Unify the no_std and std impls of FontSystem

Cargo.toml

@@ -21,6 +21,8 @@ unicode-linebreak = "0.1.4"
 unicode-script = "0.5.5"
 unicode-segmentation = "1.10.0"
 rangemap = "1.2.0"
+hashbrown = { version = "0.14.0", default-features = false }
+rustc-hash = { version = "1.1.0", default-features = false }
 
 [dependencies.unicode-bidi]
 version = "0.3.8"

src/font/system.rs

@@ -0,0 +1,207 @@
+use crate::{Attrs, AttrsOwned, Font};
+use alloc::string::String;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+use core::fmt;
+use core::hash::BuildHasherDefault;
+use core::ops::{Deref, DerefMut};
+
+type HashMap<K, V> = hashbrown::HashMap<K, V, BuildHasherDefault<rustc_hash::FxHasher>>;
+
+// re-export fontdb and rustybuzz
+pub use fontdb;
+pub use rustybuzz;
+
+/// Access to the system fonts.
+pub struct FontSystem {
+    /// The locale of the system.
+    locale: String,
+
+    /// The underlying font database.
+    db: fontdb::Database,
+
+    /// Cache for loaded fonts from the database.
+    font_cache: HashMap<fontdb::ID, Option<Arc<Font>>>,
+
+    /// Cache for font matches.
+    font_matches_cache: HashMap<AttrsOwned, Arc<Vec<fontdb::ID>>>,
+}
+
+impl fmt::Debug for FontSystem {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("FontSystem")
+            .field("locale", &self.locale)
+            .field("db", &self.db)
+            .finish()
+    }
+}
+
+impl FontSystem {
+    /// Create a new [`FontSystem`], that allows access to any installed system fonts
+    ///
+    /// # Timing
+    ///
+    /// This function takes some time to run. On the release build, it can take up to a second,
+    /// while debug builds can take up to ten times longer. For this reason, it should only be
+    /// called once, and the resulting [`FontSystem`] should be shared.
+    pub fn new() -> Self {
+        Self::new_with_fonts(core::iter::empty())
+    }
+
+    /// Create a new [`FontSystem`] with a pre-specified set of fonts.
+    pub fn new_with_fonts(fonts: impl IntoIterator<Item = fontdb::Source>) -> Self {
+        let locale = Self::get_locale();
+        log::debug!("Locale: {}", locale);
+
+        let mut db = fontdb::Database::new();
+        Self::load_fonts(&mut db, fonts.into_iter());
+
+        //TODO: configurable default fonts
+        db.set_monospace_family("Fira Mono");
+        db.set_sans_serif_family("Fira Sans");
+        db.set_serif_family("DejaVu Serif");
+
+        Self::new_with_locale_and_db(locale, db)
+    }
+
+    /// Create a new [`FontSystem`] with a pre-specified locale and font database.
+    pub fn new_with_locale_and_db(locale: String, db: fontdb::Database) -> Self {
+        Self {
+            locale,
+            db,
+            font_cache: HashMap::default(),
+            font_matches_cache: HashMap::default(),
+        }
+    }
+
+    /// Get the locale.
+    pub fn locale(&self) -> &str {
+        &self.locale
+    }
+
+    /// Get the database.
+    pub fn db(&self) -> &fontdb::Database {
+        &self.db
+    }
+
+    /// Get a mutable reference to the database.
+    pub fn db_mut(&mut self) -> &mut fontdb::Database {
+        self.font_matches_cache.clear();
+        &mut self.db
+    }
+
+    /// Consume this [`FontSystem`] and return the locale and database.
+    pub fn into_locale_and_db(self) -> (String, fontdb::Database) {
+        (self.locale, self.db)
+    }
+
+    /// Get a font by its ID.
+    pub fn get_font(&mut self, id: fontdb::ID) -> Option<Arc<Font>> {
+        self.font_cache
+            .entry(id)
+            .or_insert_with(|| {
+                #[cfg(feature = "std")]
+                unsafe {
+                    self.db.make_shared_face_data(id);
+                }
+                let face = self.db.face(id)?;
+                match Font::new(face) {
+                    Some(font) => Some(Arc::new(font)),
+                    None => {
+                        log::warn!("failed to load font '{}'", face.post_script_name);
+                        None
+                    }
+                }
+            })
+            .clone()
+    }
+
+    pub fn get_font_matches(&mut self, attrs: Attrs<'_>) -> Arc<Vec<fontdb::ID>> {
+        self.font_matches_cache
+            //TODO: do not create AttrsOwned unless entry does not already exist
+            .entry(AttrsOwned::new(attrs))
+            .or_insert_with(|| {
+                #[cfg(all(feature = "std", not(target_arch = "wasm32")))]
+                let now = std::time::Instant::now();
+
+                let ids = self
+                    .db
+                    .faces()
+                    .filter(|face| attrs.matches(face))
+                    .map(|face| face.id)
+                    .collect::<Vec<_>>();
+
+                #[cfg(all(feature = "std", not(target_arch = "wasm32")))]
+                {
+                    let elapsed = now.elapsed();
+                    log::debug!("font matches for {:?} in {:?}", attrs, elapsed);
+                }
+
+                Arc::new(ids)
+            })
+            .clone()
+    }
+
+    #[cfg(feature = "std")]
+    fn get_locale() -> String {
+        sys_locale::get_locale().unwrap_or_else(|| {
+            log::warn!("failed to get system locale, falling back to en-US");
+            String::from("en-US")
+        })
+    }
+
+    #[cfg(not(feature = "std"))]
+    fn get_locale() -> String {
+        String::from("en-US")
+    }
+
+    #[cfg(feature = "std")]
+    fn load_fonts(db: &mut fontdb::Database, fonts: impl Iterator<Item = fontdb::Source>) {
+        #[cfg(not(target_arch = "wasm32"))]
+        let now = std::time::Instant::now();
+
+        #[cfg(target_os = "redox")]
+        db.load_fonts_dir("/ui/fonts");
+
+        db.load_system_fonts();
+
+        for source in fonts {
+            db.load_font_source(source);
+        }
+
+        #[cfg(not(target_arch = "wasm32"))]
+        log::info!(
+            "Parsed {} font faces in {}ms.",
+            db.len(),
+            now.elapsed().as_millis()
+        );
+    }
+
+    #[cfg(not(feature = "std"))]
+    fn load_fonts(db: &mut fontdb::Database, fonts: impl Iterator<Item = fontdb::Source>) {
+        for source in fonts {
+            db.load_font_source(source);
+        }
+    }
+}
+
+/// A value borrowed together with an [`FontSystem`]
+#[derive(Debug)]
+pub struct BorrowedWithFontSystem<'a, T> {
+    pub(crate) inner: &'a mut T,
+    pub(crate) font_system: &'a mut FontSystem,
+}
+
+impl<'a, T> Deref for BorrowedWithFontSystem<'a, T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        self.inner
+    }
+}
+
+impl<'a, T> DerefMut for BorrowedWithFontSystem<'a, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.inner
+    }
+}