Replace ab_glyph with Skrifa + vello_cpu; enable font hinting (#7694)

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I'll probably come back to this and clean it up a bit. This PR
reimplements ab_glyph's functionality on top of Skrifa, a somewhat
lower-level font API that's being used in Chrome now.

Skrifa doesn't perform rasterization itself, so I'm using
[vello_cpu](https://github.com/linebender/vello) from the Linebender
project for rasterization. It's still in its early days, but I believe
it's already quite fast. It also supports color and gradient fills, so
color emoji support will be easier.

Skrifa also supports font hinting, which should make text look a bit
nicer / less blurry.

Here's the current ab_glyph rendering:

<img width="1592" height="1068" alt="image"
src="https://github.com/user-attachments/assets/2385b66e-23f8-4c6e-b8c2-ea90e0eea4e4"
/>

Here's Skrifa *without* hinting--it looks almost identical, but there
are some subpixel differences, probably due to rasterizer behavior:

<img width="1592" height="1068" alt="image"
src="https://github.com/user-attachments/assets/a815f3e9-65ac-4940-bc00-571177bef53d"
/>

Here's Skrifa  *with* hinting:

<img width="1592" height="1068" alt="image"
src="https://github.com/user-attachments/assets/d6cc0669-3537-4377-bba9-ed5ef09664db"
/>

Hinting does make the horizontal strokes look a bit bolder, which makes
me wonder once again about increasing the font weight from "light" to
"regular".

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/epaint/Cargo.toml

@@ -61,12 +61,14 @@ _override_unity = []
 emath.workspace = true
 ecolor.workspace = true
 
-ab_glyph.workspace = true
 ahash.workspace = true
 log.workspace = true
 nohash-hasher.workspace = true
 parking_lot.workspace = true # Using parking_lot over std::sync::Mutex gives 50% speedups in some real-world scenarios.
-profiling = { workspace = true }
+profiling.workspace = true
+self_cell.workspace = true
+skrifa.workspace = true
+vello_cpu.workspace = true
 
 #! ### Optional dependencies
 bytemuck = { workspace = true, optional = true, features = ["derive"] }

crates/epaint/benches/benchmark.rs

@@ -1,8 +1,8 @@
 use criterion::{Criterion, criterion_group, criterion_main};
 
 use epaint::{
-    AlphaFromCoverage, ClippedShape, Color32, Mesh, PathStroke, Pos2, Rect, Shape, Stroke,
-    TessellationOptions, Tessellator, TextureAtlas, Vec2, pos2, tessellator::Path,
+    ClippedShape, Color32, Mesh, PathStroke, Pos2, Rect, Shape, Stroke, TessellationOptions,
+    Tessellator, TextureAtlas, Vec2, pos2, tessellator::Path,
 };
 
 use std::hint::black_box;
@@ -68,7 +68,7 @@ fn tessellate_circles(c: &mut Criterion) {
         let pixels_per_point = 2.0;
         let options = TessellationOptions::default();
 
-        let atlas = TextureAtlas::new([4096, 256], AlphaFromCoverage::default());
+        let atlas = TextureAtlas::new([4096, 256], Default::default());
         let font_tex_size = atlas.size();
         let prepared_discs = atlas.prepared_discs();
 

crates/epaint/src/lib.rs

@@ -62,7 +62,7 @@ pub use self::{
     stats::PaintStats,
     stroke::{PathStroke, Stroke, StrokeKind},
     tessellator::{TessellationOptions, Tessellator},
-    text::{FontFamily, FontId, Fonts, FontsView, Galley},
+    text::{FontFamily, FontId, Fonts, FontsView, Galley, TextOptions},
     texture_atlas::TextureAtlas,
     texture_handle::TextureHandle,
     textures::TextureManager,

crates/epaint/src/shapes/text_shape.rs

@@ -185,11 +185,7 @@ mod tests {
 
     #[test]
     fn text_bounding_box_under_rotation() {
-        let mut fonts = Fonts::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = Fonts::new(TextOptions::default(), FontDefinitions::default());
         let font = FontId::monospace(12.0);
 
         let mut t = crate::Shape::text(

crates/epaint/src/text/font.rs

@@ -1,13 +1,20 @@
+#![allow(clippy::mem_forget)]
+
 use std::collections::BTreeMap;
 
-use ab_glyph::{Font as _, OutlinedGlyph, PxScale};
 use emath::{GuiRounding as _, OrderedFloat, Vec2, vec2};
+use self_cell::self_cell;
+use skrifa::{
+    MetadataProvider as _,
+    raw::{TableProvider as _, tables::kern::SubtableKind},
+};
+use vello_cpu::{color, kurbo};
 
 use crate::{
-    TextureAtlas,
+    TextOptions, TextureAtlas,
     text::{
         FontTweak,
-        fonts::{CachedFamily, FontFaceKey},
+        fonts::{Blob, CachedFamily, FontFaceKey},
     },
 };
 
@@ -43,9 +50,9 @@ pub struct GlyphInfo {
     /// Doesn't need to be unique.
     ///
     /// Is `None` for a special "invisible" glyph.
-    pub(crate) id: Option<ab_glyph::GlyphId>,
+    pub(crate) id: Option<skrifa::GlyphId>,
 
-    /// In [`ab_glyph`]s "unscaled" coordinate system.
+    /// In [`skrifa`]s "unscaled" coordinate system.
     pub advance_width_unscaled: OrderedFloat<f32>,
 }
 
@@ -123,8 +130,8 @@ pub struct GlyphAllocation {
     /// Used for pair-kerning.
     ///
     /// Doesn't need to be unique.
-    /// Use `ab_glyph::GlyphId(0)` if you just want to have an id, and don't care.
-    pub(crate) id: ab_glyph::GlyphId,
+    /// Use [`skrifa::GlyphId::NOTDEF`] if you just want to have an id, and don't care.
+    pub(crate) id: skrifa::GlyphId,
 
     /// Unit: screen pixels.
     pub advance_width_px: f32,
@@ -139,7 +146,7 @@ struct GlyphCacheKey(u64);
 impl nohash_hasher::IsEnabled for GlyphCacheKey {}
 
 impl GlyphCacheKey {
-    fn new(glyph_id: ab_glyph::GlyphId, metrics: &ScaledMetrics, bin: SubpixelBin) -> Self {
+    fn new(glyph_id: skrifa::GlyphId, metrics: &ScaledMetrics, bin: SubpixelBin) -> Self {
         let ScaledMetrics {
             pixels_per_point,
             px_scale_factor,
@@ -164,41 +171,229 @@ impl GlyphCacheKey {
 
