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Add basic language and script fallback for the Android backend. #29

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merged 1 commit into from
Apr 19, 2024
Merged

Add basic language and script fallback for the Android backend. #29

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96 changes: 88 additions & 8 deletions src/fontique/backend/android.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,10 +4,11 @@
use std::{path::Path, str::FromStr, sync::Arc};

use hashbrown::HashMap;
use roxmltree::Document;
use icu_locid::LanguageIdentifier;
use roxmltree::{Document, Node};

use super::{
scan, FallbackKey, FamilyId, FamilyInfo, FamilyNameMap, GenericFamily, GenericFamilyMap,
scan, FallbackKey, FamilyId, FamilyInfo, FamilyNameMap, GenericFamily, GenericFamilyMap, Script,
};

// TODO: Use actual generic families here, where available, when fonts.xml is properly parsed.
Expand All @@ -33,6 +34,8 @@ pub struct SystemFonts {
pub name_map: Arc<FamilyNameMap>,
pub generic_families: Arc<GenericFamilyMap>,
family_map: HashMap<FamilyId, FamilyInfo>,
locale_fallback: Box<[(Box<str>, FamilyId)]>,
script_fallback: Box<[(Script, FamilyId)]>,
}

impl SystemFonts {
Expand All @@ -42,6 +45,7 @@ impl SystemFonts {
let scan::ScannedCollection {
family_names: mut name_map,
families: family_map,
postscript_names,
..
} = scan::ScannedCollection::from_paths(Path::new(&android_root).join("fonts").to_str(), 8);
let mut generic_families = GenericFamilyMap::default();
Expand All @@ -55,6 +59,9 @@ impl SystemFonts {
);
}

let mut locale_fallback = vec![];
let mut script_fallback = vec![];

// Try to get generic info from fonts.xml
if let Ok(s) = std::fs::read_to_string(Path::new(&android_root).join("etc/fonts.xml")) {
if let Ok(doc) = Document::parse(s.clone().as_str()) {
Expand Down Expand Up @@ -90,11 +97,62 @@ impl SystemFonts {
// smarter, or something dumb that meets expecta­
// tions on Android.
}
} else if let Some(_langs) = child
} else if let Some(langs) = child
.attribute("lang")
.map(|s| s.split(',').collect::<Vec<&str>>())
{
// TODO: implement language fallback "family" elements
let (_has_for, hasnt_for): (Vec<Node>, Vec<Node>) = child
.children()
.partition(|c| c.attribute("fallbackFor").is_some());
{
// general fallback families
let (ps_named, _ps_unnamed): (Vec<Node>, Vec<Node>) =
hasnt_for.iter().partition(|c| {
c.attribute("postScriptName").is_some()
});

if let Some(family) = ps_named.iter().find_map(|x| {
postscript_names
.get(x.attribute("postScriptName").unwrap())
}) {
for lang in langs {
if let Some(scr) = lang.strip_prefix("und-") {
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// Undefined lang for script-only fallbacks
script_fallback.push((scr.into(), *family));
} else if let Ok(locale) =
LanguageIdentifier::try_from_bytes(
lang.as_bytes(),
)
{
if let Some(scr) = locale.script {
// Also fallback for the script on its own
script_fallback
.push((scr.as_str().into(), *family));
if "Hant" == scr.as_str() {
// This works around ambiguous han char­
// acters going unmapped with current
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// fallback code. This should be done in
// a locale-dependent manner, since that
// is the norm.
script_fallback
.push(("Hani".into(), *family));
}
}
locale_fallback
.push((locale.to_string().into(), *family));
}
}
}

// TODO: handle mapping to family names from file names
// when postScriptName is unavailable.
}

// family-specific fallback families, currently unimplemented
// because it requires a GenericFamily to be plumbed through
// the `RangedStyle` `font_stack` from `resolve` where it is
// currently thrown away.
{}
}
// TODO: interpret variant="compact" without fallbackFor as a
// fallback for system-ui, as falling back to a
Expand All @@ -112,15 +170,37 @@ impl SystemFonts {
name_map: Arc::new(name_map),
generic_families: Arc::new(generic_families),
family_map,
locale_fallback: locale_fallback.into(),
script_fallback: script_fallback.into(),
}
}

pub fn family(&mut self, id: FamilyId) -> Option<FamilyInfo> {
pub fn family(&self, id: FamilyId) -> Option<FamilyInfo> {
self.family_map.get(&id).cloned()
}

pub fn fallback(&mut self, _key: impl Into<FallbackKey>) -> Option<FamilyId> {
// FIXME: This is a stub
Some(self.generic_families.get(GenericFamily::SansSerif)[0])
pub fn fallback(&self, key: impl Into<FallbackKey>) -> Option<FamilyId> {
let key: FallbackKey = key.into();
let script = key.script();

key.locale()
.and_then(|li| {
self.locale_fallback
.iter()
.find(|(lid, _)| li == lid.as_ref())
.map(|(_, fid)| *fid)
})
.or_else(|| {
self.script_fallback
.iter()
.find(|(s, _)| script == *s)
.map(|(_, fid)| *fid)
})
.or_else(|| {
self.generic_families
.get(GenericFamily::SansSerif)
.first()
.copied()
})
}
}
2 changes: 2 additions & 0 deletions src/fontique/collection/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -352,6 +352,8 @@ impl Inner {
if let Some(families) = self.data.fallbacks.get(selector) {
self.fallback_cache.set(script, lang_key, families);
} else if let Some(system) = self.system.as_ref() {
// Some platforms don't need mut System
#[allow(unused_mut)]
let mut system = system.fonts.lock().unwrap();
if let Some(family) = system.fallback(selector) {
self.data.fallbacks.set(selector, core::iter::once(family));
Expand Down