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/* 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 https://mozilla.org/MPL/2.0/. */
use std::fmt::{Debug, Error, Formatter};
use std::ops::RangeInclusive;
use std::sync::Arc;
use atomic_refcell::AtomicRefCell;
use malloc_size_of_derive::MallocSizeOf;
use serde::{Deserialize, Serialize};
use servo_url::ServoUrl;
use style::computed_values::font_stretch::T as FontStretch;
use style::computed_values::font_style::T as FontStyle;
use style::stylesheets::DocumentStyleSheet;
use style::values::computed::font::FontWeight;
use crate::font::{FontDescriptor, PlatformFontMethods};
use crate::font_cache_thread::{
CSSFontFaceDescriptors, ComputedFontStyleDescriptor, FontIdentifier,
};
use crate::platform::font::PlatformFont;
use crate::platform::font_list::LocalFontIdentifier;
/// A reference to a [`FontTemplate`] with shared ownership and mutability.
pub type FontTemplateRef = Arc<AtomicRefCell<FontTemplate>>;
/// Describes how to select a font from a given family. This is very basic at the moment and needs
/// to be expanded or refactored when we support more of the font styling parameters.
///
/// NB: If you change this, you will need to update `style::properties::compute_font_hash()`.
#[derive(Clone, Debug, Deserialize, Hash, MallocSizeOf, PartialEq, Serialize)]
pub struct FontTemplateDescriptor {
pub weight: (FontWeight, FontWeight),
pub stretch: (FontStretch, FontStretch),
pub style: (FontStyle, FontStyle),
#[ignore_malloc_size_of = "MallocSizeOf does not yet support RangeInclusive"]
pub unicode_range: Option<Vec<RangeInclusive<u32>>>,
}
impl Default for FontTemplateDescriptor {
fn default() -> Self {
Self::new(FontWeight::normal(), FontStretch::NORMAL, FontStyle::NORMAL)
}
}
/// FontTemplateDescriptor contains floats, which are not Eq because of NaN. However,
/// we know they will never be NaN, so we can manually implement Eq.
impl Eq for FontTemplateDescriptor {}
impl FontTemplateDescriptor {
#[inline]
pub fn new(weight: FontWeight, stretch: FontStretch, style: FontStyle) -> Self {
Self {
weight: (weight, weight),
stretch: (stretch, stretch),
style: (style, style),
unicode_range: None,
}
}
pub fn is_variation_font(&self) -> bool {
self.weight.0 != self.weight.1 ||
self.stretch.0 != self.stretch.1 ||
self.style.0 != self.style.1
}
/// Returns a score indicating how far apart visually the two font descriptors are. This is
/// used for implmenting the CSS Font Matching algorithm:
/// <https://drafts.csswg.org/css-fonts/#font-matching-algorithm>.
///
/// The smaller the score, the better the fonts match. 0 indicates an exact match. This must
/// be commutative (distance(A, B) == distance(B, A)).
#[inline]
fn distance_from(&self, target: &FontDescriptor) -> f32 {
let stretch_distance = target.stretch.match_distance(&self.stretch);
let style_distance = target.style.match_distance(&self.style);
let weight_distance = target.weight.match_distance(&self.weight);
// Sanity-check that the distances are within the expected range
// (update if implementation of the distance functions is changed).
assert!((0.0..=2000.0).contains(&stretch_distance));
assert!((0.0..=500.0).contains(&style_distance));
assert!((0.0..=1600.0).contains(&weight_distance));
// Factors used to weight the distances between the available and target font
// properties during font-matching. These ensure that we respect the CSS-fonts
// requirement that font-stretch >> font-style >> font-weight; and in addition,
// a mismatch between the desired and actual glyph presentation (emoji vs text)
// will take precedence over any of the style attributes.