 // ----------------------------------------------------------------------------
 
+struct DependentFontData<'a> {
+    skrifa: skrifa::FontRef<'a>,
+    charmap: skrifa::charmap::Charmap<'a>,
+    outline_glyphs: skrifa::outline::OutlineGlyphCollection<'a>,
+    metrics: skrifa::metrics::Metrics,
+    glyph_metrics: skrifa::metrics::GlyphMetrics<'a>,
+    hinting_instance: Option<skrifa::outline::HintingInstance>,
+}
+
+self_cell! {
+    struct FontCell {
+        owner: Blob,
+
+        #[covariant]
+        dependent: DependentFontData,
+    }
+}
+
+impl FontCell {
+    fn px_scale_factor(&self, scale: f32) -> f32 {
+        let units_per_em = self.borrow_dependent().metrics.units_per_em as f32;
+        scale / units_per_em
+    }
+
+    fn allocate_glyph_uncached(
+        &mut self,
+        atlas: &mut TextureAtlas,
+        metrics: &ScaledMetrics,
+        glyph_info: &GlyphInfo,
+        bin: SubpixelBin,
+    ) -> Option<GlyphAllocation> {
+        let glyph_id = glyph_info.id?;
+
+        debug_assert!(
+            glyph_id != skrifa::GlyphId::NOTDEF,
+            "Can't allocate glyph for id 0"
+        );
+
+        let mut path = kurbo::BezPath::new();
+        let mut pen = VelloPen {
+            path: &mut path,
+            x_offset: bin.as_float() as f64,
+        };
+
+        self.with_dependent_mut(|_, font_data| {
+            let outline = font_data.outline_glyphs.get(glyph_id)?;
+
+            if let Some(hinting_instance) = &mut font_data.hinting_instance {
+                let size = skrifa::instance::Size::new(metrics.scale);
+                if hinting_instance.size() != size {
+                    hinting_instance
+                        .reconfigure(
+                            &font_data.outline_glyphs,
+                            size,
+                            skrifa::instance::LocationRef::default(),
+                            skrifa::outline::Target::Smooth {
+                                mode: skrifa::outline::SmoothMode::Normal,
+                                symmetric_rendering: true,
+                                preserve_linear_metrics: true,
+                            },
+                        )
+                        .ok()?;
+                }
+                let draw_settings = skrifa::outline::DrawSettings::hinted(hinting_instance, false);
+                outline.draw(draw_settings, &mut pen).ok()?;
+            } else {
+                let draw_settings = skrifa::outline::DrawSettings::unhinted(
+                    skrifa::instance::Size::new(metrics.scale),
+                    skrifa::instance::LocationRef::default(),
+                );
+                outline.draw(draw_settings, &mut pen).ok()?;
+            }
+
+            Some(())
+        })?;
+
+        let bounds = path.control_box().expand();
+        let width = bounds.width() as u16;
+        let height = bounds.height() as u16;
+
+        let mut ctx = vello_cpu::RenderContext::new(width, height);
+        ctx.set_transform(kurbo::Affine::translate((-bounds.x0, -bounds.y0)));
+        ctx.set_paint(color::OpaqueColor::<color::Srgb>::WHITE);
+        ctx.fill_path(&path);
+        let mut dest = vello_cpu::Pixmap::new(width, height);
+        ctx.render_to_pixmap(&mut dest);
+        let uv_rect = if width == 0 || height == 0 {
+            UvRect::default()
+        } else {
+            let glyph_pos = {
+                let alpha_from_coverage = atlas.options().alpha_from_coverage;
+                let (glyph_pos, image) = atlas.allocate((width as usize, height as usize));
+                let pixels = dest.data_as_u8_slice();
+                for y in 0..height as usize {
+                    for x in 0..width as usize {
+                        image[(x + glyph_pos.0, y + glyph_pos.1)] = alpha_from_coverage
+                            .color_from_coverage(
+                                pixels[((y * width as usize) + x) * 4 + 3] as f32 / 255.0,
+                            );
+                    }
+                }
+                glyph_pos
+            };
+            let offset_in_pixels = vec2(bounds.x0 as f32, bounds.y0 as f32);
+            let offset =
+                offset_in_pixels / metrics.pixels_per_point + metrics.y_offset_in_points * Vec2::Y;
+            UvRect {
+                offset,
+                size: vec2(width as f32, height as f32) / metrics.pixels_per_point,
+                min: [glyph_pos.0 as u16, glyph_pos.1 as u16],
+                max: [
+                    (glyph_pos.0 + width as usize) as u16,
+                    (glyph_pos.1 + height as usize) as u16,
+                ],
+            }
+        };
+
+        Some(GlyphAllocation {
+            id: glyph_id,
+            advance_width_px: glyph_info.advance_width_unscaled.0 * metrics.px_scale_factor,
+            uv_rect,
+        })
+    }
+}
+
+struct VelloPen<'a> {
+    path: &'a mut kurbo::BezPath,
+    x_offset: f64,
+}
+
+impl skrifa::outline::OutlinePen for VelloPen<'_> {
+    fn move_to(&mut self, x: f32, y: f32) {
+        self.path.move_to((x as f64 + self.x_offset, -y as f64));
+    }
+
+    fn line_to(&mut self, x: f32, y: f32) {
+        self.path.line_to((x as f64 + self.x_offset, -y as f64));
+    }
+
+    fn quad_to(&mut self, cx0: f32, cy0: f32, x: f32, y: f32) {
+        self.path.quad_to(
+            (cx0 as f64 + self.x_offset, -cy0 as f64),
+            (x as f64 + self.x_offset, -y as f64),
+        );
+    }
+
+    fn curve_to(&mut self, cx0: f32, cy0: f32, cx1: f32, cy1: f32, x: f32, y: f32) {
+        self.path.curve_to(
+            (cx0 as f64 + self.x_offset, -cy0 as f64),
+            (cx1 as f64 + self.x_offset, -cy1 as f64),
+            (x as f64 + self.x_offset, -y as f64),
+        );
+    }
+
+    fn close(&mut self) {
+        self.path.close_path();
+    }
+}
+
 /// A specific font face.
 /// The interface uses points as the unit for everything.
-pub struct FontImpl {
+pub struct FontFace {
     name: String,
-    ab_glyph_font: ab_glyph::FontArc,
+    font: FontCell,
     tweak: FontTweak,
     glyph_info_cache: ahash::HashMap<char, GlyphInfo>,
     glyph_alloc_cache: ahash::HashMap<GlyphCacheKey, GlyphAllocation>,
 }
 
