Auto merge of #16931 - nox:font-feature-descriptor, r=emilio

Support font-feature-settings as a @font-face descriptor

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7 files changed, 191 insertions, 124 deletions

diff --git a/components/style/font_face.rs b/components/style/font_face.rs
index 3d81476fd12..4c953c3b028 100644
--- a/components/style/font_face.rs
+++ b/components/style/font_face.rs
@@ -9,7 +9,7 @@
 #![deny(missing_docs)]
 
 #[cfg(feature = "gecko")]
-use computed_values::{font_style, font_weight, font_stretch};
+use computed_values::{font_feature_settings, font_stretch, font_style, font_weight};
 use computed_values::font_family::FamilyName;
 use cssparser::{AtRuleParser, DeclarationListParser, DeclarationParser, Parser};
 use cssparser::SourceLocation;
@@ -72,6 +72,17 @@ impl ToCss for UrlSource {
     }
 }
 
+/// A font-display value for a @font-face rule.
+/// The font-display descriptor determines how a font face is displayed based
+/// on whether and when it is downloaded and ready to use.
+define_css_keyword_enum!(FontDisplay:
+                         "auto" => Auto,
+                         "block" => Block,
+                         "swap" => Swap,
+                         "fallback" => Fallback,
+                         "optional" => Optional);
+add_impls_for_keyword_enum!(FontDisplay);
+
 /// Parse the block inside a `@font-face` rule.
 ///
 /// Note that the prelude parsing code lives in the `stylesheets` module.
@@ -332,12 +343,20 @@ font_face_descriptors! {
         /// The stretch of this font face
         "font-stretch" stretch / mStretch: font_stretch::T = font_stretch::T::normal,
 
+        /// The display of this font face
+        "font-display" display / mDisplay: FontDisplay = FontDisplay::Auto,
+
         /// The ranges of code points outside of which this font face should not be used.
         "unicode-range" unicode_range / mUnicodeRange: Vec<UnicodeRange> = vec![
             UnicodeRange { start: 0, end: 0x10FFFF }
         ],
 
-        // FIXME: add font-feature-settings, font-language-override, and font-display
+        /// The feature settings of this font face.
+        "font-feature-settings" feature_settings / mFontFeatureSettings: font_feature_settings::T = {
+            font_feature_settings::T::Normal
+        },
+
+        // FIXME: add font-language-override.
     ]
 }
 
diff --git a/components/style/gecko/rules.rs b/components/style/gecko/rules.rs
index f41fcb1e0b1..80aa7a7acb2 100644
--- a/components/style/gecko/rules.rs
+++ b/components/style/gecko/rules.rs
@@ -4,18 +4,19 @@
 
 //! Bindings for CSS Rule objects
 
-use computed_values::{font_style, font_weight, font_stretch};
+use byteorder::{BigEndian, WriteBytesExt};
+use computed_values::{font_feature_settings, font_stretch, font_style, font_weight};
 use computed_values::font_family::FamilyName;
 use counter_style;
 use cssparser::UnicodeRange;
-use font_face::{FontFaceRuleData, Source};
+use font_face::{FontFaceRuleData, Source, FontDisplay};
 use gecko_bindings::bindings;
 use gecko_bindings::structs::{self, nsCSSFontFaceRule, nsCSSValue};
 use gecko_bindings::structs::{nsCSSCounterDesc, nsCSSCounterStyleRule};
 use gecko_bindings::sugar::ns_css_value::ToNsCssValue;
 use gecko_bindings::sugar::refptr::{RefPtr, UniqueRefPtr};
 use shared_lock::{ToCssWithGuard, SharedRwLockReadGuard};
-use std::fmt;
+use std::{fmt, str};
 
 /// A @font-face rule
 pub type FontFaceRule = RefPtr<nsCSSFontFaceRule>;
@@ -32,6 +33,27 @@ impl ToNsCssValue for font_weight::T {
     }
 }
 
+impl ToNsCssValue for font_feature_settings::T {
+    fn convert(self, nscssvalue: &mut nsCSSValue) {
+        match self {
+            font_feature_settings::T::Normal => nscssvalue.set_normal(),
+            font_feature_settings::T::Tag(tags) => {
+                nscssvalue.set_pair_list(tags.into_iter().map(|entry| {
+                    let mut feature = nsCSSValue::null();
+                    let mut raw = [0u8; 4];
+                    (&mut raw[..]).write_u32::<BigEndian>(entry.tag).unwrap();
+                    feature.set_string(str::from_utf8(&raw).unwrap());
+
+                    let mut index = nsCSSValue::null();
+                    index.set_integer(entry.value as i32);
+
+                    (feature, index)
+                }))
+            }
+        }
+    }
+}
+
 macro_rules! map_enum {
     (
         $(
@@ -115,6 +137,18 @@ impl ToNsCssValue for Vec<UnicodeRange> {
     }
 }
 
