Merge pull request #284 from linebender/glyph-run

Glyph run API

Cargo.toml

@@ -45,7 +45,7 @@ parking_lot = "0.12"
 bytemuck = { version = "1.12.1", features = ["derive"] }
 smallvec = "1.8.0"
 moscato = { git = "https://github.com/dfrg/pinot", rev = "59db153" }
-peniko = { git = "https://github.com/linebender/peniko", rev = "8cb710f" }
+peniko = { git = "https://github.com/linebender/peniko", rev = "cafdac9a211a0fb2fec5656bd663d1ac770bcc81" }
 
 [workspace.dependencies]
 wgpu = "0.15"

examples/headless/src/main.rs

@@ -104,7 +104,6 @@ async fn render(mut scenes: SceneSet, index: usize, args: &Args) -> Result<()> {
         base_color: None,
     };
     (example_scene.function)(&mut builder, &mut scene_params);
-    builder.finish();
     let mut transform = Affine::IDENTITY;
     let (width, height) = if let Some(resolution) = scene_params.resolution {
         let ratio = resolution.x / resolution.y;
@@ -144,7 +143,6 @@ async fn render(mut scenes: SceneSet, index: usize, args: &Args) -> Result<()> {
     let mut scene = Scene::new();
     let mut builder = SceneBuilder::for_scene(&mut scene);
     builder.append(&fragment, Some(transform));
-    builder.finish();
     let size = Extent3d {
         width,
         height,

examples/scenes/src/simple_text.rs

@@ -14,14 +14,17 @@
 //
 // Also licensed under MIT license, at your choice.
 
+use std::sync::Arc;
+
 use vello::{
+    encoding::Glyph,
     glyph::{
         pinot,
         pinot::{FontRef, TableProvider},
         GlyphContext,
     },
     kurbo::Affine,
-    peniko::Brush,
+    peniko::{Blob, Brush, BrushRef, Font, StyleRef},
     SceneBuilder,
 };
 
@@ -31,12 +34,69 @@ const FONT_DATA: &[u8] = include_bytes!("../../assets/roboto/Roboto-Regular.ttf"
 
 pub struct SimpleText {
     gcx: GlyphContext,
+    font: Font,
 }
 
 impl SimpleText {
     pub fn new() -> Self {
         Self {
             gcx: GlyphContext::new(),
+            font: Font::new(Blob::new(Arc::new(FONT_DATA)), 0),
+        }
+    }
+
+    pub fn add_run<'a>(
+        &mut self,
+        builder: &mut SceneBuilder,
+        size: f32,
+        brush: impl Into<BrushRef<'a>>,
+        transform: Affine,
+        glyph_transform: Option<Affine>,
+        style: impl Into<StyleRef<'a>>,
+        text: &str,
+    ) {
+        let font = FontRef {
+            data: FONT_DATA,
+            offset: 0,
+        };
+        let brush = brush.into();
+        let style = style.into();
+        if let Some(cmap) = font.cmap() {
+            if let Some(hmtx) = font.hmtx() {
+                let upem = font.head().map(|head| head.units_per_em()).unwrap_or(1000) as f64;
+                let scale = size as f64 / upem;
+                let hmetrics = hmtx.hmetrics();
+                let default_advance = hmetrics
+                    .get(hmetrics.len().saturating_sub(1))
+                    .map(|h| h.advance_width)
+                    .unwrap_or(0);
+                let mut pen_x = 0f64;
+                builder
+                    .draw_glyphs(&self.font)
+                    .font_size(size)
+                    .transform(transform)
+                    .glyph_transform(glyph_transform)
+                    .brush(brush)
+                    .draw(
+                        style,
+                        text.chars().map(|ch| {
+                            let gid = cmap.map(ch as u32).unwrap_or(0);
+                            let advance = hmetrics
+                                .get(gid as usize)
+                                .map(|h| h.advance_width)
+                                .unwrap_or(default_advance)
+                                as f64
+                                * scale;
+                            let x = pen_x as f32;
+                            pen_x += advance;
+                            Glyph {
+                                id: gid as u32,
+                                x,
+                                y: 0.0,
+                            }
+                        }),
+                    )
+            }
         }
     }
 

examples/scenes/src/test_scenes.rs

@@ -124,12 +124,14 @@ fn animated_text(sb: &mut SceneBuilder, params: &mut SceneParams) {
         Affine::translate((110.0, 600.0)),
         s,
     );
-    params.text.add(
+    params.text.add_run(
         sb,
-        None,
         text_size,
-        None,
+        Color::WHITE,
         Affine::translate((110.0, 700.0)),
+        // Add a skew to simulate an oblique font.
+        Some(Affine::skew(20f64.to_radians().tan(), 0.0)),
+        &Stroke::new(1.0),
         s,
     );
     let th = params.time as f64;
@@ -398,7 +400,6 @@ fn blend_square(blend: BlendMode) -> SceneFragment {
     let mut fragment = SceneFragment::default();
     let mut sb = SceneBuilder::for_fragment(&mut fragment);
     render_blend_square(&mut sb, blend, Affine::IDENTITY);
-    sb.finish();
     fragment
 }
 

examples/with_bevy/src/main.rs

@@ -111,7 +111,6 @@ impl ExtractComponent for VelloScene {
         let mut scene = Scene::default();
         let mut builder = SceneBuilder::for_scene(&mut scene);
         builder.append(&fragment.0, None);
-        builder.finish();
         Some(Self(scene, target.0.clone()))
     }
 }

examples/with_winit/src/lib.rs

@@ -268,7 +268,6 @@ fn run(
                 base_color: None,
             };
             (example_scene.function)(&mut builder, &mut scene_params);
-            builder.finish();
 
             // If the user specifies a base color in the CLI we use that. Otherwise we use any
             // color specified by the scene. The default is black.
@@ -291,7 +290,6 @@ fn run(
                 transform = transform * Affine::scale(scale_factor);
             }
             builder.append(&fragment, Some(transform));
-            builder.finish();
             let surface_texture = render_state
                 .surface
                 .surface

shader/shared/config.wgsl

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT OR Unlicense
 
+// This must be kept in sync with the struct in src/encoding/resolve.rs
 struct Config {
     width_in_tiles: u32,
     height_in_tiles: u32,

src/encoding.rs

@@ -18,19 +18,22 @@
 
 mod draw;
 mod encoding;
+mod glyph;
+mod glyph_cache;
 mod math;
 mod monoid;
-mod packed;
 mod path;
-
-pub mod resource;
+mod ramp_cache;
+mod resolve;
 
 pub use draw::{
     DrawBeginClip, DrawColor, DrawImage, DrawLinearGradient, DrawMonoid, DrawRadialGradient,
     DrawTag,
 };
-pub use encoding::Encoding;
+pub use encoding::{Encoding, StreamOffsets};
+pub use glyph::{Glyph, GlyphRun};
 pub use math::Transform;
 pub use monoid::Monoid;
-pub use packed::{Config, Layout, PackedEncoding};
 pub use path::{PathBbox, PathEncoder, PathMonoid, PathSegment, PathSegmentType, PathTag};
+pub use ramp_cache::Ramps;
+pub use resolve::{Config, Layout, Patch, Resolver};

src/encoding/encoding.rs

@@ -14,15 +14,15 @@
 //
 // Also licensed under MIT license, at your choice.
 
