Added distance

- Also added `CIVector` default conformance to `DualTwoDimensional`
- Also added `magnitude` to `DualTwoDimensional`s where the `Length`s match and the distance can be determined. This was done for `CIVector` as sugar for its `.distance` between its two points
- Improved description of how `Rectangle`'s `DualTwoDimensional` conformance needs both `Length`s to be the same. Thankfully didn't need to remove the `associatedtype Length`
- Added an "Easy To Adopt" section to the README, inspired by this new `.distance` API

README.md

@@ -8,6 +8,15 @@ Who knew there was so much to be done with rectangles?
 
 
 
+## Easy To Adopt
+
+This library aims to never get in your way. Minimal arbitrary decisions, maximum flexibility.
+
+For example, other frameworks might say that they help you find the distance from any `CGPoint` to another, but doesn't provide that functionality to any other type. 
+This one doesn't care what types the two are, as long as thier `x` and `y` coordinates use the same type. That means if you want to measure the distance from some `CGPoint` to some custom 2D point-like structure which also uses `CGFlaot`s, this will happily let you do that with no fuss.
+
+
+
 ## Thoroughly Tested ##
 
 Over 2,000 test assertions prove that this library works as it says it does

Sources/RectangleTools/Basic Protocols/Rectangle.swift

@@ -13,7 +13,10 @@ import Foundation
 // MARK: - Rectangle
 
 /// A two-dimensional rectangle
-public protocol Rectangle: DualTwoDimensional, CartesianMeasurable {
+public protocol Rectangle: DualTwoDimensional, CartesianMeasurable
+where FirstDimensionPair.Length == SecondDimensionPair.Length,
+      FirstDimensionPair.Length == Self.Length
+{
 
     /// The unit in which the origin and size are defined
     associatedtype Length

Sources/RectangleTools/Default Conformances/CIVector + DualTwoDimensional.swift

@@ -0,0 +1,40 @@
+//
+//  CIVector + DualTwoDimensional.swift
+//
+//
+//  Created by The Northstar✨ System on 2023-11-16.
+//
+
+import CoreImage
+
+
+
+extension CIVector: DualTwoDimensional {
+
+    public var firstDimensionPair: FirstDimensionPair {
+        .init(x: x, y: y)
+    }
+
+
+    public var secondDimensionPair: SecondDimensionPair {
+        .init(x: z, y: w)
+    }
+
+
+
+    public typealias FirstDimensionPair = CGPoint
+    public typealias SecondDimensionPair = CGPoint
+}
+
+
+
+public extension DualTwoDimensional where Self: CIVector {
+
+    init(firstDimensionPair: FirstDimensionPair,
+         secondDimensionPair: SecondDimensionPair) {
+        self.init(x: firstDimensionPair.x,
+                  y: firstDimensionPair.y,
+                  z: secondDimensionPair.x,
+                  w: secondDimensionPair.y)
+    }
+}

Sources/RectangleTools/Synthesized Conveniences/DualTwoDimensional Extensions.swift

@@ -8,6 +8,8 @@
 
 import Foundation
 
+import MultiplicativeArithmetic
+
 
 
 public extension DualTwoDimensional
@@ -179,3 +181,29 @@ public extension DualTwoDimensional
     @inlinable
     static var one: Self { self.init(firstDimensionPair: .one, secondDimensionPair: .one) }
 }
+
+
+
+public extension DualTwoDimensional
+where FirstDimensionPair.Length == SecondDimensionPair.Length
+{
+    typealias Length = FirstDimensionPair.Length
+}
+
+
+
+// MARK: - Math!
+
+public extension DualTwoDimensional
+where FirstDimensionPair: Point2D,
+      SecondDimensionPair: Point2D,
+      FirstDimensionPair.Length == SecondDimensionPair.Length,
+      Length: MultiplicativeArithmetic,
+      Length: AdditiveArithmetic,
+      Length: ExpressibleByIntegerLiteral
+{
+    /// The magnitude of a vector is the distance from its anchor to its farthest indicated location
+    var magnitude: Length {
+        firstDimensionPair.distance(to: secondDimensionPair)
+    }
+}

Sources/RectangleTools/Synthesized Conveniences/Point2D Extensions.swift

@@ -8,6 +8,8 @@
 
 import Foundation
 
+import MultiplicativeArithmetic
+
 
 
 public extension Point2D {
@@ -19,3 +21,24 @@ public extension Point2D {
         self.init(x: other.x, y: other.y)
     }
 }
+
+
+
+public extension Point2D
+where Length: MultiplicativeArithmetic,
+      Length: AdditiveArithmetic,
+      Length: ExpressibleByIntegerLiteral
+{
+    /// Measures the distance from this point to another point
+    ///
+    /// - Parameter other: The remote point, to which you want to know the distance from this point
+    /// - Returns: An absolute distance to the other point (always greater than zero, not implying any direction)
+    func distance<Other: Point2D>(to other: Other) -> Length
+    where Other.Length == Self.Length
+    {
+        sqrt(
+            (other.x - x).pow(2)
+            + (other.y - y).pow(2)
+        )
+    }
+}

Tests/RectangleToolsTests/Point Tests.swift

@@ -0,0 +1,25 @@
+//
+//  Point Tests.swift
+//
+//
+//  Created by The Northstar✨ System on 2023-10-26.
+//
+
+import XCTest
+import RectangleTools
+
+
+
+final class Point_Tests: XCTestCase {
+
+    func testDistance() {
+        XCTAssertEqual(CGPoint(x: 0, y: 0).distance(to: CGPoint(x: 1, y: 1)), sqrt(2))
+        XCTAssertEqual(CGPoint(x: 0, y: 0).distance(to: CGPoint(x: -1, y: -1)), sqrt(2))
+    }
+
+
+    func testMagnitude() {
+        // https://www.wolframalpha.com/input?i=distance+from+%28-2%2C-1%29+to+%285%2C6%29
+        XCTAssertEqual(CIVector(x: -2, y: -1, z: 5, w: 6).magnitude, 7 * sqrt(2))
+    }
+}