wehub-resource-sync
77 lines
2.5 KiB
TypeScript
77 lines
2.5 KiB
TypeScript
/**
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* Minimal PDF builder for fixtures. Produces a syntactically valid PDF 1.4
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* with one Helvetica text object per page — small enough to build in-memory
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* and ship through pdfjs-dist's loader the same way an uploaded file would.
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*/
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export function buildSimplePdf(pageTexts: string[]): Buffer {
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const parts: Buffer[] = [];
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const offsets: number[] = [];
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let totalLen = 0;
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function emit(s: string | Buffer) {
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const buf = typeof s === 'string' ? Buffer.from(s, 'binary') : s;
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parts.push(buf);
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totalLen += buf.length;
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}
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function recordObj() {
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offsets.push(totalLen);
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}
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emit('%PDF-1.4\n');
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emit('%\xE2\xE3\xCF\xD3\n'); // 4-byte binary marker so readers treat it as binary
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recordObj();
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emit('1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n');
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const numPages = pageTexts.length;
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const pageObjIds: number[] = [];
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const contentObjIds: number[] = [];
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for (let i = 0; i < numPages; i++) {
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pageObjIds.push(3 + i * 2);
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contentObjIds.push(4 + i * 2);
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}
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recordObj();
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emit(`2 0 obj\n<< /Type /Pages /Kids [${pageObjIds
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.map((id) => `${id} 0 R`)
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.join(' ')}] /Count ${numPages} >>\nendobj\n`);
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for (let i = 0; i < numPages; i++) {
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const text = escapePdfString(pageTexts[i]);
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const streamContent = `BT /F1 24 Tf 72 720 Td (${text}) Tj ET`;
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const streamLen = Buffer.byteLength(streamContent, 'binary');
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recordObj();
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emit(
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`${pageObjIds[i]} 0 obj\n` +
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`<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] /Contents ${contentObjIds[i]} 0 R ` +
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`/Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Helvetica >> >> >> >>\n` +
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`endobj\n`,
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);
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recordObj();
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emit(
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`${contentObjIds[i]} 0 obj\n` +
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`<< /Length ${streamLen} >>\nstream\n${streamContent}\nendstream\nendobj\n`,
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);
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}
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const xrefStart = totalLen;
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const totalObjs = 1 + offsets.length;
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emit(`xref\n0 ${totalObjs}\n`);
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emit('0000000000 65535 f \n');
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for (const offset of offsets) {
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emit(`${offset.toString().padStart(10, '0')} 00000 n \n`);
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}
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emit(`trailer\n<< /Size ${totalObjs} /Root 1 0 R >>\n`);
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emit(`startxref\n${xrefStart}\n`);
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emit('%%EOF\n');
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return Buffer.concat(parts);
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}
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function escapePdfString(s: string): string {
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return s.replace(/\\/g, '\\\\').replace(/\(/g, '\\(').replace(/\)/g, '\\)');
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}
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