-trait FontExt {
-    fn px_scale_factor(&self, scale: f32) -> f32;
-}
+impl FontFace {
+    pub fn new(
+        options: TextOptions,
+        name: String,
+        font_data: Blob,
+        index: u32,
+        tweak: FontTweak,
+    ) -> Result<Self, Box<dyn std::error::Error>> {
+        let font = FontCell::try_new(font_data, |font_data| {
+            let skrifa_font =
+                skrifa::FontRef::from_index(AsRef::<[u8]>::as_ref(font_data.as_ref()), index)?;
 
-impl<T> FontExt for T
-where
-    T: ab_glyph::Font,
-{
-    fn px_scale_factor(&self, scale: f32) -> f32 {
-        let units_per_em = self.units_per_em().unwrap_or_else(|| {
-            panic!("The font unit size exceeds the expected range (16..=16384)")
-        });
-        scale / units_per_em
-    }
-}
+            let charmap = skrifa_font.charmap();
+            let glyphs = skrifa_font.outline_glyphs();
+            let metrics = skrifa_font.metrics(
+                skrifa::instance::Size::unscaled(),
+                skrifa::instance::LocationRef::default(),
+            );
+            let glyph_metrics = skrifa_font.glyph_metrics(
+                skrifa::instance::Size::unscaled(),
+                skrifa::instance::LocationRef::default(),
+            );
 
-impl FontImpl {
-    pub fn new(name: String, ab_glyph_font: ab_glyph::FontArc, tweak: FontTweak) -> Self {
-        Self {
+            let hinting_enabled = tweak.hinting_override.unwrap_or(options.font_hinting);
+            let hinting_instance = hinting_enabled
+                .then(|| {
+                    // It doesn't really matter what we put here for options. Since the size is `unscaled()`, we will
+                    // always reconfigure this hinting instance with the real options when rendering for the first time.
+                    skrifa::outline::HintingInstance::new(
+                        &glyphs,
+                        skrifa::instance::Size::unscaled(),
+                        skrifa::instance::LocationRef::default(),
+                        skrifa::outline::Target::default(),
+                    )
+                    .ok()
+                })
+                .flatten();
+
+            Ok::<DependentFontData<'_>, Box<dyn std::error::Error>>(DependentFontData {
+                skrifa: skrifa_font,
+                charmap,
+                outline_glyphs: glyphs,
+                metrics,
+                glyph_metrics,
+                hinting_instance,
+            })
+        })?;
+        Ok(Self {
             name,
-            ab_glyph_font,
+            font,
             tweak,
             glyph_info_cache: Default::default(),
             glyph_alloc_cache: Default::default(),
-        }
+        })
     }
 
     /// Code points that will always be replaced by the replacement character.
@@ -223,10 +418,11 @@ impl FontImpl {
 
     /// An un-ordered iterator over all supported characters.
     fn characters(&self) -> impl Iterator<Item = char> + '_ {
-        self.ab_glyph_font
-            .codepoint_ids()
-            .map(|(_, chr)| chr)
-            .filter(|&chr| !self.ignore_character(chr))
+        self.font
+            .borrow_dependent()
+            .charmap
+            .mappings()
+            .filter_map(|(chr, _)| char::from_u32(chr).filter(|c| !self.ignore_character(*c)))
     }
 
     /// `\n` will result in `None`
@@ -258,7 +454,7 @@ impl FontImpl {
             // https://en.wikipedia.org/wiki/Thin_space
 
             if let Some(space) = self.glyph_info(' ') {
-                let em = self.ab_glyph_font.units_per_em().unwrap_or(1.0);
+                let em = self.font.borrow_dependent().metrics.units_per_em as f32;
                 let advance_width = f32::min(em / 6.0, space.advance_width_unscaled.0 * 0.5); // TODO(emilk): make configurable
                 let glyph_info = GlyphInfo {
                     advance_width_unscaled: advance_width.into(),
@@ -275,52 +471,68 @@ impl FontImpl {
             return Some(glyph_info);
         }
 
-        // Add new character:
-        let glyph_id = self.ab_glyph_font.glyph_id(c);
+        let font_data = self.font.borrow_dependent();
 
-        if glyph_id.0 == 0 {
-            None // unsupported character
-        } else {
-            let glyph_info = GlyphInfo {
-                id: Some(glyph_id),
-                advance_width_unscaled: self.ab_glyph_font.h_advance_unscaled(glyph_id).into(),
-            };
-            self.glyph_info_cache.insert(c, glyph_info);
-            Some(glyph_info)
-        }
+        // Add new character:
+        let glyph_id = font_data
+            .charmap
+            .map(c)
+            .filter(|id| *id != skrifa::GlyphId::NOTDEF)?;
+
+        let glyph_info = GlyphInfo {
+            id: Some(glyph_id),
+            advance_width_unscaled: font_data
+                .glyph_metrics
+                .advance_width(glyph_id)
+                .unwrap_or_default()
+                .into(),
+        };
+        self.glyph_info_cache.insert(c, glyph_info);
+        Some(glyph_info)
     }
 
     #[inline]
     pub(super) fn pair_kerning_pixels(
         &self,
         metrics: &ScaledMetrics,
-        last_glyph_id: ab_glyph::GlyphId,
-        glyph_id: ab_glyph::GlyphId,
+        last_glyph_id: skrifa::GlyphId,
+        glyph_id: skrifa::GlyphId,
     ) -> f32 {
-        self.ab_glyph_font.kern_unscaled(last_glyph_id, glyph_id) * metrics.px_scale_factor
+        let skrifa_font = &self.font.borrow_dependent().skrifa;
+        let Ok(kern) = skrifa_font.kern() else {
+            return 0.0;
+        };
+        kern.subtables()
+            .find_map(|st| match st.ok()?.kind().ok()? {
+                SubtableKind::Format0(table_ref) => table_ref.kerning(last_glyph_id, glyph_id),
+                SubtableKind::Format1(_) => None,
+                SubtableKind::Format2(subtable2) => subtable2.kerning(last_glyph_id, glyph_id),
+                SubtableKind::Format3(table_ref) => table_ref.kerning(last_glyph_id, glyph_id),
+            })
+            .unwrap_or_default() as f32
+            * metrics.px_scale_factor
     }
 
     #[inline]
     pub fn pair_kerning(
         &self,
         metrics: &ScaledMetrics,
-        last_glyph_id: ab_glyph::GlyphId,
-        glyph_id: ab_glyph::GlyphId,
+        last_glyph_id: skrifa::GlyphId,
+        glyph_id: skrifa::GlyphId,
     ) -> f32 {
         self.pair_kerning_pixels(metrics, last_glyph_id, glyph_id) / metrics.pixels_per_point
     }
 
