Allow serialize() to use formats from other color spaces, closes #246

Author: LeaVerou

src/Format.js

@@ -88,7 +88,7 @@ export default class Format {
 	}
 
 	static get (format, ...args) {
-		if (format instanceof Format) {
+		if (!format || format instanceof Format) {
 			return format;
 		}
 

src/serialize.js

@@ -2,6 +2,7 @@ import * as util from "./util.js";
 import ColorSpace from "./space.js";
 import defaults from "./defaults.js";
 import getColor from "./getColor.js";
+import to from "./to.js";
 import checkInGamut from "./inGamut.js";
 import toGamut from "./toGamut.js";
 import clone from "./clone.js";
@@ -29,9 +30,16 @@ export default function serialize (color, options = {}) {
 
 	let formatId = format;
 	format = color.space.getFormat(format)
+	       ?? ColorSpace.findFormat(format)
 	       ?? color.space.getFormat("default")
 	       ?? ColorSpace.DEFAULT_FORMAT;
 
+	if (format.space && format.space !== color.space) {
+		// Format specified belongs to a different color space,
+		// need to convert to it first
+		color = to(color, format.space);
+	}
+
 	// The assignment to coords and inGamut needs to stay in the order they are now
 	// The order of the assignment was changed as a workaround for a bug in Next.js
 	// See this issue for details: https://github.com/color-js/color.js/issues/260

test/serialize.js

@@ -84,7 +84,12 @@ const tests = {
 				{
 					name: "Hex on non-sRGB color",
 					args: ["hsl", [0, 100, 50], 1, {format: "hex"}],
-					expect: "#ff0000",
+					expect: "#f00",
+				},
+				{
+					name: "Cannot serialize as keyword",
+					args: ["srgb", [1, 0.5, 0], 1, {format: "keyword"}],
+					throws: true,
 				},
 			],
 		},