Auto merge of #20191 - jfkthame:font-shorthand-resets-variation-settings, r=emilio

style: Make 'font' shorthand reset 'font-variation-settings' property

As required by the spec: https://drafts.csswg.org/css-fonts-4/#font-prop

See https://bugzilla.mozilla.org/show_bug.cgi?id=1435983

Basically, make font-variation-settings work in the same way as font-feature-settings
already does.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

- [ ] There are tests for these changes OR
- [X] These changes do not require tests because font-variation-settings isn't supported in servo; it is implemented here for gecko/stylo, and will be tested by mozilla-central mochitests.

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components/style/font_face.rs

@@ -26,7 +26,7 @@ use style_traits::{Comma, CssWriter, OneOrMoreSeparated, ParseError};
 use style_traits::{StyleParseErrorKind, ToCss};
 use values::computed::font::FamilyName;
 #[cfg(feature = "gecko")]
-use values::specified::font::{SpecifiedFontFeatureSettings, FontVariationSettings};
+use values::specified::font::{SpecifiedFontFeatureSettings, SpecifiedFontVariationSettings};
 use values::specified::url::SpecifiedUrl;
 
 /// A source for a font-face rule.
@@ -397,7 +397,7 @@ font_face_descriptors! {
         "font-feature-settings" feature_settings / mFontFeatureSettings: SpecifiedFontFeatureSettings,
 
         /// The variation settings of this font face.
-        "font-variation-settings" variation_settings / mFontVariationSettings: FontVariationSettings,
+        "font-variation-settings" variation_settings / mFontVariationSettings: SpecifiedFontVariationSettings,
 
         /// The language override of this font face.
         "font-language-override" language_override / mFontLanguageOverride: font_language_override::SpecifiedValue,

components/style/gecko/rules.rs

@@ -22,7 +22,7 @@ use std::str;
 use str::CssStringWriter;
 use values::computed::font::FamilyName;
 use values::generics::font::FontTag;
-use values::specified::font::{FontVariationSettings, SpecifiedFontFeatureSettings};
+use values::specified::font::{SpecifiedFontVariationSettings, SpecifiedFontFeatureSettings};
 
 /// A @font-face rule
 pub type FontFaceRule = RefPtr<nsCSSFontFaceRule>;
@@ -74,7 +74,7 @@ impl ToNsCssValue for SpecifiedFontFeatureSettings {
     }
 }
 
-impl ToNsCssValue for FontVariationSettings {
+impl ToNsCssValue for SpecifiedFontVariationSettings {
     fn convert(self, nscssvalue: &mut nsCSSValue) {
         if self.0.is_empty() {
             nscssvalue.set_normal();

components/style/properties/data.py

@@ -19,7 +19,8 @@ SYSTEM_FONT_LONGHANDS = """font_family font_size font_style
                            font_size_adjust font_variant_alternates
                            font_variant_ligatures font_variant_east_asian
                            font_variant_numeric font_language_override
-                           font_feature_settings font_optical_sizing""".split()
+                           font_feature_settings font_variation_settings
+                           font_optical_sizing""".split()
 
 
 def maybe_moz_logical_alias(product, side, prop):

components/style/properties/longhand/font.mako.rs

@@ -167,6 +167,7 @@ ${helpers.predefined_type("font-variation-settings",
                           products="gecko",
                           gecko_pref="layout.css.font-variations.enabled",
                           initial_value="computed::FontVariationSettings::normal()",
+                          initial_specified_value="specified::FontVariationSettings::normal()",
                           animation_value_type="ComputedValue",
                           flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
                           spec="${variation_spec}")}
@@ -371,6 +372,7 @@ ${helpers.predefined_type("-x-text-zoom",
                     font_language_override: longhands::font_language_override::computed_value
                                                      ::T(system.languageOverride),
                     font_feature_settings: longhands::font_feature_settings::get_initial_value(),
+                    font_variation_settings: longhands::font_variation_settings::get_initial_value(),
                     font_variant_alternates: longhands::font_variant_alternates::get_initial_value(),
                     system_font: *self,
                     default_font_type: system.fontlist.mDefaultFontType,

components/style/properties/shorthand/font.mako.rs

@@ -17,7 +17,8 @@
                                     ${'font-variant-numeric' if product == 'gecko' else ''}
                                     ${'font-variant-position' if product == 'gecko' else ''}
                                     ${'font-language-override' if product == 'gecko' else ''}
-                                    ${'font-feature-settings' if product == 'gecko' else ''}"
+                                    ${'font-feature-settings' if product == 'gecko' else ''}
+                                    ${'font-variation-settings' if product == 'gecko' else ''}"
                     spec="https://drafts.csswg.org/css-fonts-3/#propdef-font">
     use parser::Parse;
     use properties::longhands::{font_family, font_style, font_weight, font_stretch};
@@ -32,7 +33,7 @@
                                 variant_alternates variant_east_asian \
                                 variant_ligatures variant_numeric \
                                 variant_position feature_settings \
-                                optical_sizing".split()
+                                variation_settings optical_sizing".split()
     %>
     % if product == "gecko":
         % for prop in gecko_sub_properties:
@@ -162,9 +163,14 @@
                     return Ok(());
                 }
             }
+            if let Some(v) = self.font_variation_settings {
+                if v != &font_variation_settings::get_initial_specified_value() {
+                    return Ok(());
+                }
+            }
 
