Bézier-rs: Add utils to subpath (#1058)

* Add utils to bezier-rs subpath

* Apply code review changes

* Remove tan from constant

* Fix compile

* Fix tests

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

@@ -2,6 +2,8 @@ use super::*;
 use crate::utils::SubpathTValue;
 use crate::utils::TValue;
 
+use glam::DAffine2;
+
 /// Helper function to ensure the index and t value pair is mapped within a maximum index value.
 /// Allows for the point to be fetched without needing to handle an additional edge case.
 /// - Ex. Via `subpath.iter().nth(index).evaluate(t);`
@@ -263,6 +265,13 @@ impl<ManipulatorGroupId: crate::Identifier> Subpath<ManipulatorGroupId> {
 			closed: false,
 		}
 	}
+
+	/// Apply a transformation to all of the [ManipulatorGroup]s in the [Subpath].
+	pub fn apply_transform(&mut self, affine_transform: DAffine2) {
+		for manipulator_group in &mut self.manipulator_groups {
+			manipulator_group.apply_transform(affine_transform);
+		}
+	}
 }
 
 #[cfg(test)]
@@ -719,4 +728,10 @@ mod tests {
 		assert!(result.manipulator_groups[0].out_handle.is_none());
 		assert_eq!(result.manipulator_groups.len(), 1);
 	}
+
+	fn transform_subpath() {
+		let mut subpath = set_up_open_subpath();
+		subpath.apply_transform(glam::DAffine2::IDENTITY);
+		assert_eq!(subpath, set_up_open_subpath());
+	}
 }