finally, operators for CoreGraphics geometric constructs

CoreGraphics+Geometry.swift

/*
MIT License
Copyright (c) 2018 Julian Dunskus
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

// from https://gist.github.com/juliand665/e79a8dff63cff51aa69e753017cf4981

import CoreGraphics

protocol Vector2 {
	var x: CGFloat { get set }
	var y: CGFloat { get set }
	
	init(x: CGFloat, y: CGFloat)
	
	var asVector: CGVector { get }
	var asPoint: CGPoint { get }
	var asSize: CGSize { get }
	
	var length: CGFloat { get }
	var angle: CGFloat { get }
	
	var min: CGFloat { get }
	var max: CGFloat { get }
	
	func clamped(to length: CGFloat) -> Self
	
	func map(_ transform: (CGFloat) throws -> CGFloat) rethrows -> Self
	
	static var zero: Self { get }
	static var one: Self { get }
	
	static func += <V: Vector2>(lhs: inout Self, rhs: V)
	static func -= <V: Vector2>(lhs: inout Self, rhs: V)
	static func *= (vec: inout Self, scale: CGFloat)
	static func /= (vec: inout Self, scale: CGFloat)
	
	static prefix func - (vec: Self) -> Self
	
	static func + <V: Vector2>(lhs: Self, rhs: V) -> Self
	static func - <V: Vector2>(lhs: Self, rhs: V) -> Self
	static func * (vec: Self, scale: CGFloat) -> Self
	static func * (scale: CGFloat, vec: Self) -> Self
	static func * <V: Vector2>(lhs: Self, rhs: V) -> Self
	static func / (vec: Self, scale: CGFloat) -> Self
	static func / <V: Vector2>(lhs: Self, rhs: V) -> Self
}

extension Vector2 {
	static var zero: Self {
		return Self(x: 0, y: 0)
	}
	
	static var one: Self {
		return Self(x: 1, y: 1)
	}
	
	var asVector: CGVector {
		return CGVector(dx: x, dy: y)
	}
	
	var asPoint: CGPoint {
		return CGPoint(x: x, y: y)
	}
	
	var asSize: CGSize {
		return CGSize(width: x, height: y)
	}
	
	var length: CGFloat {
		return hypot(x, y)
	}
	
	var angle: CGFloat {
		return atan2(y, x)
	}
	
	var min: CGFloat {
		return Swift.min(x, y)
	}
	
	var max: CGFloat {
		return Swift.max(x, y)
	}
	
	func clamped(to length: CGFloat) -> Self {
		let len = self.length
		
		if len > length {
			return self * (length / len)
		}
		return self
	}
	
	func map(_ transform: (CGFloat) throws -> CGFloat) rethrows -> Self {
		return Self(x: try transform(x),
					y: try transform(y))
	}
	
	static func += <V: Vector2>(lhs: inout Self, rhs: V) {
		lhs.x += rhs.x
		lhs.y += rhs.y
	}
	
	static func -= <V: Vector2>(lhs: inout Self, rhs: V) {
		lhs.x -= rhs.x
		lhs.y -= rhs.y
	}
	
	static func *= (vec: inout Self, scale: CGFloat) {
		vec.x *= scale
		vec.y *= scale
	}
	
	static func /= (vec: inout Self, scale: CGFloat) {
		vec.x /= scale
		vec.y /= scale
	}
	
	static func + <V: Vector2>(lhs: Self, rhs: V) -> Self {
		return Self(x: lhs.x + rhs.x,
					y: lhs.y + rhs.y)
	}
	
	static func - <V: Vector2>(lhs: Self, rhs: V) -> Self {
		return Self(x: lhs.x - rhs.x,
					y: lhs.y - rhs.y)
	}
	
	static func * (vec: Self, scale: CGFloat) -> Self {
		return Self(x: vec.x * scale,
					y: vec.y * scale)
	}
	
	static func * (scale: CGFloat, vec: Self) -> Self {
		return Self(x: vec.x * scale,
					y: vec.y * scale)
	}
	
	static func * <V: Vector2>(lhs: Self, rhs: V) -> Self {
		return Self(x: lhs.x * rhs.x,
					y: lhs.y * rhs.y)
	}
	
	static func / (vec: Self, scale: CGFloat) -> Self {
		return Self(x: vec.x / scale,
					y: vec.y / scale)
	}
	
	static prefix func - (vec: Self) -> Self {
		return Self(x: -vec.x,
					y: -vec.y)
	}
	
	static func / <V: Vector2>(lhs: Self, rhs: V) -> Self {
		return Self(x: lhs.x / rhs.x,
					y: lhs.y / rhs.y)
	}
}

extension CGPoint: Vector2 {}

extension CGVector: Vector2 {
	var x: CGFloat {
		get { return dx }
		set { dx = newValue }
	}
	
	var y: CGFloat {
		get { return dy }
		set { dy = newValue }
	}
	
	init(x: CGFloat, y: CGFloat) {
		self.init(dx: x, dy: y)
	}
}

extension CGSize: Vector2 {
	var x: CGFloat {
		get { return width }
		set { width = newValue }
	}
	
	var y: CGFloat {
		get { return height }
		set { height = newValue }
	}
	
	init(x: CGFloat, y: CGFloat) {
		self.init(width: x, height: y)
	}
}

extension CGRect {
	static func * <V: Vector2>(rect: CGRect, scale: V) -> CGRect {
		return CGRect(origin: rect.origin * scale, size: rect.size * scale)
	}
	
	static func * <V: Vector2>(scale: V, rect: CGRect) -> CGRect {
		return CGRect(origin: rect.origin * scale, size: rect.size * scale)
	}
	
	static func / <V: Vector2>(rect: CGRect, scale: V) -> CGRect {
		return CGRect(origin: rect.origin / scale, size: rect.size / scale)
	}
	
	static func / <V: Vector2>(scale: V, rect: CGRect) -> CGRect {
		return CGRect(origin: rect.origin / scale, size: rect.size / scale)
	}
}