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Prior to this change, if none of the fonts specified in CSS contained a glyph for a codepoint, we tried only one fallback font. If that font didn't contain the glyph, we'd give up. With this change, we try multiple fonts in turn. The font names we try differ across each platform, and based on the codepoint we're trying to match. The current implementation is heavily inspired by the analogous code in Gecko, but I've used to ucd lib to make it more readable, whereas Gecko matches raw unicode ranges. This fixes some of the issues reported in #17267, although colour emoji support is not implemented. == Notes on changes to WPT metadata == === css/css-text/i18n/css3-text-line-break-opclns-* === A bunch of these have started failing on macos when they previously passed. These tests check that the browser automatically inserts line breaks near certain characters that are classified as "opening and closing punctuation". The idea is that if we have e.g. an opening parenthesis, it does not make sense for it to appear at the end of a line box; it should "stick" to the next character and go into the next line box. Before this change, a lot of these codepoints rendered as a missing glyph on Mac and Linux. In some cases, that meant that the test was passing. After this change, a bunch of these codepoints are now rendering glyphs on Mac (but not Linux). In some cases, the test should continue to pass where it previously did when rendering with the missing glyph. However, it seems this has also exposed a layout bug. The "ref" div in these tests contains a <br> element, and it seems that this, combined with these punctuation characters, makes the spacing between glyphs ever so slightly different to the "test" div. (Speculation: might be something to do with shaping?) Therefore I've had to mark a bunch of these tests failing on mac. === css/css-text/i18n/css3-text-line-break-baspglwj-* === Some of these previously passed on Mac due to a missing glyph. Now that we're rendering the correct glyph, they are failing. === css/css-text/word-break/word-break-normal-bo-000.html === The characters now render correctly on Mac, and the test is passing. But we do not find a suitable fallback font on Linux, so it is still failing on that platform. === css/css-text/word-break/word-break-break-all-007.html === This was previously passing on Mac, but only because missing character glyphs were rendered. Now that a fallback font is able to be found, it (correctly) fails. === mozilla/tests/css/font_fallback_* === These are new tests added in this commit. 01 and 02 are marked failing on Linux because the builders don't have the appropriate fonts installed (that will be a follow-up). Fix build errors from rebase FontTemplateDescriptor can no longer just derive(Hash). We need to implement it on each component part, because the components now generally wrap floats, which do not impl Hash because of NaN. However in this case we know that we won't have a NaN, so it is safe to manually impl Hash.
240 lines
6.8 KiB
Rust
240 lines
6.8 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! Generic types for font stuff.
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use app_units::Au;
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use byteorder::{BigEndian, ReadBytesExt};
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use cssparser::Parser;
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use num_traits::One;
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use parser::{Parse, ParserContext};
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use std::fmt::{self, Write};
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use std::io::Cursor;
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use style_traits::{CssWriter, KeywordsCollectFn, ParseError};
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use style_traits::{SpecifiedValueInfo, StyleParseErrorKind, ToCss};
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use values::distance::{ComputeSquaredDistance, SquaredDistance};
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/// https://drafts.csswg.org/css-fonts-4/#feature-tag-value
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#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo,
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ToComputedValue)]
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pub struct FeatureTagValue<Integer> {
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/// A four-character tag, packed into a u32 (one byte per character).
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pub tag: FontTag,
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/// The actual value.
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pub value: Integer,
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}
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impl<Integer> ToCss for FeatureTagValue<Integer>
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where
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Integer: One + ToCss + PartialEq,
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{
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fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
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where
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W: Write,
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{
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self.tag.to_css(dest)?;
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// Don't serialize the default value.
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if self.value != Integer::one() {
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dest.write_char(' ')?;
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self.value.to_css(dest)?;
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}
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Ok(())
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}
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}
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/// Variation setting for a single feature, see:
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///
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/// https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def
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#[derive(Animate, Clone, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo,
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ToComputedValue, ToCss)]
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pub struct VariationValue<Number> {
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/// A four-character tag, packed into a u32 (one byte per character).
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#[animation(constant)]
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pub tag: FontTag,
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/// The actual value.
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pub value: Number,
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}
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impl<Number> ComputeSquaredDistance for VariationValue<Number>
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where
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Number: ComputeSquaredDistance,
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{
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#[inline]
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fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
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if self.tag != other.tag {
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return Err(());
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}
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self.value.compute_squared_distance(&other.value)
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}
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}
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/// A value both for font-variation-settings and font-feature-settings.
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#[css(comma)]
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#[derive(Clone, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo,
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ToComputedValue, ToCss)]
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pub struct FontSettings<T>(#[css(if_empty = "normal", iterable)] pub Box<[T]>);
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impl<T> FontSettings<T> {
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/// Default value of font settings as `normal`.
