6b2c4b25c0
A PDF that needs a signature, a highlight or a page removed currently sends the user out to a desktop application or, worse, to a web service that wants the document uploaded first. Both are poor answers for a browser whose point is that nothing has to leave the machine. This is a full-tab editor that opens a PDF, marks it up, fills its forms and saves a new copy, entirely locally. Two engines, vendored rather than installed, because an add-on ships as a self-contained folder over the signed update channel and nothing runs a package manager on the way: pdf.js reads and renders, pdf-lib writes. They share no state. Everything in between lives in PDF user space — points, origin bottom-left — which is the one coordinate vocabulary both speak, so a mark survives zooming, rotating and reordering with no conversion table and save-time needs to know nothing about how a page happened to be displayed. The page strip is built from pdf.js's PDFPageView components rather than its PDFViewer, which renders pages in the file's own order and cannot hide, reorder or individually rotate one — three of the features here. Text layers are ours and stay attached for every page, drawn or not, because Theseus's find bar is Chromium's findInPage over the live DOM and a torn-down text layer is a page Ctrl+F cannot see. Canvases are virtualised; a letter page at 100% is 3.4 MB of bitmap. Redaction is the part worth being careful about. A black box over text hides nothing — the text stays in the content stream and comes straight out of a copy-paste — so the editor says so in a modal before the tool can be used, and on save rebuilds each redacted page as an image, which genuinely removes it. Pages that were not redacted are untouched. Form widgets and links are kept, since they were never the leak. Saving never writes over the original: every save reloads the source bytes and replays the session onto a fresh copy, so a botched save cannot poison the next one. Out of scope for this first version: editing the text that is already in the document, and writing XFA forms back (pdf-lib cannot, so those are fill-and- print only, and the editor says so on open).
62 lines
3 KiB
Markdown
62 lines
3 KiB
Markdown
# Vendored libraries
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Both engines are copied in rather than installed, because Theseus's own
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`node_modules` is a build-time tree and an add-on has to be a self-contained
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folder: it is copied to `<userData>/addons/pdf-editor/` on first run and
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shipped as a tarball over the signed update channel, neither of which runs a
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package manager.
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| Path | Library | Version | Licence |
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|---|---|---|---|
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| `vendor/pdfjs/` | [pdf.js](https://mozilla.github.io/pdf.js/) (`pdfjs-dist`) | 6.3.289 | Apache-2.0 |
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| `vendor/pdf-lib/` | [pdf-lib](https://pdf-lib.js.org/) | 1.17.1 | MIT |
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Licence texts ship beside the code: `vendor/pdfjs/LICENSE`,
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`vendor/pdfjs/wasm/LICENSE_*` and `vendor/pdf-lib/LICENSE.md`.
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pdf.js reads; pdf-lib writes. They never look at each other's state — the
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editor holds the document model in between, in PDF user-space coordinates,
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which is the only vocabulary both of them speak.
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## What was taken, and what was left behind
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From `pdfjs-dist`:
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- `build/pdf.min.mjs`, `build/pdf.worker.min.mjs` — the API and its worker.
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- `web/pdf_viewer.mjs` + `web/pdf_viewer.css` + `web/images/` — the viewer
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*components*, for `PDFPageView`, `PDFLinkService` and `EventBus`. Not the
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full viewer application. There is no minified build of this file upstream.
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- `standard_fonts/` — the base-14 metrics. A PDF that names Helvetica without
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embedding it is extremely common, and without these it renders wrong.
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- `wasm/*.wasm` — JPEG 2000, JBIG2 and colour management.
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- `iccs/` — ICC profiles for the colour management above.
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Left out on purpose:
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- `cmaps/` (~1.5 MB) — needed only for CJK documents that use a non-embedded
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CID font. Dropping it keeps the add-on at about 4 MB. If CJK support is
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wanted, copy `cmaps/` in and pass `cMapUrl: "vendor/pdfjs/cmaps/"` to
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`getDocument` in `editor.js`; nothing else changes.
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- `wasm/*_nowasm_fallback.js` (~580 KB) — pure-JS fallbacks for engines
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without WebAssembly. Electron always has it.
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- `wasm/quickjs-eval.*` and `build/pdf.sandbox.*` (~525 KB) — the interpreter
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for JavaScript embedded in a PDF. The editor loads documents with
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`enableScripting: false`, so a document's own scripts never run.
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- Every `.map` file, the TypeScript definitions, the CommonJS and `legacy`
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builds, and `image_decoders/`.
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From `pdf-lib`, only `dist/pdf-lib.esm.min.js`.
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## Upgrading
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Re-run the extraction against a fresh tarball, keeping the list above, then
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run the verification suite in `scratchpad/verify-pdf-editor/`. Two things to
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watch, because both have bitten this add-on already:
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- `web/pdf_viewer.mjs` reads the core API off `globalThis.pdfjsLib` instead of
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importing it, so `editor.js` must keep assigning that global *before* it
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imports the components bundle.
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- pdf.js's `AnnotationStorage` has no stable public shape. `getAll()`, which
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older releases had, does not exist in 6.x — form values are read through
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`has(id)` and `getRawValue(id)` against the ids from `getFieldObjects()`.
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A silent change here looks like a form that saves nothing.
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