Merge pull request #55 from regexident/grayscaled-mode

Add support for grayscale modes

README.md

@@ -99,7 +99,14 @@ let desaturatedColor = originalColor.desaturated()
 // equivalent to
 // desaturatedColor = originalColor.desaturated(amount: 0.2)
 
+// equivalent to
+// let grayscaledColor = originalColor.grayscaled(mode: .luminance)
 let grayscaledColor = originalColor.grayscaled()
+
+let grayscaledColorLuminance = originalColor.grayscaled(mode: .luminance)
+let grayscaledColorLightness = originalColor.grayscaled(mode: .lightness)
+let grayscaledColorAverage = originalColor.grayscaled(mode: .average)
+let grayscaledColorValue = originalColor.grayscaled(mode: .value)
 ```
 
 #### Adjust-hue & Complement

Sources/DynamicColor+Deriving.swift

@@ -99,13 +99,25 @@ public extension DynamicColor {
   /**
    Creates and returns a color object converted to grayscale.
 
-   This is identical to desaturateColor(1).
-
    - returns: A grayscale DynamicColor.
-   - seealso: desaturateColor:
+   - seealso: desaturated:
    */
-  final func grayscaled() -> DynamicColor {
+  final func grayscaled(mode: GrayscalingMode = .lightness) -> DynamicColor {
-    return desaturated(amount: 1)
+    let (r, g, b, a) = self.toRGBAComponents()
+
+    let l: CGFloat
+    switch mode {
+    case .luminance:
+      l = (0.299 * r) + (0.587 * g) + (0.114 * b)
+    case .lightness:
+      l = 0.5 * (max(r, g, b) + min(r, g, b))
+    case .average:
+      l = (1.0 / 3.0) * (r + g + b)
+    case .value:
+      l = max(r, g, b)
+    }
+
+    return HSL(hue: 0.0, saturation: 0.0, lightness: l, alpha: a).toDynamicColor()
   }
 
   /**

Sources/Utils.swift

@@ -71,3 +71,19 @@ internal func roundToHex(_ x: CGFloat) -> UInt32 {
   
   return UInt32(rounded)
 }
+
+/**
+ Defines the mode (i.e color space) used for grayscaling.
+
+ [More info](https://en.wikipedia.org/wiki/Lightness#Lightness_and_human_perception)
+*/
+public enum GrayscalingMode {
+    /// XYZ luminance
+    case luminance
+    /// HSL lightness
+    case lightness
+    /// RGB average
+    case average
+    /// HSV value
+    case value
+}

Tests/DynamicColor+XCTAssertEqual.swift

@@ -0,0 +1,47 @@
+/*
+* DynamicColor
+*
+* Copyright 2015-present Yannick Loriot.
+* http://yannickloriot.com
+*
+* 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.
+*
+*/
+
+import XCTest
+@testable import DynamicColor
+
+func XCTAssertEqual(_ expression1: @autoclosure () throws -> DynamicColor, _ expression2: @autoclosure () throws -> DynamicColor, accuracy: CGFloat, _ message: @autoclosure () -> String = "", file: StaticString = #file, line: UInt = #line) {
+
+    let message = message()
+
+    do {
+        let (color1, color2) = (try expression1(), try expression2())
+
+        let (r1, g1, b1, a1) = color1.toRGBAComponents()
+        let (r2, g2, b2, a2) = color2.toRGBAComponents()
+
+        XCTAssertEqual(r1, r2, accuracy: accuracy, message, file: file, line: line)
+        XCTAssertEqual(g1, g2, accuracy: accuracy, message, file: file, line: line)
+        XCTAssertEqual(b1, b2, accuracy: accuracy, message, file: file, line: line)
+        XCTAssertEqual(a1, a2, accuracy: accuracy, message, file: file, line: line)
+    } catch let error {
+        XCTFail("\(error)", file: file, line: line)
+    }
+}

Tests/DynamicColorTests.swift

@@ -287,10 +287,26 @@ class DynamicColorTests: XCTestCase {
   }
 
   func testGrayscaleColor() {
-    let grayscale   = DynamicColor(hex: 0xc0392b).grayscaled()
+    let baseColor = DynamicColor(hex: 0xc0392b)
-    let desaturated = DynamicColor(hex: 0xc0392b).desaturated(amount: 1)
 
-    XCTAssert(grayscale.isEqual(desaturated), "Colors should be the same")
+    let grayscaleByLuminance = baseColor.grayscaled(mode: .luminance)
+    let expectedGrayscaleByLuminance = DynamicColor(white: 0.376, alpha: 1.0)
+    XCTAssertEqual(grayscaleByLuminance, expectedGrayscaleByLuminance, accuracy: 0.001, "Colors should be the same")
+
+    let grayscaleByLightness = baseColor.grayscaled(mode: .lightness)
+    let expectedGrayscaleByLightness = DynamicColor(white: 0.461, alpha: 1.0)
+    XCTAssertEqual(grayscaleByLightness, expectedGrayscaleByLightness, accuracy: 0.001, "Colors should be the same")
+
+    let grayscaleByAverage = baseColor.grayscaled(mode: .average)
+    let expectedGrayscaleByAverage = DynamicColor(white: 0.382, alpha: 1.0)
+    XCTAssertEqual(grayscaleByAverage, expectedGrayscaleByAverage, accuracy: 0.001, "Colors should be the same")
+
+    let grayscaleByValue = baseColor.grayscaled(mode: .value)
+    let expectedGrayscaleByValue = DynamicColor(white: 0.753, alpha: 1.0)
+    XCTAssertEqual(grayscaleByValue, expectedGrayscaleByValue, accuracy: 0.001, "Colors should be the same")
+
+    let grayscaleByDefault = baseColor.grayscaled()
+    XCTAssert(grayscaleByDefault.isEqual(grayscaleByLightness), "Colors should be the same")
   }
 
   func testInvertColor() {