Allow coord grammar to be specified for the color syntax

Some non CSS level 4 color spaces need coordinate grammars that go beyond what is currently allowed for the color() syntax. For example the luv colorspace requires <percentage>[-1, 1] to be specified for its u and v coordinates. Other color spaces such as hsluv, hpluv, okhsl, okhsv have coordinates that are angles.
color-js · Nov 28, 2023 · 65c7c5d · 65c7c5d
1 parent 9124e50
commit 65c7c5d
Showing 1 changed file with 58 additions and 37 deletions.
diff --git a/src/parse.js b/src/parse.js
@@ -4,6 +4,56 @@ import ColorSpace from "./space.js";
 
 const noneTypes = new Set(["<number>", "<percentage>", "<angle>"]);
 
+/**
+ * Validates the coordinates of a color against a format's coord grammar and
+ * maps the coordinates to the range or refRange of the coordinates.
+ * @param {ColorSpace} space - Colorspace the coords are in
+ * @param {object} format - the format object to validate against
+ * @param {string} name - the name of the color function. e.g. "oklab" or "color"
+ * @returns {object[]} - an array of type metadata for each coordinate
+ */
+function coerceCoords (space, format, name, coords) {
+	let types = Object.entries(space.coords).map(([id, coordMeta], i) => {
+		let coordGrammar = format.coordGrammar[i];
+		let arg = coords[i];
+		let providedType = arg?.type;
+
+		// Find grammar alternative that matches the provided type
+		// Non-strict equals is intentional because we are comparing w/ string objects
+		let type;
+		if (arg.none) {
+			type = coordGrammar.find(c => noneTypes.has(c));
+		}
+		else {
+			type = coordGrammar.find(c => c == providedType);
+		}
+
+		// Check that each coord conforms to its grammar
+		if (!type) {
+			// Type does not exist in the grammar, throw
+			let coordName = coordMeta.name || id;
+			throw new TypeError(`${providedType ?? arg.raw} not allowed for ${coordName} in ${name}()`);
+		}
+
+		let fromRange = type.range;
+
+		if (providedType === "<percentage>") {
+			fromRange ||= [0, 1];
+		}
+
+		let toRange = coordMeta.range || coordMeta.refRange;
+
+		if (fromRange && toRange) {
+			coords[i] = util.mapRange(fromRange, toRange, coords[i]);
+		}
+
+		return type;
+	});
+
+	return types;
+}
+
+
 /**
  * Convert a CSS Color string to a color object
  * @param {string} str
@@ -40,8 +90,14 @@ export default function parse (str, {meta} = {}) {
 						// If less <number>s or <percentage>s are provided than parameters that the colorspace takes, the missing parameters default to 0. (This is particularly convenient for multichannel printers where the additional inks are spot colors or varnishes that most colors on the page won’t use.)
 						const coords = Object.keys(space.coords).map((_, i) => env.parsed.args[i] || 0);
 
+						let types;
+
+						if (colorSpec.coordGrammar) {
+							types = coerceCoords(space, colorSpec, "color", coords);
+						}
+
 						if (meta) {
-							meta.formatId = "color";
+							Object.assign(meta, {formatId: "color", types});
 						}
 
 						return {spaceId: space.id, coords, alpha};
@@ -78,42 +134,7 @@ export default function parse (str, {meta} = {}) {
 					let types;
 
 					if (format.coordGrammar) {
-						types = Object.entries(space.coords).map(([id, coordMeta], i) => {
-							let coordGrammar = format.coordGrammar[i];
-							let arg = coords[i];
-							let providedType = arg?.type;
-
-							// Find grammar alternative that matches the provided type
-							// Non-strict equals is intentional because we are comparing w/ string objects
-							let type;
-							if (arg.none) {
-								type = coordGrammar.find(c => noneTypes.has(c));
-							}
-							else {
-								type = coordGrammar.find(c => c == providedType);
-							}
-
-							// Check that each coord conforms to its grammar
-							if (!type) {
-								// Type does not exist in the grammar, throw
-								let coordName = coordMeta.name || id;
-								throw new TypeError(`${providedType ?? arg.raw} not allowed for ${coordName} in ${name}()`);
-							}
-
-							let fromRange = type.range;
-
-							if (providedType === "<percentage>") {
-								fromRange ||= [0, 1];
-							}
-
-							let toRange = coordMeta.range || coordMeta.refRange;
-
-							if (fromRange && toRange) {
-								coords[i] = util.mapRange(fromRange, toRange, coords[i]);
-							}
-
-							return type;
-						});
+						types = coerceCoords(space, format, name, coords);
 					}
 
 					if (meta) {