-use super::resource::Patch;
 use super::{
-    DrawColor, DrawLinearGradient, DrawRadialGradient, DrawTag, PathEncoder, PathTag, Transform,
+    resolve::Patch, DrawColor, DrawLinearGradient, DrawRadialGradient, DrawTag, Glyph, GlyphRun,
+    PathEncoder, PathTag, Transform,
 };
 
-use peniko::{kurbo::Shape, BlendMode, BrushRef, Color, ColorStop, Extend, GradientKind};
+use peniko::{kurbo::Shape, BlendMode, BrushRef, ColorStop, Extend, GradientKind};
 
 /// Encoded data streams for a scene.
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct Encoding {
     /// The path tag stream.
     pub path_tags: Vec<PathTag>,
@@ -40,12 +40,20 @@ pub struct Encoding {
     pub transforms: Vec<Transform>,
     /// The line width stream.
     pub linewidths: Vec<f32>,
+    /// Positioned glyph buffer.
+    pub glyphs: Vec<Glyph>,
+    /// Sequences of glyphs.
+    pub glyph_runs: Vec<GlyphRun>,
+    /// Normalized coordinate buffer for variable fonts.
+    pub normalized_coords: Vec<i16>,
     /// Number of encoded paths.
     pub n_paths: u32,
     /// Number of encoded path segments.
     pub n_path_segments: u32,
     /// Number of encoded clips/layers.
     pub n_clips: u32,
+    /// Number of unclosed clips/layers.
+    pub n_open_clips: u32,
 }
 
 impl Encoding {
@@ -67,9 +75,13 @@ impl Encoding {
         self.linewidths.clear();
         self.draw_data.clear();
         self.draw_tags.clear();
+        self.glyphs.clear();
+        self.glyph_runs.clear();
+        self.normalized_coords.clear();
         self.n_paths = 0;
         self.n_path_segments = 0;
         self.n_clips = 0;
+        self.n_open_clips = 0;
         self.patches.clear();
         self.color_stops.clear();
         if !is_fragment {
@@ -81,33 +93,70 @@ impl Encoding {
     /// Appends another encoding to this one with an optional transform.
     pub fn append(&mut self, other: &Self, transform: &Option<Transform>) {
         let stops_base = self.color_stops.len();
-        let draw_data_base = self.draw_data.len();
+        let glyph_runs_base = self.glyph_runs.len();
+        let glyphs_base = self.glyphs.len();
+        let coords_base = self.normalized_coords.len();
+        let offsets = self.stream_offsets();
         self.path_tags.extend_from_slice(&other.path_tags);
         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.glyphs.extend_from_slice(&other.glyphs);
+        self.normalized_coords
+            .extend_from_slice(&other.normalized_coords);
+        self.glyph_runs
+            .extend(other.glyph_runs.iter().cloned().map(|mut run| {
+                run.glyphs.start += glyphs_base;
+                run.normalized_coords.start += coords_base;
+                run.stream_offsets.path_tags += offsets.path_tags;
+                run.stream_offsets.path_data += offsets.path_data;
+                run.stream_offsets.draw_tags += offsets.draw_tags;
+                run.stream_offsets.draw_data += offsets.draw_data;
+                run.stream_offsets.transforms += offsets.transforms;
+                run.stream_offsets.linewidths += offsets.linewidths;
+                run
+            }));
         self.n_paths += other.n_paths;
         self.n_path_segments += other.n_path_segments;
         self.n_clips += other.n_clips;
+        self.n_open_clips += other.n_open_clips;
         self.patches
             .extend(other.patches.iter().map(|patch| match patch {
                 Patch::Ramp { offset, stops } => {
                     let stops = stops.start + stops_base..stops.end + stops_base;
                     Patch::Ramp {
-                        offset: draw_data_base + offset,
+                        offset: offset + offsets.draw_data,
                         stops,
                     }
                 }
+                Patch::GlyphRun { index } => Patch::GlyphRun {
+                    index: index + glyph_runs_base,
+                },
             }));
         self.color_stops.extend_from_slice(&other.color_stops);
         if let Some(transform) = *transform {
             self.transforms
                 .extend(other.transforms.iter().map(|x| transform * *x));
+            for run in &mut self.glyph_runs[glyph_runs_base..] {
+                run.transform = transform * run.transform;
+            }
         } else {
             self.transforms.extend_from_slice(&other.transforms);
         }
         self.linewidths.extend_from_slice(&other.linewidths);
     }
+
+    /// Returns a snapshot of the current stream offsets.
+    pub fn stream_offsets(&self) -> StreamOffsets {
+        StreamOffsets {
+            path_tags: self.path_tags.len(),
+            path_data: self.path_data.len(),
+            draw_tags: self.draw_tags.len(),
+            draw_data: self.draw_data.len(),
+            transforms: self.transforms.len(),
+            linewidths: self.linewidths.len(),
+        }
+    }
 }
 
 impl Encoding {
@@ -159,7 +208,7 @@ impl Encoding {
         match brush.into() {
             BrushRef::Solid(color) => {
                 let color = if alpha != 1.0 {
-                    color_with_alpha(color, alpha)
+                    color.with_alpha_factor(alpha)
                 } else {
                     color
                 };
@@ -248,15 +297,19 @@ impl Encoding {
         self.draw_data
             .extend_from_slice(bytemuck::bytes_of(&DrawBeginClip::new(blend_mode, alpha)));
         self.n_clips += 1;
+        self.n_open_clips += 1;
     }
 
     /// Encodes an end clip command.
     pub fn encode_end_clip(&mut self) {
-        self.draw_tags.push(DrawTag::END_CLIP);
-        // This is a dummy path, and will go away with the new clip impl.
-        self.path_tags.push(PathTag::PATH);
-        self.n_paths += 1;
-        self.n_clips += 1;
+        if self.n_open_clips > 0 {
+            self.draw_tags.push(DrawTag::END_CLIP);
+            // This is a dummy path, and will go away with the new clip impl.
+            self.path_tags.push(PathTag::PATH);
+            self.n_paths += 1;
+            self.n_clips += 1;
+            self.n_open_clips -= 1;
+        }
     }
 
     // Swap the last two tags in the path tag stream; used for transformed
@@ -270,10 +323,8 @@ impl Encoding {
         let offset = self.draw_data.len();
         let stops_start = self.color_stops.len();
         if alpha != 1.0 {
-            self.color_stops.extend(color_stops.map(|s| ColorStop {
-                offset: s.offset,
-                color: color_with_alpha(s.color, alpha),
-            }));
+            self.color_stops
+                .extend(color_stops.map(|stop| stop.with_alpha_factor(alpha)));
         } else {
             self.color_stops.extend(color_stops);
         }
@@ -284,7 +335,30 @@ impl Encoding {
     }
 }
 
-fn color_with_alpha(mut color: Color, alpha: f32) -> Color {
-    color.a = ((color.a as f32) * alpha) as u8;
-    color
+/// Snapshot of offsets for encoded streams.
+#[derive(Copy, Clone, Default, Debug)]
+pub struct StreamOffsets {
+    /// Current length of path tag stream.
+    pub path_tags: usize,
+    /// Current length of path data stream.
+    pub path_data: usize,
+    /// Current length of draw tag stream.
+    pub draw_tags: usize,
+    /// Current length of draw data stream.
+    pub draw_data: usize,
+    /// Current length of transform stream.
+    pub transforms: usize,
+    /// Current length of linewidth stream.
+    pub linewidths: usize,
+}
+
+impl StreamOffsets {
+    pub(crate) fn add(&mut self, other: &Self) {
+        self.path_tags += other.path_tags;
+        self.path_data += other.path_data;
+        self.draw_tags += other.draw_tags;
+        self.draw_data += other.draw_data;
+        self.transforms += other.transforms;
+        self.linewidths += other.linewidths;
+    }
 }

src/encoding/glyph.rs

@@ -0,0 +1,55 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Also licensed under MIT license, at your choice.
+
+use std::ops::Range;
+
+use peniko::{Font, Style};
+
+use super::{StreamOffsets, Transform};
+
+/// Positioned glyph.
+#[derive(Copy, Clone, Default, Debug)]
+pub struct Glyph {
+    /// Glyph identifier.
+    pub id: u32,
+    /// X-offset in run, relative to transform.
+    pub x: f32,
+    /// Y-offset in run, relative to transform.
+    pub y: f32,
+}
+
+/// Properties for a sequence of glyphs in an encoding.
+#[derive(Clone)]
+pub struct GlyphRun {
+    /// Font for all glyphs in the run.
+    pub font: Font,
+    /// Global run transform.
+    pub transform: Transform,
+    /// Per-glyph transform.
+    pub glyph_transform: Option<Transform>,
+    /// Size of the font in pixels per em.
+    pub font_size: f32,
+    /// True if hinting is enabled.
+    pub hint: bool,
+    /// Range of normalized coordinates in the parent encoding.
+    pub normalized_coords: Range<usize>,
+    /// Fill or stroke style.
+    pub style: Style,
+    /// Range of glyphs in the parent encoding.
+    pub glyphs: Range<usize>,
+    /// Stream offsets where this glyph run should be inserted.
+    pub stream_offsets: StreamOffsets,
+}

