From d297a6a48a87d2c63266be21993dca1e61f2b4f5 Mon Sep 17 00:00:00 2001
From: Edgar Geier <geieredgar@gmail.com>
Date: Tue, 14 Mar 2023 00:39:50 +0100
Subject: [PATCH] Call `get_font` lazily

---
 src/font/fallback/mod.rs  | 96 +++++++++++++++++++++++++--------------
 src/font/mod.rs           | 52 ++++++---------------
 src/font/system/no_std.rs | 20 ++++----
 src/font/system/std.rs    | 10 ++--
 src/shape.rs              | 18 ++++----
 5 files changed, 97 insertions(+), 99 deletions(-)

diff --git a/src/font/fallback/mod.rs b/src/font/fallback/mod.rs
index 5cbeb8f..410dfac 100644
--- a/src/font/fallback/mod.rs
+++ b/src/font/fallback/mod.rs
@@ -3,9 +3,10 @@
 use alloc::sync::Arc;
 #[cfg(not(feature = "std"))]
 use alloc::vec::Vec;
+use fontdb::Family;
 use unicode_script::Script;
 
-use crate::Font;
+use crate::{Font, FontSystem};
 
 use self::platform::*;
 
@@ -26,11 +27,11 @@ mod platform;
 mod platform;
 
 pub struct FontFallbackIter<'a> {
-    fonts: &'a [Arc<Font>],
-    default_families: &'a [&'a str],
+    font_system: &'a mut FontSystem,
+    font_ids: &'a [fontdb::ID],
+    default_families: &'a [&'a Family<'a>],
     default_i: usize,
     scripts: Vec<Script>,
-    locale: &'a str,
     script_i: (usize, usize),
     common_i: usize,
     other_i: usize,
@@ -39,17 +40,17 @@ pub struct FontFallbackIter<'a> {
 
 impl<'a> FontFallbackIter<'a> {
     pub fn new(
-        fonts: &'a [Arc<Font>],
-        default_families: &'a [&'a str],
+        font_system: &'a mut FontSystem,
+        font_ids: &'a [fontdb::ID],
+        default_families: &'a [&'a Family<'a>],
         scripts: Vec<Script>,
-        locale: &'a str,
     ) -> Self {
         Self {
-            fonts,
+            font_system,
+            font_ids,
             default_families,
             default_i: 0,
             scripts,
-            locale,
             script_i: (0, 0),
             common_i: 0,
             other_i: 0,
@@ -57,21 +58,20 @@ impl<'a> FontFallbackIter<'a> {
         }
     }
 
-    pub fn check_missing(&self, word: &str) {
+    pub fn check_missing(&mut self, word: &str) {
         if self.end {
             log::debug!(
                 "Failed to find any fallback for {:?} locale '{}': '{}'",
                 self.scripts,
-                self.locale,
+                self.font_system.locale(),
                 word
             );
         } else if self.other_i > 0 {
-            let font = &self.fonts[self.other_i - 1];
             log::debug!(
                 "Failed to find preset fallback for {:?} locale '{}', used '{}': '{}'",
                 self.scripts,
-                self.locale,
-                font.name(),
+                self.font_system.locale(),
+                self.face_name(self.font_ids[self.other_i - 1]),
                 word
             );
         } else if !self.scripts.is_empty() && self.common_i > 0 {
@@ -79,24 +79,48 @@ impl<'a> FontFallbackIter<'a> {
             log::debug!(
                 "Failed to find script fallback for {:?} locale '{}', used '{}': '{}'",
                 self.scripts,
-                self.locale,
+                self.font_system.locale(),
                 family,
                 word
             );
         }
     }
+
+    pub fn face_name(&self, id: fontdb::ID) -> &str {
+        if let Some(face) = self.font_system.db().face(id) {
+            if let Some((name, _)) = face.families.first() {
+                name
+            } else {
+                &face.post_script_name
+            }
+        } else {
+            "invalid font id"
+        }
+    }
+
+    fn face_contains_family(&self, id: fontdb::ID, family_name: &str) -> bool {
+        if let Some(face) = self.font_system.db().face(id) {
+            face.families.iter().any(|(name, _)| name == family_name)
+        } else {
+            false
+        }
+    }
 }
 