//
// Also relevant for font selection is the emoji presentation preference, but this
// is handled later when filtering fonts based on the glyphs they contain.
const STRETCH_FACTOR: f32 = 1.0e8;
const STYLE_FACTOR: f32 = 1.0e4;
const WEIGHT_FACTOR: f32 = 1.0e0;
stretch_distance * STRETCH_FACTOR +
style_distance * STYLE_FACTOR +
weight_distance * WEIGHT_FACTOR
}
fn matches(&self, descriptor_to_match: &FontDescriptor) -> bool {
self.weight.0 <= descriptor_to_match.weight &&
self.weight.1 >= descriptor_to_match.weight &&
self.style.0 <= descriptor_to_match.style &&
self.style.1 >= descriptor_to_match.style &&
self.stretch.0 <= descriptor_to_match.stretch &&
self.stretch.1 >= descriptor_to_match.stretch
}
fn override_values_with_css_font_template_descriptors(
&mut self,
css_font_template_descriptors: &CSSFontFaceDescriptors,
) {
if let Some(weight) = css_font_template_descriptors.weight {
self.weight = weight;
}
self.style = match css_font_template_descriptors.style {
Some(ComputedFontStyleDescriptor::Italic) => (FontStyle::ITALIC, FontStyle::ITALIC),
Some(ComputedFontStyleDescriptor::Normal) => (FontStyle::NORMAL, FontStyle::NORMAL),
Some(ComputedFontStyleDescriptor::Oblique(angle_1, angle_2)) => (
FontStyle::oblique(angle_1.to_float()),
FontStyle::oblique(angle_2.to_float()),
),
None => self.style,
};
if let Some(stretch) = css_font_template_descriptors.stretch {
self.stretch = stretch;
}
if let Some(ref unicode_range) = css_font_template_descriptors.unicode_range {
self.unicode_range = Some(unicode_range.clone());
}
}
}
/// This describes all the information needed to create
/// font instance handles. It contains a unique
/// FontTemplateData structure that is platform specific.
#[derive(Clone)]
pub struct FontTemplate {
pub identifier: FontIdentifier,
pub descriptor: FontTemplateDescriptor,
/// The data to use for this [`FontTemplate`]. For web fonts, this is always filled, but
/// for local fonts, this is loaded only lazily in layout.
pub data: Option<Arc<Vec<u8>>>,
/// If this font is a web font, this is a reference to the stylesheet that
/// created it. This will be used to remove this font from caches, when the
/// stylesheet is removed.
pub stylesheet: Option<DocumentStyleSheet>,
}
impl malloc_size_of::MallocSizeOf for FontTemplate {
fn size_of(&self, ops: &mut malloc_size_of::MallocSizeOfOps) -> usize {
self.identifier.size_of(ops) +
self.descriptor.size_of(ops) +
self.data.as_ref().map_or(0, |data| (*data).size_of(ops))
}
}
impl Debug for FontTemplate {
fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
self.identifier.fmt(f)
}
}
/// Holds all of the template information for a font that
/// is common, regardless of the number of instances of
/// this font handle per thread.
impl FontTemplate {
/// Create a new [`FontTemplate`] for a system font installed locally.
pub fn new_for_local_font(
identifier: LocalFontIdentifier,
descriptor: FontTemplateDescriptor,
) -> FontTemplate {
FontTemplate {
identifier: FontIdentifier::Local(identifier),
descriptor,
data: None,
stylesheet: None,
}
}
/// Create a new [`FontTemplate`] for a `@font-family` with a `url(...)` `src` font.
pub fn new_for_remote_web_font(
url: ServoUrl,
data: Arc<Vec<u8>>,
css_font_template_descriptors: &CSSFontFaceDescriptors,
stylesheet: Option<DocumentStyleSheet>,
) -> Result<FontTemplate, &'static str> {
let identifier = FontIdentifier::Web(url.clone());
let Ok(handle) = PlatformFont::new_from_data(identifier, data.clone(), 0, None) else {
return Err("Could not initialize platform font data for: {url:?}");
};
let mut descriptor = handle.descriptor();
descriptor
.override_values_with_css_font_template_descriptors(css_font_template_descriptors);
Ok(FontTemplate {
identifier: FontIdentifier::Web(url),
descriptor,
data: Some(data),
stylesheet,
})
}
/// Create a new [`FontTemplate`] for a `@font-family` with a `local(...)` `src`. This takes in
/// the template of the local font and creates a new one that reflects the properties specified
/// by `@font-family` in the stylesheet.