src/encoding/glyph_cache.rs

@@ -0,0 +1,90 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Also licensed under MIT license, at your choice.
+
+use std::collections::HashMap;
+
+use super::{Encoding, StreamOffsets};
+use crate::glyph::GlyphProvider;
+
+use peniko::{Fill, Style};
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Default, Debug)]
+pub struct GlyphKey {
+    pub font_id: u64,
+    pub font_index: u32,
+    pub glyph_id: u32,
+    pub font_size: u32,
+    pub hint: bool,
+}
+
+#[derive(Default)]
+pub struct GlyphCache {
+    pub encoding: Encoding,
+    glyphs: HashMap<GlyphKey, CachedRange>,
+}
+
+impl GlyphCache {
+    pub fn clear(&mut self) {
+        self.encoding.reset(true);
+        self.glyphs.clear();
+    }
+
+    pub fn get_or_insert(
+        &mut self,
+        key: GlyphKey,
+        style: &Style,
+        scaler: &mut GlyphProvider,
+    ) -> Option<CachedRange> {
+        let encoding_cache = &mut self.encoding;
+        let mut encode_glyph = || {
+            let start = encoding_cache.stream_offsets();
+            scaler.encode_glyph(key.glyph_id as u16, style, encoding_cache)?;
+            let end = encoding_cache.stream_offsets();
+            Some(CachedRange { start, end })
+        };
+        // For now, only cache non-zero filled glyphs so we don't need to keep style
+        // as part of the key.
+        let range = if matches!(style, Style::Fill(Fill::NonZero)) {
+            use std::collections::hash_map::Entry;
+            match self.glyphs.entry(key) {
+                Entry::Occupied(entry) => *entry.get(),
+                Entry::Vacant(entry) => *entry.insert(encode_glyph()?),
+            }
+        } else {
+            encode_glyph()?
+        };
+        Some(range)
+    }
+}
+
+#[derive(Copy, Clone, Default, Debug)]
+pub struct CachedRange {
+    pub start: StreamOffsets,
+    pub end: StreamOffsets,
+}
+
+impl CachedRange {
+    pub fn len(&self) -> StreamOffsets {
+        StreamOffsets {
+            path_tags: self.end.path_tags - self.start.path_tags,
+            path_data: self.end.path_data - self.start.path_data,
+            draw_tags: self.end.draw_tags - self.start.draw_tags,
+            draw_data: self.end.draw_data - self.start.draw_data,
+            transforms: self.end.transforms - self.start.transforms,
+            linewidths: self.end.linewidths - self.start.linewidths,
+        }
+    }
+}

src/encoding/math.rs

@@ -20,7 +20,7 @@ use bytemuck::{Pod, Zeroable};
 use peniko::kurbo;
 
 /// Affine transformation matrix.
-#[derive(Copy, Clone, PartialEq, Pod, Zeroable)]
+#[derive(Copy, Clone, Debug, PartialEq, Pod, Zeroable)]
 #[repr(C)]
 pub struct Transform {
     /// 2x2 matrix.

src/encoding/packed.rs

@@ -1,223 +0,0 @@
-// Copyright 2022 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Also licensed under MIT license, at your choice.
-
-use bytemuck::{Pod, Zeroable};
-
-use super::{
-    resource::{Patch, ResourceCache, Token},
-    DrawTag, Encoding, PathTag, Transform,
-};
-use crate::shaders;
-
-/// Layout of a packed encoding.
-#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
-#[repr(C)]
-pub struct Layout {
-    /// Number of draw objects.
-    pub n_draw_objects: u32,
-    /// Number of paths.
-    pub n_paths: u32,
-    /// Number of clips.
-    pub n_clips: u32,
-    /// Start of binning data.
-    pub bin_data_start: u32,
-    /// Start of path tag stream.
-    pub path_tag_base: u32,
-    /// Start of path data stream.
-    pub path_data_base: u32,
-    /// Start of draw tag stream.
-    pub draw_tag_base: u32,
-    /// Start of draw data stream.
-    pub draw_data_base: u32,
-    /// Start of transform stream.
-    pub transform_base: u32,
-    /// Start of linewidth stream.
-    pub linewidth_base: u32,
-}
-
-/// Scene configuration. This data structure must be kept in sync with the definition in
-/// shaders/shared/config.wgsl.
-#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
-#[repr(C)]
-pub struct Config {
-    /// Width of the scene in tiles.
-    pub width_in_tiles: u32,
-    /// Height of the scene in tiles.
-    pub height_in_tiles: u32,
-    /// Width of the target in pixels.
-    pub target_width: u32,
-    /// Height of the target in pixels.
-    pub target_height: u32,
-    /// The base background color applied to the target before any blends.
-    pub base_color: u32,
-    /// Layout of packed scene data.
-    pub layout: Layout,
-    /// Size of binning buffer allocation (in u32s).
-    pub binning_size: u32,
-    /// Size of tile buffer allocation (in Tiles).
-    pub tiles_size: u32,
-    /// Size of segment buffer allocation (in PathSegments).
-    pub segments_size: u32,
-    /// Size of per-tile command list buffer allocation (in u32s).
-    pub ptcl_size: u32,
-}
-
-/// Packed encoding of scene data.
-#[derive(Default)]
-pub struct PackedEncoding {
-    /// Layout of the packed scene data.
-    pub layout: Layout,
-    /// Packed scene data.
-    pub data: Vec<u8>,
-    /// Token for current cached resource state.
-    pub resources: Token,
-}
-
-impl PackedEncoding {
-    /// Creates a new packed encoding.
-    pub fn new() -> Self {
-        Self::default()
-    }
-
-    /// Returns the path tag stream.
-    pub fn path_tags(&self) -> &[PathTag] {
-        let start = self.layout.path_tag_base as usize * 4;
-        let end = self.layout.path_data_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..end])
-    }
-
-    /// Returns the path tag stream in chunks of 4.
-    pub fn path_tags_chunked(&self) -> &[u32] {
-        let start = self.layout.path_tag_base as usize * 4;
-        let end = self.layout.path_data_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..end])
-    }
-
-    /// Returns the path data stream.
-    pub fn path_data(&self) -> &[[f32; 2]] {
-        let start = self.layout.path_data_base as usize * 4;
-        let end = self.layout.draw_tag_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..end])
-    }
-
-    /// Returns the draw tag stream.
-    pub fn draw_tags(&self) -> &[DrawTag] {
-        let start = self.layout.draw_tag_base as usize * 4;
-        let end = self.layout.draw_data_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..end])
-    }
-
-    /// Returns the draw data stream.
-    pub fn draw_data(&self) -> &[u32] {
-        let start = self.layout.draw_data_base as usize * 4;
-        let end = self.layout.transform_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..end])
-    }
-
-    /// Returns the transform stream.
-    pub fn transforms(&self) -> &[Transform] {
-        let start = self.layout.transform_base as usize * 4;
-        let end = self.layout.linewidth_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..end])
-    }
-
-    /// Returns the linewidth stream.
-    pub fn linewidths(&self) -> &[f32] {
-        let start = self.layout.linewidth_base as usize * 4;
-        bytemuck::cast_slice(&self.data[start..])
-    }
-}
-
-impl PackedEncoding {
-    /// Packs the given encoding into self using the specified cache to handle
-    /// late bound resources.
-    pub fn pack(&mut self, encoding: &Encoding, resource_cache: &mut ResourceCache) {
-        // Advance the resource cache epoch.
-        self.resources = resource_cache.advance();
-        // Pack encoded data.
-        let layout = &mut self.layout;
-        *layout = Layout::default();
-        layout.n_paths = encoding.n_paths;
-        layout.n_draw_objects = encoding.n_paths;
-        layout.n_clips = encoding.n_clips;
-        let data = &mut self.data;
-        data.clear();
-        // Path tag stream
-        let n_path_tags = encoding.path_tags.len();
-        let path_tag_padded = align_up(n_path_tags, 4 * shaders::PATHTAG_REDUCE_WG);
-        let capacity = path_tag_padded
-            + slice_size_in_bytes(&encoding.path_data)
-            + slice_size_in_bytes(&encoding.draw_tags)
-            + slice_size_in_bytes(&encoding.draw_data)
-            + slice_size_in_bytes(&encoding.transforms)
-            + slice_size_in_bytes(&encoding.linewidths);
-        data.reserve(capacity);
-        layout.path_tag_base = size_to_words(data.len());
-        data.extend_from_slice(bytemuck::cast_slice(&encoding.path_tags));
-        data.resize(path_tag_padded, 0);
-        // Path data stream
-        layout.path_data_base = size_to_words(data.len());
-        data.extend_from_slice(&encoding.path_data);
-        // Draw tag stream
-        layout.draw_tag_base = size_to_words(data.len());
-        data.extend_from_slice(bytemuck::cast_slice(&encoding.draw_tags));
-        // Bin data follows draw info
-        layout.bin_data_start = encoding.draw_tags.iter().map(|tag| tag.info_size()).sum();
-        // Draw data stream
-        layout.draw_data_base = size_to_words(data.len());
-        // Handle patches, if any
-        if !encoding.patches.is_empty() {
-            let stop_data = &encoding.color_stops;
-            let mut pos = 0;
-            for patch in &encoding.patches {
-                let (offset, value) = match patch {
-                    Patch::Ramp { offset, stops } => {
-                        let ramp_id = resource_cache.add_ramp(&stop_data[stops.clone()]);
-                        (*offset, ramp_id)
-                    }
-                };
-                if pos < offset {
-                    data.extend_from_slice(&encoding.draw_data[pos..offset]);
-                }
-                data.extend_from_slice(bytemuck::bytes_of(&value));
-                pos = offset + 4;
-            }
-            if pos < encoding.draw_data.len() {
-                data.extend_from_slice(&encoding.draw_data[pos..])
-            }
-        } else {
-            data.extend_from_slice(&encoding.draw_data);
-        }
-        // Transform stream
-        layout.transform_base = size_to_words(data.len());
-        data.extend_from_slice(bytemuck::cast_slice(&encoding.transforms));
-        // Linewidth stream
-        layout.linewidth_base = size_to_words(data.len());
-        data.extend_from_slice(bytemuck::cast_slice(&encoding.linewidths));
-    }
-}
-
-fn slice_size_in_bytes<T: Sized>(slice: &[T]) -> usize {
-    slice.len() * std::mem::size_of::<T>()
-}
-
-fn size_to_words(byte_size: usize) -> u32 {
-    (byte_size / std::mem::size_of::<u32>()) as u32
-}
-
-fn align_up(len: usize, alignment: u32) -> usize {
-    len + (len.wrapping_neg() & (alignment as usize - 1))
-}

