85 lines
3.8 KiB
Markdown
85 lines
3.8 KiB
Markdown
# epiphany-render-svg
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Agent I's **SVG renderer** behind the Epiphany `RenderIR` interface (spec
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Chapter 7): turns a `ResolvedLayoutIR` into well-formed **SVG 1.1**, drawing each
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glyph from **genuine Bravura SMuFL** data — inline outline `<path>`s by default
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(`GlyphMode::PathOutline`), or `<text>` set in an `@font-face`-embedded Bravura
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subset (`GlyphMode::EmbeddedFont`). It is the visible end of the v0
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`Score → layout IR` pipeline.
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## Status
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The `Score → layout IR → SVG` pipeline renders **recognizable notation** — clefs,
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noteheads at clef-relative staff positions, accidentals, key/time signatures,
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rests, barlines, and the staff lines and stems that connect them. Output is
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golden-locked against **both** the interface-only stub solver and Agent I's real
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`epiphany-engrave` solver (whose horizontal spacing pass re-spaces the glyphs),
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and the layout round-trip (criterion 6) runs through both. What the renderer
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itself guarantees, independent of engraving quality: real Bravura glyphs,
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provenance preserved to the score graph, output XML-valid and deterministic. The
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renderer consumes any solver's `ResolvedLayoutIR`.
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## Demo
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```sh
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# Render a fixture to SVG (stub solver by default):
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cargo run -p epiphany-render-svg --example render_fixture -- \
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ten_measure_single_staff > out.svg
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# Drive Agent I's engrave solver instead, to bisect renderer-vs-solver:
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cargo run -p epiphany-render-svg --example render_fixture -- \
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ten_measure_single_staff --solver=real > out.svg
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# Use the embedded-font glyph mode (<text> + @font-face) instead of inline paths:
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cargo run -p epiphany-render-svg --example render_fixture -- \
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ten_measure_single_staff --glyph-mode=embedded > out.svg
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```
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Fixtures: `ten_measure_single_staff`, `valid_score_rich`, `valid_score`. Stats and
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diagnostics go to stderr; the SVG goes to stdout.
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## Library
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```rust
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use epiphany_render_svg::{render, RenderOptions};
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let out = render(&resolved_layout_ir, &RenderOptions::default());
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assert!(out.is_well_formed());
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println!("{}", out.svg);
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```
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`render` is pure and deterministic. `RenderOptions` controls SVG-encoding choices
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only (display scale, margin, provenance attributes, and `glyph_mode` — inline
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`PathOutline` vs `EmbeddedFont`) — nothing that changes engraving.
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## Bundled Bravura data
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Two generated artifacts come from the official OFL `Bravura.otf` via
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`epiphany-glyphs`'s `tools/extract_bravura_outlines.py` — the font is **not
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vendored**, only the generated Rust is committed. **The outlines moved to
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`epiphany-glyphs` in T4-pre W2** (a canvas renderer needs them too, so they are
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a shared asset rather than a renderer-private one); the font subset stayed here,
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because an embeddable OTF is a renderer concern:
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- `epiphany-glyphs/src/outlines_generated.rs` — the inline glyph outlines
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(geometry-only, so byte-stable across fontTools versions). This crate reaches
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them through `epiphany_glyphs::outline`, and re-exports
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`bundled_glyph_count`/`smufl_codepoint` unchanged;
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- `src/font_subset_generated.rs` — a base64 OTF **subset** (just the pipeline's
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glyphs) for `GlyphMode::EmbeddedFont`. As a Modified Version, its primary font
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name is renamed off the Reserved Font Name "Bravura" per the OFL; a content
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BLAKE3 + decoded length are committed alongside as an integrity lock.
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Bravura is © Steinberg Media Technologies GmbH under the SIL Open Font License 1.1
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(`../epiphany-glyphs/tools/OFL.txt`, which travels with the redistributed
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outlines); both artifacts are redistributed under the same license. To
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regenerate both (the subset step also needs the `blake3` package):
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```sh
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cd crates/epiphany-glyphs/tools
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python3 -m venv .venv && . .venv/bin/activate && pip install fonttools blake3
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python3 extract_bravura_outlines.py \
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--font-out ../../epiphany-render-svg/src/font_subset_generated.rs \
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> ../src/outlines_generated.rs
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```
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