From f20d78a21a151ee8e93ac1f4ff331a407b9a5950 Mon Sep 17 00:00:00 2001
From: Chris Lilley <chris@w3.org>
Date: Mon, 18 Dec 2023 09:41:19 -0500
Subject: [PATCH] [spaces/hsl] Better handling of negative saturation on very
 oog colors

---
 src/spaces/hsl.js | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/spaces/hsl.js b/src/spaces/hsl.js
index afbb22043..091819a45 100644
--- a/src/spaces/hsl.js
+++ b/src/spaces/hsl.js
@@ -22,7 +22,7 @@ export default new ColorSpace({
 
 	base: sRGB,
 
-	// Adapted from https://en.wikipedia.org/wiki/HSL_and_HSV#From_RGB
+	// Adapted from https://drafts.csswg.org/css-color-4/better-rgbToHsl.js
 	fromBase: rgb => {
 		let max = Math.max(...rgb);
 		let min = Math.min(...rgb);
@@ -42,6 +42,18 @@ export default new ColorSpace({
 			h = h * 60;
 		}
 
+	// Very out of gamut colors can produce negative saturation
+    // If so, just rotate the hue by 180 and use a positive saturation
+    // see https://github.com/w3c/csswg-drafts/issues/9222
+    if (s < 0) {
+        h += 180;
+        s = Math.abs(s);
+    }
+
+    if (h >= 360) {
+        h -= 360;
+    }
+
 		return [h, s * 100, l * 100];
 	},