+impl ToNsCssValue for FontDisplay {
+    fn convert(self, nscssvalue: &mut nsCSSValue) {
+        nscssvalue.set_enum(match self {
+            FontDisplay::Auto => structs::NS_FONT_DISPLAY_AUTO,
+            FontDisplay::Block => structs::NS_FONT_DISPLAY_BLOCK,
+            FontDisplay::Swap => structs::NS_FONT_DISPLAY_SWAP,
+            FontDisplay::Fallback => structs::NS_FONT_DISPLAY_FALLBACK,
+            FontDisplay::Optional => structs::NS_FONT_DISPLAY_OPTIONAL,
+        } as i32)
+    }
+}
+
 impl From<FontFaceRuleData> for FontFaceRule {
     fn from(data: FontFaceRuleData) -> FontFaceRule {
         let mut result = unsafe {
diff --git a/components/style/lib.rs b/components/style/lib.rs
index fc61dd1b001..7eb74bd6d42 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -83,6 +83,9 @@ extern crate time;
 #[allow(unused_extern_crates)]
 extern crate unicode_segmentation;
 
+#[macro_use]
+mod macros;
+
 pub mod animation;
 #[allow(missing_docs)] // TODO.
 #[cfg(feature = "servo")] pub mod attr;
diff --git a/components/style/macros.rs b/components/style/macros.rs
new file mode 100644
index 00000000000..ce040891a74
--- /dev/null
+++ b/components/style/macros.rs
@@ -0,0 +1,115 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Various macro helpers.
+
+macro_rules! define_numbered_css_keyword_enum {
+    ($name: ident: $( $css: expr => $variant: ident = $value: expr ),+,) => {
+        define_numbered_css_keyword_enum!($name: $( $css => $variant = $value ),+);
+    };
+    ($name: ident: $( $css: expr => $variant: ident = $value: expr ),+) => {
+        #[allow(non_camel_case_types, missing_docs)]
+        #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
+        pub enum $name {
+            $( $variant = $value ),+
+        }
+
+        impl $crate::parser::Parse for $name {
+            #[allow(missing_docs)]
+            fn parse(_context: &$crate::parser::ParserContext, input: &mut ::cssparser::Parser) -> Result<$name, ()> {
+                match_ignore_ascii_case! { &try!(input.expect_ident()),
+                    $( $css => Ok($name::$variant), )+
+                    _ => Err(())
+                }
+            }
+        }
+
+        impl ::style_traits::values::ToCss for $name {
+            fn to_css<W>(&self, dest: &mut W) -> ::std::fmt::Result
+                where W: ::std::fmt::Write,
+            {
+                match *self {
+                    $( $name::$variant => dest.write_str($css) ),+
+                }
+            }
+        }
+    }
+}
+
+/// A macro used to implement HasViewportPercentage trait
+/// for a given type that may never contain viewport units.
+macro_rules! no_viewport_percentage {
+    ($name: ident) => {
+        impl $crate::values::HasViewportPercentage for $name {
+            #[inline]
+            fn has_viewport_percentage(&self) -> bool {
+                false
+            }
+        }
+    };
+}
+
+/// A macro for implementing `ComputedValueAsSpecified`, `Parse`
+/// and `HasViewportPercentage` traits for the enums defined
+/// using `define_css_keyword_enum` macro.
+///
+/// NOTE: We should either move `Parse` trait to `style_traits`
+/// or `define_css_keyword_enum` macro to this crate, but that
+/// may involve significant cleanup in both the crates.
+macro_rules! add_impls_for_keyword_enum {
+    ($name:ident) => {
+        impl $crate::parser::Parse for $name {
+            #[inline]
+            fn parse(_context: &$crate::parser::ParserContext,
+                     input: &mut ::cssparser::Parser)
+                     -> Result<Self, ()> {
+                $name::parse(input)
+            }
+        }
+
+        impl $crate::values::computed::ComputedValueAsSpecified for $name {}
+        no_viewport_percentage!($name);
+    };
+}
+
+macro_rules! define_keyword_type {
+    ($name: ident, $css: expr) => {
+        #[derive(Clone, PartialEq, Copy)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        #[allow(missing_docs)]
+        pub struct $name;
+
+        impl ::style_traits::ToCss for $name {
+            fn to_css<W>(&self, dest: &mut W) -> ::std::fmt::Result where W: ::std::fmt::Write {
+                write!(dest, $css)
+            }
+        }
+
+        impl $crate::properties::animated_properties::Animatable for $name {
+            #[inline]
+            fn add_weighted(&self, _other: &Self, _self_progress: f64, _other_progress: f64)
+                -> Result<Self, ()> {
+                Ok($name)
+            }
+        }
+
+        impl fmt::Debug for $name {
+            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                write!(f, $css)
+            }
+        }
+
+        impl $crate::parser::Parse for $name {
+            fn parse(_context: &$crate::parser::ParserContext,
+                     input: &mut ::cssparser::Parser)
+                     -> Result<$name, ()> {
+                input.expect_ident_matching($css).map(|_| $name)
+            }
+        }
+
+        impl $crate::values::computed::ComputedValueAsSpecified for $name {}
+        no_viewport_percentage!($name);
+    };
+}
diff --git a/components/style/properties/longhand/font.mako.rs b/components/style/properties/longhand/font.mako.rs
index 9d2ec4215d4..9461d1a688f 100644
--- a/components/style/properties/longhand/font.mako.rs
+++ b/components/style/properties/longhand/font.mako.rs
@@ -1803,14 +1803,14 @@ ${helpers.single_keyword_system("font-variant-position",
         use std::fmt;
         use style_traits::ToCss;
 