     #[inline(always)]
     pub fn scaled_metrics(&self, pixels_per_point: f32, font_size: f32) -> ScaledMetrics {
-        let pt_scale_factor = self
-            .ab_glyph_font
-            .px_scale_factor(font_size * self.tweak.scale);
-        let ascent = (self.ab_glyph_font.ascent_unscaled() * pt_scale_factor).round_ui();
-        let descent = (self.ab_glyph_font.descent_unscaled() * pt_scale_factor).round_ui();
-        let line_gap = (self.ab_glyph_font.line_gap_unscaled() * pt_scale_factor).round_ui();
+        let pt_scale_factor = self.font.px_scale_factor(font_size * self.tweak.scale);
+        let font_data = self.font.borrow_dependent();
+        let ascent = (font_data.metrics.ascent * pt_scale_factor).round_ui();
+        let descent = (font_data.metrics.descent * pt_scale_factor).round_ui();
+        let line_gap = (font_data.metrics.leading * pt_scale_factor).round_ui();
 
         let scale = font_size * self.tweak.scale * pixels_per_point;
-        let px_scale_factor = self.ab_glyph_font.px_scale_factor(scale);
+        let px_scale_factor = self.font.px_scale_factor(scale);
 
         let y_offset_in_points = ((font_size * self.tweak.scale * self.tweak.y_offset_factor)
             + self.tweak.y_offset)
@@ -329,6 +541,7 @@ impl FontImpl {
         ScaledMetrics {
             pixels_per_point,
             px_scale_factor,
+            scale,
             y_offset_in_points,
             ascent,
             row_height: ascent - descent + line_gap,
@@ -370,77 +583,20 @@ impl FontImpl {
             std::collections::hash_map::Entry::Vacant(entry) => entry,
         };
 
-        debug_assert!(glyph_id.0 != 0, "Can't allocate glyph for id 0");
+        let allocation = self
+            .font
+            .allocate_glyph_uncached(atlas, metrics, &glyph_info, bin)
+            .unwrap_or_default();
 
-        let uv_rect = self.ab_glyph_font.outline(glyph_id).map(|outline| {
-            let glyph = ab_glyph::Glyph {
-                id: glyph_id,
-                // We bypass ab-glyph's scaling method because it uses the wrong scale
-                // (https://github.com/alexheretic/ab-glyph/issues/15), and this field is never accessed when
-                // rasterizing. We can just put anything here.
-                scale: PxScale::from(0.0),
-                position: ab_glyph::Point {
-                    x: bin.as_float(),
-                    y: 0.0,
-                },
-            };
-            let outlined = OutlinedGlyph::new(
-                glyph,
-                outline,
-                ab_glyph::PxScaleFactor {
-                    horizontal: metrics.px_scale_factor,
-                    vertical: metrics.px_scale_factor,
-                },
-            );
-            let bb = outlined.px_bounds();
-            let glyph_width = bb.width() as usize;
-            let glyph_height = bb.height() as usize;
-            if glyph_width == 0 || glyph_height == 0 {
-                UvRect::default()
-            } else {
-                let glyph_pos = {
-                    let text_alpha_from_coverage = atlas.text_alpha_from_coverage;
-                    let (glyph_pos, image) = atlas.allocate((glyph_width, glyph_height));
-                    outlined.draw(|x, y, v| {
-                        if 0.0 < v {
-                            let px = glyph_pos.0 + x as usize;
-                            let py = glyph_pos.1 + y as usize;
-                            image[(px, py)] = text_alpha_from_coverage.color_from_coverage(v);
-                        }
-                    });
-                    glyph_pos
-                };
-
-                let offset_in_pixels = vec2(bb.min.x, bb.min.y);
-                let offset = offset_in_pixels / metrics.pixels_per_point
-                    + metrics.y_offset_in_points * Vec2::Y;
-                UvRect {
-                    offset,
-                    size: vec2(glyph_width as f32, glyph_height as f32) / metrics.pixels_per_point,
-                    min: [glyph_pos.0 as u16, glyph_pos.1 as u16],
-                    max: [
-                        (glyph_pos.0 + glyph_width) as u16,
-                        (glyph_pos.1 + glyph_height) as u16,
-                    ],
-                }
-            }
-        });
-        let uv_rect = uv_rect.unwrap_or_default();
-
-        let allocation = GlyphAllocation {
-            id: glyph_id,
-            advance_width_px,
-            uv_rect,
-        };
         entry.insert(allocation);
         (allocation, h_pos_round)
     }
 }
 
 // TODO(emilk): rename?
-/// Wrapper over multiple [`FontImpl`] (e.g. a primary + fallbacks for emojis)
+/// Wrapper over multiple [`FontFace`] (e.g. a primary + fallbacks for emojis)
 pub struct Font<'a> {
-    pub(super) fonts_by_id: &'a mut nohash_hasher::IntMap<FontFaceKey, FontImpl>,
+    pub(super) fonts_by_id: &'a mut nohash_hasher::IntMap<FontFaceKey, FontFace>,
     pub(super) cached_family: &'a mut CachedFamily,
     pub(super) atlas: &'a mut TextureAtlas,
 }
@@ -471,7 +627,7 @@ impl Font<'_> {
             .fonts
             .first()
             .and_then(|key| self.fonts_by_id.get(key))
-            .map(|font_impl| font_impl.scaled_metrics(pixels_per_point, font_size))
+            .map(|font_face| font_face.scaled_metrics(pixels_per_point, font_size))
             .unwrap_or_default()
     }
 
@@ -479,7 +635,7 @@ impl Font<'_> {
     pub fn glyph_width(&mut self, c: char, font_size: f32) -> f32 {
         let (key, glyph_info) = self.glyph_info(c);
         if let Some(font) = &self.fonts_by_id.get(&key) {
-            glyph_info.advance_width_unscaled.0 * font.ab_glyph_font.px_scale_factor(font_size)
+            glyph_info.advance_width_unscaled.0 * font.font.px_scale_factor(font_size)
         } else {
             0.0
         }
@@ -524,7 +680,10 @@ pub struct ScaledMetrics {
     /// Translates "unscaled" units to physical (screen) pixels.
     pub px_scale_factor: f32,
 
-    /// Vertical offset, in UI points.
+    /// Absolute scale in screen pixels, for skrifa.
+    pub scale: f32,
+
+    /// Vertical offset, in UI points (not screen-space).
     pub y_offset_in_points: f32,
 
     /// This is the distance from the top to the baseline.
@@ -540,7 +699,7 @@ pub struct ScaledMetrics {
 