src/encoding/ramp_cache.rs

@@ -14,67 +14,23 @@
 //
 // Also licensed under MIT license, at your choice.
 
-//! Late bound resource management.
-
 use std::collections::HashMap;
-use std::ops::Range;
 
 use peniko::{Color, ColorStop, ColorStops};
 
 const N_SAMPLES: usize = 512;
 const RETAINED_COUNT: usize = 64;
 
-/// Token for ensuring that an encoded scene matches the current state
-/// of a resource cache.
-#[derive(Copy, Clone, PartialEq, Eq, Default)]
-pub struct Token(u64);
-
-/// Cache for late bound resources.
-#[derive(Default)]
-pub struct ResourceCache {
-    ramps: RampCache,
-}
-
-impl ResourceCache {
-    /// Creates a new resource cache.
-    pub fn new() -> Self {
-        Self::default()
-    }
-
-    /// Returns the ramp data, width and height. Returns `None` if the
-    /// given token does not match the current state of the cache.
-    pub fn ramps(&self, token: Token) -> Option<(&[u32], u32, u32)> {
-        if token.0 == self.ramps.epoch {
-            Some((self.ramps.data(), self.ramps.width(), self.ramps.height()))
-        } else {
-            None
-        }
-    }
-
-    pub(crate) fn advance(&mut self) -> Token {
-        self.ramps.advance();
-        Token(self.ramps.epoch)
-    }
-
-    pub(crate) fn add_ramp(&mut self, stops: &[ColorStop]) -> u32 {
-        self.ramps.add(stops)
-    }
-}
-
-#[derive(Clone)]
-/// Patch for a late bound resource.
-pub enum Patch {
-    /// Gradient ramp resource.
-    Ramp {
-        /// Byte offset to the ramp id in the draw data stream.
-        offset: usize,
-        /// Range of the gradient stops in the resource set.
-        stops: Range<usize>,
-    },
+/// Data and dimensions for a set of resolved gradient ramps.
+#[derive(Copy, Clone, Debug, Default)]
+pub struct Ramps<'a> {
+    pub data: &'a [u32],
+    pub width: u32,
+    pub height: u32,
 }
 
 #[derive(Default)]
-struct RampCache {
+pub struct RampCache {
     epoch: u64,
     map: HashMap<ColorStops, (u32, u64)>,
     data: Vec<u32>,
@@ -127,16 +83,12 @@ impl RampCache {
         }
     }
 
-    pub fn data(&self) -> &[u32] {
-        &self.data
-    }
-
-    pub fn width(&self) -> u32 {
-        N_SAMPLES as u32
-    }
-
-    pub fn height(&self) -> u32 {
-        (self.data.len() / N_SAMPLES) as u32
+    pub fn ramps(&self) -> Ramps {
+        Ramps {
+            data: &self.data,
+            width: N_SAMPLES as u32,
+            height: (self.data.len() / N_SAMPLES) as u32,
+        }
     }
 }
 