-        #[derive(Debug, Clone, PartialEq)]
+        #[derive(Clone, Debug, Eq, PartialEq)]
         #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub enum T {
             Normal,
             Tag(Vec<FeatureTagValue>)
         }
 
-        #[derive(Debug, Clone, PartialEq)]
+        #[derive(Clone, Debug, Eq, PartialEq)]
         #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
         pub struct FeatureTagValue {
             pub tag: u32,
@@ -1836,6 +1836,16 @@ ${helpers.single_keyword_system("font-variant-position",
             }
         }
 
+        impl Parse for T {
+            /// https://www.w3.org/TR/css-fonts-3/#propdef-font-feature-settings
+            fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+                if input.try(|i| i.expect_ident_matching("normal")).is_ok() {
+                    return Ok(T::Normal);
+                }
+                input.parse_comma_separated(|i| FeatureTagValue::parse(context, i)).map(T::Tag)
+            }
+        }
+
         impl ToCss for FeatureTagValue {
             fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
                 use std::str;
@@ -1908,12 +1918,7 @@ ${helpers.single_keyword_system("font-variant-position",
 
     /// normal | <feature-tag-value>#
     pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
-        if input.try(|input| input.expect_ident_matching("normal")).is_ok() {
-            Ok(SpecifiedValue::Value(computed_value::T::Normal))
-        } else {
-            input.parse_comma_separated(|i| computed_value::FeatureTagValue::parse(context, i))
-                 .map(computed_value::T::Tag).map(SpecifiedValue::Value)
-        }
+        computed_value::T::parse(context, input).map(SpecifiedValue::Value)
     }
 </%helpers:longhand>
 
diff --git a/components/style/values/mod.rs b/components/style/values/mod.rs
index 4ce3d1f8dc1..63bcc366bad 100644
--- a/components/style/values/mod.rs
+++ b/components/style/values/mod.rs
@@ -11,81 +11,12 @@
 use Atom;
 pub use cssparser::{RGBA, Token, Parser, serialize_identifier, serialize_string};
 use parser::{Parse, ParserContext};
-use properties::animated_properties::Animatable;
 use std::ascii::AsciiExt;
 use std::borrow::Cow;
 use std::fmt::{self, Debug};
 use std::hash;
 use style_traits::ToCss;
 
