Add font embolden

vello/src/scene.rs

@@ -9,7 +9,7 @@ use peniko::{
     BlendMode, Blob, Brush, BrushRef, Color, ColorStop, ColorStops, ColorStopsSource, Compose,
     Extend, Fill, Font, Gradient, Image, Mix, StyleRef,
     color::{AlphaColor, DynamicColor, Srgb, palette},
-    kurbo::{Affine, BezPath, Point, Rect, Shape, Stroke, StrokeOpts, Vec2},
+    kurbo::{Affine, BezPath, Join, Point, Rect, Shape, Stroke, StrokeOpts, Vec2},
 };
 use png::{BitDepth, ColorType, Transformations};
 use skrifa::{
@@ -22,7 +22,7 @@ use skrifa::{
 };
 #[cfg(feature = "bump_estimate")]
 use vello_encoding::BumpAllocatorMemory;
-use vello_encoding::{Encoding, Glyph, GlyphRun, NormalizedCoord, Patch, Transform};
+use vello_encoding::{EmboldenStyle, Encoding, Glyph, GlyphRun, NormalizedCoord, Patch, Transform};
 
 // TODO - Document invariants and edge cases (#470)
 // - What happens when we pass a transform matrix with NaN values to the Scene?
@@ -361,6 +361,7 @@ impl<'a> DrawGlyphs<'a> {
                 transform: Transform::IDENTITY,
                 glyph_transform: None,
                 font_size: 16.0,
+                embolden_style: EmboldenStyle::default(),
                 hint: false,
                 normalized_coords: coords_start..coords_start,
                 style: Fill::NonZero.into(),
@@ -411,6 +412,37 @@ impl<'a> DrawGlyphs<'a> {
         self
     }
 
+    /// Sets the amount of emboldening to apply.
+    ///
+    /// The value represents the amount to embolden in em units.
+    /// A value of 0.0 means no emboldening (the default).
+    /// Typical values range from 0.01 to 0.1.
+    ///
+    /// The default value is 0.0 (no emboldening).
+    #[must_use]
+    pub fn embolden(mut self, amount: f32) -> Self {
+        self.run.embolden_style.embolden = amount;
+        self
+    }
+
+    /// Sets the join to use when emboldening.
+    ///
+    /// The default value is Miter.
+    #[must_use]
+    pub fn embolden_join(mut self, join: Join) -> Self {
+        self.run.embolden_style.join = join;
+        self
+    }
+
+    /// Sets the miter limit to use when emboldening with a miter join.
+    ///
+    /// The default value is 4.0.
+    #[must_use]
+    pub fn embolden_miter_limit(mut self, miter_limit: f32) -> Self {
+        self.run.embolden_style.miter_limit = miter_limit;
+        self
+    }
+
     /// Sets the normalized design space coordinates for a variable font instance.
     #[must_use]
     pub fn normalized_coords(mut self, coords: &[NormalizedCoord]) -> Self {
@@ -796,15 +828,18 @@ impl ColorPainter for DrawColorGlyphs<'_> {
             return;
         };
 
-        let mut path = BezPathOutline(BezPath::new());
         let draw_settings = DrawSettings::unhinted(Size::unscaled(), self.location);
-
-        let Ok(_) = outline.draw(draw_settings, &mut path) else {
-            return;
+        let path = {
+            let mut path = BezPathOutline(BezPath::new());
+            let Ok(_) = outline.draw(draw_settings, &mut path) else {
+                return;
+            };
+            path.0
         };
+
         self.clip_depth += 1;
         self.scene
-            .push_layer(Mix::Clip, 1.0, self.last_transform().to_kurbo(), &path.0);
+            .push_layer(Mix::Clip, 1.0, self.last_transform().to_kurbo(), &path);
     }
 
     fn push_clip_box(&mut self, clip_box: skrifa::raw::types::BoundingBox<f32>) {
@@ -878,11 +913,14 @@ impl ColorPainter for DrawColorGlyphs<'_> {
             return;
         };
 
-        let mut path = BezPathOutline(BezPath::new());
         let draw_settings = DrawSettings::unhinted(Size::unscaled(), self.location);
 
-        let Ok(_) = outline.draw(draw_settings, &mut path) else {
-            return;
+        let path = {
+            let mut path = BezPathOutline(BezPath::new());
+            let Ok(_) = outline.draw(draw_settings, &mut path) else {
+                return;
+            };
+            path.0
         };
 
         let transform = self.last_transform();
@@ -893,7 +931,7 @@ impl ColorPainter for DrawColorGlyphs<'_> {
             brush_transform
                 .map(conv_skrifa_transform)
                 .map(|it| it.to_kurbo()),
-            &path.0,
+            &path,
         );
     }
 }