 /// Code points that will always be invisible (zero width).
 ///
-/// See also [`FontImpl::ignore_character`].
+/// See also [`FontFace::ignore_character`].
 #[inline]
 fn invisible_char(c: char) -> bool {
     if c == '\r' {

crates/epaint/src/text/fonts.rs

@@ -1,4 +1,5 @@
 use std::{
+    borrow::Cow,
     collections::BTreeMap,
     sync::{
         Arc,
@@ -7,10 +8,10 @@ use std::{
 };
 
 use crate::{
-    AlphaFromCoverage, TextureAtlas,
+    TextureAtlas,
     text::{
-        Galley, LayoutJob, LayoutSection,
-        font::{Font, FontImpl, GlyphInfo},
+        Galley, LayoutJob, LayoutSection, TextOptions,
+        font::{Font, FontFace, GlyphInfo},
     },
 };
 use emath::{NumExt as _, OrderedFloat};
@@ -116,7 +117,7 @@ impl std::fmt::Display for FontFamily {
 #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub struct FontData {
     /// The content of a `.ttf` or `.otf` file.
-    pub font: std::borrow::Cow<'static, [u8]>,
+    pub font: Cow<'static, [u8]>,
 
     /// Which font face in the file to use.
     /// When in doubt, use `0`.
@@ -129,7 +130,7 @@ pub struct FontData {
 impl FontData {
     pub fn from_static(font: &'static [u8]) -> Self {
         Self {
-            font: std::borrow::Cow::Borrowed(font),
+            font: Cow::Borrowed(font),
             index: 0,
             tweak: Default::default(),
         }
@@ -137,7 +138,7 @@ impl FontData {
 
     pub fn from_owned(font: Vec<u8>) -> Self {
         Self {
-            font: std::borrow::Cow::Owned(font),
+            font: Cow::Owned(font),
             index: 0,
             tweak: Default::default(),
         }
@@ -184,6 +185,11 @@ pub struct FontTweak {
     ///
     /// Example value: `2.0`.
     pub y_offset: f32,
+
+    /// Override the global font hinting setting for this specific font.
+    ///
+    /// `None` means use the global setting.
+    pub hinting_override: Option<bool>,
 }
 
 impl Default for FontTweak {
@@ -192,24 +198,20 @@ impl Default for FontTweak {
             scale: 1.0,
             y_offset_factor: 0.0,
             y_offset: 0.0,
+            hinting_override: None,
         }
     }
 }
 
 // ----------------------------------------------------------------------------
 
-fn ab_glyph_font_from_font_data(name: &str, data: &FontData) -> ab_glyph::FontArc {
-    match &data.font {
-        std::borrow::Cow::Borrowed(bytes) => {
-            ab_glyph::FontRef::try_from_slice_and_index(bytes, data.index)
-                .map(ab_glyph::FontArc::from)
-        }
-        std::borrow::Cow::Owned(bytes) => {
-            ab_glyph::FontVec::try_from_vec_and_index(bytes.clone(), data.index)
-                .map(ab_glyph::FontArc::from)
-        }
+pub type Blob = Arc<dyn AsRef<[u8]> + Send + Sync>;
+
+fn blob_from_font_data(data: &FontData) -> Blob {
+    match data.clone().font {
+        Cow::Borrowed(bytes) => Arc::new(bytes) as Blob,
+        Cow::Owned(bytes) => Arc::new(bytes) as Blob,
     }
-    .unwrap_or_else(|err| panic!("Error parsing {name:?} TTF/OTF font file: {err}"))
 }
 
 /// Describes the font data and the sizes to use.
@@ -438,7 +440,7 @@ pub(super) struct CachedFamily {
 impl CachedFamily {
     fn new(
         fonts: Vec<FontFaceKey>,
-        fonts_by_id: &mut nohash_hasher::IntMap<FontFaceKey, FontImpl>,
+        fonts_by_id: &mut nohash_hasher::IntMap<FontFaceKey, FontFace>,
     ) -> Self {
         if fonts.is_empty() {
             return Self {
@@ -476,11 +478,11 @@ impl CachedFamily {
     pub(crate) fn glyph_info_no_cache_or_fallback(
         &mut self,
         c: char,
-        fonts_by_id: &mut nohash_hasher::IntMap<FontFaceKey, FontImpl>,
+        fonts_by_id: &mut nohash_hasher::IntMap<FontFaceKey, FontFace>,
     ) -> Option<(FontFaceKey, GlyphInfo)> {
         for font_key in &self.fonts {
-            let font_impl = fonts_by_id.get_mut(font_key).expect("Nonexistent font ID");
-            if let Some(glyph_info) = font_impl.glyph_info(c) {
+            let font_face = fonts_by_id.get_mut(font_key).expect("Nonexistent font ID");
+            if let Some(glyph_info) = font_face.glyph_info(c) {
                 self.glyph_info_cache.insert(c, (*font_key, glyph_info));
                 return Some((*font_key, glyph_info));
             }
@@ -508,43 +510,29 @@ pub struct Fonts {
 impl Fonts {
     /// Create a new [`Fonts`] for text layout.
     /// This call is expensive, so only create one [`Fonts`] and then reuse it.
-    ///
-    /// * `max_texture_side`: largest supported texture size (one side).
-    pub fn new(
-        max_texture_side: usize,
-        text_alpha_from_coverage: AlphaFromCoverage,
-        definitions: FontDefinitions,
-    ) -> Self {
+    pub fn new(options: TextOptions, definitions: FontDefinitions) -> Self {
         Self {
-            fonts: FontsImpl::new(max_texture_side, text_alpha_from_coverage, definitions),
+            fonts: FontsImpl::new(options, definitions),
             galley_cache: Default::default(),
         }
     }
 
-    /// Call at the start of each frame with the latest known
-    /// `pixels_per_point`, `max_texture_side`, and `text_alpha_from_coverage`.
+    /// Call at the start of each frame with the latest known [`TextOptions`].
     ///
     /// Call after painting the previous frame, but before using [`Fonts`] for the new frame.
     ///
-    /// This function will react to changes in `pixels_per_point`, `max_texture_side`, and `text_alpha_from_coverage`,
+    /// This function will react to changes in [`TextOptions`],
     /// as well as notice when the font atlas is getting full, and handle that.
-    pub fn begin_pass(
-        &mut self,
-        max_texture_side: usize,
-        text_alpha_from_coverage: AlphaFromCoverage,
-    ) {
-        let max_texture_side_changed = self.fonts.max_texture_side != max_texture_side;
-        let text_alpha_from_coverage_changed =
-            self.fonts.atlas.text_alpha_from_coverage != text_alpha_from_coverage;
+    pub fn begin_pass(&mut self, options: TextOptions) {
+        let text_options_changed = self.fonts.options() != &options;
         let font_atlas_almost_full = self.fonts.atlas.fill_ratio() > 0.8;
-        let needs_recreate =
-            max_texture_side_changed || text_alpha_from_coverage_changed || font_atlas_almost_full;
+        let needs_recreate = text_options_changed || font_atlas_almost_full;
 
         if needs_recreate {
             let definitions = self.fonts.definitions.clone();
 
