Add `move` function

2 files changed, 46 insertions, 3 deletions

diff --git a/src/library/layout.rs b/src/library/layout.rs
index f7fb2882..e5650664 100644
--- a/src/library/layout.rs
+++ b/src/library/layout.rs
@@ -143,7 +143,7 @@ pub fn v(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
 }
 
 /// `box`: Place content in a rectangular box.
-pub fn boxed(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+pub fn box_(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     let width = args.named("width")?;
     let height = args.named("height")?;
     let fill = args.named("fill")?;
@@ -191,6 +191,48 @@ pub fn pad(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     })))
 }
 
+/// `move`: Move content without affecting layout.
+pub fn move_(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
+    #[derive(Debug, Hash)]
+    struct MoveNode {
+        offset: Spec<Option<Linear>>,
+        child: ShapeNode,
+    }
+
+    impl InlineLevel for MoveNode {
+        fn layout(&self, ctx: &mut LayoutContext, space: Length, base: Size) -> Frame {
+            let offset = Point::new(
+                self.offset.x.map(|x| x.resolve(base.w)).unwrap_or_default(),
+                self.offset.y.map(|y| y.resolve(base.h)).unwrap_or_default(),
+            );
+
+            let mut frame = self.child.layout(ctx, space, base);
+            for (point, _) in &mut frame.children {
+                *point += offset;
+            }
+
+            frame
+        }
+    }
+
+    let x = args.named("x")?;
+    let y = args.named("y")?;
+    let body: Template = args.expect("body")?;
+
+    Ok(Value::Template(Template::from_inline(move |style| {
+        MoveNode {
+            offset: Spec::new(x, y),
+            child: ShapeNode {
+                shape: ShapeKind::Rect,
+                width: None,
+                height: None,
+                fill: None,
+                child: Some(body.to_stack(style).pack()),
+            },
+        }
+    })))
+}
+
 /// `stack`: Stack children along an axis.
 pub fn stack(_: &mut EvalContext, args: &mut Args) -> TypResult<Value> {
     enum Child {
diff --git a/src/library/mod.rs b/src/library/mod.rs
index ac2085eb..6d3de11d 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -20,7 +20,7 @@ use crate::diag::{At, TypResult};
 use crate::eval::{Args, Array, EvalContext, Scope, Str, Template, Value};
 use crate::font::{FontFamily, FontStretch, FontStyle, FontWeight, VerticalFontMetric};
 use crate::geom::*;
-use crate::layout::{BlockLevel, Spacing};
+use crate::layout::{BlockLevel, Frame, InlineLevel, LayoutContext, Spacing};
 use crate::style::Style;
 use crate::syntax::{Span, Spanned};
 
@@ -43,9 +43,10 @@ pub fn new() -> Scope {
     std.def_func("h", h);
     std.def_func("v", v);
     std.def_func("align", align);
-    std.def_func("box", boxed);
+    std.def_func("box", box_);
     std.def_func("block", block);
     std.def_func("pad", pad);
+    std.def_func("move", move_);
     std.def_func("stack", stack);
     std.def_func("grid", grid);