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C API: add OpenType script selection and feature queries - #521
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This was referenced Oct 8, 2026
dfrg
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Oct 9, 2026
Regenerate C headers while preserving the new OpenType queries and deprecated MATH flag alias. Keep layout tags and sentinel indices unsigned for C++ source compatibility.
Combine OpenType query documentation and tests with the merged color, palette, axis/name, and AAT APIs. Regenerate the core and HarfBuzz compatibility headers from the combined source.
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Chromium's small-caps probing and feature enumeration still need three OpenType queries after the earlier compatibility work landed. Add
hr_ot_layout_table_select_script,hr_ot_layout_language_find_feature, andhr_ot_layout_table_get_feature_tags, with their HarfBuzz aliases, layout tag/index constants, and the deprecated MATH extender-flag spelling Chromium uses.Script selection honors requested-tag order and the DFLT/dflt/latn fallback chain. Feature lookup returns table-wide indices and excludes the required feature; enumeration preserves duplicate feature tags and follows HarfBuzz's pagination/null-query conventions. Queries use read-fonts and support callback-created faces. Script lookup uses Rust's native binary search; no duplicate-script selection behavior is promised for invalid fonts.
Validation: 139 C API tests; 37,987 comparisons against HarfBuzz 14.5.1 across 495 font faces; workspace Clippy 1.99 with all features/targets; Rust 1.85 checking; GCC/Clang C99 linking and C++17 header checks. The differential harness skips absent or HarfBuzz-rejected layout tables, since Fontations queries readable metadata without HarfBuzz's whole-table sanitizer.
Part of #520; also addresses the remaining script/feature queries in #468.