Bezier-rs: Add SubpathTValue and euclidean parameterization for subpaths (#1027)

* Added SubpathTValue and euclidean parameterization for subpaths

* Small fix

* Added bounds checking to get_segment

* Code review

* code review nit for clarity

---------

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

libraries/bezier-rs/src/subpath/structs.rs

@@ -1,3 +1,5 @@
+use super::Bezier;
+
 use glam::DVec2;
 use std::fmt::{Debug, Formatter, Result};
 
@@ -22,3 +24,18 @@ impl Debug for ManipulatorGroup {
 		}
 	}
 }
+
+impl ManipulatorGroup {
+	pub fn to_bezier(&self, end_group: &ManipulatorGroup) -> Bezier {
+		let start = self.anchor;
+		let end = end_group.anchor;
+		let out_handle = self.out_handle;
+		let in_handle = end_group.in_handle;
+
+		match (out_handle, in_handle) {
+			(Some(handle1), Some(handle2)) => Bezier::from_cubic_dvec2(start, handle1, handle2, end),
+			(Some(handle), None) | (None, Some(handle)) => Bezier::from_quadratic_dvec2(start, handle, end),
+			(None, None) => Bezier::from_linear_dvec2(start, end),
+		}
+	}
+}