pdf-lib/es/core/pdf-document/PDFDocumentWriter.js

Library for creating and modifying PDF files in JavaScript

import isFunction from 'lodash/isFunction';
import last from 'lodash/last';
import sortBy from 'lodash/sortBy';
import { PDFDictionary, PDFIndirectObject, PDFNumber, PDFStream, } from '../pdf-objects';
import { PDFCatalog, PDFObjectStream, PDFTrailer } from '../pdf-structures';
import PDFXRefStreamFactory from '../pdf-structures/factories/PDFXRefStreamFactory';
import PDFXRefTableFactory from '../pdf-structures/factories/PDFXRefTableFactory';
import { error } from '../../utils';
var createIndirectObjectsFromIndex = function (_a) {
    var index = _a.index;
    var catalogRef;
    var streamObjects = [];
    var nonStreamObjects = [];
    index.forEach(function (object, ref) {
        if (object instanceof PDFCatalog)
            catalogRef = ref;
        var array = object instanceof PDFStream ? streamObjects : nonStreamObjects;
        array.push(PDFIndirectObject.of(object).setReference(ref));
    });
    return { catalogRef: catalogRef, streamObjects: streamObjects, nonStreamObjects: nonStreamObjects };
};
var computeOffsets = function (startingOffset, indirectObjects) {
    return indirectObjects.map(function (object) { return ({
        objectNumber: object.reference.objectNumber,
        generationNumber: object.reference.generationNumber,
        startOffset: startingOffset,
        endOffset: startingOffset += object.bytesSize(),
    }); });
};
var PDFDocumentWriter = /** @class */ (function () {
    function PDFDocumentWriter() {
    }
    /**
     * Converts a [[PDFDocument]] object into the raw bytes of a PDF document.
     * These raw bytes could, for example, be saved as a file and opened in a
     * PDF reader.
     *
     * `options.useObjectStreams` controls whether or not to use Object Streams
     * when saving the document. Using Object Streams will result in a smaller
     * file size for many documents. This option is `true` by default. If set to
     * `false`, then Object Streams will not be used.
     *
     * @param pdfDoc  The [[PDFDocument]] to be converted to bytes.
     * @param options An options object.
     *
     * @returns A `Uint8Array` containing the raw bytes of a PDF document.
     */
    PDFDocumentWriter.saveToBytes = function (pdfDoc, options) {
        if (options === void 0) { options = { useObjectStreams: true }; }
        return options.useObjectStreams === false
            ? PDFDocumentWriter.saveToBytesWithXRefTable(pdfDoc)
            : PDFDocumentWriter.saveToBytesWithObjectStreams(pdfDoc);
    };
    PDFDocumentWriter.saveToBytesWithXRefTable = function (pdfDoc) {
        /* ===== (1) Compute indirect object offsets and sort by objectnumber ===== */
        var _a = createIndirectObjectsFromIndex(pdfDoc.index), catalogRef = _a.catalogRef, streamObjects = _a.streamObjects, nonStreamObjects = _a.nonStreamObjects;
        if (!catalogRef)
            error('Missing PDFCatalog');
        streamObjects.forEach(function (streamObj) {
            if (isFunction(streamObj.pdfObject.encode))
                streamObj.pdfObject.encode();
        });
        var merged = streamObjects.concat(nonStreamObjects);
        var offsets = computeOffsets(pdfDoc.header.bytesSize(), merged);
        var sortedOffsets = sortBy(offsets, 'objectNumber');
        /* ===== (2) Create XRefTable and Trailer ===== */
        var table = PDFXRefTableFactory.forOffsets(sortedOffsets);
        var tableOffset = last(offsets).endOffset;
        var trailer = PDFTrailer.from(tableOffset, PDFDictionary.from({
            Size: PDFNumber.fromNumber(last(sortedOffsets).objectNumber + 1),
            Root: catalogRef,
        }, pdfDoc.index));
        /* ===== (3) Create buffer and copy objects into it ===== */
        var bufferSize = tableOffset + table.bytesSize() + trailer.bytesSize();
        var buffer = new Uint8Array(bufferSize);
        var remaining = pdfDoc.header.copyBytesInto(buffer);
        remaining = merged.reduce(function (remBytes, indirectObj) { return indirectObj.copyBytesInto(remBytes); }, remaining);
        remaining = table.copyBytesInto(remaining);
        remaining = trailer.copyBytesInto(remaining);
        return buffer;
    };
    PDFDocumentWriter.saveToBytesWithObjectStreams = function (pdfDoc) {
        /* ===== (1) Split objects into streams and nonstreams ===== */
        var _a = createIndirectObjectsFromIndex(pdfDoc.index), catalogRef = _a.catalogRef, streamObjects = _a.streamObjects, nonStreamObjects = _a.nonStreamObjects;
        if (!catalogRef)
            error('Missing PDFCatalog');
        streamObjects.forEach(function (streamObj) {
            if (isFunction(streamObj.pdfObject.encode))
                streamObj.pdfObject.encode();
        });
        /* ===== (2) Create ObjectStream ===== */
        var objectStream = PDFObjectStream.create(pdfDoc.index, nonStreamObjects);
        objectStream.encode();
        var objectStreamIndObj = PDFIndirectObject.of(objectStream).setReferenceNumbers(pdfDoc.index.highestObjectNumber + 1, 0);
        streamObjects.push(objectStreamIndObj);
        /* ===== (3) Compute indirect object offsets ===== */
        var offsets = computeOffsets(pdfDoc.header.bytesSize(), streamObjects);
        var trailerOffset = last(offsets).endOffset;
        /* ===== (4) Create XRefStream and Trailer ===== */
        var xrefStream = PDFXRefStreamFactory.forOffsetsAndObjectStream(offsets, objectStreamIndObj, catalogRef, pdfDoc.index);
        streamObjects.push(xrefStream);
        var trailer = PDFTrailer.from(trailerOffset);
        /* ===== (5) Create buffer and copy objects into it ===== */
        var bufferSize = trailerOffset + xrefStream.bytesSize() + trailer.bytesSize();
        var buffer = new Uint8Array(bufferSize);
        var remaining = pdfDoc.header.copyBytesInto(buffer);
        remaining = streamObjects.reduce(function (remBytes, obj) { return obj.copyBytesInto(remBytes); }, remaining);
        remaining = trailer.copyBytesInto(remaining);
        return buffer;
    };
    return PDFDocumentWriter;
}());
export default PDFDocumentWriter;