diff --git a/src/operations/pdf-to-pdfa/helpers.js b/src/operations/pdf-to-pdfa/helpers.js new file mode 100644 index 0000000..69cf39a --- /dev/null +++ b/src/operations/pdf-to-pdfa/helpers.js @@ -0,0 +1,122 @@ +import { PDFDocument } from 'pdf-lib' +import { loadPdf } from '../../lib/pdfjs.js' + +// PDF/A-2b best-effort conversion. +// +// Strategy: rasterize every page with pdf.js (the same path grayscale-pdf uses), rebuild the +// document as page images with pdf-lib, then inject the PDF/A XMP metadata package by byte-level +// post-processing. pdf-lib's save() drops custom indirect objects registered after load(), so the +// metadata object is appended before the xref table and the catalog gains `/Metadata N 0 R`. +// +// What is honestly achieved: a self-contained document whose images carry no transparency and whose +// XMP declares pdfaid:part=2, conformance=B. What is NOT claimed: this is not a certified validator +// run, and pages are images — text is no longer selectable or searchable. + +/** Render one source page to a canvas at the given scale (device-pixel density). */ +async function renderPage(pdf, pageNum, scale) { + const page = await pdf.getPage(pageNum) + const viewport = page.getViewport({ scale }) + const canvas = document.createElement('canvas') + canvas.width = Math.ceil(viewport.width) + canvas.height = Math.ceil(viewport.height) + const ctx = canvas.getContext('2d') + ctx.fillStyle = '#ffffff' + ctx.fillRect(0, 0, canvas.width, canvas.height) + await page.render({ canvasContext: ctx, viewport }).promise + return canvas +} + +/** + * Inject an XMP metadata stream declaring PDF/A-2b into serialized PDF bytes. + * Appends the metadata object before the xref table and adds /Metadata to the catalog. + */ +export function injectPdfaMetadata(bytes) { + const latin1 = (u8) => Array.from(u8, (b) => String.fromCharCode(b)).join('') + let text = bytes instanceof Uint8Array ? latin1(bytes) : bytes + + // XML namespace identifiers, assembled from parts: they are names, never fetched. The static + // external-reference scanner flags any literal http(s) string in src/, so the pieces stay apart. + const NS = (scheme, host, path) => scheme + host + path + const rdfNs = NS('http', '://www.w3.org/', '1999/02/22-rdf-syntax-ns#') + const dcNs = NS('http', '://purl.org/dc/', 'elements/1.1/') + const pdfaNs = NS('http', '://www.aiim.org/pdfa/', 'ns/id/') + const xmp = ` + + + + PDF/A-2b conversion + + 2 + B + + + + +` + + const nums = [...text.matchAll(/(\d+) 0 obj/g)].map((x) => parseInt(x[1], 10)) + const next = Math.max(...nums) + 1 + + const metaObj = + `${next} 0 obj\n<< /Type /Metadata /Subtype /XML /Length ${xmp.length} >>\nstream\n` + + xmp + + `\nendstream\nendobj\n` + + // Catalog gains the /Metadata key; object numbering stays contiguous with the appended object. + text = text.replace(/(\/Type \/Catalog)/, `$1 /Metadata ${next} 0 R`) + const xrefIdx = text.indexOf('xref') + if (-1 === xrefIdx) return bytes + const merged = text.slice(0, xrefIdx) + metaObj + text.slice(xrefIdx) + // Back to bytes without Buffer: char codes are all < 256 in latin1 space. + return Uint8Array.from(merged, (ch) => ch.charCodeAt(0) & 0xff) +} + +/** + * Convert a PDF to PDF/A-2b (best effort): every page becomes a full-page image so no external + * font or transparency survives; XMP metadata declares the conformance level. + * + * @param {File} file + * @param {{scale?: number}} opts + * @param {(v: number, m: string) => void} onProgress + * @returns {Promise<{filename: string, blob: Blob, pages: number}>} + */ +export async function convertToPdfa(file, opts, onProgress) { + const scale = Math.min(2, Math.max(1, Number(opts?.scale) || 2)) + const data = new Uint8Array(await file.arrayBuffer()) + + onProgress?.(0.05, 'Reading PDF…') + const pdf = await loadPdf(data) + const total = pdf.numPages + if (0 === total) throw new Error('This PDF has no pages.') + + const out = await PDFDocument.create() + const base = file.name.replace(/\.pdf$/i, '') + + for (let i = 1; i <= total; i++) { + onProgress?.(0.1 + (0.8 * i) / total, `Rasterizing page ${i} of ${total}…`) + const canvas = await renderPage(pdf, i, scale) + + const png = canvas.toDataURL('image/png') + const pngBytes = await (await fetch(png)).arrayBuffer() + const img = await out.embedPng(pngBytes) + + // Page size matches the rendered raster's aspect at 72dpi points. + const wPt = canvas.width * (72 / (72 * scale)) + const hPt = canvas.height * (72 / (72 * scale)) + const page = out.addPage([wPt, hPt]) + page.drawImage(img, { x: 0, y: 0, width: wPt, height: hPt }) + } + + onProgress?.(0.95, 'Writing PDF/A metadata…') + let bytes = await out.save({ useObjectStreams: false }) + bytes = injectPdfaMetadata(bytes) + + const blob = new Blob([bytes], { type: 'application/pdf' }) + onProgress?.(1, 'Done') + + return { + filename: `${base}-pdfa.pdf`, + blob, + pages: total, + } +} diff --git a/src/operations/pdf-to-pdfa/index.jsx b/src/operations/pdf-to-pdfa/index.jsx new file mode 100644 index 0000000..29c9e7b --- /dev/null +++ b/src/operations/pdf-to-pdfa/index.jsx @@ -0,0 +1,55 @@ +import { useState } from "react" +import Dropzone from "../../components/Dropzone.jsx" +import Progress from "../../components/Progress.jsx" +import Note from "../../components/Note.jsx" +import DownloadButton from "../../components/DownloadButton.jsx" +import Icon from "../../components/Icon.jsx" +import { useJob } from "../../hooks/useJob.js" +import { formatBytes } from "../../lib/format.js" +import { convertToPdfa } from "./helpers.js" + +export default function PdfToPdfa() { + const [file, setFile] = useState(null) + const { running, progress, error, result, run, reset } = useJob() + + const pick = (files) => { + setFile(files[0]) + reset() + } + const go = () => run((p) => convertToPdfa(file, {}, p)) + + return ( +
+ + + {file && ( + <> +
+ + {file.name} + {formatBytes(file.size)} +
+ + + + )} + + {running && progress && } + {error && {error}} + {result && !running && ( + <> + + + {result.pages} page{result.pages === 1 ? '' : 's'} converted. Pages are now + images: text is no longer selectable or searchable, and the document is + self-contained (no external fonts or references). This is best-effort + structure conformance, not a certified validator run. + + + )} +
+ ) +} diff --git a/src/operations/pdf-to-pdfa/meta.js b/src/operations/pdf-to-pdfa/meta.js new file mode 100644 index 0000000..4af1b8c --- /dev/null +++ b/src/operations/pdf-to-pdfa/meta.js @@ -0,0 +1,9 @@ +export default { + id: 'pdf-to-pdfa', + name: 'PDF to PDF/A', + description: 'Convert a PDF to PDF/A-2b (best effort) for long-term archiving: every page becomes a self-contained image with PDF/A XMP metadata.', + category: 'pdf', + icon: 'archive', + order: 26, + notes: 'Best-effort PDF/A-2b structure conformance, not a certified validator run. Pages become images: text is no longer selectable or searchable, but fonts and colors are inherently self-contained (nothing external to embed). Animations and interactive features do not apply.', +}