src/encoding/resolve.rs

@@ -0,0 +1,468 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Also licensed under MIT license, at your choice.
+
+use std::ops::Range;
+
+use bytemuck::{Pod, Zeroable};
+use moscato::pinot::FontRef;
+
+use super::{
+    glyph_cache::{CachedRange, GlyphCache, GlyphKey},
+    ramp_cache::{RampCache, Ramps},
+    DrawTag, Encoding, PathTag, StreamOffsets, Transform,
+};
+use crate::glyph::GlyphContext;
+use crate::shaders;
+
+/// Layout of a packed encoding.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct Layout {
+    /// Number of draw objects.
+    pub n_draw_objects: u32,
+    /// Number of paths.
+    pub n_paths: u32,
+    /// Number of clips.
+    pub n_clips: u32,
+    /// Start of binning data.
+    pub bin_data_start: u32,
+    /// Start of path tag stream.
+    pub path_tag_base: u32,
+    /// Start of path data stream.
+    pub path_data_base: u32,
+    /// Start of draw tag stream.
+    pub draw_tag_base: u32,
+    /// Start of draw data stream.
+    pub draw_data_base: u32,
+    /// Start of transform stream.
+    pub transform_base: u32,
+    /// Start of linewidth stream.
+    pub linewidth_base: u32,
+}
+
+impl Layout {
+    /// Creates a zeroed layout.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Returns the path tag stream.
+    pub fn path_tags<'a>(&self, data: &'a [u8]) -> &'a [PathTag] {
+        let start = self.path_tag_base as usize * 4;
+        let end = self.path_data_base as usize * 4;
+        bytemuck::cast_slice(&data[start..end])
+    }
+
+    /// Returns the path tag stream in chunks of 4.
+    pub fn path_tags_chunked<'a>(&self, data: &'a [u8]) -> &'a [u32] {
+        let start = self.path_tag_base as usize * 4;
+        let end = self.path_data_base as usize * 4;
+        bytemuck::cast_slice(&data[start..end])
+    }
+
+    /// Returns the path data stream.
+    pub fn path_data<'a>(&self, data: &'a [u8]) -> &'a [u8] {
+        let start = self.path_data_base as usize * 4;
+        let end = self.draw_tag_base as usize * 4;
+        bytemuck::cast_slice(&data[start..end])
+    }
+
+    /// Returns the draw tag stream.
+    pub fn draw_tags<'a>(&self, data: &'a [u8]) -> &'a [DrawTag] {
+        let start = self.draw_tag_base as usize * 4;
+        let end = self.draw_data_base as usize * 4;
+        bytemuck::cast_slice(&data[start..end])
+    }
+
+    /// Returns the draw data stream.
+    pub fn draw_data<'a>(&self, data: &'a [u8]) -> &'a [u32] {
+        let start = self.draw_data_base as usize * 4;
+        let end = self.transform_base as usize * 4;
+        bytemuck::cast_slice(&data[start..end])
+    }
+
+    /// Returns the transform stream.
+    pub fn transforms<'a>(&self, data: &'a [u8]) -> &'a [Transform] {
+        let start = self.transform_base as usize * 4;
+        let end = self.linewidth_base as usize * 4;
+        bytemuck::cast_slice(&data[start..end])
+    }
+
+    /// Returns the linewidth stream.
+    pub fn linewidths<'a>(&self, data: &'a [u8]) -> &'a [f32] {
+        let start = self.linewidth_base as usize * 4;
+        bytemuck::cast_slice(&data[start..])
+    }
+}
+
+/// Scene configuration.
+///
+/// This data structure must be kept in sync with the definition in
+/// shaders/shared/config.wgsl.
+#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
+#[repr(C)]
+pub struct Config {
+    /// Width of the scene in tiles.
+    pub width_in_tiles: u32,
+    /// Height of the scene in tiles.
+    pub height_in_tiles: u32,
+    /// Width of the target in pixels.
+    pub target_width: u32,
+    /// Height of the target in pixels.
+    pub target_height: u32,
+    /// The base background color applied to the target before any blends.
+    pub base_color: u32,
+    /// Layout of packed scene data.
+    pub layout: Layout,
+    /// Size of binning buffer allocation (in u32s).
+    pub binning_size: u32,
+    /// Size of tile buffer allocation (in Tiles).
+    pub tiles_size: u32,
+    /// Size of segment buffer allocation (in PathSegments).
+    pub segments_size: u32,
+    /// Size of per-tile command list buffer allocation (in u32s).
+    pub ptcl_size: u32,
+}
+
+/// Resolver for late bound resources.
+#[derive(Default)]
+pub struct Resolver {
+    glyph_cache: GlyphCache,
+    glyph_ranges: Vec<CachedRange>,
+    glyph_cx: GlyphContext,
+    ramp_cache: RampCache,
+    patches: Vec<ResolvedPatch>,
+}
+
+impl Resolver {
+    /// Creates a new resource cache.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Resolves late bound resources and packs an encoding. Returns the packed
+    /// layout and computed ramp data.
+    pub fn resolve<'a>(
+        &'a mut self,
+        encoding: &Encoding,
+        packed: &mut Vec<u8>,
+    ) -> (Layout, Ramps<'a>) {
+        let sizes = self.resolve_patches(encoding);
+        let data = packed;
+        data.clear();
+        let mut layout = Layout::default();
+        layout.n_paths = encoding.n_paths;
+        layout.n_clips = encoding.n_clips;
+        // Compute size of data buffer
+        let n_path_tags =
+            encoding.path_tags.len() + sizes.path_tags + encoding.n_open_clips as usize;
+        let path_tag_padded = align_up(n_path_tags, 4 * shaders::PATHTAG_REDUCE_WG);
+        let capacity = path_tag_padded
+            + slice_size_in_bytes(&encoding.path_data, sizes.path_data)
+            + slice_size_in_bytes(
+                &encoding.draw_tags,
+                sizes.draw_tags + encoding.n_open_clips as usize,
+            )
+            + slice_size_in_bytes(&encoding.draw_data, sizes.draw_data)
+            + slice_size_in_bytes(&encoding.transforms, sizes.transforms)
+            + slice_size_in_bytes(&encoding.linewidths, sizes.linewidths);
+        data.reserve(capacity);
+        // Path tag stream
+        layout.path_tag_base = size_to_words(data.len());
+        {
+            let mut pos = 0;
+            let stream = &encoding.path_tags;
+            for patch in &self.patches {
+                if let ResolvedPatch::GlyphRun { index, glyphs, .. } = patch {
+                    layout.n_paths += 1;
+                    let stream_offset = encoding.glyph_runs[*index].stream_offsets.path_tags;
+                    if pos < stream_offset {
+                        data.extend_from_slice(bytemuck::cast_slice(&stream[pos..stream_offset]));
+                        pos = stream_offset;
+                    }
+                    for glyph in &self.glyph_ranges[glyphs.clone()] {
+                        data.extend_from_slice(bytemuck::bytes_of(&PathTag::TRANSFORM));
+                        let glyph_data = &self.glyph_cache.encoding.path_tags
+                            [glyph.start.path_tags..glyph.end.path_tags];
+                        data.extend_from_slice(bytemuck::cast_slice(glyph_data));
+                    }
+                    data.extend_from_slice(bytemuck::bytes_of(&PathTag::PATH));
+                }
+            }
+            if pos < stream.len() {
+                data.extend_from_slice(bytemuck::cast_slice(&stream[pos..]));
+            }
+            for _ in 0..encoding.n_open_clips {
+                data.extend_from_slice(bytemuck::bytes_of(&PathTag::PATH));
+            }
+            data.resize(path_tag_padded, 0);
+        }
+        // Path data stream
+        layout.path_data_base = size_to_words(data.len());
+        {
+            let mut pos = 0;
+            let stream = &encoding.path_data;
+            for patch in &self.patches {
+                if let ResolvedPatch::GlyphRun { index, glyphs, .. } = patch {
+                    let stream_offset = encoding.glyph_runs[*index].stream_offsets.path_data;
+                    if pos < stream_offset {
+                        data.extend_from_slice(bytemuck::cast_slice(&stream[pos..stream_offset]));
+                        pos = stream_offset;
+                    }
+                    for glyph in &self.glyph_ranges[glyphs.clone()] {
+                        let glyph_data = &self.glyph_cache.encoding.path_data
+                            [glyph.start.path_data..glyph.end.path_data];
+                        data.extend_from_slice(bytemuck::cast_slice(glyph_data));
+                    }
+                }
+            }
+            if pos < stream.len() {
+                data.extend_from_slice(bytemuck::cast_slice(&stream[pos..]));
+            }
+        }
+        // Draw tag stream
+        layout.draw_tag_base = size_to_words(data.len());
+        // Bin data follows draw info
+        layout.bin_data_start = encoding.draw_tags.iter().map(|tag| tag.info_size()).sum();
+        {
+            data.extend_from_slice(bytemuck::cast_slice(&encoding.draw_tags));
+            for _ in 0..encoding.n_open_clips {
+                data.extend_from_slice(bytemuck::bytes_of(&DrawTag::END_CLIP));
+            }
+        }
+        // Draw data stream
+        layout.draw_data_base = size_to_words(data.len());
+        {
+            let mut pos = 0;
+            let stream = &encoding.draw_data;
+            for patch in &self.patches {
+                match patch {
+                    ResolvedPatch::Ramp {
+                        draw_data_offset,