 impl<'a> Iterator for FontFallbackIter<'a> {
-    type Item = &'a Arc<Font>;
+    type Item = Arc<Font>;
     fn next(&mut self) -> Option<Self::Item> {
         while self.default_i < self.default_families.len() {
-            let default_family = self.default_families[self.default_i];
             self.default_i += 1;
-
-            for font in self.fonts.iter() {
-                if font.contains_family(default_family) {
-                    return Some(font);
+            for id in self.font_ids.iter() {
+                let default_family = self
+                    .font_system
+                    .db()
+                    .family_name(self.default_families[self.default_i - 1]);
+                if self.face_contains_family(*id, default_family) {
+                    if let Some(font) = self.font_system.get_font(*id) {
+                        return Some(font);
+                    }
                 }
             }
         }
@@ -104,20 +128,22 @@ impl<'a> Iterator for FontFallbackIter<'a> {
         while self.script_i.0 < self.scripts.len() {
             let script = self.scripts[self.script_i.0];
 
-            let script_families = script_fallback(script, self.locale);
+            let script_families = script_fallback(script, self.font_system.locale());
             while self.script_i.1 < script_families.len() {
                 let script_family = script_families[self.script_i.1];
                 self.script_i.1 += 1;
-                for font in self.fonts.iter() {
-                    if font.contains_family(script_family) {
-                        return Some(font);
+                for id in self.font_ids.iter() {
+                    if self.face_contains_family(*id, script_family) {
+                        if let Some(font) = self.font_system.get_font(*id) {
+                            return Some(font);
+                        }
                     }
                 }
                 log::debug!(
                     "failed to find family '{}' for script {:?} and locale '{}'",
                     script_family,
                     script,
-                    self.locale
+                    self.font_system.locale(),
                 );
             }
 
@@ -129,9 +155,11 @@ impl<'a> Iterator for FontFallbackIter<'a> {
         while self.common_i < common_families.len() {
             let common_family = common_families[self.common_i];
             self.common_i += 1;
-            for font in self.fonts.iter() {
-                if font.contains_family(common_family) {
-                    return Some(font);
+            for id in self.font_ids.iter() {
+                if self.face_contains_family(*id, common_family) {
+                    if let Some(font) = self.font_system.get_font(*id) {
+                        return Some(font);
+                    }
                 }
             }
             log::debug!("failed to find family '{}'", common_family);
@@ -140,14 +168,16 @@ impl<'a> Iterator for FontFallbackIter<'a> {
         //TODO: do we need to do this?
         //TODO: do not evaluate fonts more than once!
         let forbidden_families = forbidden_fallback();
-        while self.other_i < self.fonts.len() {
-            let font = &self.fonts[self.other_i];
+        while self.other_i < self.font_ids.len() {
+            let id = self.font_ids[self.other_i];
             self.other_i += 1;
             if forbidden_families
                 .iter()
-                .all(|family| !font.contains_family(family))
+                .all(|family_name| !self.face_contains_family(id, family_name))
             {
-                return Some(font);
+                if let Some(font) = self.font_system.get_font(id) {
+                    return Some(font);
+                }
             }
         }
 
diff --git a/src/font/mod.rs b/src/font/mod.rs
index 56cdee8..ea7b9be 100644
--- a/src/font/mod.rs
+++ b/src/font/mod.rs
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 pub(crate) mod fallback;
 
