Add default_fonts feature: Turn off if you use your own fonts

egui/Cargo.toml

@@ -20,7 +20,7 @@ include = [
 
 [dependencies]
 ahash = { version = "0.6", features = ["std"], default-features = false }
-atomic_refcell = { version = "0.1", optional = true } # Used instead of parking_lot when you are always using Egui in a single thread. About as fast as parking_lot.
+atomic_refcell = { version = "0.1", optional = true } # Used instead of parking_lot when you are always using Egui in a single thread. About as fast as parking_lot. Panics on multi-threaded use of egui::Context.
 parking_lot = { version = "0.11", optional = true } # Using parking_lot over std::sync::Mutex gives 50% speedups in some real-world scenarios
 rusttype = "0.9"
 serde = { version = "1", features = ["derive"], optional = true }
@@ -30,8 +30,14 @@ serde_json = { version = "1", optional = true }
 criterion = { version = "0.3", default-features = false }
 
 [features]
-default = ["atomic_refcell"]  # Using the same egui::Context from multiple threads will result in a panic.
+default = ["atomic_refcell", "default_fonts"]
-multi_threaded = ["parking_lot"] # Only needed if you plan to use the same egui::Context from multiple threads.
+
+# If set, egui will use `include_bytes!` to bundle some fonts.
+# If you plan on specifying your own fonts you may disable this feature.
+default_fonts = []
+
+# Only needed if you plan to use the same egui::Context from multiple threads.
+multi_threaded = ["parking_lot"]
 
 [[bench]]
 name = "benchmark"

egui/src/paint/font.rs

@@ -142,6 +142,7 @@ type FontIndex = usize;
 
 // TODO: rename?
 /// Wrapper over multiple `FontImpl` (e.g. a primary + fallbacks for emojis)
+#[derive(Default)]
 pub struct Font {
     fonts: Vec<Arc<FontImpl>>,
     replacement_glyph: (FontIndex, GlyphInfo),
@@ -152,7 +153,10 @@ pub struct Font {
 
 impl Font {
     pub fn new(fonts: Vec<Arc<FontImpl>>) -> Self {
-        assert!(!fonts.is_empty());
+        if fonts.is_empty() {
+            return Default::default();
+        }
+
         let pixels_per_point = fonts[0].pixels_per_point();
         let row_height = fonts[0].row_height();
 
@@ -239,6 +243,7 @@ impl Font {
         let mut last_glyph_id = None;
 
         for c in text.chars() {
+            if !self.fonts.is_empty() {
                 let (font_index, glyph_info) = self.glyph_info(c);
                 let font_impl = &self.fonts[font_index];
 
@@ -248,6 +253,7 @@ impl Font {
                 cursor_x_in_points += glyph_info.advance_width;
                 cursor_x_in_points = self.round_to_pixel(cursor_x_in_points);
                 last_glyph_id = Some(glyph_info.id);
+            }
 
             x_offsets.push(cursor_x_in_points);
         }

egui/src/paint/fonts.rs

@@ -89,7 +89,15 @@ impl Default for FontDefinitions {
 impl FontDefinitions {
     /// Default values for the fonts
     pub fn default_with_pixels_per_point(pixels_per_point: f32) -> Self {
+        #[allow(unused)]
         let mut font_data: BTreeMap<String, FontData> = BTreeMap::new();
+
+        let mut fonts_for_family = BTreeMap::new();
+
+        #[cfg(feature = "default_fonts")]
+        {
+            // TODO: figure out a way to make the WASM smaller despite including fonts. Zip them?
+
             // Use size 13 for this. NOTHING ELSE:
             font_data.insert(
                 "ProggyClean".to_owned(),
@@ -100,7 +108,7 @@ impl FontDefinitions {
                 std::borrow::Cow::Borrowed(include_bytes!("../../fonts/Ubuntu-Light.ttf")),
             );
 
-        // Few, but good looking. Use as first priority:
+            // Some good looking emojis. Use as first priority:
             font_data.insert(
                 "NotoEmoji-Regular".to_owned(),
                 std::borrow::Cow::Borrowed(include_bytes!("../../fonts/NotoEmoji-Regular.ttf")),
@@ -111,9 +119,6 @@ impl FontDefinitions {
                 std::borrow::Cow::Borrowed(include_bytes!("../../fonts/emoji-icon-font.ttf")),
             );
 
-        // TODO: figure out a way to make the WASM smaller despite including fonts. Zip them?
-
-        let mut fonts_for_family = BTreeMap::new();
             fonts_for_family.insert(
                 FontFamily::Monospace,
                 vec![
@@ -131,6 +136,13 @@ impl FontDefinitions {
                     "emoji-icon-font".to_owned(),
                 ],
             );
+        }
+
+        #[cfg(not(feature = "default_fonts"))]
+        {
+            fonts_for_family.insert(FontFamily::Monospace, vec![]);
+            fonts_for_family.insert(FontFamily::VariableWidth, vec![]);
+        }
 
         let mut family_and_size = BTreeMap::new();
         family_and_size.insert(TextStyle::Small, (FontFamily::VariableWidth, 10.0));
@@ -196,7 +208,11 @@ impl Fonts {
             .family_and_size
             .iter()
             .map(|(&text_style, &(family, scale_in_points))| {
-                let fonts: Vec<Arc<FontImpl>> = self.definitions.fonts_for_family[&family]
+                let fonts = &self.definitions.fonts_for_family.get(&family);
+                let fonts = fonts.unwrap_or_else(|| {
+                    panic!("FontFamily::{:?} is not bound to any fonts", family)
+                });
+                let fonts: Vec<Arc<FontImpl>> = fonts
                     .iter()
                     .map(|font_name| font_impl_cache.font_impl(font_name, scale_in_points))
                     .collect();