
 
+impl PlacedNode {
+    /// 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.child
+            .downcast::<AlignNode>()
+            .map_or(false, |node| node.aligns.y.is_some())
+    }
+}
+
 impl Layout for PlacedNode {
     fn layout(
         &self,
         ctx: &mut LayoutContext,
         regions: &Regions,
     ) -> Vec<Constrained<Rc<Frame>>> {
-        let mut frames = self.child.layout(ctx, regions);
-        for frame in frames.iter_mut() {
-            Rc::make_mut(&mut frame.item).size = Size::zero();
+        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 (current).
+        let pod = {
+            let expand = if out_of_flow { Spec::splat(true) } else { regions.expand };
+            Regions::one(regions.base, regions.base, expand)
+        };
+
+        let mut frames = self.child.layout(ctx, &pod);
+        let Constrained { item: frame, cts } = &mut frames[0];
+
+        // 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.current, Size::zero());
+        Rc::make_mut(frame).resize(target, Align::LEFT_TOP);
+
+        // Place relative to parent's base origin by offsetting our elements by
+        // the negative cursor position.
+        if out_of_flow {
+            let offset = (regions.current - regions.base).to_point();
+            Rc::make_mut(frame).translate(offset);
         }
+
+        // Set base constraint because our pod size is base and exact
+        // constraints if we needed to expand or offset.
+        *cts = Constraints::new(regions.expand);
+        cts.base = regions.base.map(Some);
+        cts.exact = regions.current.filter(regions.expand | out_of_flow);
+
         frames
     }
 }
diff --git a/src/library/sized.rs b/src/library/sized.rs
index 9b2cdf22..f421637b 100644
--- a/src/library/sized.rs
+++ b/src/library/sized.rs
@@ -56,14 +56,14 @@ impl Layout for SizedNode {
         };
 
         let mut frames = self.child.layout(ctx, &pod);
+        let Constrained { cts, .. } = &mut frames[0];
 
         // Set base & exact constraints if the child is automatically sized
-        // since we don't know what the child might do. Also set base if our
-        // sizing is relative.
-        let frame = &mut frames[0];
-        frame.cts = Constraints::new(regions.expand);
-        frame.cts.exact = regions.current.filter(is_auto);
-        frame.cts.base = regions.base.filter(is_auto | is_rel);
+        // since we don't know what the child might have done. Also set base if
+        // our sizing is relative.
+        *cts = Constraints::new(regions.expand);
+        cts.exact = regions.current.filter(is_auto);
+        cts.base = regions.base.filter(is_auto | is_rel);
 
         frames
     }
diff --git a/src/library/transform.rs b/src/library/transform.rs
index c8b48666..9ba71ecf 100644
--- a/src/library/transform.rs
+++ b/src/library/transform.rs
@@ -30,7 +30,7 @@ fn transform_impl(args: &mut Args, transform: Transform) -> TypResult<Value> {
     let origin = args
         .named("origin")?
         .unwrap_or(Spec::splat(None))
-        .unwrap_or(Spec::new(Align::Center, Align::Horizon));
+        .unwrap_or(Align::CENTER_HORIZON);
 
     Ok(Value::Template(Template::from_inline(move |style| {
         body.pack(style).transformed(transform, origin)
@@ -56,11 +56,12 @@ impl Layout for TransformNode {
     ) -> Vec<Constrained<Rc<Frame>>> {
         let mut frames = self.child.layout(ctx, regions);
 
-        for Constrained { item: frame, .. } in frames.iter_mut() {
+        for Constrained { item: frame, .. } in &mut frames {
             let Spec { x, y } = self.origin.zip(frame.size).map(|(o, s)| o.resolve(s));
             let transform = Transform::translation(x, y)
                 .pre_concat(self.transform)
                 .pre_concat(Transform::translation(-x, -y));
+
             Rc::make_mut(frame).transform(transform);
         }