-use fontdb::FaceInfo;
+use alloc::sync::Arc;
 
 pub use self::system::*;
 mod system;
@@ -12,8 +12,9 @@ pub struct Font(FontInner);
 #[ouroboros::self_referencing]
 #[allow(dead_code)]
 struct FontInner {
-    info: fontdb::FaceInfo,
-    #[borrows(info)]
+    id: fontdb::ID,
+    data: Arc<dyn AsRef<[u8]> + Send + Sync>,
+    #[borrows(data)]
     #[covariant]
     rustybuzz: rustybuzz::Face<'this>,
     // workaround, since ouroboros does not work with #[cfg(feature = "swash")]
@@ -30,18 +31,18 @@ impl Font {
     pub fn new(info: &fontdb::FaceInfo) -> Option<Self> {
         #[allow(unused_variables)]
         let data = match &info.source {
-            fontdb::Source::Binary(data) => (**data).as_ref(),
+            fontdb::Source::Binary(data) => Arc::clone(data),
             #[cfg(feature = "std")]
             fontdb::Source::File(path) => {
                 log::warn!("Unsupported fontdb Source::File('{}')", path.display());
                 return None;
             }
             #[cfg(feature = "std")]
-            fontdb::Source::SharedFile(_path, data) => (**data).as_ref(),
+            fontdb::Source::SharedFile(_path, data) => Arc::clone(data),
         };
         Some(Self(
             FontInnerTryBuilder {
-                info: info.clone(),
+                id: info.id,
                 swash: {
                     #[cfg(feature = "swash")]
                     let swash = {
@@ -53,8 +54,9 @@ impl Font {
                     let swash = ();
                     swash
                 },
-                rustybuzz_builder: |info| {
-                    rustybuzz::Face::from_slice(get_data(info), info.index).ok_or(())
+                data,
+                rustybuzz_builder: |data| {
+                    rustybuzz::Face::from_slice((**data).as_ref(), info.index).ok_or(())
                 },
             }
             .try_build()
@@ -62,36 +64,23 @@ impl Font {
         ))
     }
 
-    pub fn info(&self) -> &FaceInfo {
-        self.0.borrow_info()
+    pub fn id(&self) -> fontdb::ID {
+        *self.0.borrow_id()
     }
 
     pub fn data(&self) -> &[u8] {
-        get_data(self.0.borrow_info())
+        (**self.0.borrow_data()).as_ref()
     }
 
     pub fn rustybuzz(&self) -> &rustybuzz::Face {
         self.0.borrow_rustybuzz()
     }
 
-    pub fn name(&self) -> &str {
-        if let Some((name, _)) = self.info().families.first() {
-            name
-        } else {
-            &self.info().post_script_name
-        }
-    }
-
-    pub fn contains_family(&self, family: &str) -> bool {
-        self.info().families.iter().any(|(name, _)| name == family)
-    }
-
     #[cfg(feature = "swash")]
     pub fn as_swash(&self) -> swash::FontRef {
-        let info = self.0.borrow_info();
         let swash = self.0.borrow_swash();
         swash::FontRef {
-            data: get_data(info),
+            data: self.data(),
             offset: swash.0,
             key: swash.1,
         }
@@ -104,16 +93,3 @@ impl Font {
         self.0.borrow_swash();
     }
 }
-
-fn get_data(info: &FaceInfo) -> &[u8] {
-    match &info.source {
-        fontdb::Source::Binary(data) => (**data).as_ref(),
-        #[cfg(feature = "std")]
-        fontdb::Source::File(path) => {
-            // This should never happen, because `Font::new` verified the source isn't a file
-            panic!("Unsupported fontdb Source::File('{}')", path.display());
-        }
-        #[cfg(feature = "std")]
-        fontdb::Source::SharedFile(_path, data) => (**data).as_ref(),
-    }
-}
diff --git a/src/font/system/no_std.rs b/src/font/system/no_std.rs
index 28c9459..e4078b1 100644
--- a/src/font/system/no_std.rs
+++ b/src/font/system/no_std.rs
@@ -51,19 +51,15 @@ impl FontSystem {
         get_font(&self.db, id)
     }
 