             % for name in gecko_sub_properties:
-            % if name != "optical_sizing":
+            % if name != "optical_sizing" and name != "variation_settings":
             if self.font_${name} != &font_${name}::get_initial_specified_value() {
                 return Ok(());
             }
@@ -203,7 +209,7 @@
             let mut all = true;
 
             % for prop in SYSTEM_FONT_LONGHANDS:
-            % if prop == "font_optical_sizing":
+            % if prop == "font_optical_sizing" or prop == "font_variation_settings":
             if let Some(value) = self.${prop} {
             % else:
             {

components/style/values/specified/font.rs

@@ -1653,7 +1653,7 @@ impl Parse for FontVariantNumeric {
     }
 }
 
-/// This property provides low-level control over OpenType or TrueType font variations.
+/// This property provides low-level control over OpenType or TrueType font features.
 pub type SpecifiedFontFeatureSettings = FontSettings<FeatureTagValue<Integer>>;
 
 /// Define initial settings that apply when the font defined by an @font-face
@@ -1910,7 +1910,71 @@ impl Parse for FontLanguageOverride {
 
 /// This property provides low-level control over OpenType or TrueType font
 /// variations.
-pub type FontVariationSettings = FontSettings<VariationValue<Number>>;
+pub type SpecifiedFontVariationSettings = FontSettings<VariationValue<Number>>;
+
+/// Define initial settings that apply when the font defined by an @font-face
+/// rule is rendered.
+#[derive(Clone, Debug, MallocSizeOf, PartialEq, ToCss)]
+pub enum FontVariationSettings {
+    /// Value of `FontSettings`
+    Value(SpecifiedFontVariationSettings),
+    /// System font
+    System(SystemFont)
+}
+
+impl FontVariationSettings {
+    #[inline]
+    /// Get default value of `font-variation-settings` as normal
+    pub fn normal() -> FontVariationSettings {
+        FontVariationSettings::Value(FontSettings::normal())
+    }
+
+    /// Get `font-variation-settings` with system font
+    pub fn system_font(f: SystemFont) -> Self {
+        FontVariationSettings::System(f)
+    }
+
+    /// Get system font
+    pub fn get_system(&self) -> Option<SystemFont> {
+        if let FontVariationSettings::System(s) = *self {
+            Some(s)
+        } else {
+            None
+        }
+    }
+}
+
+impl ToComputedValue for FontVariationSettings {
+    type ComputedValue = computed::FontVariationSettings;
+
+    fn to_computed_value(&self, context: &Context) -> computed::FontVariationSettings {
+        match *self {
+            FontVariationSettings::Value(ref v) => v.to_computed_value(context),
+            FontVariationSettings::System(_) => {
+                #[cfg(feature = "gecko")] {
+                    context.cached_system_font.as_ref().unwrap().font_variation_settings.clone()
+                }
+                #[cfg(feature = "servo")] {
+                    unreachable!()
+                }
+            }
+        }
+    }
+
+    fn from_computed_value(other: &computed::FontVariationSettings) -> Self {
+        FontVariationSettings::Value(ToComputedValue::from_computed_value(other))
+    }
+}
+
+impl Parse for FontVariationSettings {
+    /// normal | <variation-tag-value>#
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>
+    ) -> Result<FontVariationSettings, ParseError<'i>> {
+        SpecifiedFontVariationSettings::parse(context, input).map(FontVariationSettings::Value)
+    }
+}
 
 fn parse_one_feature_value<'i, 't>(
     context: &ParserContext,

ports/geckolib/glue.rs

@@ -4857,7 +4857,7 @@ pub extern "C" fn Servo_ParseFontDescriptor(
     use style::font_face::{FontDisplay, FontWeight, Source};
     use style::properties::longhands::font_language_override;
     use style::values::computed::font::FamilyName;
-    use style::values::specified::font::{SpecifiedFontFeatureSettings, FontVariationSettings};
+    use style::values::specified::font::{SpecifiedFontFeatureSettings, SpecifiedFontVariationSettings};
 
     let string = unsafe { (*value).to_string() };
     let mut input = ParserInput::new(&string);
@@ -4907,7 +4907,7 @@ pub extern "C" fn Servo_ParseFontDescriptor(
             eCSSFontDesc_Src / Vec<Source>,
             eCSSFontDesc_UnicodeRange / Vec<UnicodeRange>,
             eCSSFontDesc_FontFeatureSettings / SpecifiedFontFeatureSettings,
-            eCSSFontDesc_FontVariationSettings / FontVariationSettings,
+            eCSSFontDesc_FontVariationSettings / SpecifiedFontVariationSettings,
             eCSSFontDesc_FontLanguageOverride / font_language_override::SpecifiedValue,
             eCSSFontDesc_Display / FontDisplay,
         ]

ports/geckolib/tests/size_of.rs

@@ -40,7 +40,7 @@ size_of_test!(test_size_of_rule_node, RuleNode, 80);
 
 // This is huge, but we allocate it on the stack and then never move it,
 // we only pass `&mut SourcePropertyDeclaration` references around.
-size_of_test!(test_size_of_parsed_declaration, style::properties::SourcePropertyDeclaration, 576);
+size_of_test!(test_size_of_parsed_declaration, style::properties::SourcePropertyDeclaration, 608);
 
 size_of_test!(test_size_of_computed_image, computed::image::Image, 40);
 size_of_test!(test_size_of_specified_image, specified::image::Image, 40);