pdf2json/lib/pdf.js

PDF file parser that converts PDF binaries to JSON and text, powered by porting a fork of PDF.JS to Node.js

import process from "process";
import console from "console";
import fs from "fs";
import nodeUtil from "util";
import { EventEmitter } from "events";

import { _PARSER_SIG } from "./pkinfo.js";
import PDFField from "./pdffield.js";
import PDFFont from "./pdffont.js";
import PDFUnit from "./pdfunit.js";
import PTIXmlParser from "./ptixmlinject.js";
import { createScratchCanvas } from "./pdfcanvas.js";

import { PDFJS } from "./pdfjs-code.js"; // created via `npm run build`

//start of helper classes
class PDFPageParser {
	//static
	static RenderingStates = {
		INITIAL: 0,
		RUNNING: 1,
		PAUSED: 2,
		FINISHED: 3,
	};

	//public
	id = -1;
	pdfPage = null;
	ptiParser = null;
	scale = 0;
	viewport = null;
	renderingState = -1;

	Fields = null;
	Boxsets = null;
	ctxCanvas = null;

	#_addField(field) {
		if (!PDFField.isFormElement(field)) {
			nodeUtil.p2jwarn("NOT valid form element", field);
			return;
		}

		const oneField = new PDFField(
			field,
			this.viewport,
			this.Fields,
			this.Boxsets
		);
		oneField.processField();
	}

	// constructor
	constructor(pdfPage, id, scale, ptiParser) {
		// public, this instance copies
		this.id = id;
		this.pdfPage = pdfPage;
		this.ptiParser = ptiParser;

		this.scale = scale || 1.0;

		//leave out the 2nd parameter in order to use page's default rotation (for both portrait and landscape form)
		this.viewport = this.pdfPage.getViewport(this.scale);

		this.renderingState = PDFPageParser.RenderingStates.INITIAL;

		//form elements other than radio buttons and check boxes
		this.Fields = [];
		//form elements: radio buttons and check boxes
		this.Boxsets = [];
		this.ctxCanvas = {};
	}

	get width() {
		return PDFUnit.toFormX(this.viewport.width);
	}
	get height() {
		return PDFUnit.toFormY(this.viewport.height);
	}
	get HLines() {
		return this.ctxCanvas.HLines;
	}
	get VLines() {
		return this.ctxCanvas.VLines;
	}
	get Fills() {
		return this.ctxCanvas.Fills;
	}
	get Texts() {
		return this.ctxCanvas.Texts;
	}

	destroy() {
		this.pdfPage.destroy();
		this.pdfPage = null;

		this.ptiParser = null;
		this.Fields = null;
		this.Boxsets = null;
		this.ctxCanvas = null;
	}

	getPagePoint(x, y) {
		return this.viewport.convertToPdfPoint(x, y);
	}

	parsePage(callback, errorCallBack) {
		if (this.renderingState !== PDFPageParser.RenderingStates.INITIAL) {
			errorCallBack("Must be in new state before drawing");
			return;
		}

		this.renderingState = PDFPageParser.RenderingStates.RUNNING;

		const canvas = createScratchCanvas(1, 1);
		const ctx = canvas.getContext("2d");

		const selfAddField = this.#_addField.bind(this);
		function pageViewDrawCallback(error) {
			this.renderingState = PDFPageParser.RenderingStates.FINISHED;

			if (error) {
				console.error(error);
				errorCallBack(`Error: Page ${this.id + 1}: ${error.message}`);
			} else {
				if (this.ptiParser) {
					const extraFields = this.ptiParser.getFields(parseInt(this.id) + 1);
					extraFields.forEach((field) => selfAddField(field));
				}

				this.ctxCanvas = ctx.canvas;
				this.stats = this.pdfPage.stats;

				nodeUtil.p2jinfo(`Success: Page ${this.id + 1}`);
				callback();
			}
		}

		const renderContext = {
			canvasContext: ctx,
			viewport: this.viewport,
		};

		this.pdfPage.render(renderContext).then(
			(data) => {
				this.pdfPage.getAnnotations().then(
					(fields) => {
						fields.forEach((field) => this.#_addField(field));
						pageViewDrawCallback.call(this, null);
					},
					(err) => errorCallBack(`pdfPage.getAnnotations error:${err}`)
				);
			},
			(err) => pageViewDrawCallback.call(this, err)
		);
	}
}

