Copy pages across PDFs (#52)

* Working implementation of page copying

* Protect against cyclic traversals when copying in pages

* Add PDFObjectCopier class

* PDFObjectIndex.set -> PDFObjectIndex.assign

* Fix compilation errors

* WIP: Clone objects when copying from another PDF

* WIP: Working implementation of cloned page copying

* Cleanup

* Implement clone() on all PDFObjects

* Cleanup

* Preserve inherited entries during page copy

* Add integration test for page copying

* Add PDFObjectCopier unit tests

* Add more PDFObjectCopier unit tests

* Add more PDFObjectCopier unit tests

* Add more PDFObjectCopier unit tests

* Fix tests

* Add more PDFObjectCopier unit tests

* Add PDFObject.clone() unit tests

* Cleanup

* Update docs

* Add PDFPage.clone() unit test

* Update README

* Cleanup

Author: Hopding

README.md

@@ -5,3 +5,4 @@ export { default as test4 } from './test4';
 export { default as test5 } from './test5';
 export { default as test6 } from './test6';
 export { default as test7 } from './test7';
+export { default as test8 } from './test8';

__integration_tests__/tests/index.ts

@@ -0,0 +1,95 @@
+import round from 'lodash/round';
+import sum from 'lodash/sum';
+
+import {
+  drawText,
+  PDFDocument,
+  PDFDocumentFactory,
+  PDFDocumentWriter,
+  PDFNumber,
+} from '../../src';
+
+import { ITestAssets, ITestKernel } from '../models';
+
+const createDonorPdf = () => {
+  const pdfDoc = PDFDocumentFactory.create();
+  const [FontHelvetica] = pdfDoc.embedStandardFont('Helvetica');
+
+  const contentStream = pdfDoc.register(
+    pdfDoc.createContentStream(
+      drawText(`I am upside down!`, {
+        font: 'Helvetica',
+        x: 50,
+        y: 225,
+        size: 50,
+      }),
+    ),
+  );
+  const page = pdfDoc
+    .createPage([500, 500])
+    .addFontDictionary('Helvetica', FontHelvetica)
+    .addContentStreams(contentStream);
+  pdfDoc.addPage(page);
+
+  pdfDoc.catalog.Pages.set('Rotate', PDFNumber.fromNumber(180));
+
+  return pdfDoc;
+};
+
+const kernel: ITestKernel = (assets: ITestAssets) => {
+  const pdfDoc = PDFDocumentFactory.load(
+    assets.pdfs.with_missing_endstream_eol_and_polluted_ctm,
+  );
+
+  const allDonorPdfBytes: Uint8Array[] = [
+    assets.pdfs.normal,
+    assets.pdfs.with_update_sections,
+    assets.pdfs.linearized_with_object_streams,
+    assets.pdfs.with_large_page_count,
+  ];
+
+  allDonorPdfBytes.forEach((donorBytes) => {
+    const donorPdf = PDFDocumentFactory.load(donorBytes);
+    pdfDoc.addPage(donorPdf.getPages()[0]);
+  });
+
+  const anotherDonorPdf = createDonorPdf();
+  pdfDoc.insertPage(1, anotherDonorPdf.getPages()[0]);
+
+  const savedBytes = PDFDocumentWriter.saveToBytes(pdfDoc);
+
+  const sizeOfAllDonorPdfs = sum(
+    allDonorPdfBytes
+      .concat(PDFDocumentWriter.saveToBytes(anotherDonorPdf))
+      .map((bytes) => bytes.length),
+  );
+  const sizeOfCreatedPdf = savedBytes.length;
+
+  console.log();
+  console.log(
+    'Since pdf-lib only copies the minimum necessary resources from a donor PDF needed to show a copied page, the size of the PDF we create from copied pages should be smaller than the size of all the donor PDFs added together:',
+  );
+  console.log();
+  console.log(
+    '  sizeOfRecipientPdf / sizeOfAllDonorPdfs = ',
+    round(sizeOfCreatedPdf / sizeOfAllDonorPdfs, 2),
+  );
+
+  return savedBytes;
+};
+
+export default {
+  kernel,
+  title: 'Page Copying Test',
+  description:
+    'This tests that pages can be copied from donor PDFs into a receipient PDF.',
+  checklist: [
+    'the document contains 6 pages.',
+    'the first page is a refund receipt.',
+    'the second page is an inverted white square containing the text "I am upside down!".',
+    'the third page is a D-2210 income tax form.',
+    'the fourth page is a 2013, 1040-V tax form.',
+    'the fifth page is a 2013, 1040 tax form title sheet.',
+    'the sixth page is the title sheet of the PDF 1.7 specification.',
+  ],
+};