pub fn new_for_local_web_font(
local_template: FontTemplateRef,
css_font_template_descriptors: &CSSFontFaceDescriptors,
stylesheet: DocumentStyleSheet,
) -> Result<FontTemplate, &'static str> {
let mut alias_template = local_template.borrow().clone();
alias_template
.descriptor
.override_values_with_css_font_template_descriptors(css_font_template_descriptors);
alias_template.stylesheet = Some(stylesheet);
Ok(alias_template)
}
pub fn identifier(&self) -> &FontIdentifier {
&self.identifier
}
/// Returns a reference to the bytes in this font if they are in memory.
/// This function never performs disk I/O.
pub fn data_if_in_memory(&self) -> Option<Arc<Vec<u8>>> {
self.data.clone()
}
}
pub trait FontTemplateRefMethods {
/// Returns a reference to the data in this font. This may be a hugely expensive
/// operation (depending on the platform) which performs synchronous disk I/O
/// and should never be done lightly.
fn data(&self) -> Arc<Vec<u8>>;
/// Get the descriptor.
fn descriptor(&self) -> FontTemplateDescriptor;
/// Get the [`FontIdentifier`] for this template.
fn identifier(&self) -> FontIdentifier;
/// Returns true if the given descriptor matches the one in this [`FontTemplate`].
fn matches_font_descriptor(&self, descriptor_to_match: &FontDescriptor) -> bool;
/// Calculate the distance from this [`FontTemplate`]s descriptor and return it
/// or None if this is not a valid [`FontTemplate`].
fn descriptor_distance(&self, descriptor_to_match: &FontDescriptor) -> f32;
/// Whether or not this character is in the unicode ranges specified in
/// this temlates `@font-face` definition, if any.
fn char_in_unicode_range(&self, character: char) -> bool;
}
impl FontTemplateRefMethods for FontTemplateRef {
fn descriptor(&self) -> FontTemplateDescriptor {
self.borrow().descriptor.clone()
}
fn identifier(&self) -> FontIdentifier {
self.borrow().identifier.clone()
}
fn matches_font_descriptor(&self, descriptor_to_match: &FontDescriptor) -> bool {
self.descriptor().matches(descriptor_to_match)
}
fn descriptor_distance(&self, descriptor_to_match: &FontDescriptor) -> f32 {
self.descriptor().distance_from(descriptor_to_match)
}
fn data(&self) -> Arc<Vec<u8>> {
if let Some(data) = self.borrow().data.clone() {
return data;
}
let mut template = self.borrow_mut();
let identifier = template.identifier.clone();
template
.data
.get_or_insert_with(|| match identifier {
FontIdentifier::Local(local_identifier) => {
Arc::new(local_identifier.read_data_from_file())
},
FontIdentifier::Web(_) => unreachable!("Web fonts should always have data."),
})
.clone()
}
fn char_in_unicode_range(&self, character: char) -> bool {
let character = character as u32;
self.borrow()
.descriptor
.unicode_range
.as_ref()
.map_or(true, |ranges| {
ranges.iter().any(|range| range.contains(&character))
})
}
}
/// A trait for implementing the CSS font matching algorithm against various font features.
/// See <https://drafts.csswg.org/css-fonts/#font-matching-algorithm>.
///
/// This implementation is ported from Gecko at:
/// <https://searchfox.org/mozilla-central/rev/0529464f0d2981347ef581f7521ace8b7af7f7ac/gfx/thebes/gfxFontUtils.h#1217>.
trait FontMatchDistanceMethod: Sized {
fn match_distance(&self, range: &(Self, Self)) -> f32;
fn to_float(&self) -> f32;
}
impl FontMatchDistanceMethod for FontStretch {
fn match_distance(&self, range: &(Self, Self)) -> f32 {
// stretch distance ==> [0,2000]
const REVERSE_DISTANCE: f32 = 1000.0;
let min_stretch = range.0;
let max_stretch = range.1;
// The stretch value is a (non-negative) percentage; currently we support
// values in the range 0 .. 1000. (If the upper limit is ever increased,
// the kReverseDistance value used here may need to be adjusted.)
