1 files changed, 135 insertions, 0 deletions
diff --git a/src/library/elements.rs b/src/library/elements.rs
new file mode 100644
index 00000000..b1b5c1f9
--- /dev/null
+++ b/src/library/elements.rs
@@ -0,0 +1,135 @@
+use std::f64::consts::SQRT_2;
+
+use decorum::N64;
+
+use super::*;
+use crate::color::Color;
+use crate::layout::{
+    BackgroundNode, BackgroundShape, Fill, FixedNode, ImageNode, PadNode,
+};
+
+/// `image`: An image.
+pub fn image(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    let path = args.expect::<Spanned<String>>(ctx, "path to image file");
+    let width = args.named(ctx, "width");
+    let height = args.named(ctx, "height");
+
+    let mut node = None;
+    if let Some(path) = &path {
+        if let Some((resolved, _)) = ctx.resolve(&path.v, path.span) {
+            if let Some(id) = ctx.cache.image.load(ctx.loader, &resolved) {
+                node = Some(ImageNode { id, width, height });
+            } else {
+                ctx.diag(error!(path.span, "failed to load image"));
+            }
+        }
+    }
+
+    Value::template("image", move |ctx| {
+        if let Some(node) = node {
+            ctx.push_into_par(node);
+        }
+    })
+}
+
+/// `rect`: A rectangle with optional content.
+pub fn rect(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    let width = args.named(ctx, "width");
+    let height = args.named(ctx, "height");
+    let fill = args.named(ctx, "fill");
+    let body = args.eat::<TemplateValue>(ctx).unwrap_or_default();
+    rect_impl("rect", width, height, None, fill, body)
+}
+
+/// `square`: A square with optional content.
+pub fn square(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    let length = args.named::<Length>(ctx, "length").map(Linear::from);
+    let width = length.or_else(|| args.named(ctx, "width"));
+    let height = width.is_none().then(|| args.named(ctx, "height")).flatten();
+    let fill = args.named(ctx, "fill");
+    let body = args.eat::<TemplateValue>(ctx).unwrap_or_default();
+    rect_impl("square", width, height, Some(N64::from(1.0)), fill, body)
+}
+
+fn rect_impl(
+    name: &str,
+    width: Option<Linear>,
+    height: Option<Linear>,
+    aspect: Option<N64>,
+    fill: Option<Color>,
+    body: TemplateValue,
+) -> Value {
+    Value::template(name, move |ctx| {
+        let mut stack = ctx.exec_template_stack(&body);
+        stack.aspect = aspect;
+
+        let fixed = FixedNode { width, height, child: stack.into() };
+
+        if let Some(color) = fill {
+            ctx.push_into_par(BackgroundNode {
+                shape: BackgroundShape::Rect,
+                fill: Fill::Color(color),
+                child: fixed.into(),
+            });
+        } else {
+            ctx.push_into_par(fixed);
+        }
+    })
+}
+
+/// `ellipse`: An ellipse with optional content.
+pub fn ellipse(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    let width = args.named(ctx, "width");
+    let height = args.named(ctx, "height");
+    let fill = args.named(ctx, "fill");
+    let body = args.eat::<TemplateValue>(ctx).unwrap_or_default();
+    ellipse_impl("ellipse", width, height, None, fill, body)
+}
+
+/// `circle`: A circle with optional content.
+pub fn circle(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    let radius = args.named::<Length>(ctx, "radius").map(|r| 2.0 * Linear::from(r));
+    let width = radius.or_else(|| args.named(ctx, "width"));
+    let height = width.is_none().then(|| args.named(ctx, "height")).flatten();
+    let fill = args.named(ctx, "fill");
+    let body = args.eat::<TemplateValue>(ctx).unwrap_or_default();
+    ellipse_impl("circle", width, height, Some(N64::from(1.0)), fill, body)
+}
+
+fn ellipse_impl(
+    name: &str,
+    width: Option<Linear>,
+    height: Option<Linear>,
+    aspect: Option<N64>,
+    fill: Option<Color>,
+    body: TemplateValue,
+) -> Value {
+    Value::template(name, move |ctx| {
+        // This padding ratio ensures that the rectangular padded region fits
+        // perfectly into the ellipse.
+        const PAD: f64 = 0.5 - SQRT_2 / 4.0;
+
+        let mut stack = ctx.exec_template_stack(&body);
+        stack.aspect = aspect;
+
+        let fixed = FixedNode {
+            width,
+            height,
+            child: PadNode {
+                padding: Sides::splat(Relative::new(PAD).into()),
+                child: stack.into(),
+            }
+            .into(),
+        };
+
+        if let Some(color) = fill {
+            ctx.push_into_par(BackgroundNode {
+                shape: BackgroundShape::Ellipse,
+                fill: Fill::Color(color),
+                child: fixed.into(),
+            });
+        } else {
+            ctx.push_into_par(fixed);
+        }
+    })
+}