vello_encoding/src/encoding.rs

@@ -1,6 +1,8 @@
 // Copyright 2022 the Vello Authors
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
+use crate::path::{EmboldenStyle, WindingPathEncoder};
+
 use super::{
     DrawBlurRoundedRect, DrawColor, DrawImage, DrawLinearGradient, DrawRadialGradient,
     DrawSweepGradient, DrawTag, Glyph, GlyphRun, NormalizedCoord, Patch, PathEncoder, PathTag,
@@ -33,6 +35,8 @@ pub struct Encoding {
     pub transforms: Vec<Transform>,
     /// The style stream
     pub styles: Vec<Style>,
+    /// Winding information for subpaths of filled shapes
+    pub path_windings: Vec<f32>,
     /// Late bound resource data.
     pub resources: Resources,
     /// Number of encoded paths.
@@ -77,6 +81,7 @@ impl Encoding {
         self.styles.clear();
         self.draw_data.clear();
         self.draw_tags.clear();
+        self.path_windings.clear();
         self.n_paths = 0;
         self.n_path_segments = 0;
         self.n_clips = 0;
@@ -112,6 +117,7 @@ impl Encoding {
                     run.stream_offsets.draw_data += offsets.draw_data;
                     run.stream_offsets.transforms += offsets.transforms;
                     run.stream_offsets.styles += offsets.styles;
+                    run.stream_offsets.path_windings += offsets.path_windings;
                     run
                 }));
             self.resources
@@ -149,6 +155,7 @@ impl Encoding {
         self.path_data.extend_from_slice(&other.path_data);
         self.draw_tags.extend_from_slice(&other.draw_tags);
         self.draw_data.extend_from_slice(&other.draw_data);
+        self.path_windings.extend_from_slice(&other.path_windings);
         self.n_paths += other.n_paths;
         self.n_path_segments += other.n_path_segments;
         self.n_clips += other.n_clips;
@@ -175,6 +182,7 @@ impl Encoding {
             draw_data: self.draw_data.len(),
             transforms: self.transforms.len(),
             styles: self.styles.len(),
+            path_windings: self.path_windings.len(),
         }
     }
 
@@ -188,6 +196,16 @@ impl Encoding {
         self.encode_style(Style::from_stroke(stroke));
     }
 
+    /// Encodes a fill style with embolden.
+    pub fn encode_fill_style_embolden(&mut self, fill: Fill, embolden_fill: EmboldenStyle) {
+        self.encode_style(Style::from_embolden_fill(fill, embolden_fill));
+    }
+
+    /// Encodes a stroke style with embolden.
+    pub fn encode_stroke_style_embolden(&mut self, stroke: &Stroke, embolden: f32) {
+        self.encode_style(Style::from_stroke(stroke).with_embolden(embolden));
+    }
+
     fn encode_style(&mut self, style: Style) {
         if self.flags & Self::FORCE_NEXT_STYLE != 0 || self.styles.last() != Some(&style) {
             self.path_tags.push(PathTag::STYLE);
@@ -225,6 +243,18 @@ impl Encoding {
         )
     }
 
+    /// Returns an encoder for encoding a filled path with winding data for expansion.
+    pub fn encode_winding_path(&mut self, is_fill: bool) -> WindingPathEncoder<'_> {
+        WindingPathEncoder::new(
+            &mut self.path_tags,
+            &mut self.path_data,
+            &mut self.n_path_segments,
+            &mut self.n_paths,
+            &mut self.path_windings,
+            is_fill,
+        )
+    }
+
     /// Encodes a shape. If `is_fill` is true, all subpaths will be automatically closed.
     /// Returns true if a non-zero number of segments were encoded.
     pub fn encode_shape(&mut self, shape: &impl Shape, is_fill: bool) -> bool {
@@ -572,6 +602,8 @@ pub struct StreamOffsets {
     pub transforms: usize,
     /// Current length of style stream.
     pub styles: usize,
+    /// Current length of path winding stream.
+    pub path_windings: usize,
 }
 
 impl StreamOffsets {
@@ -582,6 +614,7 @@ impl StreamOffsets {
         self.draw_data += other.draw_data;
         self.transforms += other.transforms;
         self.styles += other.styles;
+        self.path_windings += other.path_windings;
     }
 }
 

vello_encoding/src/glyph.rs

@@ -3,9 +3,10 @@
 
 use std::ops::Range;
 
-use peniko::{Font, Style};
+use crate::path::EmboldenStyle;
 
 use super::{StreamOffsets, Transform};
+use peniko::{Font, Style};
 
 /// Positioned glyph.
 #[derive(Copy, Clone, Default, Debug)]
@@ -29,6 +30,8 @@ pub struct GlyphRun {
     pub glyph_transform: Option<Transform>,
     /// Size of the font in pixels per em.
     pub font_size: f32,
+    /// The style to use when emboldening with embolden in em.
+    pub embolden_style: EmboldenStyle,
     /// True if hinting is enabled.
     pub hint: bool,
     /// Range of normalized coordinates in the parent encoding.

