Stage five. pdf.js draws pages as pictures, so selecting means laying
transparent spans over them exactly where each word was painted. The
layer carries the same scale as the canvas — they drift apart otherwise
and a selection lands on the wrong words. While drawing it stops taking
pointer events entirely, or a stroke would come out as a selection.
The text is also extracted and handed to the index that already holds the
notes, so one search box finds a sentence whether it was typed or
imported. Extraction runs after the document is on screen and yields
between pages: it must never stand between the reader and the first page.
The extracted text is deliberately not sent to the server. It is
derivable from a file the server already holds, so storing it again costs
space and a second thing to encrypt for nothing gained. The price, stated
plainly in the readme, is that a PDF becomes searchable on a device once
that device has opened it — the same shape as the limitation notes have.
Text runs are joined on pdf.js's hasEOL rather than concatenated. Without
it the last word of a line glues to the first of the next and matches
nothing when searched for.
The minimal text-layer CSS is written out rather than importing
pdfjs-dist/web/pdf_viewer.css, which carries the whole reference viewer's
toolbars and dialogs.
Suite now checks the layer sits over the page rather than stacked in a
corner, that the text is transparent, that dragging selects real words,
that a word from inside the file finds the note and one that is not in it
finds nothing.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Stage three: the viewer. Drawing on pages comes next.
pdf.js stays out of the bundle everyone downloads — it is larger than the
rest of the application put together, so it is behind a dynamic import and
a session that never opens a PDF never fetches it. Main bundle grew by
8 kB for the viewer shell; the 162 kB library arrives only when needed.
The worker is bundled rather than pulled from a CDN, because a viewer
that stops working during someone else's outage is not one you can rely
on offline.
Two things that only showed up once it ran in a browser:
- pdf.js 6 calls Uint8Array.prototype.toHex, which only very recent
browsers have. Anything older failed with "n.toHex is not a function",
which says nothing about the cause. Now on the legacy build, which
compiles those away — a little larger, and the difference between
working everywhere and working on this year's browsers.
- nginx has no MIME type for .mjs and served the worker as
octet-stream, which a browser refuses to run as a module.
Pages are laid out at their true proportions before anything is drawn, so
the scrollbar is honest immediately and a document mixing portrait and
landscape keeps both — the first version scaled every page to the widest
one, which the suite caught by checking the two aspect ratios differ.
Bytes come from the authenticated attachment route and are cached in
IndexedDB. Content-addressed storage means a cached copy can never be
stale, so a document opened once needs no connection again. Verified with
the network switched off.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
