style: Update font-stretch to css-fonts-4.

These won't "just work", pending changes from bug 1436048 to use a floating
point representation for those.

Bug: 1454883
Reviewed-by: xidorn
MozReview-Commit-ID: Bi5iTdFreMA

components/style/properties/gecko.mako.rs

@@ -2601,7 +2601,7 @@ fn static_assert() {
     }
 
     pub fn set_font_weight(&mut self, v: longhands::font_weight::computed_value::T) {
-        unsafe { Gecko_FontWeight_SetFloat(&mut self.gecko.mFont.weight, v.0 as f32) };
+        unsafe { Gecko_FontWeight_SetFloat(&mut self.gecko.mFont.weight, v.0) };
     }
     ${impl_simple_copy('font_weight', 'mFont.weight')}
 
@@ -2610,6 +2610,21 @@ fn static_assert() {
         longhands::font_weight::computed_value::T(weight)
     }
 
+    pub fn set_font_stretch(&mut self, v: longhands::font_stretch::computed_value::T) {
+        unsafe { bindings::Gecko_FontStretch_SetFloat(&mut self.gecko.mFont.stretch, (v.0).0) };
+    }
+    ${impl_simple_copy('font_stretch', 'mFont.stretch')}
+
+    pub fn clone_font_stretch(&self) -> longhands::font_stretch::computed_value::T {
+        use values::computed::Percentage;
+        use values::generics::NonNegative;
+
+        let stretch = self.gecko.mFont.stretch as f32 / 100.;
+        debug_assert!(stretch >= 0.);
+
+        NonNegative(Percentage(stretch))
+    }
+
     ${impl_simple_type_with_conversion("font_synthesis", "mFont.synthesis")}
 
     pub fn set_font_size_adjust(&mut self, v: longhands::font_size_adjust::computed_value::T) {

components/style/properties/helpers/animated_properties.mako.rs

@@ -19,7 +19,6 @@ use num_traits::Zero;
 use properties::{CSSWideKeyword, PropertyDeclaration};
 use properties::longhands;
 use properties::longhands::font_weight::computed_value::T as FontWeight;
-use properties::longhands::font_stretch::computed_value::T as FontStretch;
 use properties::longhands::visibility::computed_value::T as Visibility;
 use properties::PropertyId;
 use properties::{LonghandId, ShorthandId};
@@ -880,61 +879,6 @@ impl ToAnimatedZero for FontWeight {
     }
 }
 
-/// <https://drafts.csswg.org/css-fonts/#font-stretch-prop>
-impl Animate for FontStretch {
-    #[inline]
-    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
-        let from = f64::from(*self);
-        let to = f64::from(*other);
-        let normal = f64::from(FontStretch::Normal);
-        let (this_weight, other_weight) = procedure.weights();
-        let result = (from - normal) * this_weight + (to - normal) * other_weight + normal;
-        Ok(result.into())
-    }
-}
-
-impl ComputeSquaredDistance for FontStretch {
-    #[inline]
-    fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
-        f64::from(*self).compute_squared_distance(&(*other).into())
-    }
-}
-
-impl ToAnimatedZero for FontStretch {
-    #[inline]
-    fn to_animated_zero(&self) -> Result<Self, ()> { Err(()) }
-}
-
-/// We should treat font stretch as real number in order to interpolate this property.
-/// <https://drafts.csswg.org/css-fonts-3/#font-stretch-animation>
-impl From<FontStretch> for f64 {
-    fn from(stretch: FontStretch) -> f64 {
-        use self::FontStretch::*;
-        match stretch {
-            UltraCondensed => 1.0,
-            ExtraCondensed => 2.0,
-            Condensed => 3.0,
-            SemiCondensed => 4.0,
-            Normal => 5.0,
-            SemiExpanded => 6.0,
-            Expanded => 7.0,
-            ExtraExpanded => 8.0,
-            UltraExpanded => 9.0,
-        }
-    }
-}
-
-impl Into<FontStretch> for f64 {
-    fn into(self) -> FontStretch {
-        use properties::longhands::font_stretch::computed_value::T::*;
-        let index = (self + 0.5).floor().min(9.0).max(1.0);
-        static FONT_STRETCH_ENUM_MAP: [FontStretch; 9] =
-            [ UltraCondensed, ExtraCondensed, Condensed, SemiCondensed, Normal,
-              SemiExpanded, Expanded, ExtraExpanded, UltraExpanded ];
-        FONT_STRETCH_ENUM_MAP[(index - 1.0) as usize]
-    }
-}
-
 /// <https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def>
 impl Animate for FontVariationSettings {
     #[inline]