////////////////////////////////Start of Node.js Module
export default class PDFJSClass extends EventEmitter {
	pdfDocument = null;
	pages = null;
	rawTextContents = null;

	needRawText = null;

	// constructor
	constructor(needRawText) {
		super();

		// public, this instance copies
		this.pdfDocument = null;
		this.pages = [];
		this.rawTextContents = [];

		this.needRawText = needRawText;
	}

	raiseErrorEvent(errMsg) {
		console.error(errMsg);
		process.nextTick(() => this.emit("pdfjs_parseDataError", errMsg));
		// this.emit("error", errMsg);
		return errMsg;
	}

	raiseReadyEvent(data) {
		process.nextTick(() => this.emit("pdfjs_parseDataReady", data));
		return data;
	}

	parsePDFData(arrayBuffer, password) {
		this.pdfDocument = null;

		const parameters = { password, data: arrayBuffer };
		PDFJS.getDocument(parameters).then(
			(pdfDocument) => this.load(pdfDocument, 1),
			(error) => this.raiseErrorEvent(error)
		);
	}

	tryLoadFieldInfoXML(pdfFilePath) {
		const _sufInfo = "_fieldInfo.xml";
		const fieldInfoXMLPath = pdfFilePath.replace(".pdf", _sufInfo);
		if (
			fieldInfoXMLPath.indexOf(_sufInfo) < 1 ||
			!fs.existsSync(fieldInfoXMLPath)
		) {
			return;
		}
		nodeUtil.p2jinfo(`About to load fieldInfo XML : ${  fieldInfoXMLPath}`);

		this.ptiParser = new PTIXmlParser();
		this.ptiParser.parseXml(fieldInfoXMLPath, (err) => {
			if (err) {
				nodeUtil.p2jwarn(`fieldInfo XML Error: ${  JSON.stringify(err)}`);
				this.ptiParser = null;
			} else {
				nodeUtil.p2jinfo("fieldInfo XML loaded.");
			}
		});
	}

	load(pdfDocument, scale) {
		this.pdfDocument = pdfDocument;

		return this.loadMetaData().then(
			() => this.loadPages(),
			(error) => this.raiseErrorEvent(`loadMetaData error: ${error}`)
		);
	}

	loadMetaData() {
		return this.pdfDocument.getMetadata().then(
			(data) => {
				this.documentInfo = data.info;
				this.metadata = data.metadata?.metadata ?? {};
				this.parseMetaData();
			},
			(error) => this.raiseErrorEvent(`pdfDocument.getMetadata error: ${error}`)
		);
	}

	parseMetaData() {
		const meta = {
			Transcoder: _PARSER_SIG,
			Meta: { ...this.documentInfo, Metadata: this.metadata },
		};
		this.raiseReadyEvent(meta);
		this.emit("readable", meta);
	}

	loadPages() {
		const pagesCount = this.pdfDocument.numPages;
		const pagePromises = [];
		for (let i = 1; i <= pagesCount; i++)
			pagePromises.push(this.pdfDocument.getPage(i));

		const pagesPromise = PDFJS.Promise.all(pagePromises);

		nodeUtil.p2jinfo(`PDF loaded. pagesCount = ${pagesCount}`);

		return pagesPromise.then(
			(promisedPages) => this.parsePage(promisedPages, 0, 1.5),
			(error) => this.raiseErrorEvent(`pagesPromise error: ${error}`)
		);
	}

	parsePage(promisedPages, id, scale) {
		nodeUtil.p2jinfo(`start to parse page:${id + 1}`);

		const pdfPage = promisedPages[id];
		const pageParser = new PDFPageParser(pdfPage, id, scale, this.ptiParser);

