commit ab91e25575a5d89d0e62693e9d9cc5622241fd5e
parent 26ad5eb1cb7a252335a50a18812391c70946e589
Author: Serban Stanca <sstanca@mozilla.com>
Date: Tue, 28 Oct 2025 16:13:36 +0200
Revert "Bug 1682439 - Add a basic WPT reftest for results of the contrast-color() function. r=firefox-style-system-reviewers,emilio" for causing mochitests failures in test_bug877690.html.
This reverts commit 69695ad2db5c218f4cc5b64ab22bc7553f1ecd15.
This reverts commit f4fa1425b081fd0fe8d11f4314cc409bf8d83ef9.
Diffstat:
8 files changed, 54 insertions(+), 232 deletions(-)
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
@@ -9969,13 +9969,6 @@
mirror: always
rust: true
-# Is support for the contrast-color() function enabled?
-- name: layout.css.contrast-color.enabled
- type: RelaxedAtomicBool
- value: true
- mirror: always
- rust: true
-
# Whether alt text in content is enabled.
- name: layout.css.content.alt-text.enabled
type: RelaxedAtomicBool
diff --git a/servo/components/style/values/computed/color.rs b/servo/components/style/values/computed/color.rs
@@ -34,11 +34,6 @@ impl ToCss for Color {
Self::ColorFunction(ref color_function) => color_function.to_css(dest),
Self::CurrentColor => dest.write_str("currentcolor"),
Self::ColorMix(ref m) => m.to_css(dest),
- Self::ContrastColor(ref c) => {
- dest.write_str("contrast-color(")?;
- c.to_css(dest)?;
- dest.write_char(')')
- },
}
}
}
@@ -86,42 +81,6 @@ impl Color {
mix.flags,
)
},
- Self::ContrastColor(ref c) => {
- let bg_color = c.resolve_to_absolute(current_color);
- if Self::contrast_ratio(&bg_color, &AbsoluteColor::BLACK)
- > Self::contrast_ratio(&bg_color, &AbsoluteColor::WHITE)
- {
- AbsoluteColor::BLACK
- } else {
- AbsoluteColor::WHITE
- }
- },
- }
- }
-
- fn contrast_ratio(a: &AbsoluteColor, b: &AbsoluteColor) -> f32 {
- // TODO: This just implements the WCAG 2.1 algorithm,
- // https://www.w3.org/TR/WCAG21/#dfn-contrast-ratio
- // Consider using a more sophisticated contrast algorithm, e.g. see
- // https://apcacontrast.com
- let compute = |c| -> f32 {
- if c <= 0.04045 {
- c / 12.92
- } else {
- f32::powf((c + 0.055) / 1.055, 2.4)
- }
- };
- let luminance = |r, g, b| -> f32 { 0.2126 * r + 0.7152 * g + 0.0722 * b };
- let a = a.into_srgb_legacy();
- let b = b.into_srgb_legacy();
- let a = a.raw_components();
- let b = b.raw_components();
- let la = luminance(compute(a[0]), compute(a[1]), compute(a[2])) + 0.05;
- let lb = luminance(compute(b[0]), compute(b[1]), compute(b[2])) + 0.05;
- if la > lb {
- la / lb
- } else {
- lb / la
}
}
}
diff --git a/servo/components/style/values/generics/color.rs b/servo/components/style/values/generics/color.rs
@@ -24,8 +24,6 @@ pub enum GenericColor<Percentage> {
CurrentColor,
/// The color-mix() function.
ColorMix(Box<GenericColorMix<Self, Percentage>>),
- /// The contrast-color() function.
- ContrastColor(Box<Self>),
}
/// Flags used to modify the calculation of a color mix result.
diff --git a/servo/components/style/values/specified/color.rs b/servo/components/style/values/specified/color.rs
@@ -125,8 +125,6 @@ pub enum Color {
ColorMix(Box<ColorMix>),
/// A light-dark() color.
LightDark(Box<GenericLightDark<Self>>),
- /// The contrast-color function.