vello_encoding/src/glyph_cache.rs

@@ -4,6 +4,8 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 
+use crate::path::EmboldenStyle;
+
 use super::{Encoding, StreamOffsets};
 
 use peniko::{Font, Style};
@@ -30,6 +32,7 @@ impl GlyphCache {
         size: f32,
         hint: bool,
         style: &'a Style,
+        embolden_fill: EmboldenStyle,
     ) -> Option<GlyphCacheSession<'a>> {
         let font_id = font.data.id();
         let font_index = font.index;
@@ -64,10 +67,12 @@ impl GlyphCache {
         };
         // TODO: we're ignoring dashing for now
         let style_bits = match style {
-            Style::Fill(fill) => super::path::Style::from_fill(*fill),
-            Style::Stroke(stroke) => super::path::Style::from_stroke(stroke),
+            Style::Fill(fill) => super::path::Style::from_embolden_fill(*fill, embolden_fill),
+            Style::Stroke(stroke) => {
+                super::path::Style::from_stroke(stroke).with_embolden(embolden_fill.embolden)
+            }
         };
-        let style_bits: [u32; 2] = bytemuck::cast(style_bits);
+        let style_bits: [u32; 3] = bytemuck::cast(style_bits);
         Some(GlyphCacheSession {
             free_list: &mut self.free_list,
             map,
@@ -82,6 +87,7 @@ impl GlyphCache {
             hinter,
             serial: self.serial,
             cached_count: &mut self.cached_count,
+            embolden_fill_style: embolden_fill,
         })
     }
 
@@ -141,11 +147,12 @@ pub(crate) struct GlyphCacheSession<'a> {
     size: Size,
     size_bits: u32,
     style: &'a Style,
-    style_bits: [u32; 2],
+    style_bits: [u32; 3],
     outlines: OutlineGlyphCollection<'a>,
     hinter: Option<&'a HintingInstance>,
     serial: u64,
     cached_count: &'a mut usize,
+    embolden_fill_style: EmboldenStyle,
 }
 
 impl GlyphCacheSession<'_> {
@@ -171,30 +178,53 @@ impl GlyphCacheSession<'_> {
         encoding_ptr.reset();
         let is_fill = match &self.style {
             Style::Fill(fill) => {
-                encoding_ptr.encode_fill_style(*fill);
+                encoding_ptr.encode_fill_style_embolden(*fill, self.embolden_fill_style);
                 true
             }
             Style::Stroke(stroke) => {
-                encoding_ptr.encode_stroke_style(stroke);
+                encoding_ptr
+                    .encode_stroke_style_embolden(stroke, self.embolden_fill_style.embolden);
                 false
             }
         };
         use skrifa::outline::DrawSettings;
-        let mut path = encoding_ptr.encode_path(is_fill);
-        let draw_settings = if key.hint {
-            if let Some(hinter) = self.hinter {
-                DrawSettings::hinted(hinter, false)
+        let fill_style = self.embolden_fill_style;
+        if fill_style.embolden != 0. {
+            let mut path = encoding_ptr.encode_winding_path(is_fill);
+            let draw_settings = if key.hint {
+                if let Some(hinter) = self.hinter {
+                    DrawSettings::hinted(hinter, false)
+                } else {
+                    DrawSettings::unhinted(self.size, self.coords)
+                }
             } else {
                 DrawSettings::unhinted(self.size, self.coords)
+            };
+
+            outline.draw(draw_settings, &mut path).ok()?;
+            if path.finish(false) == 0 {
+                encoding_ptr.reset();
             }
         } else {
-            DrawSettings::unhinted(self.size, self.coords)
-        };
-        outline.draw(draw_settings, &mut path).ok()?;
-        if path.finish(false) == 0 {
-            encoding_ptr.reset();
+            let mut path = encoding_ptr.encode_path(is_fill);
+            let draw_settings = if key.hint {
+                if let Some(hinter) = self.hinter {
+                    DrawSettings::hinted(hinter, false)
+                } else {
+                    DrawSettings::unhinted(self.size, self.coords)
+                }
+            } else {
+                DrawSettings::unhinted(self.size, self.coords)
+            };
+
+            outline.draw(draw_settings, &mut path).ok()?;
+            if path.finish(false) == 0 {
+                encoding_ptr.reset();
+            }
         }
+
         let stream_sizes = encoding_ptr.stream_offsets();
+
         self.map.insert(
             key,
             GlyphEntry {
@@ -214,7 +244,7 @@ struct GlyphKey {
     font_index: u32,
     glyph_id: u32,
     font_size_bits: u32,
-    style_bits: [u32; 2],
+    style_bits: [u32; 3],
     hint: bool,
 }
 

vello_encoding/src/lib.rs

@@ -63,8 +63,8 @@ pub use mask::{make_mask_lut, make_mask_lut_16};
 pub use math::Transform;
 pub use monoid::Monoid;
 pub use path::{
-    Cubic, LineSoup, Path, PathBbox, PathEncoder, PathMonoid, PathSegment, PathSegmentType,
-    PathTag, SegmentCount, Style, Tile,
+    Cubic, EmboldenStyle, LineSoup, Path, PathBbox, PathEncoder, PathMonoid, PathSegment,
+    PathSegmentType, PathTag, SegmentCount, Style, Tile,
 };
 pub use ramp_cache::Ramps;
 pub use resolve::{Layout, Patch, Resolver, resolve_solid_paths_only};