             *self = Self {
-                fonts: FontsImpl::new(max_texture_side, text_alpha_from_coverage, definitions),
+                fonts: FontsImpl::new(options, definitions),
                 galley_cache: Default::default(),
             };
         }
@@ -558,8 +546,8 @@ impl Fonts {
     }
 
     #[inline]
-    pub fn max_texture_side(&self) -> usize {
-        self.fonts.max_texture_side
+    pub fn options(&self) -> &TextOptions {
+        self.texture_atlas().options()
     }
 
     #[inline]
@@ -628,8 +616,8 @@ pub struct FontsView<'a> {
 
 impl FontsView<'_> {
     #[inline]
-    pub fn max_texture_side(&self) -> usize {
-        self.fonts.max_texture_side
+    pub fn options(&self) -> &TextOptions {
+        self.fonts.options()
     }
 
     #[inline]
@@ -671,6 +659,7 @@ impl FontsView<'_> {
     /// Height of one row of text in points.
     ///
     /// Returns a value rounded to [`emath::GUI_ROUNDING`].
+    #[inline]
     pub fn row_height(&mut self, font_id: &FontId) -> f32 {
         self.fonts
             .font(&font_id.family)
@@ -716,6 +705,7 @@ impl FontsView<'_> {
     /// Will wrap text at the given width and line break at `\n`.
     ///
     /// The implementation uses memoization so repeated calls are cheap.
+    #[inline]
     pub fn layout(
         &mut self,
         text: String,
@@ -730,6 +720,7 @@ impl FontsView<'_> {
     /// Will line break at `\n`.
     ///
     /// The implementation uses memoization so repeated calls are cheap.
+    #[inline]
     pub fn layout_no_wrap(
         &mut self,
         text: String,
@@ -743,6 +734,7 @@ impl FontsView<'_> {
     /// Like [`Self::layout`], made for when you want to pick a color for the text later.
     ///
     /// The implementation uses memoization so repeated calls are cheap.
+    #[inline]
     pub fn layout_delayed_color(
         &mut self,
         text: String,
@@ -759,10 +751,9 @@ impl FontsView<'_> {
 ///
 /// Required in order to paint text.
 pub struct FontsImpl {
-    max_texture_side: usize,
     definitions: FontDefinitions,
     atlas: TextureAtlas,
-    fonts_by_id: nohash_hasher::IntMap<FontFaceKey, FontImpl>,
+    fonts_by_id: nohash_hasher::IntMap<FontFaceKey, FontFace>,
     fonts_by_name: ahash::HashMap<String, FontFaceKey>,
     family_cache: ahash::HashMap<FontFamily, CachedFamily>,
 }
@@ -770,36 +761,36 @@ pub struct FontsImpl {
 impl FontsImpl {
     /// Create a new [`FontsImpl`] for text layout.
     /// This call is expensive, so only create one [`FontsImpl`] and then reuse it.
-    pub fn new(
-        max_texture_side: usize,
-        text_alpha_from_coverage: AlphaFromCoverage,
-        definitions: FontDefinitions,
-    ) -> Self {
-        let texture_width = max_texture_side.at_most(16 * 1024);
+    pub fn new(options: TextOptions, definitions: FontDefinitions) -> Self {
+        let texture_width = options.max_texture_side.at_most(16 * 1024);
         let initial_height = 32; // Keep initial font atlas small, so it is fast to upload to GPU. This will expand as needed anyways.
-        let atlas = TextureAtlas::new([texture_width, initial_height], text_alpha_from_coverage);
+        let atlas = TextureAtlas::new([texture_width, initial_height], options);
 
-        let mut fonts_by_id: nohash_hasher::IntMap<FontFaceKey, FontImpl> = Default::default();
-        let mut font_impls: ahash::HashMap<String, FontFaceKey> = Default::default();
+        let mut fonts_by_id: nohash_hasher::IntMap<FontFaceKey, FontFace> = Default::default();
+        let mut fonts_by_name: ahash::HashMap<String, FontFaceKey> = Default::default();
         for (name, font_data) in &definitions.font_data {
             let tweak = font_data.tweak;
-            let ab_glyph = ab_glyph_font_from_font_data(name, font_data);
-            let font_impl = FontImpl::new(name.clone(), ab_glyph, tweak);
+            let blob = blob_from_font_data(font_data);
+            let font_face = FontFace::new(options, name.clone(), blob, font_data.index, tweak)
+                .unwrap_or_else(|err| panic!("Error parsing {name:?} TTF/OTF font file: {err}"));
             let key = FontFaceKey::new();
-            fonts_by_id.insert(key, font_impl);
-            font_impls.insert(name.clone(), key);
+            fonts_by_id.insert(key, font_face);
+            fonts_by_name.insert(name.clone(), key);
         }
 
         Self {
-            max_texture_side,
             definitions,
             atlas,
             fonts_by_id,
-            fonts_by_name: font_impls,
+            fonts_by_name,
             family_cache: Default::default(),
         }
     }
 
+    pub fn options(&self) -> &TextOptions {
+        self.atlas.options()
+    }
+
     /// Get the right font implementation from [`FontFamily`].
     pub fn font(&mut self, family: &FontFamily) -> Font<'_> {
         let cached_family = self.family_cache.entry(family.clone()).or_insert_with(|| {
@@ -1192,12 +1183,7 @@ mod tests {
     #[test]
     fn test_split_paragraphs() {
         for pixels_per_point in [1.0, 2.0_f32.sqrt(), 2.0] {
-            let max_texture_side = 4096;
-            let mut fonts = FontsImpl::new(
-                max_texture_side,
-                AlphaFromCoverage::default(),
-                FontDefinitions::default(),
-            );
+            let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
 
             for halign in [Align::Min, Align::Center, Align::Max] {
                 for justify in [false, true] {
@@ -1255,11 +1241,7 @@ mod tests {
         let rounded_output_to_gui = [false, true];
 
         for pixels_per_point in pixels_per_point {
-            let mut fonts = FontsImpl::new(
-                1024,
-                AlphaFromCoverage::default(),
-                FontDefinitions::default(),
-            );
+            let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
 
             for &max_width in &max_widths {
                 for round_output_to_gui in rounded_output_to_gui {
@@ -1306,7 +1288,7 @@ mod tests {
 
