fix(pptx): harden serialize output — media dedupe, DEFLATE, SVG fallback#94
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serializeDeck round-trips produced invalid / oversized packages:
- Media de-duplication: shared images (icons, logos, backgrounds) were
copied once PER reference under slidewise_preserved_N_ names — a 1.5 MB
deck ballooned to ~6 MB with one image written 9×. Copies are now keyed
on the immutable source path and written once; every referencing rel
points at that single copy (new PreservedPartRegistry / preserveSourcePart,
threaded through injectIntoSlide, copyPartDependencies, injectSlideBg).
- Compression: the package shipped with JSZip's default STORE (0%), so
multi-MB slide XML went out raw. generateAsync now uses DEFLATE, matching
the source archive. With dedupe: ~6 MB → ~1.1 MB on the repro deck.
- SVG raster fallback (1.19.1 follow-ups):
- F1: the last-resort transparent PNG had a bad IDAT CRC (decodes in
lenient readers, rejected by strict PNG/OOXML validators). Replaced
with a CRC-correct 1×1 transparent PNG.
- F2: added an optional `rasterizeSvg` hook to SerializeOptions so the
headless Node/SSR path can emit a faithful raster (host injects e.g.
@resvg/resvg-js) instead of a blank transparent PNG. Resolution order:
host hook → browser canvas → transparent fallback. Non-PNG/throwing
hook output is ignored.
Tests: media-dedup.test.ts (dedupe + DEFLATE) and svg-fallback.test.ts
(F1 CRC + F2 hook); both verified to fail pre-fix. Full suite 165 passing;
repo typecheck clean.
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TL;DR
After a small edit, saving a deck ballooned it from 1.5 MB to ~6 MB and produced images that break outside PowerPoint. This hardens the serializer so a round-trip stays valid and compact — dedupe shared media, DEFLATE the package, and emit a valid SVG raster fallback (with an optional
rasterizeSvghook so our headless pipeline can rasterize faithfully).Summary
slidewise_preserved_N_names; one image was written 9×. Copies are now keyed on the immutable source path and written once, with every referencing rel pointing at that single copy. NewPreservedPartRegistry/preserveSourcePart, threaded throughinjectIntoSlide,copyPartDependencies, andinjectSlideBg.generateAsyncshipped with JSZip's defaultSTORE(0%), so multi-MB slide XML went out raw. NowDEFLATE(level 6), matching the source archive. Combined with dedupe: ~6 MB → ~1.1 MB on the repro deck.rasterizeSvghook toSerializeOptions(exportedSvgRasterizer). On Node/SSR (no canvas) the SVG raster fallback degraded to a blank transparent PNG; a host can now inject e.g.@resvg/resvg-js. Order: host hook → browser canvas → transparent fallback; non-PNG / throwing output is ignored.Review focus
SerializeOptions.rasterizeSvg+SvgRasterizertype (optional, backward-compatible). Chose a host-injected hook over a hard@resvg/resvg-jsdependency because the library is isomorphic and a native dep would break the browser bundle.relativeTarget; the dependency walk now runs once per source part across the whole serialize (reg.depsWalked).DEFLATEon already-compressed media (PNG/JPEG) is a negligible-CPU no-op; the win is on XML.Test plan
media-dedup.test.ts— shared image written once + both rels resolve it; package is DEFLATE-compressed (both fail pre-fix)svg-fallback.test.ts— F1 emits CRC-correct PNG on headless path; F2 uses host rasterizer; bogus/throwing rasterizer ignored (all fail pre-fix)