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#[inline]
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pub fn normal() -> Self {
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FontSettings(vec![].into_boxed_slice())
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}
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}
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impl<T: Parse> Parse for FontSettings<T> {
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/// https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-feature-settings
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/// https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def
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fn parse<'i, 't>(
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context: &ParserContext,
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input: &mut Parser<'i, 't>,
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) -> Result<Self, ParseError<'i>> {
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if input.try(|i| i.expect_ident_matching("normal")).is_ok() {
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return Ok(Self::normal());
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}
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Ok(FontSettings(
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input
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.parse_comma_separated(|i| T::parse(context, i))?
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.into_boxed_slice(),
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))
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}
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}
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/// A font four-character tag, represented as a u32 for convenience.
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///
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/// See:
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/// https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def
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/// https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-feature-settings
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///
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#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq, SpecifiedValueInfo,
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ToComputedValue)]
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pub struct FontTag(pub u32);
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impl ToCss for FontTag {
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fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
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where
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W: Write,
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{
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use byteorder::{BigEndian, ByteOrder};
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use std::str;
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let mut raw = [0u8; 4];
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BigEndian::write_u32(&mut raw, self.0);
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str::from_utf8(&raw).unwrap_or_default().to_css(dest)
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}
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}
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impl Parse for FontTag {
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fn parse<'i, 't>(
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_context: &ParserContext,
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input: &mut Parser<'i, 't>,
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) -> Result<Self, ParseError<'i>> {
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let location = input.current_source_location();
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let tag = input.expect_string()?;
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// allowed strings of length 4 containing chars: <U+20, U+7E>
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if tag.len() != 4 || tag.as_bytes().iter().any(|c| *c < b' ' || *c > b'~') {
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return Err(location.new_custom_error(StyleParseErrorKind::UnspecifiedError));
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}
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let mut raw = Cursor::new(tag.as_bytes());
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Ok(FontTag(raw.read_u32::<BigEndian>().unwrap()))
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}
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}
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#[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf, PartialEq,
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ToAnimatedValue, ToAnimatedZero, ToCss)]
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/// Additional information for keyword-derived font sizes.
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pub struct KeywordInfo<Length> {
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/// The keyword used
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pub kw: KeywordSize,
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/// A factor to be multiplied by the computed size of the keyword
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#[css(skip)]
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pub factor: f32,
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/// An additional Au offset to add to the kw*factor in the case of calcs
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#[css(skip)]
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pub offset: Length,
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}
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impl<L> KeywordInfo<L>
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where
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Au: Into<L>,
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{
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/// KeywordInfo value for font-size: medium
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pub fn medium() -> Self {
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KeywordSize::Medium.into()
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}
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}
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impl<L> From<KeywordSize> for KeywordInfo<L>
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where
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Au: Into<L>,
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{
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fn from(x: KeywordSize) -> Self {
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KeywordInfo {
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kw: x,
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factor: 1.,
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offset: Au(0).into(),
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}
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}
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}
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impl<L> SpecifiedValueInfo for KeywordInfo<L> {
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fn collect_completion_keywords(f: KeywordsCollectFn) {
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<KeywordSize as SpecifiedValueInfo>::collect_completion_keywords(f);
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}
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}
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/// CSS font keywords
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#[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf,
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Parse, PartialEq, SpecifiedValueInfo, ToAnimatedValue, ToAnimatedZero,
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ToCss)]
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#[allow(missing_docs)]
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pub enum KeywordSize {
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#[css(keyword = "xx-small")]
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XXSmall,
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XSmall,
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Small,
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Medium,
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Large,
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XLarge,
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#[css(keyword = "xx-large")]
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XXLarge,
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// This is not a real font keyword and will not parse
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// HTML font-size 7 corresponds to this value
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#[css(skip)]
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XXXLarge,
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}
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impl KeywordSize {
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/// Convert to an HTML <font size> value
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#[inline]
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pub fn html_size(self) -> u8 {
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self as u8
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}
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}
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impl Default for KeywordSize {
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fn default() -> Self {
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KeywordSize::Medium
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}
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}
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/// A generic value for the `font-style` property.
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///
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/// https://drafts.csswg.org/css-fonts-4/#font-style-prop
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#[allow(missing_docs)]
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#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
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#[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, Hash, MallocSizeOf,
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PartialEq, SpecifiedValueInfo, ToAnimatedValue, ToAnimatedZero)]
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pub enum FontStyle<Angle> {
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#[animation(error)]
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Normal,
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#[animation(error)]
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Italic,
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#[value_info(starts_with_keyword)]
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Oblique(Angle),
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}
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