     #[test]
     fn test_fallback_glyph_width() {
-        let mut fonts = Fonts::new(1024, AlphaFromCoverage::default(), FontDefinitions::empty());
+        let mut fonts = Fonts::new(TextOptions::default(), FontDefinitions::empty());
         let mut view = fonts.with_pixels_per_point(1.0);
 
         let width = view.glyph_width(&FontId::new(12.0, FontFamily::Proportional), ' ');

crates/epaint/src/text/mod.rs

@@ -20,3 +20,31 @@ pub use {
 
 /// Suggested character to use to replace those in password text fields.
 pub const PASSWORD_REPLACEMENT_CHAR: char = '•';
+
+/// Controls how we render text
+#[derive(Clone, Copy, Debug, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct TextOptions {
+    /// Maximum size of the font texture.
+    pub max_texture_side: usize,
+
+    /// Controls how to convert glyph coverage to alpha.
+    pub alpha_from_coverage: crate::AlphaFromCoverage,
+
+    /// Whether to enable font hinting
+    ///
+    /// (round some font coordinates to pixels for sharper text).
+    ///
+    /// Default is `true`.
+    pub font_hinting: bool,
+}
+
+impl Default for TextOptions {
+    fn default() -> Self {
+        Self {
+            max_texture_side: 2048, // Small but portable
+            alpha_from_coverage: crate::AlphaFromCoverage::default(),
+            font_hinting: true,
+        }
+    }
+}

crates/epaint/src/text/text_layout.rs

@@ -176,7 +176,7 @@ fn layout_section(
 
     // Optimization: only recompute `ScaledMetrics` when the concrete `FontImpl` changes.
     let mut current_font = FontFaceKey::INVALID;
-    let mut current_font_impl_metrics = ScaledMetrics::default();
+    let mut current_font_face_metrics = ScaledMetrics::default();
 
     for chr in job.text[byte_range.clone()].chars() {
         if job.break_on_newline && chr == '\n' {
@@ -185,20 +185,20 @@ fn layout_section(
             paragraph.empty_paragraph_height = line_height; // TODO(emilk): replace this hack with actually including `\n` in the glyphs?
         } else {
             let (font_id, glyph_info) = font.glyph_info(chr);
-            let mut font_impl = font.fonts_by_id.get_mut(&font_id);
+            let mut font_face = font.fonts_by_id.get_mut(&font_id);
             if current_font != font_id {
                 current_font = font_id;
-                current_font_impl_metrics = font_impl
+                current_font_face_metrics = font_face
                     .as_ref()
-                    .map(|font_impl| font_impl.scaled_metrics(pixels_per_point, font_size))
+                    .map(|font_face| font_face.scaled_metrics(pixels_per_point, font_size))
                     .unwrap_or_default();
             }
 
-            if let (Some(font_impl), Some(last_glyph_id), Some(glyph_id)) =
-                (&font_impl, last_glyph_id, glyph_info.id)
+            if let (Some(font_face), Some(last_glyph_id), Some(glyph_id)) =
+                (&font_face, last_glyph_id, glyph_info.id)
             {
-                paragraph.cursor_x_px += font_impl.pair_kerning_pixels(
-                    &current_font_impl_metrics,
+                paragraph.cursor_x_px += font_face.pair_kerning_pixels(
+                    &current_font_face_metrics,
                     last_glyph_id,
                     glyph_id,
                 );
@@ -207,10 +207,10 @@ fn layout_section(
                 paragraph.cursor_x_px += extra_letter_spacing * pixels_per_point;
             }
 
-            let (glyph_alloc, physical_x) = if let Some(font_impl) = font_impl.as_mut() {
-                font_impl.allocate_glyph(
+            let (glyph_alloc, physical_x) = if let Some(font_face) = font_face.as_mut() {
+                font_face.allocate_glyph(
                     font.atlas,
-                    &current_font_impl_metrics,
+                    &current_font_face_metrics,
                     glyph_info,
                     chr,
                     paragraph.cursor_x_px,
@@ -224,8 +224,8 @@ fn layout_section(
                 pos: pos2(physical_x as f32 / pixels_per_point, f32::NAN),
                 advance_width: glyph_alloc.advance_width_px / pixels_per_point,
                 line_height,
-                font_impl_height: current_font_impl_metrics.row_height,
-                font_impl_ascent: current_font_impl_metrics.ascent,
+                font_face_height: current_font_face_metrics.row_height,
+                font_face_ascent: current_font_face_metrics.ascent,
                 font_height: font_metrics.row_height,
                 font_ascent: font_metrics.ascent,
                 uv_rect: glyph_alloc.uv_rect,
@@ -463,22 +463,22 @@ fn replace_last_glyph_with_overflow_character(
         let font_size = section.format.font_id.size;
 
         let (font_id, glyph_info) = font.glyph_info(overflow_character);
-        let mut font_impl = font.fonts_by_id.get_mut(&font_id);
-        let font_impl_metrics = font_impl
+        let mut font_face = font.fonts_by_id.get_mut(&font_id);
+        let font_face_metrics = font_face
             .as_mut()
             .map(|f| f.scaled_metrics(pixels_per_point, font_size))
             .unwrap_or_default();
 
         let overflow_glyph_x = if let Some(prev_glyph) = row.glyphs.last() {
             // Kern the overflow character properly
-            let pair_kerning = font_impl
+            let pair_kerning = font_face
                 .as_mut()
-                .map(|font_impl| {
+                .map(|font_face| {
                     if let (Some(prev_glyph_id), Some(overflow_glyph_id)) = (
-                        font_impl.glyph_info(prev_glyph.chr).and_then(|g| g.id),
-                        font_impl.glyph_info(overflow_character).and_then(|g| g.id),
+                        font_face.glyph_info(prev_glyph.chr).and_then(|g| g.id),
+                        font_face.glyph_info(overflow_character).and_then(|g| g.id),
                     ) {
-                        font_impl.pair_kerning(&font_impl_metrics, prev_glyph_id, overflow_glyph_id)
+                        font_face.pair_kerning(&font_face_metrics, prev_glyph_id, overflow_glyph_id)
                     } else {
                         0.0
                     }
@@ -490,10 +490,10 @@ fn replace_last_glyph_with_overflow_character(
             0.0 // TODO(emilk): heed paragraph leading_space 😬
         };
 
-        let replacement_glyph_width = font_impl
+        let replacement_glyph_width = font_face
             .as_mut()
             .and_then(|f| f.glyph_info(overflow_character))
-            .map(|i| i.advance_width_unscaled.0 * font_impl_metrics.px_scale_factor)
+            .map(|i| i.advance_width_unscaled.0 * font_face_metrics.px_scale_factor)
             .unwrap_or_default();
 
         // Check if we're within width budget:
@@ -502,12 +502,12 @@ fn replace_last_glyph_with_overflow_character(
         {
             // we are done
 
