Bezier-rs: Subpath offset and bezier offset improvements (#1039)

* Added subpath offset

* Enhanced offset to produce smooth curves

* Lots of outline bugfixes

* Fixed failing unit tests

* Added subpath outline

* Refactor bezier offset and outline to return Subpaths

* Fix outline bug due to smooth joining and removed reduce optimization that causes jumping approximations

* Bugfix when subpath angle is acute but doesn't intersect

* Stylistic changes per review

* Stylistic changes per review and updated doc comments

---------

Co-authored-by: Hannah Li <hannahli2010@gmail.com>
Co-authored-by: Keavon Chambers <keavon@keavon.com>

website/other/bezier-rs-demos/wasm/src/subpath.rs

@@ -376,4 +376,29 @@ impl WasmSubpath {
 
 		wrap_svg_tag(format!("{}{}", self.to_default_svg(), trimmed_subpath_svg))
 	}
+
+	pub fn offset(&self, distance: f64) -> String {
+		let offset_subpath = self.0.offset(distance, bezier_rs::Joint::Bevel);
+
+		let mut offset_svg = String::new();
+		offset_subpath.to_svg(&mut offset_svg, CURVE_ATTRIBUTES.to_string().replace(BLACK, RED), String::new(), String::new(), String::new());
+
+		wrap_svg_tag(format!("{}{offset_svg}", self.to_default_svg()))
+	}
+
+	pub fn outline(&self, distance: f64) -> String {
+		let (outline_piece1, outline_piece2) = self.0.outline(distance, bezier_rs::Joint::Bevel);
+
+		let mut outline_piece1_svg = String::new();
+		outline_piece1.to_svg(&mut outline_piece1_svg, CURVE_ATTRIBUTES.to_string().replace(BLACK, RED), String::new(), String::new(), String::new());
+
+		let mut outline_piece2_svg = String::new();
+		if outline_piece2.is_some() {
+			outline_piece2
+				.unwrap()
+				.to_svg(&mut outline_piece2_svg, CURVE_ATTRIBUTES.to_string().replace(BLACK, RED), String::new(), String::new(), String::new());
+		}
+
+		wrap_svg_tag(format!("{}{outline_piece1_svg}{outline_piece2_svg}", self.to_default_svg()))
+	}
 }