Chromiumly

A lightweight Typescript library that interacts with Gotenberg's different routes to convert a variety of document formats to PDF files.

Table of Contents

1. Introduction

   • Install
   • Prerequisites
   • Get Started

2. Configuration

   • dotenv
   • config
   • code

3. Basic Authentication

4. Modules

   • Chromium
     • URL
     • HTML
     • Markdown
   • Customization
     • Conversion
     • Screenshot
   • LibreOffice
   • PDFEngines
     • convert
     • merge
     • readMetadata
     • writeMetadata
     • generate

5. Snippet

Install

Using npm:

npm install chromiumly

Using yarn:

yarn add chromiumly

Prerequisites

Before attempting to use Chromiumly, be sure you install Docker if you have not already done so.

After that, you can start a default Docker container of Gotenberg as follows:

docker run --rm -p 3000:3000 gotenberg/gotenberg:8

Get Started

Configuration

Chromiumly supports configurations via both dotenv and config configuration libraries or directly via code to add Gotenberg endpoint to your project.

dotenv

GOTENBERG_ENDPOINT=http://localhost:3000

config

{
  "gotenberg": {
    "endpoint": "http://localhost:3000"
  }
}

code

import { Chromiumly } from "chromiumly";

Chromiumly.configure({ endpoint: "http://localhost:3000" });

Basic Authentication

Gotenberg introduces basic authentication support starting from version 8.4.0. Suppose you are running a Docker container using the command below:

docker run --rm -p 3000:3000 \
-e GOTENBERG_API_BASIC_AUTH_USERNAME=user \
-e GOTENBERG_API_BASIC_AUTH_PASSWORD=pass \
gotenberg/gotenberg:8.4.0 gotenberg --api-enable-basic-auth

To integrate this setup with Chromiumly, you need to update your configuration as outlined below:

GOTENBERG_ENDPOINT=http://localhost:3000
GOTENBERG_API_BASIC_AUTH_USERNAME=user
GOTENBERG_API_BASIC_AUTH_PASSWORD=pass

Or

{
  "gotenberg": {
    "endpoint": "http://localhost:3000",
    "api": {
      "basicAuth": {
        "username": "user",
        "password": "pass"
      }
    }
  }
}

Or

Chromiumly.configure({
  endpoint: "http://localhost:3000",
  username: "user",
  password: "pass",
});

Advanced Authentication with Custom HTTP Headers

To implement advanced authentication or add custom HTTP headers to your requests, you can use the customHttpHeaders option within the configure method. This allows you to pass additional headers, such as authentication tokens or custom metadata, with each API call.

For example, you can include a Bearer token for authentication along with a custom header as follows:

const token = await generateToken();

Chromiumly.configure({
  endpoint: "http://localhost:3000",
  customHttpHeaders: {
    Authorization: `Bearer ${token}`,
    "X-Custom-Header": "value",
  },
});

Modules

Modules

Chromiumly introduces different classes that serve as wrappers to Gotenberg's routes. These classes encompass methods featuring an input file parameter, such as html, header, footer, and markdown, capable of accepting inputs in the form of a string (i.e. file path), Buffer, or ReadStream.

Chormium

There are three different classes that come with a single method (i.e.convert) which calls one of Chromium's Conversion routes to convert html and markdown files, or a url to a buffer which contains the converted PDF file content.

Similarly, a new set of classes have been added to harness the recently introduced Gotenberg Screenshot routes. These classes include a single method called capture, which allows capturing full-page screenshots of html, markdown, and url.

URL

import { UrlConverter } from "chromiumly";

const urlConverter = new UrlConverter();
const buffer = await urlConverter.convert({
  url: "https://www.example.com/",
});

import { UrlScreenshot } from "chromiumly";

const screenshot = new UrlScreenshot();
const buffer = await screenshot.capture({
  url: "https://www.example.com/",
});

HTML

The only requirement is that the file name should be index.html.

import { HtmlConverter } from "chromiumly";

const htmlConverter = new HtmlConverter();
const buffer = await htmlConverter.convert({
  html: "path/to/index.html",
});

import { HtmlScreenshot } from "chromiumly";

const screenshot = new HtmlScreenshot();
const buffer = await screenshot.capture({
  html: "path/to/index.html",
});

