style: Make Canvas/CanvasText and Link colors color-scheme-aware

For that, add `.dark` version of the browser.display* prefs that control the light version of these colors. The default for background/foreground colors are taken from the GenericDarkColors used in LookAndFeel. The defaults for links are based on this discussion: whatwg/html#5426 (comment) (So they effectively match Chrome). Whether the dark colors should be exposed in about:preferences (like the light colors are) is TBD. With this patch, we pass all the tests in: /html/semantics/document-metadata/the-meta-element/color-scheme/ Use the colors to paint the default canvas background and the default colors. There are three "regressions", though they are really progressions: we now render the reference as the test expects (before we rendered a light canvas background even for the reference). Apart of these iframe tests (which we should look into, I filed https://bugzilla.mozilla.org/show_bug.cgi?id=1738380), there are three remaining test failures. Two of them are due to `color: initial` not changing based on the color-scheme. Safari also fails these tests, and the thing they're really testing is whether system colors are preserved at computed-value time: w3c/csswg-drafts#3847 Regarding that change, I'm not so sure the trade-offs there are worth it, as that not only complicates interpolation (we wouldn't be able to use system colors in color-mix among others, see w3c/csswg-drafts#5780) plus it changes inheritance behavior in sorta unexpected ways, see: w3c/csswg-drafts#6773 Which I just filed because apparently no browser implements this correctly. So for now will punt on those (keep matching Safari). There's an svg-as-image test: https://searchfox.org/mozilla-central/rev/f8576fec48d866c5f988baaf1fa8d2f8cce2a82f/testing/web-platform/tests/css/css-color-adjust/rendering/dark-color-scheme/svg-as-image.html Which isn't using the feature at all and I'm not sure why is it supposed to pass (why prefers-color-scheme: dark is supposed to match that SVG image). This test fails in all browsers apparently: https://wpt.fyi/results/css/css-color-adjust/rendering/dark-color-scheme/svg-as-image.html?label=master&label=experimental&aligned I sent web-platform-tests/wpt#31407 to remove it and hopefully get it reviewed by some Chromium folks. Differential Revision: https://phabricator.services.mozilla.com/D129746
Loirooriol · May 30, 2023 · f70b0e7 · f70b0e7
1 parent c332293
commit f70b0e7
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Showing 3 changed files with 15 additions and 7 deletions.
diff --git a/components/style/gecko/media_queries.rs b/components/style/gecko/media_queries.rs
@@ -93,7 +93,9 @@ impl Device {
             document,
             default_values: ComputedValues::default_values(doc),
             root_font_size: AtomicU32::new(FONT_MEDIUM_PX.to_bits()),
-            body_text_color: AtomicUsize::new(prefs.mColors.mDefault as usize),
+            // This gets updated when we see the <body>, so it doesn't really
+            // matter which color-scheme we look at here.
+            body_text_color: AtomicUsize::new(prefs.mLightColors.mDefault as usize),
             used_root_font_size: AtomicBool::new(false),
             used_font_metrics: AtomicBool::new(false),
             used_viewport_size: AtomicBool::new(false),
@@ -386,13 +388,18 @@ impl Device {
     }
 
     /// Returns the default background color.
-    pub fn default_background_color(&self) -> RGBA {
-        convert_nscolor_to_rgba(self.pref_sheet_prefs().mColors.mDefaultBackground)
+    ///
+    /// This is only for forced-colors/high-contrast, so looking at light colors
+    /// is ok.
+    pub fn default_background_color_for_forced_colors(&self) -> RGBA {
+        convert_nscolor_to_rgba(self.pref_sheet_prefs().mLightColors.mDefaultBackground)
     }
 
     /// Returns the default foreground color.
-    pub fn default_color(&self) -> RGBA {
-        convert_nscolor_to_rgba(self.pref_sheet_prefs().mColors.mDefault)
+    ///
+    /// See above for looking at light colors only.
+    pub fn default_color_for_forced_colors(&self) -> RGBA {
+        convert_nscolor_to_rgba(self.pref_sheet_prefs().mLightColors.mDefault)
     }
 
     /// Returns the current effective text zoom.

diff --git a/components/style/properties/cascade.rs b/components/style/properties/cascade.rs
@@ -430,7 +430,7 @@ fn tweak_when_ignoring_colors(
             // widget background color's rgb channels but not alpha...
             let alpha = alpha_channel(color, context);
             if alpha != 0 {
-                let mut color = context.builder.device.default_background_color();
+                let mut color = context.builder.device.default_background_color_for_forced_colors();
                 color.alpha = alpha;
                 declarations_to_apply_unless_overriden
                     .push(PropertyDeclaration::BackgroundColor(color.into()))
@@ -448,7 +448,7 @@ fn tweak_when_ignoring_colors(
             // override this with a non-transparent color, then override it with
             // the default color. Otherwise just let it inherit through.
             if context.builder.get_parent_inherited_text().clone_color().alpha == 0 {
-                let color = context.builder.device.default_color();
+                let color = context.builder.device.default_color_for_forced_colors();
                 declarations_to_apply_unless_overriden.push(PropertyDeclaration::Color(
                     specified::ColorPropertyValue(color.into()),
                 ))

diff --git a/components/style/properties/longhands/inherited_ui.mako.rs b/components/style/properties/longhands/inherited_ui.mako.rs
@@ -104,6 +104,7 @@ ${helpers.predefined_type(
     gecko_pref="layout.css.color-scheme.enabled",
     animation_value_type="discrete",
     has_effect_on_gecko_scrollbars=False,
+    ignored_when_colors_disabled=True,
     enabled_in="chrome",
 )}