- ContrastColor(Box<Color>),
/// Quirksmode-only rule for inheriting color from the body
#[cfg(feature = "gecko")]
InheritFromBodyQuirk,
@@ -457,17 +455,6 @@ impl Color {
return Ok(Color::LightDark(Box::new(ld)));
}
- if static_prefs::pref!("layout.css.contrast-color.enabled") {
- if let Ok(c) = input.try_parse(|i| {
- i.expect_function_matching("contrast-color")?;
- i.parse_nested_block(|i| {
- Self::parse_internal(context, i, preserve_authored)
- })
- }) {
- return Ok(Color::ContrastColor(Box::new(c)));
- }
- }
-
match e.kind {
ParseErrorKind::Basic(BasicParseErrorKind::UnexpectedToken(t)) => {
Err(e.location.new_custom_error(StyleParseErrorKind::ValueError(
@@ -542,11 +529,6 @@ impl ToCss for Color {
Color::ColorFunction(ref color_function) => color_function.to_css(dest),
Color::ColorMix(ref mix) => mix.to_css(dest),
Color::LightDark(ref ld) => ld.to_css(dest),
- Color::ContrastColor(ref c) => {
- dest.write_str("contrast-color(")?;
- c.to_css(dest)?;
- dest.write_char(')')
- },
#[cfg(feature = "gecko")]
Color::System(system) => system.to_css(dest),
#[cfg(feature = "gecko")]
@@ -581,7 +563,6 @@ impl Color {
mix.left.honored_in_forced_colors_mode(allow_transparent)
&& mix.right.honored_in_forced_colors_mode(allow_transparent)
},
- Self::ContrastColor(ref c) => c.honored_in_forced_colors_mode(allow_transparent),
}
}
@@ -787,9 +768,6 @@ impl Color {
flags: mix.flags,
})
},
- Color::ContrastColor(ref c) => {
- ComputedColor::ContrastColor(Box::new(c.to_computed_color(context)?))
- },
#[cfg(feature = "gecko")]
Color::System(system) => system.compute(context?),
#[cfg(feature = "gecko")]
@@ -825,9 +803,6 @@ impl ToComputedValue for Color {
ComputedColor::ColorMix(ref mix) => {
Color::ColorMix(Box::new(ToComputedValue::from_computed_value(&**mix)))
},
- ComputedColor::ContrastColor(ref c) => {
- Self::ContrastColor(Box::new(ToComputedValue::from_computed_value(&**c)))
- },
}
}
}
@@ -855,7 +830,6 @@ impl SpecifiedValueInfo for Color {
"oklab",
"oklch",
"color-mix",
- "contrast-color",
"light-dark",
]);
}
diff --git a/testing/web-platform/meta/css/css-color/parsing/color-computed-contrast-color-function.html.ini b/testing/web-platform/meta/css/css-color/parsing/color-computed-contrast-color-function.html.ini
@@ -1,3 +1,30 @@
[color-computed-contrast-color-function.html]
+ [Property background-color value 'contrast-color(white)']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(black)']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(pink)']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(color(srgb 1 0 1 / 0.5))']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(lab(0.2 0.5 0.2))']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(color(srgb 10 10 10))']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(color(srgb -10 -10 -10))']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(contrast-color(pink))']
+ expected: FAIL
+
+ [Property background-color value 'contrast-color(currentcolor)']
+ expected: FAIL
+
[Property background-color value 'contrast-color(color(srgb calc(1 + (sign(20cqw - 10px) * 1)) calc(1 + (sign(20cqw - 10px) * 1)) calc(1 + (sign(20cqw - 10px) * 1))))']
expected: FAIL
diff --git a/testing/web-platform/meta/css/css-color/parsing/color-valid-contrast-color-function.html.ini b/testing/web-platform/meta/css/css-color/parsing/color-valid-contrast-color-function.html.ini
@@ -1,3 +1,30 @@
[color-valid-contrast-color-function.html]
+ [e.style['background-color'\] = "contrast-color(white)" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(black)" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(pink)" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(color(srgb 1 0 1 / 0.5))" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(lab(0.2 0.5 0.2))" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(color(srgb 10 10 10))" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(color(srgb -10 -10 -10))" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(contrast-color(pink))" should set the property value]
+ expected: FAIL
+
+ [e.style['background-color'\] = "contrast-color(currentcolor)" should set the property value]
+ expected: FAIL
+
[e.style['background-color'\] = "contrast-color(color(srgb calc(0.5) calc(1 + (sign(20cqw - 10px) * 0.5)) 1 / .5))" should set the property value]
expected: FAIL
diff --git a/testing/web-platform/tests/css/css-color/contrast-color-001-ref.html b/testing/web-platform/tests/css/css-color/contrast-color-001-ref.html
@@ -1,70 +0,0 @@
-<!D<!DOCTYPE html>
-<meta charset="utf-8">
-
-<title>CSS Color 5 reference: contrast-color</title>
-
-<link rel="help" href="https://drafts.csswg.org/css-color-5/#contrast-color">
-<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
-
-<style>
-body {
- background: ivory;
- color: magenta;
-}
-p {
- font: bold 16px sans-serif;
- padding: .5em;
-}
-p.test1 {
- background: white;
- color: black;
-}
-p.test2 {
- background: aliceblue;
- color: black;
-}
-p.test3 {
- background: mistyrose;
- color: black;
-}
-p.test4 {
- background: lightyellow;
- color: black;
-}
-p.test5 {
- background: palegreen;
- color: black;
-}
-p.test6 {
- background: darkblue;
- color: white;
-}
-p.test7 {
- background: maroon;
- color: white;
-}
-p.test8 {
- background: purple;
- color: white;
-}
-p.test9 {
- background: brown;
- color: white;
-}
-p.test10 {
- background: black;
- color: white;
-}
-</style>
-
-<p class=test1>This text should be black</p>
-<p class=test2>This text should be black</p>
-<p class=test3>This text should be black</p>
-<p class=test4>This text should be black</p>
-<p class=test5>This text should be black</p>
-
-<p class=test6>This text should be white</p>
-<p class=test7>This text should be white</p>
-<p class=test8>This text should be white</p>
-<p class=test9>This text should be white</p>
-<p class=test10>This text should be white</p>
diff --git a/testing/web-platform/tests/css/css-color/contrast-color-001.html b/testing/web-platform/tests/css/css-color/contrast-color-001.html
@@ -1,86 +0,0 @@
-<!D<!DOCTYPE html>
-<meta charset="utf-8">
-
-<title>CSS Color 5: contrast-color</title>
-
-<link rel="help" href="https://drafts.csswg.org/css-color-5/#contrast-color">
-<link rel="author" title="Jonathan Kew" href="mailto:jkew@mozilla.com">
-
-<link rel="match" href="contrast-color-001-ref.html">
-
-<!--
-Although the spec says that
-
- "The precise color contrast algorithm for determining whether to output
- a light or dark color is UA-defined",
-
-it does require that
-
- "contrast-color() resolves to either white or black, whichever produces
- maximum color contrast..."
-
-so although the exact definition of "contrast" is unspecified, it is clear that
-for very light colors, it must resolve to black, and for very dark ones, it must
-resolve to white. It would only be for intermediate colors nearer the middle of
-the lightness range that the result may be UA-dependent.
-
-Here, we check that contrast-color() resolves to black for a selection of very
-light colors, and to white for some dark ones.
--->
-
-<style>
-body {
- background: ivory;
- color: magenta;
-}
-p {
- font: bold 16px sans-serif;
- padding: .5em;
- background: var(--bgcolor);
- color: contrast-color(var(--bgcolor));
-}
-/* light colors for which contrast-color() should be black: */
-p.test1 {
- --bgcolor: white;
-}
-p.test2 {
- --bgcolor: aliceblue;
-}
-p.test3 {
- --bgcolor: mistyrose;
-}
-p.test4 {
- --bgcolor: lightyellow;
-}
-p.test5 {
- --bgcolor: palegreen;
-}
-/* dark colors for which contrast-color() should be white: */
-p.test6 {
- --bgcolor: darkblue;
-}
-p.test7 {
- --bgcolor: maroon;
-}
-p.test8 {
- --bgcolor: purple;
-}
-p.test9 {
- --bgcolor: brown;
-}
-p.test10 {
- --bgcolor: black;
-}
-</style>
-
-<p class=test1>This text should be black</p>
-<p class=test2>This text should be black</p>
-<p class=test3>This text should be black</p>
-<p class=test4>This text should be black</p>
-<p class=test5>This text should be black</p>
-
-<p class=test6>This text should be white</p>
-<p class=test7>This text should be white</p>
-<p class=test8>This text should be white</p>
-<p class=test9>This text should be white</p>
-<p class=test10>This text should be white</p>