Markdown

This route accepts an index.html file plus a markdown file.

import { MarkdownConverter } from "chromiumly";

const markdownConverter = new MarkdownConverter();
const buffer = await markdownConverter.convert({
  html: "path/to/index.html",
  markdown: "path/to/file.md",
});

import { MarkdownScreenshot } from "chromiumly";

const screenshot = new MarkdownScreenshot();
const buffer = await screenshot.capture({
  html: "path/to/index.html",
  markdown: "path/to/file.md",
});

Customization

Conversion

convert() method takes an optional properties parameter of the following type which dictates how the PDF generated file will look like.

type PageProperties = {
  singlePage?: boolean; // Print the entire content in one single page (default false)
  size?: {
    width: number; // Paper width, in inches (default 8.5)
    height: number; //Paper height, in inches (default 11)
  };
  margins?: {
    top: number; // Top margin, in inches (default 0.39)
    bottom: number; // Bottom margin, in inches (default 0.39)
    left: number; // Left margin, in inches (default 0.39)
    right: number; // Right margin, in inches (default 0.39)
  };
  preferCssPageSize?: boolean; // Define whether to prefer page size as defined by CSS (default false)
  printBackground?: boolean; // Print the background graphics (default false)
  omitBackground?: boolean; // Hide the default white background and allow generating PDFs with transparency (default false)
  landscape?: boolean; // Set the paper orientation to landscape (default false)
  scale?: number; // The scale of the page rendering (default 1.0)
  nativePageRanges?: { from: number; to: number }; // Page ranges to print
};

In addition to the PageProperties customization options, the convert() method also accepts a set of parameters to further enhance the versatility of the conversion process. Here's an overview of the full list of parameters:

type ConversionOptions = {
  properties?: PageProperties; // Customize the appearance of the generated PDF
  pdfFormat?: PdfFormat; // Define the PDF format for the conversion
  pdfUA?: boolean; // Enable PDF for Universal Access for optimal accessibility (default false)
  userAgent?: string; // Customize the user agent string sent during conversion
  header?: PathLikeOrReadStream; // Specify a custom header for the PDF
  footer?: PathLikeOrReadStream; // Specify a custom footer for the PDF
  emulatedMediaType?: EmulatedMediaType; // Specify the emulated media type for conversion
  waitDelay?: string; // Duration (e.g., '5s') to wait when loading an HTML document before conversion
  waitForExpression?: string; // JavaScript expression to wait before converting an HTML document into PDF
  extraHttpHeaders?: Record<string, string>; // Include additional HTTP headers in the request
  failOnHttpStatusCodes?: number[]; // List of HTTP status codes triggering a 409 Conflict response (default [499, 599])
  failOnConsoleExceptions?: boolean; // Return a 409 Conflict response if there are exceptions in the Chromium console (default false)
  skipNetworkIdleEvent?: boolean; // Do not wait for Chromium network to be idle (default true)
  metadata?: Metadata; // Metadata to be written.
  cookies?: Cookie[]; // Cookies to be written.
  downloadFrom?: DownloadFrom; //Download a file from a URL. It must return a Content-Disposition header with a filename parameter.
};

Screenshot

Similarly, the capture() method takes an optional properties parameter of the specified type, influencing the appearance of the captured screenshot file.

type ImageProperties = {
  format: "png" | "jpeg" | "webp"; //The image compression format, either "png", "jpeg" or "webp".
  quality?: number; // The compression quality from range 0 to 100 (jpeg only).
  omitBackground?: boolean; // Hide the default white background and allow generating screenshots with transparency.
  width?: number; // The device screen width in pixels (default 800).
  height?: number; // The device screen height in pixels (default 600).
  clip?: boolean; // Define whether to clip the screenshot according to the device dimensions (default false).
};