-    pub fn get_font_matches(&mut self, attrs: Attrs) -> Arc<Vec<Arc<Font>>> {
-        let mut fonts = Vec::new();
-        for face in self.db.faces() {
-            if !attrs.matches(face) {
-                continue;
-            }
+    pub fn get_font_matches(&mut self, attrs: Attrs) -> Arc<Vec<fontdb::ID>> {
+        let ids = self
+            .db
+            .faces()
+            .filter(|face| attrs.matches(face))
+            .map(|face| face.id)
+            .collect::<Vec<_>>();
 
-            if let Some(font) = get_font(&self.db, face.id) {
-                fonts.push(font);
-            }
-        }
-
-        Arc::new(fonts)
+        Arc::new(ids)
     }
 }
 
diff --git a/src/font/system/std.rs b/src/font/system/std.rs
index 6f0d08a..eb87bd8 100644
--- a/src/font/system/std.rs
+++ b/src/font/system/std.rs
@@ -9,7 +9,7 @@ pub struct FontSystem {
     locale: String,
     db: fontdb::Database,
     font_cache: HashMap<fontdb::ID, Option<Arc<Font>>>,
-    font_matches_cache: HashMap<AttrsOwned, Arc<Vec<Arc<Font>>>>,
+    font_matches_cache: HashMap<AttrsOwned, Arc<Vec<fontdb::ID>>>,
 }
 
 impl FontSystem {
@@ -92,7 +92,7 @@ impl FontSystem {
         get_font(&mut self.font_cache, &mut self.db, id)
     }
 
-    pub fn get_font_matches(&mut self, attrs: Attrs) -> Arc<Vec<Arc<Font>>> {
+    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))
@@ -106,10 +106,6 @@ impl FontSystem {
                     .filter(|face| attrs.matches(face))
                     .map(|face| face.id)
                     .collect::<Vec<_>>();
-                let fonts = ids
-                    .into_iter()
-                    .filter_map(|id| get_font(&mut self.font_cache, &mut self.db, id))
-                    .collect();
 
                 #[cfg(not(target_arch = "wasm32"))]
                 {
@@ -117,7 +113,7 @@ impl FontSystem {
                     log::debug!("font matches for {:?} in {:?}", attrs, elapsed);
                 }
 
-                Arc::new(fonts)
+                Arc::new(ids)
             })
             .clone()
     }
diff --git a/src/shape.rs b/src/shape.rs
index dae7bc5..b685501 100644
--- a/src/shape.rs
+++ b/src/shape.rs
@@ -62,7 +62,7 @@ fn shape_fallback(
             y_advance,
             x_offset,
             y_offset,
-            font_id: font.info().id,
+            font_id: font.id(),
             glyph_id: info.glyph_id.try_into().expect("failed to cast glyph ID"),
             //TODO: color should not be related to shaping
             color_opt: attrs.color_opt,
@@ -125,16 +125,13 @@ fn shape_run(
 
     let fonts = font_system.get_font_matches(attrs);
 
-    let db = font_system.db();
-
-    let default_families = [db.family_name(&attrs.family)];
-    let mut font_iter =
-        FontFallbackIter::new(&fonts, &default_families, scripts, font_system.locale());
+    let default_families = [&attrs.family];
+    let mut font_iter = FontFallbackIter::new(font_system, &fonts, &default_families, scripts);
 
     let font = font_iter.next().expect("no default font found");
 
     let (mut glyphs, mut missing) =
-        shape_fallback(font, line, attrs_list, start_run, end_run, span_rtl);
+        shape_fallback(&font, line, attrs_list, start_run, end_run, span_rtl);
 
     //TODO: improve performance!
     while !missing.is_empty() {
@@ -143,9 +140,12 @@ fn shape_run(
             None => break,
         };
 
-        log::trace!("Evaluating fallback with font '{}'", font.name());
+        log::trace!(
+            "Evaluating fallback with font '{}'",
+            font_iter.face_name(font.id())
+        );
         let (mut fb_glyphs, fb_missing) =
-            shape_fallback(font, line, attrs_list, start_run, end_run, span_rtl);
+            shape_fallback(&font, line, attrs_list, start_run, end_run, span_rtl);
 
         // Insert all matching glyphs
         let mut fb_i = 0;