Port to harfrust/skrifa with hinting and variable font support #1004
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Copy fontdb 0.23.0 source code into crates/fontdb/ as a first step toward replacing ttf-parser with skrifa for font metadata parsing. Source: https://github.com/RazrFalcon/fontdb (MIT licensed) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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This eliminates the ttf-parser dependency by modifying the vendored fontdb to use skrifa for font parsing. Key changes: - Replace ttf_parser::fonts_in_collection with FileRef::new().len() - Replace ttf_parser::RawFace with FontRef::from_index() - Replace ttf_parser name table parsing with font.localized_strings() - Replace OS/2 table parsing with font.attributes() - Replace post table parsing with font.metrics() and font.post() - Add local Language enum (simplified: EnglishUnitedStates + Unknown) - Add local Stretch enum with to_number() for CSS matching - Add stretch_from_skrifa() for skrifa::attribute::Stretch conversion - Update usvg to use vendored fontdb via path dependency - Update Rust 2024 edition patterns (remove redundant ref bindings) The MAC_ROMAN encoding table is removed as skrifa handles all name table encodings internally via LocalizedString::chars(). Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Fix incorrect safety comment on mmap (fontdb) - Replace deprecated core::u64::MAX with u64::MAX (fontdb) - Use .first() instead of .get(0) (fontdb) - Fix potential panics on empty slices in font fallback (usvg/text/mod.rs) - Add empty path check in path_length() (usvg/parser/text.rs) - Add ASCII validation for font variation tags (usvg/parser/text.rs) - Use idiomatic .or() instead of .map_or() (usvg/parser/text.rs) - Return &TextFlow instead of clone in text_flow() (usvg/tree/text.rs) - Add logging for checked_sub failure (usvg/text/layout.rs) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Move `variations`, `font_optical_sizing`, and `hinting` fields from `PositionedGlyph` to `Span` struct since these values are uniform for all glyphs within a span. Benefits: - Reduces memory by not duplicating Vec<FontVariation> per glyph - Cleaner data model: span-level properties at span level - Minor perf improvement: needs_variations check once per span Based on PR linebender#997 review feedback. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
The empty --drop-tables= flag doesn't do anything. Remove it. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Replace the simple (font_id, glyph_id) HashMap cache with a comprehensive LRU cache that captures all parameters affecting glyph outline shape: - Font ID and glyph ID - PPEM for hinting (stored as f32::to_bits() for exact matching) - Hinting settings (target, mode, engine, symmetric, preserve_linear_metrics) - Variation hash (computed from sorted variations + auto-opsz) Key changes: - Add `lru` crate dependency for bounded cache with LRU eviction - Add OutlineCacheKey struct capturing all outline-affecting parameters - Add CacheStats for tracking hits/misses/evictions - Add compute_variation_hash() for consistent variation hashing - Replace HashMap with LruCache (default capacity: 10,000 entries) - Unify three code paths (simple/variable/hinted) into single cache lookup - Add cache management methods (stats, clear, resize, len, capacity) This ensures that hinted outlines and variable font outlines are now cached, significantly improving performance for text-heavy documents with repeated glyphs at the same settings. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Document all changes from the skrifa branch: - Hinting support with CSS custom properties - Variable font support with avar normalization - LRU outline cache with full parameter support - Port from ttf-parser/rustybuzz to skrifa/harfrust - Vendored fontdb ported to skrifa - Various bug fixes and improvements Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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I will be producing additional PRs based on this branch once the skrifa switch is merged |
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Supersedes #922 (nicoburns' "Port resvg to harfrust and fontations")
This patch builds upon the excellent groundwork laid out in PR #922, which identified harfrust and skrifa as the path forward for long-term maintainability. As noted in that discussion, these actively-maintained libraries offer significant advantages: harfrust passes substantially more shaping tests than rustybuzz, and skrifa provides a modern, well-designed API for font parsing.
Core Migration (shared with #922)
Additional Changes
New Features
1. Font Hinting Support
HintingOptionsin parser optionstext-renderingproperty controls per-element hinting:geometricPrecision: disables hinting (preserve exact outlines)optimizeLegibility/optimizeSpeed: enables full hintingCustom Hinting Properties (resvg extensions)
Fine-grained control via custom CSS properties or SVG attributes:
-resvg-hinting-targetsmooth,monosmooth-resvg-hinting-modenormal,light,lcd,vertical-lcdnormal-resvg-hinting-engineauto,native,auto-fallbackauto-fallback-resvg-hinting-symmetrictrue,falsetrue-resvg-hinting-preserve-linear-metricstrue,falsefalseUsage as SVG attributes (with
resvg:namespace) or CSS properties (with-resvg-prefix):2. Full Variable Font Support
font-variation-settingsCSS propertyfont-optical-sizingCSS property (auto/none)font-weight→wghtaxisfont-stretch→wdthaxisfont-style: italic→italaxisfont-style: oblique→slntaxisopszaxis based on font size whenfont-optical-sizing: autoPositionedGlyph3. Bitmap Font Mask Support
4. PNG Output with DPI Metadata
New public API for PNG encoding with resolution metadata:
resvg::encode_png_with_dpi()- Encode pixmap with DPI in pHYs chunkresvg::save_png_with_dpi()- Save pixmap with DPI metadataUseful for print output and e-ink displays where physical resolution matters.
5. Enhanced COLR Support
skrifa_colr.rsDocumentation
usvgandresvgcratesHintingSettings,HintingTarget,HintingMode,HintingEngineFontVariation,FontOpticalSizingHintingOptionsgenerate_hinting_comparison.rsTest Infrastructure
tests-hinted/directory with hinted reference imagesTrade-offs
We appreciate the careful analysis in #922 regarding the ecosystem trade-offs, particularly around compile times and binary size. This implementation accepts those trade-offs in exchange for the additional capabilities (hinting, variable fonts) that skrifa enables.
🤖 Generated with Claude Code