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ParaPDF

Limitations

Not supported yet

Section titled “Not supported yet”
  • Editing the annotations a PDF already holds. Annotations the reader creates can be moved, restyled, and deleted; those in the file stay as they are drawn.
  • Comments on created annotations, and pdf.js’s alt text dialog: images take their alternative text from addImage().
  • Form scripts (calculations, validation, and button actions), and XFA forms.
  • Right-to-left page order (/ViewerPreferences /Direction).
  • Text layers for pages outside the mounted window, so the browser’s own find and selection see only mounted pages; use usePdfSearch and getText().
  • A highlight fallback for browsers without the CSS Custom Highlight API, which find and scroll to matches without painting them.
  • More than one PdfViewport per PdfDocument.

Drawing on the main thread

Section titled “Drawing on the main thread”

Released pdfjs-dist draws pages on the main thread; its worker parses. Drawing in a worker needs pdf.js’s renderer worker (configurePdfjs({ rendererSrc })), which is only in unreleased pdf.js builds so far.

Not verified yet

Section titled “Not verified yet”
  • ParaPDF is tested in Playwright’s builds of Chromium, WebKit, and Firefox, and by hand in Safari in the iPadOS simulator. Safari on macOS and real iOS and iPadOS devices are not verified yet.
  • Chromium and Firefox give pdf.js the PDF’s preloaded download. Whether Safari does is not verified; where a browser does not, the PDF downloads twice.
  • In Safari on iPadOS, a pinch that starts while a fling still scrolls does not reach the page; the next pinch zooms.

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