-            let (replacement_glyph_alloc, physical_x) = font_impl
+            let (replacement_glyph_alloc, physical_x) = font_face
                 .as_mut()
                 .map(|f| {
                     f.allocate_glyph(
                         font.atlas,
-                        &font_impl_metrics,
+                        &font_face_metrics,
                         glyph_info,
                         overflow_character,
                         overflow_glyph_x * pixels_per_point,
@@ -526,8 +526,8 @@ fn replace_last_glyph_with_overflow_character(
                 pos: pos2(physical_x as f32 / pixels_per_point, f32::NAN),
                 advance_width: replacement_glyph_alloc.advance_width_px / pixels_per_point,
                 line_height,
-                font_impl_height: font_impl_metrics.row_height,
-                font_impl_ascent: font_impl_metrics.ascent,
+                font_face_height: font_face_metrics.row_height,
+                font_face_ascent: font_face_metrics.ascent,
                 font_height: font_metrics.row_height,
                 font_ascent: font_metrics.ascent,
                 uv_rect: replacement_glyph_alloc.uv_rect,
@@ -668,14 +668,14 @@ fn galley_from_rows(
         for glyph in &mut row.glyphs {
             let format = &job.sections[glyph.section_index as usize].format;
 
-            glyph.pos.y = glyph.font_impl_ascent
+            glyph.pos.y = glyph.font_face_ascent
 
                 // Apply valign to the different in height of the entire row, and the height of this `Font`:
                 + format.valign.to_factor() * (max_row_height - glyph.line_height)
 
                 // When mixing different `FontImpl` (e.g. latin and emojis),
                 // we always center the difference:
-                + 0.5 * (glyph.font_height - glyph.font_impl_height);
+                + 0.5 * (glyph.font_height - glyph.font_face_height);
 
             glyph.pos.y = point_scale.round_to_pixel(glyph.pos.y);
         }
@@ -1050,18 +1050,13 @@ impl RowBreakCandidates {
 
 #[cfg(test)]
 mod tests {
-    use crate::AlphaFromCoverage;
 
     use super::{super::*, *};
 
     #[test]
     fn test_zero_max_width() {
         let pixels_per_point = 1.0;
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
         let mut layout_job = LayoutJob::single_section("W".into(), TextFormat::default());
         layout_job.wrap.max_width = 0.0;
         let galley = layout(&mut fonts, pixels_per_point, layout_job.into());
@@ -1074,11 +1069,7 @@ mod tests {
 
         let pixels_per_point = 1.0;
 
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
         let text_format = TextFormat {
             font_id: FontId::monospace(12.0),
             ..Default::default()
@@ -1124,11 +1115,7 @@ mod tests {
     #[test]
     fn test_cjk() {
         let pixels_per_point = 1.0;
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
         let mut layout_job = LayoutJob::single_section(
             "日本語とEnglishの混在した文章".into(),
             TextFormat::default(),
@@ -1144,11 +1131,7 @@ mod tests {
     #[test]
     fn test_pre_cjk() {
         let pixels_per_point = 1.0;
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
         let mut layout_job = LayoutJob::single_section(
             "日本語とEnglishの混在した文章".into(),
             TextFormat::default(),
@@ -1164,11 +1147,7 @@ mod tests {
     #[test]
     fn test_truncate_width() {
         let pixels_per_point = 1.0;
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
         let mut layout_job =
             LayoutJob::single_section("# DNA\nMore text".into(), TextFormat::default());
         layout_job.wrap.max_width = f32::INFINITY;
@@ -1188,11 +1167,7 @@ mod tests {
     #[test]
     fn test_empty_row() {
         let pixels_per_point = 1.0;
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
 
         let font_id = FontId::default();
         let font_height = fonts
@@ -1225,11 +1200,7 @@ mod tests {
     #[test]
     fn test_end_with_newline() {
         let pixels_per_point = 1.0;
-        let mut fonts = FontsImpl::new(
-            1024,
-            AlphaFromCoverage::default(),
-            FontDefinitions::default(),
-        );
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
 
         let font_id = FontId::default();
         let font_height = fonts

crates/epaint/src/text/text_layout_types.rs

@@ -686,11 +686,11 @@ pub struct Glyph {
     /// The row/line height of this font.
     pub font_height: f32,
 
-    /// The ascent of the sub-font within the font (`FontImpl`).
-    pub font_impl_ascent: f32,
+    /// The ascent of the sub-font within the font (`FontFace`).
+    pub font_face_ascent: f32,
 
-    /// The row/line height of the sub-font within the font (`FontImpl`).
-    pub font_impl_height: f32,
+    /// The row/line height of the sub-font within the font (`FontFace`).
+    pub font_face_height: f32,
 
     /// Position and size of the glyph in the font texture, in texels.
     pub uv_rect: UvRect,

crates/epaint/src/texture_atlas.rs

@@ -1,7 +1,7 @@
 use ecolor::Color32;
 use emath::{Rect, remap_clamp};
 
-use crate::{AlphaFromCoverage, ColorImage, ImageDelta};
+use crate::{ColorImage, ImageDelta, TextOptions};
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 struct Rectu {
@@ -75,11 +75,11 @@ pub struct TextureAtlas {
     discs: Vec<PrerasterizedDisc>,
 
     /// Controls how to convert glyph coverage to alpha.
-    pub(crate) text_alpha_from_coverage: AlphaFromCoverage,
+    options: TextOptions,
 }
 
 impl TextureAtlas {
-    pub fn new(size: [usize; 2], text_alpha_from_coverage: AlphaFromCoverage) -> Self {
+    pub fn new(size: [usize; 2], options: TextOptions) -> Self {
         assert!(size[0] >= 1024, "Tiny texture atlas");
         let mut atlas = Self {
             image: ColorImage::filled(size, Color32::TRANSPARENT),
@@ -88,7 +88,7 @@ impl TextureAtlas {
             row_height: 0,
             overflowed: false,
             discs: vec![], // will be filled in below
-            text_alpha_from_coverage,
+            options,
         };
 
         // Make the top left pixel fully white for `WHITE_UV`, i.e. painting something with solid color:
@@ -121,7 +121,7 @@ impl TextureAtlas {
                     let coverage =
                         remap_clamp(distance_to_center, (r - 0.5)..=(r + 0.5), 1.0..=0.0);
                     image[((x as i32 + hw + dx) as usize, (y as i32 + hw + dy) as usize)] =
-                        text_alpha_from_coverage.color_from_coverage(coverage);
+                        options.alpha_from_coverage.color_from_coverage(coverage);
                 }
             }
             atlas.discs.push(PrerasterizedDisc {
@@ -138,6 +138,10 @@ impl TextureAtlas {
         atlas
     }
 
+    pub fn options(&self) -> &TextOptions {
+        &self.options
+    }
+
     pub fn size(&self) -> [usize; 2] {
         self.image.size
     }