Furthermore, alongside the customization options offered by ImageProperties, the capture() method accommodates a variety of parameters to expand the versatility of the screenshot process. Below is a comprehensive overview of all parameters available:

type ScreenshotOptions = {
  properties?: ImageProperties;
  header?: PathLikeOrReadStream;
  footer?: PathLikeOrReadStream;
  emulatedMediaType?: EmulatedMediaType;
  waitDelay?: string; // Duration (e.g, '5s') to wait when loading an HTML document before convertion.
  waitForExpression?: string; // JavaScript's expression to wait before converting an HTML document into PDF until it returns true.
  extraHttpHeaders?: Record<string, string>;
  failOnHttpStatusCodes?: number[]; // Return a 409 Conflict response if the HTTP status code is in the list (default [499,599])
  failOnConsoleExceptions?: boolean; // Return a 409 Conflict response if there are exceptions in the Chromium console (default false)
  skipNetworkIdleEvent?: boolean; // Do not wait for Chromium network to be idle (default true)
  optimizeForSpeed?: boolean; // Define whether to optimize image encoding for speed, not for resulting size.
  cookies?: Cookie[]; // Cookies to be written.
  downloadFrom?: DownloadFrom; // Download the file from a specific URL. It must return a Content-Disposition header with a filename parameter.
};

LibreOffice

The LibreOffice class comes with a single method convert. This method interacts with LibreOffice route to convert different documents to PDF files. You can find the file extensions accepted here.

import { LibreOffice } from "chromiumly";

const buffer = await LibreOffice.convert({
  files: [
    "path/to/file.docx",
    "path/to/file.png",
    { data: xlsxFileBuffer, ext: "xlsx" },
  ],
});

Similarly to Chromium's route convert method, this method takes the following optional parameters :

• properties: changes how the PDF generated file will look like. It also includes a password parameter to open the source file.
• pdfa: PDF format of the conversion resulting file (i.e. PDF/A-1a, PDF/A-2b, PDF/A-3b).
• pdfUA: enables PDF for Universal Access for optimal accessibility.
• merge: merges all the resulting files from the conversion into an individual PDF file.
• metadata: writes metadata to the generated PDF file.
• lolosslessImageCompression: allows turning lossless compression on or off to tweak image conversion performance.
• reduceImageResolution: allows turning on or off image resolution reduction to tweak image conversion performance.
• quality: specifies the quality of the JPG export. The value ranges from 1 to 100, with higher values producing higher-quality images and larger file sizes.
• maxImageResolution: specifies if all images will be reduced to the specified DPI value. Possible values are: 75, 150, 300, 600, and 1200.

PDFEngines

The PDFEngines class interacts with Gotenberg's PDF Engines routes to manupilate PDF files.

convert

This method interacts with PDF Engines convertion route to transform PDF files into the requested PDF/A format and/or PDF/UA.

import { PDFEngines } from "chromiumly";

const buffer = await PDFEngines.convert({
  files: ["path/to/file_1.pdf", "path/to/file_2.pdf"],
  pdfa: PdfFormat.A_2b,
  pdfUA: true,
});

merge

This method interacts with PDF Engines merge route which gathers different engines that can manipulate and merge PDF files such as: PDFtk, PDFcpu, QPDF, and UNO.

import { PDFEngines } from "chromiumly";

const buffer = await PDFEngines.merge({
  files: ["path/to/file_1.pdf", "path/to/file_2.pdf"],
  pdfa: PdfFormat.A_2b,
  pdfUA: true,
});

readMetadata

This method reads metadata from the provided PDF files.

import { PDFEngines } from "chromiumly";

const metadataBuffer = await PDFEngines.readMetadata([
  "path/to/file_1.pdf",
  "path/to/file_2.pdf",
]);

writeMetadata

This method writes metadata to the provided PDF files.

import { PDFEngines } from "chromiumly";

const buffer = await PDFEngines.writeMetadata({
  files: [
  "path/to/file_1.pdf",
  "path/to/file_2.pdf",
  ],
  metadata: {
    Author: 'Taha Cherfia',
    Tite: 'Chromiumly'
    Keywords: ['pdf', 'html', 'gotenberg'],
  }
});

Please consider referring to ExifTool for a comprehensive list of accessible metadata options.

generate

It is just a generic complementary method that takes the buffer returned by the convert method, and a chosen filename to generate the PDF file.

Please note that all the PDF files can be found __generated__ folder in the root folder of your project.

Snippet

The following is a short snippet of how to use the library.

import { PDFEngines, UrlConverter } from "chromiumly";

async function run() {
  const urlConverter = new UrlConverter();
  const buffer = await urlConverter.convert({
    url: "https://gotenberg.dev/",
  });

  await PDFEngines.generate("gotenberg.pdf", buffer);
}

run();