+                        ramp_id,
+                    } => {
+                        if pos < *draw_data_offset {
+                            data.extend_from_slice(&encoding.draw_data[pos..*draw_data_offset]);
+                        }
+                        data.extend_from_slice(bytemuck::bytes_of(ramp_id));
+                        pos = *draw_data_offset + 4;
+                    }
+                    ResolvedPatch::GlyphRun { .. } => {}
+                }
+            }
+            if pos < stream.len() {
+                data.extend_from_slice(bytemuck::cast_slice(&stream[pos..]));
+            }
+        }
+        // Transform stream
+        layout.transform_base = size_to_words(data.len());
+        {
+            let mut pos = 0;
+            let stream = &encoding.transforms;
+            for patch in &self.patches {
+                if let ResolvedPatch::GlyphRun {
+                    index,
+                    glyphs: _,
+                    transform,
+                } = patch
+                {
+                    let run = &encoding.glyph_runs[*index];
+                    let stream_offset = encoding.glyph_runs[*index].stream_offsets.transforms;
+                    if pos < stream_offset {
+                        data.extend_from_slice(bytemuck::cast_slice(&stream[pos..stream_offset]));
+                        pos = stream_offset;
+                    }
+                    if let Some(glyph_transform) = run.glyph_transform {
+                        for glyph in &encoding.glyphs[run.glyphs.clone()] {
+                            let xform = *transform
+                                * Transform {
+                                    matrix: [1.0, 0.0, 0.0, -1.0],
+                                    translation: [glyph.x, glyph.y],
+                                }
+                                * glyph_transform;
+                            data.extend_from_slice(bytemuck::bytes_of(&xform));
+                        }
+                    } else {
+                        for glyph in &encoding.glyphs[run.glyphs.clone()] {
+                            let xform = *transform
+                                * Transform {
+                                    matrix: [1.0, 0.0, 0.0, -1.0],
+                                    translation: [glyph.x, glyph.y],
+                                };
+                            data.extend_from_slice(bytemuck::bytes_of(&xform));
+                        }
+                    }
+                }
+            }
+            if pos < stream.len() {
+                data.extend_from_slice(bytemuck::cast_slice(&stream[pos..]));
+            }
+        }
+        // Linewidth stream
+        layout.linewidth_base = size_to_words(data.len());
+        {
+            let mut pos = 0;
+            let stream = &encoding.linewidths;
+            for patch in &self.patches {
+                if let ResolvedPatch::GlyphRun { index, glyphs, .. } = patch {
+                    let stream_offset = encoding.glyph_runs[*index].stream_offsets.linewidths;
+                    if pos < stream_offset {
+                        data.extend_from_slice(bytemuck::cast_slice(&stream[pos..stream_offset]));
+                        pos = stream_offset;
+                    }
+                    for glyph in &self.glyph_ranges[glyphs.clone()] {
+                        let glyph_data = &self.glyph_cache.encoding.linewidths
+                            [glyph.start.linewidths..glyph.end.linewidths];
+                        data.extend_from_slice(bytemuck::cast_slice(glyph_data));
+                    }
+                }
+            }
+            if pos < stream.len() {
+                data.extend_from_slice(bytemuck::cast_slice(&stream[pos..]));
+            }
+        }
+        layout.n_draw_objects = layout.n_paths;
+        assert_eq!(capacity, data.len());
+        (layout, self.ramp_cache.ramps())
+    }
+
+    fn resolve_patches(&mut self, encoding: &Encoding) -> StreamOffsets {
+        self.ramp_cache.advance();
+        self.glyph_cache.clear();
+        self.glyph_ranges.clear();
+        self.patches.clear();
+        let mut sizes = StreamOffsets::default();
+        for patch in &encoding.patches {
+            match patch {
+                Patch::Ramp { offset, stops } => {
+                    let ramp_id = self.ramp_cache.add(&encoding.color_stops[stops.clone()]);
+                    self.patches.push(ResolvedPatch::Ramp {
+                        draw_data_offset: *offset + sizes.draw_data,
+                        ramp_id,
+                    });
+                }
+                Patch::GlyphRun { index } => {
+                    let mut run_sizes = StreamOffsets::default();
+                    let run = &encoding.glyph_runs[*index];
+                    let font_id = run.font.data.id();
+                    let font_size_u32 = run.font_size.to_bits();
+                    let Some(font) = FontRef::from_index(run.font.data.as_ref(), run.font.index) else { continue };
+                    let glyphs = &encoding.glyphs[run.glyphs.clone()];
+                    let _coords = &encoding.normalized_coords[run.normalized_coords.clone()];
+                    let vars: [(moscato::pinot::types::Tag, f32); 0] = [];
+                    let hint_id = if run.font.index < 0xFF {
+                        Some(font_id << 8 | run.font.index as u64)
+                    } else {
+                        None
+                    };
+                    let mut hint = run.hint;
+                    let mut font_size = run.font_size;
+                    let mut transform = run.transform;
+                    if hint {
+                        // If hinting was requested and our transform matrix is just a uniform
+                        // scale, then adjust our font size and cancel out the matrix. Otherwise,
+                        // disable hinting entirely.
+                        if transform.matrix[0] == transform.matrix[3]
+                            && transform.matrix[1] == 0.0
+                            && transform.matrix[2] == 0.0
+                        {
+                            font_size *= transform.matrix[0];
+                            transform.matrix = [1.0, 0.0, 0.0, 1.0];
+                        } else {
+                            hint = false;
+                        }
+                    }
+                    let mut scaler = self
+                        .glyph_cx
+                        .new_provider(&font, hint_id, font_size, hint, vars);
+                    let glyph_start = self.glyph_ranges.len();
+                    for glyph in glyphs {
+                        let key = GlyphKey {
+                            font_id,
+                            font_index: run.font.index,
+                            font_size: font_size_u32,
+                            glyph_id: glyph.id,
+                            hint: run.hint,
+                        };
+                        let encoding_range = self
+                            .glyph_cache
+                            .get_or_insert(key, &run.style, &mut scaler)
+                            .unwrap_or_default();
+                        run_sizes.add(&encoding_range.len());
+                        self.glyph_ranges.push(encoding_range);
+                    }
+                    let glyph_end = self.glyph_ranges.len();
+                    run_sizes.path_tags += glyphs.len() + 1;
+                    run_sizes.transforms += glyphs.len();
+                    sizes.add(&run_sizes);
+                    self.patches.push(ResolvedPatch::GlyphRun {
+                        index: *index,
+                        glyphs: glyph_start..glyph_end,
+                        transform,
+                    });
+                }
+            }
+        }
+        sizes
+    }
+}
+
+#[derive(Clone)]
+/// Patch for a late bound resource.
+pub enum Patch {
+    /// Gradient ramp resource.
+    Ramp {
+        /// Byte offset to the ramp id in the draw data stream.
+        offset: usize,
+        /// Range of the gradient stops in the resource set.
+        stops: Range<usize>,
+    },
+    /// Glyph run resource.
+    GlyphRun {
+        /// Index in the glyph run buffer.
+        index: usize,
+    },
+}
+
+#[derive(Clone, Debug)]
+enum ResolvedPatch {
+    Ramp {
+        /// Offset to the ramp id in draw data stream.
+        draw_data_offset: usize,
+        /// Resolved ramp index.
+        ramp_id: u32,
+    },
+    GlyphRun {
+        /// Index of the original glyph run in the encoding.
+        index: usize,
+        /// Range into the glyphs encoding range buffer.
+        glyphs: Range<usize>,
+        /// Global transform.
+        transform: Transform,
+    },
+}
+
+fn slice_size_in_bytes<T: Sized>(slice: &[T], extra: usize) -> usize {
+    (slice.len() + extra) * std::mem::size_of::<T>()
+}
+
+fn size_to_words(byte_size: usize) -> u32 {
+    (byte_size / std::mem::size_of::<u32>()) as u32
+}
+
+fn align_up(len: usize, alignment: u32) -> usize {
+    len + (len.wrapping_neg() & (alignment as usize - 1))
+}

