Use system fonts for fallback

examples/text/src/font/system.rs

@@ -1,22 +1,71 @@
+use std::ops::Deref;
+
 use super::{Font, FontMatches};
 
-pub struct FontSystem<'a> {
-    fonts: Vec<Font<'a>>,
+pub struct FontSystem {
+    db: fontdb::Database,
 }
 
-impl<'a> FontSystem<'a> {
+impl FontSystem {
     pub fn new() -> Self {
+        let mut db = fontdb::Database::new();
+        let now = std::time::Instant::now();
+        db.load_system_fonts();
+        //TODO: configurable default fonts
+        db.set_monospace_family("Fira Mono");
+        db.set_sans_serif_family("Fira Sans");
+        db.set_serif_family("DejaVu Serif");
+        println!(
+            "Loaded {} font faces in {}ms.",
+            db.len(),
+            now.elapsed().as_millis()
+        );
+
+        //TODO only do this on demand!
+        assert_eq!(db.len(), db.faces().len());
+        for i in 0..db.len() {
+            let id = db.faces()[i].id;
+            unsafe {
+                db.make_shared_face_data(id);
+            }
+        }
+
         Self {
-            fonts: Vec::new(),
+            db,
         }
     }
 
-    pub fn add(&mut self, font: Font<'a>) {
-        self.fonts.push(font);
-    }
-
-    pub fn matches(&'a self, patterns: &[&str]) -> Option<FontMatches<'a>> {
+    pub fn matches<'a, F: Fn(&fontdb::FaceInfo) -> bool>(&'a self, f: F) -> Option<FontMatches<'a>> {
         let mut fonts = Vec::new();
+        for face in self.db.faces() {
+            if ! f(face) {
+                continue;
+            }
+
+            let font_opt = Font::new(
+                match &face.source {
+                    fontdb::Source::Binary(data) => {
+                        data.deref().as_ref()
+                    },
+                    fontdb::Source::File(path) => {
+                        println!("Unsupported fontdb Source::File('{}')", path.display());
+                        continue;
+                    },
+                    fontdb::Source::SharedFile(_path, data) => {
+                        data.deref().as_ref()
+                    },
+                },
+                face.index,
+            );
+
+            match font_opt {
+                Some(font) => fonts.push(font),
+                None => {
+                    eprintln!("failed to load font '{}'", face.post_script_name);
+                }
+            }
+        }
+        /*
         for font in self.fonts.iter() {
             for rec in font.rustybuzz.names() {
                 if rec.name_id == 4 && rec.is_unicode() {
@@ -52,6 +101,7 @@ impl<'a> FontSystem<'a> {
                 }
             }
         }
+        */
         if ! fonts.is_empty() {
             Some(FontMatches {
                 fonts