-macro_rules! define_numbered_css_keyword_enum {
-    ($name: ident: $( $css: expr => $variant: ident = $value: expr ),+,) => {
-        define_numbered_css_keyword_enum!($name: $( $css => $variant = $value ),+);
-    };
-    ($name: ident: $( $css: expr => $variant: ident = $value: expr ),+) => {
-        #[allow(non_camel_case_types, missing_docs)]
-        #[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
-        pub enum $name {
-            $( $variant = $value ),+
-        }
-
-        impl Parse for $name {
-            #[allow(missing_docs)]
-            fn parse(_context: &ParserContext, input: &mut ::cssparser::Parser) -> Result<$name, ()> {
-                match_ignore_ascii_case! { &try!(input.expect_ident()),
-                    $( $css => Ok($name::$variant), )+
-                    _ => Err(())
-                }
-            }
-        }
-
-        impl ToCss for $name {
-            fn to_css<W>(&self, dest: &mut W) -> ::std::fmt::Result
-                where W: ::std::fmt::Write,
-            {
-                match *self {
-                    $( $name::$variant => dest.write_str($css) ),+
-                }
-            }
-        }
-    }
-}
-
-/// A macro used to implement HasViewportPercentage trait
-/// for a given type that may never contain viewport units.
-macro_rules! no_viewport_percentage {
-    ($name: ident) => {
-        impl $crate::values::HasViewportPercentage for $name {
-            #[inline]
-            fn has_viewport_percentage(&self) -> bool {
-                false
-            }
-        }
-    };
-}
-
-/// A macro for implementing `ComputedValueAsSpecified`, `Parse`
-/// and `HasViewportPercentage` traits for the enums defined
-/// using `define_css_keyword_enum` macro.
-///
-/// NOTE: We should either move `Parse` trait to `style_traits`
-/// or `define_css_keyword_enum` macro to this crate, but that
-/// may involve significant cleanup in both the crates.
-macro_rules! add_impls_for_keyword_enum {
-    ($name:ident) => {
-        impl Parse for $name {
-            #[inline]
-            fn parse(_context: &ParserContext, input: &mut ::cssparser::Parser) -> Result<Self, ()> {
-                $name::parse(input)
-            }
-        }
-
-        impl ComputedValueAsSpecified for $name {}
-        no_viewport_percentage!($name);
-    };
-}
-
 pub mod computed;
 pub mod generics;
 pub mod specified;
@@ -112,46 +43,6 @@ impl<T: HasViewportPercentage> HasViewportPercentage for Box<T> {
     }
 }
 
-use self::computed::ComputedValueAsSpecified;
-
-macro_rules! define_keyword_type {
-    ($name: ident, $css: expr) => {
-        #[derive(Clone, PartialEq, Copy)]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-        #[allow(missing_docs)]
-        pub struct $name;
-
-        impl ::style_traits::ToCss for $name {
-            fn to_css<W>(&self, dest: &mut W) -> ::std::fmt::Result where W: ::std::fmt::Write {
-                write!(dest, $css)
-            }
-        }
-
-        impl Animatable for $name {
-            #[inline]
-            fn add_weighted(&self, _other: &Self, _self_progress: f64, _other_progress: f64)
-                -> Result<Self, ()> {
-                Ok($name)
-            }
-        }
-
-        impl fmt::Debug for $name {
-            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-                write!(f, $css)
-            }
-        }
-
-        impl Parse for $name {
-            fn parse(_context: &ParserContext, input: &mut ::cssparser::Parser) -> Result<$name, ()> {
-                input.expect_ident_matching($css).map(|_| $name)
-            }
-        }
-
-        impl ComputedValueAsSpecified for $name {}
-        no_viewport_percentage!($name);
-    };
-}
-
 define_keyword_type!(None_, "none");
 define_keyword_type!(Auto, "auto");
 define_keyword_type!(Normal, "normal");
diff --git a/components/style/values/specified/position.rs b/components/style/values/specified/position.rs
index c2991ede864..a4b4953c372 100644
--- a/components/style/values/specified/position.rs
+++ b/components/style/values/specified/position.rs
@@ -12,8 +12,8 @@ use parser::{Parse, ParserContext};
 use std::fmt;
 use style_traits::ToCss;
 use values::HasViewportPercentage;
-use values::computed::{CalcLengthOrPercentage, ComputedValueAsSpecified, Context};
-use values::computed::{LengthOrPercentage as ComputedLengthOrPercentage, ToComputedValue};
+use values::computed::{CalcLengthOrPercentage, LengthOrPercentage as ComputedLengthOrPercentage};
+use values::computed::{Context, ToComputedValue};
 use values::generics::position::Position as GenericPosition;
 use values::specified::{AllowQuirks, LengthOrPercentage, Percentage};