From 4a665f56b1e11e764124ccfb56712ce343037496 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Wed, 4 Sep 2024 20:35:55 +0000
Subject: [PATCH] Bug 1914735 - Track color-scheme dependencies for
 non-inherited rule cache. r=firefox-style-system-reviewers,boris

Differential Revision: https://phabricator.services.mozilla.com/D220134
---
 servo/components/style/rule_cache.rs          | 16 ++++++++++++++
 .../style/values/specified/color.rs           |  9 +++++++-
 .../color-scheme-rule-cache-ref.html          | 22 +++++++++++++++++++
 .../color-scheme-rule-cache.html              | 21 ++++++++++++++++++
 4 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache-ref.html
 create mode 100644 testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache.html

diff --git a/servo/components/style/rule_cache.rs b/servo/components/style/rule_cache.rs
index 70c5b797312d..54a150ed2025 100644
--- a/servo/components/style/rule_cache.rs
+++ b/servo/components/style/rule_cache.rs
@@ -11,6 +11,7 @@ use crate::rule_tree::StrongRuleNode;
 use crate::selector_parser::PseudoElement;
 use crate::shared_lock::StylesheetGuards;
 use crate::values::computed::{NonNegativeLength, Zoom};
+use crate::values::specified::color::ColorSchemeFlags;
 use fxhash::FxHashMap;
 use servo_arc::Arc;
 use smallvec::SmallVec;
@@ -22,6 +23,7 @@ pub struct RuleCacheConditions {
     font_size: Option<NonNegativeLength>,
     line_height: Option<NonNegativeLength>,
     writing_mode: Option<WritingMode>,
+    color_scheme: Option<ColorSchemeFlags>,
 }
 
 impl RuleCacheConditions {
@@ -37,6 +39,12 @@ impl RuleCacheConditions {
         self.line_height = Some(line_height);
     }
 
+    /// Sets the style as depending in the color-scheme property value.
+    pub fn set_color_scheme_dependency(&mut self, color_scheme: ColorSchemeFlags) {
+        debug_assert!(self.color_scheme.map_or(true, |cs| cs == color_scheme));
+        self.color_scheme = Some(color_scheme);
+    }
+
     /// Sets the style as uncacheable.
     pub fn set_uncacheable(&mut self) {
         self.uncacheable = true;
@@ -58,6 +66,7 @@ impl RuleCacheConditions {
 struct CachedConditions {
     font_size: Option<NonNegativeLength>,
     line_height: Option<NonNegativeLength>,
+    color_scheme: Option<ColorSchemeFlags>,
     writing_mode: Option<WritingMode>,
     zoom: Zoom,
 }
@@ -85,6 +94,12 @@ impl CachedConditions {
             }
         }
 
+        if let Some(cs) = self.color_scheme {
+            if style.get_inherited_ui().clone_color_scheme().bits != cs {
+                return false;
+            }
+        }
+
         if let Some(wm) = self.writing_mode {
             if style.writing_mode != wm {
                 return false;
@@ -208,6 +223,7 @@ impl RuleCache {
             writing_mode: conditions.writing_mode,
             font_size: conditions.font_size,
             line_height: conditions.line_height,
+            color_scheme: conditions.color_scheme,
             zoom: style.effective_zoom,
         };
         self.map
diff --git a/servo/components/style/values/specified/color.rs b/servo/components/style/values/specified/color.rs
index 850961950d0f..bdb6aecac8a0 100644
--- a/servo/components/style/values/specified/color.rs
+++ b/servo/components/style/values/specified/color.rs
@@ -141,6 +141,9 @@ impl LightDark {
     fn compute(&self, cx: &Context) -> ComputedColor {
         let style_color_scheme = cx.style().get_inherited_ui().clone_color_scheme();
         let dark = cx.device().is_dark_color_scheme(&style_color_scheme);
+        if cx.for_non_inherited_property {
+            cx.rule_cache_conditions.borrow_mut().set_color_scheme_dependency(style_color_scheme.bits);
+        }
         let used = if dark { &self.dark } else { &self.light };
         used.to_computed_value(cx)
     }
@@ -421,6 +424,9 @@ impl SystemColor {
         // TODO: We should avoid cloning here most likely, though it's cheap-ish.
         let style_color_scheme = cx.style().get_inherited_ui().clone_color_scheme();
         let color = cx.device().system_nscolor(*self, &style_color_scheme);
+        if cx.for_non_inherited_property {
+            cx.rule_cache_conditions.borrow_mut().set_color_scheme_dependency(style_color_scheme.bits);
+        }
         if color == bindings::NS_SAME_AS_FOREGROUND_COLOR {
             return ComputedColor::currentcolor();
         }
@@ -930,7 +936,8 @@ bitflags! {
 pub struct ColorScheme {
     #[ignore_malloc_size_of = "Arc"]
     idents: crate::ArcSlice<CustomIdent>,
-    bits: ColorSchemeFlags,
+    /// The computed bits for the known color schemes (plus the only keyword).
+    pub bits: ColorSchemeFlags,
 }
 
 impl ColorScheme {
diff --git a/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache-ref.html b/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache-ref.html
new file mode 100644
index 000000000000..67eaec0f190d
--- /dev/null
+++ b/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache-ref.html
@@ -0,0 +1,22 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>CSS Test Reference</title>
+<style>
+.dark {
+  color-scheme: dark;
+  background-color: Canvas;
+  color: CanvasText;
+  border: 2px solid purple;
+}
+.light {
+  background-color: white;
+  color: black;
+  border: 2px solid blue;
+}
+</style>
+<div class="light">
+  Always light
+</div>
+<div class="dark">
+  Always dark
+</div>
diff --git a/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache.html b/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache.html
new file mode 100644
index 000000000000..c8835182fc87
--- /dev/null
+++ b/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/color-scheme-rule-cache.html
@@ -0,0 +1,21 @@
+<!doctype html>
+<meta charset="utf-8">
+<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1914735">
+<link rel="author" href="mailto:kizmarh@gmail.com" title="Roman Komarov">
+<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
+<link rel="author" href="https://mozilla.org" title="Mozilla">
+<link rel="match" href="color-scheme-rule-cache-ref.html">
+<title>Dependencies from color-scheme to non-inherited properties</title>
+<style>
+div {
+  background-color: Canvas;
+  color: CanvasText;
+  border: 2px solid light-dark(blue, purple);
+}
+</style>
+<div style="color-scheme: light">
+  Always light
+</div>
+<div style="color-scheme: dark">
+  Always dark
+</div>