Divide the large Bezier-rs implementation file into smaller ones (#751)

* Refactor bezier lib file into a separate folder

* Add better implementation comments

* Update import of Subpath from bezier-rs

* Add comment to describe compare.rs

* Remove printlns and adjust spacing

libraries/bezier-rs/src/bezier/manipulators.rs

@@ -0,0 +1,87 @@
+use super::*;
+
+/// Functionality for the getters and setters of the various points in a Bezier
+impl Bezier {
+	/// Set the coordinates of the start point.
+	pub fn set_start(&mut self, s: DVec2) {
+		self.start = s;
+	}
+
+	/// Set the coordinates of the end point.
+	pub fn set_end(&mut self, e: DVec2) {
+		self.end = e;
+	}
+
+	/// Set the coordinates of the first handle point. This represents the only handle in a quadratic segment. If used on a linear segment, it will be changed to a quadratic.
+	pub fn set_handle_start(&mut self, h1: DVec2) {
+		match self.handles {
+			BezierHandles::Linear => {
+				self.handles = BezierHandles::Quadratic { handle: h1 };
+			}
+			BezierHandles::Quadratic { ref mut handle } => {
+				*handle = h1;
+			}
+			BezierHandles::Cubic { ref mut handle_start, .. } => {
+				*handle_start = h1;
+			}
+		};
+	}
+
+	/// Set the coordinates of the second handle point. This will convert both linear and quadratic segments into cubic ones. For a linear segment, the first handle will be set to the start point.
+	pub fn set_handle_end(&mut self, h2: DVec2) {
+		match self.handles {
+			BezierHandles::Linear => {
+				self.handles = BezierHandles::Cubic {
+					handle_start: self.start,
+					handle_end: h2,
+				};
+			}
+			BezierHandles::Quadratic { handle } => {
+				self.handles = BezierHandles::Cubic { handle_start: handle, handle_end: h2 };
+			}
+			BezierHandles::Cubic { ref mut handle_end, .. } => {
+				*handle_end = h2;
+			}
+		};
+	}
+
+	/// Get the coordinates of the bezier segment's start point.
+	pub fn start(&self) -> DVec2 {
+		self.start
+	}
+
+	/// Get the coordinates of the bezier segment's end point.
+	pub fn end(&self) -> DVec2 {
+		self.end
+	}
+
+	/// Get the coordinates of the bezier segment's first handle point. This represents the only handle in a quadratic segment.
+	pub fn handle_start(&self) -> Option<DVec2> {
+		match self.handles {
+			BezierHandles::Linear => None,
+			BezierHandles::Quadratic { handle } => Some(handle),
+			BezierHandles::Cubic { handle_start, .. } => Some(handle_start),
+		}
+	}
+
+	/// Get the coordinates of the second handle point. This will return `None` for a quadratic segment.
+	pub fn handle_end(&self) -> Option<DVec2> {
+		match self.handles {
+			BezierHandles::Linear { .. } => None,
+			BezierHandles::Quadratic { .. } => None,
+			BezierHandles::Cubic { handle_end, .. } => Some(handle_end),
+		}
+	}
+
+	/// Get an iterator over the coordinates of all points in a vector.
+	/// - For a linear segment, the order of the points will be: `start`, `end`.
+	/// - For a quadratic segment, the order of the points will be: `start`, `handle`, `end`.
+	/// - For a cubic segment, the order of the points will be: `start`, `handle_start`, `handle_end`, `end`.
+	pub fn get_points(&self) -> impl Iterator<Item = DVec2> {
+		match self.handles {
+			BezierHandles::Linear => [self.start, self.end, DVec2::ZERO, DVec2::ZERO].into_iter().take(2),
+			BezierHandles::Quadratic { handle } => [self.start, handle, self.end, DVec2::ZERO].into_iter().take(3),
+			BezierHandles::Cubic { handle_start, handle_end } => [self.start, handle_start, handle_end, self.end].into_iter().take(4),
+		}
+	}
+}