QPDF.js

A pure javascript library based on QPDF.

Features

• create web-optimized PDF files
• encrypt and password-protect PDF files
• merge and split PDFs

Example Usage

encrypt a PDF file

QPDF.encrypt({
  arrayBuffer: data,
  userPassword: 'hardtoguess',
  ownerPassword: 'hardtoguess',
  callback: function (err, arrayBuffer) {
    if (err) {
      alert(err.message);
    } else {
      sendFile(arrayBuffer);
    }
  }
});

execute custom QPDF commands

List QPDF command line arguments:

QPDF({
  logger: function (text) {
    console.log(text);
  },
  ready: function (qpdf) {
    qpdf.execute(['--help']);
  }
});

Decrypt a PDF file:

QPDF({
  ready: function (qpdf) {
    qpdf.save('input.pdf', arrayBuffer);
    qpdf.execute(['--decrypt', '--password', 'hardtoguess', '--', 'input.pdf', 'output.pdf']);
    qpdf.load('output.pdf', function (err, arrayBuffer) {
      if (err) {
        alert(err.message);
      } else {
        sendFile(arrayBuffer);
      }
    });
  }
});

Installation

Copy src/*.js to some directory. You can retrieve the files from this repository or using npm:

npm install qpdf.js

Then import qpdf.js from your HTML.

<script type="text/javascript" src="/path/qpdf.js"></script>

Beware, if it's not in the same directory as your HTML file, you need to tell QPDF where the qpdf-worker.js file is located relative to your .html file, or as an absolute path.

QPDF.path = '/path/'; // must end with a '/'

Description

What is QPDF?

(extracted from the QPDF website)

QPDF is a command-line program that does structural, content-preserving transformations on PDF files. It could have been called something like pdf-to-pdf. It also provides many useful capabilities to developers of PDF-producing software or for people who just want to look at the innards of a PDF file to learn more about how they work.

QPDF is capable of creating linearized (also known as web-optimized) files and encrypted files. It is also capable of converting PDF files with object streams (also known as compressed objects) to files with no compressed objects or to generate object streams from files that don't have them (or even those that already do). QPDF also supports a special mode designed to allow you to edit the content of PDF files in a text editor. For more details, please see the documentation links below.

QPDF includes support for merging and splitting PDFs through the ability to copy objects from one PDF file into another and to manipulate the list of pages in a PDF file. The QPDF library also makes it possible for you to create PDF files from scratch. In this mode, you are responsible for supplying all the contents of the file, while the QPDF library takes care off all the syntactical representation of the objects, creation of cross references tables and, if you use them, object streams, encryption, linearization, and other syntactic details.

QPDF is not a PDF content creation library, a PDF viewer, or a program capable of converting PDF into other formats. In particular, QPDF knows nothing about the semantics of PDF content streams. If you are looking for something that can do that, you should look elsewhere. However, once you have a valid PDF file, QPDF can be used to transform that file in ways perhaps your original PDF creation can't handle. For example, programs generate simple PDF files but can't password-protect them, web-optimize them, or perform other transformations of that type.

What is QPDF.js?

QPDF.js provides a simple high level interface to perform operations on PDF files, as well as a low level access interface to execute any QPDF command.

QPDF.js embeds the QPDF full command line tools in a library compiled with emscripten.

The command line tool is ran from a separate thread (a web worker).

The version distributed with this library has been compiled by @jrmuizel and pulled from this repository.

Unfortunately it's not the latest version.

API

QPDF.encrypt(options)

Create an ecrypted version of a PDF document

Options:

• logger: A function(txt) used for logging QPDF output.
• arrayBuffer: Input PDF data encoded in an ArrayBuffer.
• userPassword: The user password (default: empty string).
• ownerPassword: The owner password (default: empty string).
• keyLength: may be 40, 128, or 256 (default).
• callback: A function(err, arrayBuffer) called when processing is done.

Either or both of the user password and the owner password may be empty strings.

Example:

QPDF.encrypt({
  arrayBuffer: new Uint8Array(someData).buffer,
  userPassword: 'hardtoguess',
  ownerPassword: 'hardtoguess',
  callback: function (err, arrayBuffer) {
    if (err) {
      alert(err.message);
    } else {
      sendFile(arrayBuffer);
    }
  }
});

QPDF(options)

Start QPDF

options is an object with 2 fields:

• ready: Function called when QPDF is ready to receive commands.
• logger: A customer logger for QPDF output (default to console.log)

The ready callback takes a qpdf instance as its argument, which you will use to send commands, such as qpdf.load(), qpdf.save() and qpdf.execute() (see below).

In most common cases, you'll want to first save a file into QPDF's execution environment, then execute QPDF with some arguments, then load the resulting file.

Commands are run sequencially, in the same order as they are emitted, so you don't have to wait for the previous command to finish before sending the next one.

Example:

QPDF({
  ready: function (qpdf) {
    qpdf.save('input.pdf', arrayBuffer);
    qpdf.execute(['--some-arguments', '--', 'input.pdf', 'output.pdf']);
    qpdf.load('output.pdf', function (err, arrayBuffer) {
      ...
    });
  }
});

qpdf.save(filename, arrayBuffer, callback)

Saves a file to QPDF's virtual file system.

Data has to be provided as an ArrayBuffer.

The callback is optional.

Example:

qpdf.save('file.pdf', arrayBuffer, function(err) {
  if (err)
    alert(err.message);
  else
    console.log('file saved');
});

qpdf.execute([args], callback)

Execute a command with QPDF.

args is an array of strings, containing the arguments to pass the QPDF command line tool.

The callback is optional.

Example:

qpdf.execute(['--help'], function(err) {
  if (err)
    alert(err.message);
});

qpdf.load(filename, callback)

Loads a file from QPDF's virtual file system.

Data will be provided to the callback as an ArrayBuffer.

Example:

qpdf.load('output.pdf', function (err, arrayBuffer) {
  if (err) {
    alert(err.message);
  } else {
    console.log('it worked');
    sendFile(arrayBuffer);
  }
});

QPDF.base64ToArrayBuffer(base64)

Convert a base64 string to an ArrayBuffer.

QPDF.arrayBufferToBase64(arrayBuffer)

Convert an ArrayBuffer to a base64 string.

License and Copyright

QPDF.js is distributed under the same licensing terms as the QPDF command line tool.

The Apache License Version 2.0