// If aTargetStretch is >100, we prefer larger values if available;
// if <=100, we prefer smaller values if available.
if *self < min_stretch {
if *self > FontStretch::NORMAL {
return min_stretch.to_float() - self.to_float();
}
return (min_stretch.to_float() - self.to_float()) + REVERSE_DISTANCE;
}
if *self > max_stretch {
if *self <= FontStretch::NORMAL {
return self.to_float() - max_stretch.to_float();
}
return (self.to_float() - max_stretch.to_float()) + REVERSE_DISTANCE;
}
0.0
}
fn to_float(&self) -> f32 {
self.0.to_float()
}
}
impl FontMatchDistanceMethod for FontWeight {
// Calculate weight distance with values in the range (0..1000). In general,
// heavier weights match towards even heavier weights while lighter weights
// match towards even lighter weights. Target weight values in the range
// [400..500] are special, since they will first match up to 500, then down
// towards 0, then up again towards 999.
//
// Example: with target 600 and font weight 800, distance will be 200. With
// target 300 and font weight 600, distance will be 900, since heavier
// weights are farther away than lighter weights. If the target is 5 and the
// font weight 995, the distance would be 1590 for the same reason.
fn match_distance(&self, range: &(Self, Self)) -> f32 {
// weight distance ==> [0,1600]
const NOT_WITHIN_CENTRAL_RANGE: f32 = 100.0;
const REVERSE_DISTANCE: f32 = 600.0;
let min_weight = range.0;
let max_weight = range.1;
if *self >= min_weight && *self <= max_weight {
// Target is within the face's range, so it's a perfect match
return 0.0;
}
if *self < FontWeight::NORMAL {
// Requested a lighter-than-400 weight
if max_weight < *self {
return self.to_float() - max_weight.to_float();
}
// Add reverse-search penalty for bolder faces
return (min_weight.to_float() - self.to_float()) + REVERSE_DISTANCE;
}
if *self > FontWeight::from_float(500.) {
// Requested a bolder-than-500 weight
if min_weight > *self {
return min_weight.to_float() - self.to_float();
}
// Add reverse-search penalty for lighter faces
return (self.to_float() - max_weight.to_float()) + REVERSE_DISTANCE;
}
// Special case for requested weight in the [400..500] range
if min_weight > *self {
if min_weight <= FontWeight::from_float(500.) {
// Bolder weight up to 500 is first choice
return min_weight.to_float() - self.to_float();
}
// Other bolder weights get a reverse-search penalty
return (min_weight.to_float() - self.to_float()) + REVERSE_DISTANCE;
}
// Lighter weights are not as good as bolder ones within [400..500]
(self.to_float() - max_weight.to_float()) + NOT_WITHIN_CENTRAL_RANGE
}
fn to_float(&self) -> f32 {
self.value()
}
}
impl FontMatchDistanceMethod for FontStyle {
fn match_distance(&self, range: &(Self, Self)) -> f32 {
// style distance ==> [0,500]
let min_style = range.0;
if *self == min_style {
return 0.0; // styles match exactly ==> 0
}
// bias added to angle difference when searching in the non-preferred
// direction from a target angle
const REVERSE: f32 = 100.0;
// bias added when we've crossed from positive to negative angles or
// vice versa
const NEGATE: f32 = 200.0;
if *self == FontStyle::NORMAL {
if min_style.is_oblique() {
// to distinguish oblique 0deg from normal, we add 1.0 to the angle
let min_angle = min_style.oblique_degrees();
if min_angle >= 0.0 {
return 1.0 + min_angle;
}
let max_style = range.1;
let max_angle = max_style.oblique_degrees();
if max_angle >= 0.0 {
// [min,max] range includes 0.0, so just return our minimum
return 1.0;
}
// negative oblique is even worse than italic