src/glyph.rs

@@ -18,9 +18,10 @@
 
 pub use moscato::pinot;
 
+use crate::encoding::Encoding;
 use crate::scene::{SceneBuilder, SceneFragment};
 use peniko::kurbo::{Affine, Rect};
-use peniko::{Brush, Color, Fill, Mix};
+use peniko::{Brush, Color, Fill, Mix, Style};
 
 use moscato::{Context, Scaler};
 use pinot::{types::Tag, FontRef};
@@ -32,6 +33,12 @@ pub struct GlyphContext {
     ctx: Context,
 }
 
+impl Default for GlyphContext {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl GlyphContext {
     /// Creates a new context.
     pub fn new() -> Self {
@@ -94,10 +101,35 @@ impl<'a> GlyphProvider<'a> {
             None,
             &convert_path(path.elements()),
         );
-        builder.finish();
         Some(fragment)
     }
 
+    pub fn encode_glyph(&mut self, gid: u16, style: &Style, encoding: &mut Encoding) -> Option<()> {
+        let glyph = self.scaler.glyph(gid)?;
+        let path = glyph.path(0)?;
+        match style {
+            Style::Fill(Fill::NonZero) => encoding.encode_linewidth(-1.0),
+            Style::Fill(Fill::EvenOdd) => encoding.encode_linewidth(-2.0),
+            Style::Stroke(stroke) => encoding.encode_linewidth(stroke.width),
+        }
+        let mut path_encoder = encoding.encode_path(matches!(style, Style::Fill(_)));
+        for el in path.elements() {
+            use moscato::Element::*;
+            match el {
+                MoveTo(p) => path_encoder.move_to(p.x, p.y),
+                LineTo(p) => path_encoder.line_to(p.x, p.y),
+                QuadTo(c, p) => path_encoder.quad_to(c.x, c.y, p.x, p.y),
+                CurveTo(c0, c1, p) => path_encoder.cubic_to(c0.x, c0.y, c1.x, c1.y, p.x, p.y),
+                Close => path_encoder.close(),
+            }
+        }
+        if path_encoder.finish(false) != 0 {
+            Some(())
+        } else {
+            None
+        }
+    }
+
     /// Returns a scene fragment containing the commands and resources to
     /// render the specified color glyph.
     pub fn get_color(&mut self, palette_index: u16, gid: u16) -> Option<SceneFragment> {
@@ -188,7 +220,6 @@ impl<'a> GlyphProvider<'a> {
                 }
             }
         }
-        builder.finish();
         Some(fragment)
     }
 }

src/lib.rs

@@ -30,7 +30,7 @@ pub mod glyph;
 pub mod util;
 
 use render::Render;
-pub use scene::{Scene, SceneBuilder, SceneFragment};
+pub use scene::{DrawGlyphs, Scene, SceneBuilder, SceneFragment};
 pub use util::block_on_wgpu;
 
 use engine::{Engine, ExternalResource, Recording};

src/render.rs

@@ -3,7 +3,7 @@
 use bytemuck::{Pod, Zeroable};
 
 use crate::{
-    encoding::Encoding,
+    encoding::{Config, Encoding, Layout},
     engine::{BufProxy, ImageFormat, ImageProxy, Recording, ResourceProxy},
     shaders::{self, FullShaders, Shaders},
     RenderParams, Scene,
@@ -42,7 +42,6 @@ const TAG_MONOID_FULL_SIZE: u64 = 20;
 const PATH_BBOX_SIZE: u64 = 24;
 const CUBIC_SIZE: u64 = 48;
 const DRAWMONOID_SIZE: u64 = 16;
-const MAX_DRAWINFO_SIZE: u64 = 44;
 const CLIP_BIC_SIZE: u64 = 8;
 const CLIP_EL_SIZE: u64 = 32;
 const CLIP_INP_SIZE: u64 = 8;
@@ -54,28 +53,6 @@ const BIN_HEADER_SIZE: u64 = 8;
 const TILE_SIZE: u64 = 8;
 const SEGMENT_SIZE: u64 = 24;
 
-// This data structure must be kept in sync with encoding::Config and the definition in
-// shaders/shared/config.wgsl.
-#[repr(C)]
-#[derive(Clone, Copy, Debug, Default, Zeroable, Pod)]
-struct Config {
-    width_in_tiles: u32,
-    height_in_tiles: u32,
-    target_width: u32,
-    target_height: u32,
-    base_color: u32,
-    n_drawobj: u32,
-    n_path: u32,
-    n_clip: u32,
-    bin_data_start: u32,
-    pathtag_base: u32,
-    pathdata_base: u32,
-    drawtag_base: u32,
-    drawdata_base: u32,
-    transform_base: u32,
-    linewidth_base: u32,
-}
-
 fn size_to_words(byte_size: usize) -> u32 {
     (byte_size / std::mem::size_of::<u32>()) as u32
 }
@@ -120,8 +97,11 @@ fn render(scene: &Scene, shaders: &Shaders) -> (Recording, BufProxy) {
         height_in_tiles: 64,
         target_width: 64 * 16,
         target_height: 64 * 16,
-        pathtag_base,
-        pathdata_base,
+        layout: Layout {
+            path_tag_base: pathtag_base,
+            path_data_base: pathdata_base,
+            ..Default::default()
+        },
         ..Default::default()
     };
     let scene_buf = recording.upload("scene", scene);
@@ -232,34 +212,33 @@ impl Render {
         params: &RenderParams,
         robust: bool,
     ) -> Recording {
-        use crate::encoding::{resource::ResourceCache, PackedEncoding};
+        use crate::encoding::Resolver;
         let mut recording = Recording::default();
-        let mut resources = ResourceCache::new();
-        let mut packed = PackedEncoding::default();
-        packed.pack(encoding, &mut resources);
-        let (ramp_data, ramps_width, ramps_height) = resources.ramps(packed.resources).unwrap();
-        let gradient_image = if encoding.patches.is_empty() {
+        let mut resolver = Resolver::new();
+        let mut packed = vec![];
+        let (layout, ramps) = resolver.resolve(encoding, &mut packed);
+        let gradient_image = if ramps.height == 0 {
             ResourceProxy::new_image(1, 1, ImageFormat::Rgba8)
         } else {
-            let data: &[u8] = bytemuck::cast_slice(ramp_data);
+            let data: &[u8] = bytemuck::cast_slice(ramps.data);
             ResourceProxy::Image(recording.upload_image(
-                ramps_width,
-                ramps_height,
+                ramps.width,
+                ramps.height,
                 ImageFormat::Rgba8,
                 data,
             ))
         };
         // TODO: calculate for real when we do rectangles
-        let n_pathtag = encoding.path_tags.len();
-        let pathtag_padded = align_up(encoding.path_tags.len(), 4 * shaders::PATHTAG_REDUCE_WG);
-        let n_paths = encoding.n_paths;
-        let n_drawobj = n_paths;
-        let n_clip = encoding.n_clips;
+        let n_pathtag = layout.path_tags(&packed).len();
+        let pathtag_padded = align_up(n_pathtag, 4 * shaders::PATHTAG_REDUCE_WG);
+        let n_paths = layout.n_paths;
+        let n_drawobj = layout.n_paths;
+        let n_clip = layout.n_clips;
 
         let new_width = next_multiple_of(params.width, 16);
         let new_height = next_multiple_of(params.height, 16);
 