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

@@ -81,17 +81,16 @@ ${helpers.predefined_type("font-synthesis",
                           flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
                           spec="https://drafts.csswg.org/css-fonts/#propdef-font-synthesis")}
 
-${helpers.single_keyword_system("font-stretch",
-                                "normal ultra-condensed extra-condensed condensed \
-                                 semi-condensed semi-expanded expanded extra-expanded \
-                                 ultra-expanded",
-                                gecko_ffi_name="mFont.stretch",
-                                gecko_constant_prefix="NS_FONT_STRETCH",
-                                cast_type='i16',
-                                spec="https://drafts.csswg.org/css-fonts/#propdef-font-stretch",
-                                flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
-                                animation_value_type="ComputedValue",
-                                servo_restyle_damage="rebuild_and_reflow")}
+${helpers.predefined_type(
+    "font-stretch",
+    "FontStretch",
+    initial_value="computed::NonNegativePercentage::hundred()",
+    initial_specified_value="specified::FontStretch::normal()",
+    animation_value_type="Percentage",
+    flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
+    spec="https://drafts.csswg.org/css-fonts/#propdef-font-stretch",
+    servo_restyle_damage="rebuild_and_reflow",
+)}
 
 ${helpers.single_keyword_system("font-kerning",
                                 "auto none normal",
@@ -290,11 +289,11 @@ ${helpers.predefined_type("-x-text-zoom",
                               -moz-window -moz-document -moz-workspace -moz-desktop
                               -moz-info -moz-dialog -moz-button -moz-pull-down-menu
                               -moz-list -moz-field""".split()
-            kw_font_props = """font_style font_variant_caps font_stretch
+            kw_font_props = """font_style font_variant_caps
                                font_kerning font_variant_position font_variant_ligatures
                                font_variant_east_asian font_variant_numeric
                                font_optical_sizing""".split()
-            kw_cast = """font_style font_variant_caps font_stretch
+            kw_cast = """font_style font_variant_caps
                          font_kerning font_variant_position
                          font_optical_sizing""".split()
         %>
@@ -330,7 +329,9 @@ ${helpers.predefined_type("-x-text-zoom",
                 use gecko_bindings::bindings;
                 use gecko_bindings::structs::{LookAndFeel_FontID, nsFont};
                 use std::mem;
+                use values::computed::Percentage;
                 use values::computed::font::{FontSize, FontFamilyList};
+                use values::generics::NonNegative;
 
                 let id = match *self {
                     % for font in system_fonts:
@@ -349,7 +350,8 @@ ${helpers.predefined_type("-x-text-zoom",
                         cx.device().pres_context()
                     )
                 }
-                let weight = longhands::font_weight::computed_value::T::from_gecko_weight(system.weight);
+                let font_weight = longhands::font_weight::computed_value::T::from_gecko_weight(system.weight);
+                let font_stretch = NonNegative(Percentage(system.stretch as f32));
                 let ret = ComputedSystemFont {
                     font_family: longhands::font_family::computed_value::T(
                         FontFamilyList(
@@ -360,7 +362,8 @@ ${helpers.predefined_type("-x-text-zoom",
                             size: Au(system.size).into(),
                             keyword_info: None
                     },
-                    font_weight: weight,
+                    font_weight,
+                    font_stretch,
                     font_size_adjust: longhands::font_size_adjust::computed_value
                                                ::T::from_gecko_adjust(system.sizeAdjust),
                     % for kwprop in kw_font_props: