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Move static PDF functions to seperate file
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,55 @@ | ||
| import { PDFDocument } from 'pdf-lib'; | ||
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| /** | ||
| * joins two pdfs together, alternating pages such that if | ||
| * pdfA = [1, 2, 3] and pdfB = [A, B, C], the final pdf is | ||
| * [1, A, 2, B, 3, C] | ||
| * @param {PDFDocument} pdfA | ||
| * @param {PDFDocument} pdfB | ||
| * @returns {Promise<PDFDocument>} | ||
| */ | ||
| export async function interleavePages(pdfA, pdfB) { | ||
| const mergedPdf = await PDFDocument.create(); | ||
| const pageCount = Math.max(pdfA.getPageCount(), pdfB.getPageCount()); | ||
| for (let i = 0; i < pageCount; i++) { | ||
| const pageA = pdfA.getPage(i); | ||
| if (pageA) mergedPdf.addPage((await mergedPdf.copyPages(pdfA, [i]))[0]); | ||
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| const pageB = pdfB.getPage(i); | ||
| if (pageB) mergedPdf.addPage((await mergedPdf.copyPages(pdfB, [i]))[0]); | ||
| } | ||
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| return mergedPdf; | ||
| } | ||
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| /** | ||
| * Generates a new PDF & embeds the prescribed pages of the source PDF into it | ||
| * @param sourcePdf | ||
| * @param {(string|number)[]} [pageNumbers] - an array of page numbers. Ex: [1,5,6,7,8,'b',10] or null to embed all pages from source | ||
| * NOTE: re-construction behavior kicks in if there's 'b's in the list | ||
| * | ||
| * @return {Promise<[PDFDocument, PDFEmbeddedPage[]]>} PDF with pages embedded, embedded page array | ||
| */ | ||
| export async function embedPagesInNewPdf(sourcePdf, pageNumbers) { | ||
| const newPdf = await PDFDocument.create(); | ||
| const needsReSorting = pageNumbers != null && pageNumbers.includes('b'); | ||
| if (pageNumbers == null) { | ||
| pageNumbers = Array.from(Array(sourcePdf.getPageCount()).keys()); | ||
| } else { | ||
| pageNumbers = pageNumbers.filter((p) => { | ||
| return typeof p === 'number'; | ||
| }); | ||
| } | ||
| let embeddedPages = await newPdf.embedPdf(sourcePdf, pageNumbers); | ||
| // what a gnarly little hack. Letting this sit for now -- | ||
| // --- downstream code requires embeds to be in their 'correct' index possition | ||
| // but we want to only embed half the pages for the aggregate single sides | ||
| // thus we expand the embedded pages to allow those gaps to return. This is gross & dumb but whatever... | ||
| if (needsReSorting) { | ||
| embeddedPages = embeddedPages.reduce((acc, curVal, curI) => { | ||
| acc[pageNumbers[curI]] = curVal; | ||
| return acc; | ||
| }, []); | ||
| } | ||
| return [newPdf, embeddedPages]; | ||
| } |