Use gamma 2.40 for display-referred rec2020

CHANGELOG.md

@@ -1,3 +1,10 @@
+## 1.98.0
+
+* **Potentially breaking CSS compatibility fix:** In keeping with the latest CSS
+  specification, this release changes the algorithm for converting colors to and
+  from the `rec2020` color space. This now uses the EOTF algorithm with a gamma
+  of 2.4.
+
 ## 1.97.3
 
 * Fix a bug where nesting an at-rule within multiple style rules in plain CSS

lib/src/value/color/space/rec2020.dart

@@ -11,12 +11,6 @@ import '../conversions.dart';
 import '../space.dart';
 import 'utils.dart';
 
-/// A constant used in the rec2020 gamma encoding/decoding functions.
-const _alpha = 1.09929682680944;
-
-/// A constant used in the rec2020 gamma encoding/decoding functions.
-const _beta = 0.018053968510807;
-
 /// The rec2020 color space.
 ///
 /// https://www.w3.org/TR/css-color-4/#predefined-rec2020
@@ -29,22 +23,14 @@ final class Rec2020ColorSpace extends ColorSpace {
   const Rec2020ColorSpace() : super('rec2020', rgbChannels);
 
   @protected
-  double toLinear(double channel) {
-    // Algorithm from https://www.w3.org/TR/css-color-4/#color-conversion-code
-    var abs = channel.abs();
-    return abs < _beta * 4.5
-        ? channel / 4.5
-        : channel.sign * (math.pow((abs + _alpha - 1) / _alpha, 1 / 0.45));
-  }
+  double toLinear(double channel) =>
+      // Algorithm from https://drafts.csswg.org/css-color-4/#color-conversion-code
+      channel.sign * math.pow(channel.abs(), 2.4);
 
   @protected
-  double fromLinear(double channel) {
-    // Algorithm from https://www.w3.org/TR/css-color-4/#color-conversion-code
-    var abs = channel.abs();
-    return abs > _beta
-        ? channel.sign * (_alpha * math.pow(abs, 0.45) - (_alpha - 1))
-        : 4.5 * channel;
-  }
+  double fromLinear(double channel) =>
+      // Algorithm from https://drafts.csswg.org/css-color-4/#color-conversion-code
+      channel.sign * math.pow(channel.abs(), 1 / 2.4);
 
   @protected
   Float64List transformationMatrix(ColorSpace dest) => switch (dest) {

pkg/sass-parser/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.43
+
+* No user-visible changes.
+
 ## 0.4.42
 
 * No user-visible changes.

pkg/sass-parser/package.json

@@ -1,6 +1,6 @@
 {
   "name": "sass-parser",
-  "version": "0.4.42",
+  "version": "0.4.43",
   "description": "A PostCSS-compatible wrapper of the official Sass parser",
   "repository": "sass/dart-sass",
   "author": "Google Inc.",

pkg/sass_api/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 17.4.0
+
+* No user-visible changes.
+
 ## 17.3.3
 
 * No user-visible changes.

pkg/sass_api/pubspec.yaml

@@ -2,15 +2,15 @@ name: sass_api
 # Note: Every time we add a new Sass AST node, we need to bump the *major*
 # version because it's a breaking change for anyone who's implementing the
 # visitor interface(s).
-version: 17.3.3
+version: 17.4.0
 description: Additional APIs for Dart Sass.
 homepage: https://github.com/sass/dart-sass
 
 environment:
   sdk: ">=3.6.0 <4.0.0"
 
 dependencies:
-  sass: 1.97.3
+  sass: 1.98.0
 
 dev_dependencies:
   dartdoc: ">=8.0.14 <10.0.0"

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.97.3
+version: 1.98.0
 description: A Sass implementation in Dart.
 homepage: https://github.com/sass/dart-sass