Text decorations

3 files changed, 90 insertions, 1 deletions

diff --git a/src/library/decorations.rs b/src/library/decorations.rs
new file mode 100644
index 00000000..ef9afd37
--- /dev/null
+++ b/src/library/decorations.rs
@@ -0,0 +1,84 @@
+use crate::exec::{FontState, LineState};
+use crate::layout::Fill;
+
+use super::*;
+
+/// `strike`: Enable striken-through text.
+///
+/// # Named parameters
+/// - Color: `color`, of type `color`.
+/// - Baseline offset: `position`, of type `linear`.
+/// - Strength: `strength`, of type `linear`.
+/// - Extent that is applied on either end of the line: `extent`, of type
+///   `linear`.
+///
+/// # Return value
+/// A template that enables striken-through text. The effect is scoped to the
+/// body if present.
+pub fn strike(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    line_impl("strike", ctx, args, |font| &mut font.strikethrough)
+}
+
+/// `underline`: Enable underlined text.
+///
+/// # Named parameters
+/// - Color: `color`, of type `color`.
+/// - Baseline offset: `position`, of type `linear`.
+/// - Strength: `strength`, of type `linear`.
+/// - Extent that is applied on either end of the line: `extent`, of type
+///   `linear`.
+///
+/// # Return value
+/// A template that enables underlined text. The effect is scoped to the body if
+/// present.
+pub fn underline(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    line_impl("underline", ctx, args, |font| &mut font.underline)
+}
+
+/// `overline`: Add an overline above text.
+///
+/// # Named parameters
+/// - Color: `color`, of type `color`.
+/// - Baseline offset: `position`, of type `linear`.
+/// - Strength: `strength`, of type `linear`.
+/// - Extent that is applied on either end of the line: `extent`, of type
+///   `linear`.
+///
+/// # Return value
+/// A template that adds an overline above text. The effect is scoped to the
+/// body if present.
+pub fn overline(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
+    line_impl("overline", ctx, args, |font| &mut font.overline)
+}
+
+fn line_impl(
+    name: &str,
+    ctx: &mut EvalContext,
+    args: &mut FuncArgs,
+    substate: impl Fn(&mut FontState) -> &mut Option<LineState> + 'static,
+) -> Value {
+    let color = args.eat_named(ctx, "color");
+    let position = args.eat_named(ctx, "position");
+    let strength = args.eat_named::<Linear>(ctx, "strength");
+    let extent = args.eat_named(ctx, "extent").unwrap_or_default();
+    let body = args.eat::<TemplateValue>(ctx);
+
+    // Suppress any existing strikethrough if strength is explicitly zero.
+    let state = strength.map_or(true, |s| !s.is_zero()).then(|| LineState {
+        fill: color.map(Fill::Color),
+        strength,
+        position,
+        extent,
+    });
+
+    Value::template(name, move |ctx| {
+        let snapshot = ctx.state.clone();
+
+        *substate(&mut ctx.state.font) = state;
+
+        if let Some(body) = &body {
+            body.exec(ctx);
+            ctx.state = snapshot;
+        }
+    })
+}
diff --git a/src/library/font.rs b/src/library/font.rs
index b3b037cd..a3fe6c13 100644
--- a/src/library/font.rs
+++ b/src/library/font.rs
@@ -99,7 +99,7 @@ pub fn font(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
         }
 
         if let Some(color) = color {
-            ctx.state.font.color = Fill::Color(color);
+            ctx.state.font.fill = Fill::Color(color);
         }
 
         if let Some(FontFamilies(serif)) = &serif {
diff --git a/src/library/mod.rs b/src/library/mod.rs
index 8caddc4c..553b39e6 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -5,6 +5,7 @@
 
 mod align;
 mod basic;
+mod decorations;
 mod font;
 mod grid;
 mod image;
@@ -20,6 +21,7 @@ mod stack;
 pub use self::image::*;
 pub use align::*;
 pub use basic::*;
+pub use decorations::*;
 pub use font::*;
 pub use grid::*;
 pub use lang::*;
@@ -55,6 +57,7 @@ pub fn new() -> Scope {
     std.def_func("lang", lang);
     std.def_func("max", max);
     std.def_func("min", min);
+    std.def_func("overline", overline);
     std.def_func("pad", pad);
     std.def_func("page", page);
     std.def_func("pagebreak", pagebreak);
@@ -64,7 +67,9 @@ pub fn new() -> Scope {
     std.def_func("rgb", rgb);
     std.def_func("square", square);
     std.def_func("stack", stack);
+    std.def_func("strike", strike);
     std.def_func("type", type_);
+    std.def_func("underline", underline);
     std.def_func("v", v);
 
     // Colors.