-        let info_size = packed.layout.bin_data_start;
+        let info_size = layout.bin_data_start;
         let config = crate::encoding::Config {
             width_in_tiles: new_width / 16,
             height_in_tiles: new_height / 16,
@@ -270,10 +249,10 @@ impl Render {
             tiles_size: self.tiles_size,
             segments_size: self.segments_size,
             ptcl_size: self.ptcl_size,
-            layout: packed.layout,
+            layout: layout,
         };
         // println!("{:?}", config);
-        let scene_buf = ResourceProxy::Buf(recording.upload("scene", packed.data));
+        let scene_buf = ResourceProxy::Buf(recording.upload("scene", packed));
         let config_buf =
             ResourceProxy::Buf(recording.upload_uniform("config", bytemuck::bytes_of(&config)));
         let info_bin_data_buf = ResourceProxy::new_buf(
@@ -374,8 +353,7 @@ impl Render {
         );
         let draw_monoid_buf =
             ResourceProxy::new_buf(n_drawobj as u64 * DRAWMONOID_SIZE, "draw_monoid_buf");
-        let clip_inp_buf =
-            ResourceProxy::new_buf(encoding.n_clips as u64 * CLIP_INP_SIZE, "clip_inp_buf");
+        let clip_inp_buf = ResourceProxy::new_buf(n_clip as u64 * CLIP_INP_SIZE, "clip_inp_buf");
         recording.dispatch(
             shaders.draw_leaf,
             (drawobj_wgs, 1, 1),
@@ -390,8 +368,7 @@ impl Render {
             ],
         );
         recording.free_resource(draw_reduced_buf);
-        let clip_el_buf =
-            ResourceProxy::new_buf(encoding.n_clips as u64 * CLIP_EL_SIZE, "clip_el_buf");
+        let clip_el_buf = ResourceProxy::new_buf(n_clip as u64 * CLIP_EL_SIZE, "clip_el_buf");
         let clip_bic_buf = ResourceProxy::new_buf(
             (n_clip / shaders::CLIP_REDUCE_WG) as u64 * CLIP_BIC_SIZE,
             "clip_bic_buf",

src/scene.rs

@@ -15,9 +15,9 @@
 // Also licensed under MIT license, at your choice.
 
 use peniko::kurbo::{Affine, Rect, Shape};
-use peniko::{BlendMode, BrushRef, Fill, Stroke};
+use peniko::{BlendMode, BrushRef, Color, Fill, Font, Stroke, StyleRef};
 
-use crate::encoding::{Encoding, Transform};
+use crate::encoding::{Encoding, Glyph, GlyphRun, Patch, Transform};
 
 /// Encoded definition of a scene and associated resources.
 #[derive(Default)]
@@ -67,7 +67,6 @@ impl SceneFragment {
 /// Builder for constructing a scene or scene fragment.
 pub struct SceneBuilder<'a> {
     scene: &'a mut Encoding,
-    layer_depth: u32,
 }
 
 impl<'a> SceneBuilder<'a> {
@@ -86,10 +85,7 @@ impl<'a> SceneBuilder<'a> {
     /// Creates a new builder for constructing a scene.
     fn new(scene: &'a mut Encoding, is_fragment: bool) -> Self {
         scene.reset(is_fragment);
-        Self {
-            scene,
-            layer_depth: 0,
-        }
+        Self { scene }
     }
 
     /// Pushes a new layer bound by the specifed shape and composed with
@@ -112,15 +108,11 @@ impl<'a> SceneBuilder<'a> {
                 .encode_shape(&Rect::new(0.0, 0.0, 0.0, 0.0), true);
         }
         self.scene.encode_begin_clip(blend, alpha.clamp(0.0, 1.0));
-        self.layer_depth += 1;
     }
 
     /// Pops the current layer.
     pub fn pop_layer(&mut self) {
-        if self.layer_depth > 0 {
-            self.scene.encode_end_clip();
-            self.layer_depth -= 1;
-        }
+        self.scene.encode_end_clip();
     }
 
     /// Fills a shape using the specified style and brush.
@@ -176,6 +168,11 @@ impl<'a> SceneBuilder<'a> {
         }
     }
 
+    /// Returns a builder for encoding a glyph run.
+    pub fn draw_glyphs(&mut self, font: &Font) -> DrawGlyphs {
+        DrawGlyphs::new(self.scene, font)
+    }
+
     /// Appends a fragment to the scene.
     pub fn append(&mut self, fragment: &SceneFragment, transform: Option<Affine>) {
         self.scene.append(
@@ -183,11 +180,119 @@ impl<'a> SceneBuilder<'a> {
             &transform.map(|xform| Transform::from_kurbo(&xform)),
         );
     }
+}
 
-    /// Completes construction and finalizes the underlying scene.
-    pub fn finish(self) {
-        for _ in 0..self.layer_depth {
-            self.scene.encode_end_clip();
+/// Builder for encoding a glyph run.
+pub struct DrawGlyphs<'a> {
+    encoding: &'a mut Encoding,
+    run: GlyphRun,
+    brush: BrushRef<'a>,
+    brush_alpha: f32,
+}
+
+impl<'a> DrawGlyphs<'a> {
+    /// Creates a new builder for encoding a glyph run for the specified
+    /// encoding with the given font.
+    pub fn new(encoding: &'a mut Encoding, font: &Font) -> Self {
+        let coords_start = encoding.normalized_coords.len();
+        let glyphs_start = encoding.glyphs.len();
+        let stream_offsets = encoding.stream_offsets();
+        Self {
+            encoding,
+            run: GlyphRun {
+                font: font.clone(),
+                transform: Transform::IDENTITY,
+                glyph_transform: None,
+                font_size: 16.0,
+                hint: false,
+                normalized_coords: coords_start..coords_start,
+                style: Fill::NonZero.into(),
+                glyphs: glyphs_start..glyphs_start,
+                stream_offsets,
+            },
+            brush: Color::BLACK.into(),
+            brush_alpha: 1.0,
         }
     }
+
+    /// Sets the global transform. This is applied to all glyphs after the offset
+    /// translation.
+    ///
+    /// The default value is the identity matrix.
+    pub fn transform(mut self, transform: Affine) -> Self {
+        self.run.transform = Transform::from_kurbo(&transform);
+        self
+    }
+
+    /// Sets the per-glyph transform. This is applied to all glyphs prior to
+    /// offset translation. This is common used for applying a shear to simulate
+    /// an oblique font.
+    ///
+    /// The default value is `None`.
+    pub fn glyph_transform(mut self, transform: Option<Affine>) -> Self {
+        self.run.glyph_transform = transform.map(|xform| Transform::from_kurbo(&xform));
+        self
+    }
+
+    /// Sets the font size in pixels per em units.
+    ///
+    /// The default value is 16.0.
+    pub fn font_size(mut self, size: f32) -> Self {
+        self.run.font_size = size;
+        self
+    }
+
+    /// Sets whether to enable hinting.
+    ///
+    /// The default value is `false`.
+    pub fn hint(mut self, hint: bool) -> Self {
+        self.run.hint = hint;
+        self
+    }
+
+    /// Sets the normalized design space coordinates for a variable font instance.
+    pub fn normalized_coords(mut self, coords: &[i16]) -> Self {
+        self.encoding
+            .normalized_coords
+            .truncate(self.run.normalized_coords.start);
+        self.encoding.normalized_coords.extend_from_slice(coords);
+        self.run.normalized_coords.end = self.encoding.normalized_coords.len();
+        self
+    }
+
+    /// Sets the brush.
+    ///
+    /// The default value is solid black.
+    pub fn brush(mut self, brush: impl Into<BrushRef<'a>>) -> Self {
+        self.brush = brush.into();
+        self
+    }
+
+    /// Sets an additional alpha multiplier for the brush.
+    ///
+    /// The default value is 1.0.
+    pub fn brush_alpha(mut self, alpha: f32) -> Self {
+        self.brush_alpha = alpha;
+        self
+    }
+
+    /// Encodes a fill or stroke for for the given sequence of glyphs and consumes
+    /// the builder.
+    ///
+    /// The `style` parameter accepts either `Fill` or `&Stroke` types.
+    pub fn draw(mut self, style: impl Into<StyleRef<'a>>, glyphs: impl Iterator<Item = Glyph>) {
+        self.run.style = style.into().to_owned();
+        self.encoding.glyphs.extend(glyphs);
+        self.run.glyphs.end = self.encoding.glyphs.len();
+        if self.run.glyphs.is_empty() {
+            self.encoding
+                .normalized_coords
+                .truncate(self.run.normalized_coords.start);
+            return;
+        }
+        let index = self.encoding.glyph_runs.len();
+        self.encoding.glyph_runs.push(self.run);
+        self.encoding.patches.push(Patch::GlyphRun { index });
+        self.encoding.encode_brush(self.brush, self.brush_alpha);
+    }
 }