return NEGATE - max_angle;
}
// must be italic, which is worse than any non-negative oblique;
// treat as a match in the wrong search direction
assert!(min_style == FontStyle::ITALIC);
return REVERSE;
}
let default_oblique_angle = FontStyle::OBLIQUE.oblique_degrees();
if *self == FontStyle::ITALIC {
if min_style.is_oblique() {
let min_angle = min_style.oblique_degrees();
if min_angle >= default_oblique_angle {
return 1.0 + (min_angle - default_oblique_angle);
}
let max_style = range.1;
let max_angle = max_style.oblique_degrees();
if max_angle >= default_oblique_angle {
return 1.0;
}
if max_angle > 0.0 {
// wrong direction but still > 0, add bias of 100
return REVERSE + (default_oblique_angle - max_angle);
}
// negative oblique angle, add bias of 300
return REVERSE + NEGATE + (default_oblique_angle - max_angle);
}
// normal is worse than oblique > 0, but better than oblique <= 0
assert!(min_style == FontStyle::NORMAL);
return NEGATE;
}
// target is oblique <angle>: four different cases depending on
// the value of the <angle>, which determines the preferred direction
// of search
let target_angle = self.oblique_degrees();
if target_angle >= default_oblique_angle {
if min_style.is_oblique() {
let min_angle = min_style.oblique_degrees();
if min_angle >= target_angle {
return min_angle - target_angle;
}
let max_style = range.1;
let max_angle = max_style.oblique_degrees();
if max_angle >= target_angle {
return 0.0;
}
if max_angle > 0.0 {
return REVERSE + (target_angle - max_angle);
}
return REVERSE + NEGATE + (target_angle - max_angle);
}
if min_style == FontStyle::ITALIC {
return REVERSE + NEGATE;
}
return REVERSE + NEGATE + 1.0;
}
if target_angle <= -default_oblique_angle {
if min_style.is_oblique() {
let max_style = range.1;
let max_angle = max_style.oblique_degrees();
if max_angle <= target_angle {
return target_angle - max_angle;
}
let min_angle = min_style.oblique_degrees();
if min_angle <= target_angle {
return 0.0;
}
if min_angle < 0.0 {
return REVERSE + (min_angle - target_angle);
}
return REVERSE + NEGATE + (min_angle - target_angle);
}
if min_style == FontStyle::ITALIC {
return REVERSE + NEGATE;
}
return REVERSE + NEGATE + 1.0;
}
if target_angle >= 0.0 {
if min_style.is_oblique() {
let min_angle = min_style.oblique_degrees();
if min_angle > target_angle {
return REVERSE + (min_angle - target_angle);
}
let max_style = range.1;
let max_angle = max_style.oblique_degrees();
if max_angle >= target_angle {
return 0.0;
}
if max_angle > 0.0 {
return target_angle - max_angle;
}
return REVERSE + NEGATE + (target_angle - max_angle);
}
if min_style == FontStyle::ITALIC {
return REVERSE + NEGATE - 2.0;
}
return REVERSE + NEGATE - 1.0;
}
// last case: (targetAngle < 0.0 && targetAngle > kDefaultAngle)
if min_style.is_oblique() {
let max_style = range.1;
let max_angle = max_style.oblique_degrees();
if max_angle < target_angle {
return REVERSE + (target_angle - max_angle);
}
let min_angle = min_style.oblique_degrees();
if min_angle <= target_angle {
return 0.0;
}
if min_angle < 0.0 {
return min_angle - target_angle;
}
return REVERSE + NEGATE + (min_angle - target_angle);
}
if min_style == FontStyle::ITALIC {
return REVERSE + NEGATE - 2.0;
}
REVERSE + NEGATE - 1.0
}
fn to_float(&self) -> f32 {
unimplemented!("Don't know how to convert FontStyle to float.");
}
}
pub(crate) trait IsOblique {
fn is_oblique(&self) -> bool;
}
impl IsOblique for FontStyle {
fn is_oblique(&self) -> bool {
*self != FontStyle::NORMAL && *self != FontStyle::ITALIC
}
}