		function continueOnNextPage() {
			nodeUtil.p2jinfo(`complete parsing page:${id + 1}`);
			if (id === this.pdfDocument.numPages - 1) {
				this.raiseReadyEvent({ Pages: this.pages });
				//v1.1.2: signal end of parsed data with null
				process.nextTick(() => this.raiseReadyEvent(null));
				this.emit("data", null);
			} else {
				process.nextTick(() => this.parsePage(promisedPages, ++id, scale));
			}
		}

		pageParser.parsePage(
			(data) => {
				const page = {
					Width: pageParser.width,
					Height: pageParser.height,
					HLines: pageParser.HLines,
					VLines: pageParser.VLines,
					Fills: pageParser.Fills,
					//needs to keep current default output format, text content will output to a separate file if '-c' command line argument is set
					//                Content:pdfPage.getTextContent(),
					Texts: pageParser.Texts,
					Fields: pageParser.Fields,
					Boxsets: pageParser.Boxsets,
				};

				this.pages.push(page);
				this.emit("data", page);

				if (this.needRawText) {
					pdfPage.getTextContent().then(
						(textContent) => {
							this.rawTextContents.push(textContent);
							nodeUtil.p2jinfo(`complete parsing raw text content:${id + 1}`);
							continueOnNextPage.call(this);
						},
						(error) =>
							this.raiseErrorEvent(`pdfPage.getTextContent error: ${error}`)
					);
				} else {
					continueOnNextPage.call(this);
				}
			},
			(errMsg) => this.raiseErrorEvent(errMsg)
		);
	}

	getRawTextContent() {
		let retVal = "";
		if (!this.needRawText) return retVal;

		this.rawTextContents.forEach((textContent, index) => {
			let prevText = null;
			textContent.bidiTexts.forEach((textObj, idx) => {
				if (prevText) {
					if (Math.abs(textObj.y - prevText.y) <= 9) {
						prevText.str += textObj.str;
					} else {
						retVal += `${prevText.str}\r\n`;
						prevText = textObj;
					}
				} else {
					prevText = textObj;
				}
			});
			if (prevText) {
				retVal += prevText.str;
			}
			retVal +=
				`\r\n----------------Page (${index}) Break----------------\r\n`;
		});

		return retVal;
	}

	getAllFieldsTypes() {
		return PDFField.getAllFieldsTypes({ Pages: this.pages || [] });
	}

	getMergedTextBlocksIfNeeded() {
		for (let p = 0; p < this.pages.length; p++) {
			let prevText = null;
			const page = this.pages[p];

			page.Texts.sort(PDFFont.compareBlockPos);
			page.Texts = page.Texts.filter((t, j) => {
				const isDup = j > 0 && PDFFont.areDuplicateBlocks(page.Texts[j - 1], t);
				if (isDup) {
					nodeUtil.p2jinfo(
						`skipped: dup text block: ${decodeURIComponent(t.R[0].T)}`
					);
				}
				return !isDup;
			});

			for (let i = 0; i < page.Texts.length; i++) {
				const text = page.Texts[i];

				if (prevText) {
					if (
						PDFFont.areAdjacentBlocks(prevText, text) &&
						PDFFont.haveSameStyle(prevText, text)
					) {
						const preT = decodeURIComponent(prevText.R[0].T);
						const curT = decodeURIComponent(text.R[0].T);

						prevText.R[0].T += text.R[0].T;
						prevText.w += text.w;
						text.merged = true;

						const mergedText = decodeURIComponent(prevText.R[0].T);
						nodeUtil.p2jinfo(
							`merged text block: ${preT} + ${curT} => ${mergedText}`
						);
						prevText = null; //yeah, only merge two blocks for now
					} else {
						prevText = text;
					}
				} else {
					prevText = text;
				}
			}

			page.Texts = page.Texts.filter((t) => !t.merged);
		}

		return { Pages: this.pages };
	}

	destroy() {
		this.removeAllListeners();

		if (this.pdfDocument) this.pdfDocument.destroy();
		this.pdfDocument = null;

		this.pages = null;
		this.rawTextContents = null;
	}
}