pdf-img-convert.js

A pure javascript package to convert a PDF into images

This package is powered mainly by Mozilla's PDF.js

Motivation

There are a lot of solutions for converting PDFs with javascript already but they all make excessive use of the filesystem in the form of temporary files and use non-native binaries like ghostscript.

This solution solely uses javascript arrays, cleaning up the pipeline significantly and (hopefully) making it faster.

Installation

npm install pdf-img-convert

Usage

The package returns an Array of Uint8Array objects, each of which represents an image encoded in png format.

Here are some examples of its usage - obviously import the module first:

var pdf2img = require('pdf-img-convert');

The package has 1 function - convert. It accepts the following pdf formats as input:

• URL of a PDF (e.g. www.example.com/a.pdf)

• Path to a local pdf file (e.g. ../example.pdf)

• A Buffer object containing PDF data

• A Uint8Array object containing PDF data

• Base64-encoded PDF data

NB: it is an asynchronous function so returns a promise object.

The output can be manipulated using the conversion_config argument mentioned below.

Here's an example of how to use it in synchronous code:

// Both HTTP and local paths are supported
var outputImages1 = pdf2img.convert('http://www.example.com/pdf_online.pdf');
var outputImages2 = pdf2img.convert('../pdf_in_local_filesystem.pdf');

// From here, the images can be used for other stuff or just saved if that's required:

var fs = require('fs');

outputImages1.then(function(outputImages) {
    for (i = 0; i < outputImages.length; i++)
        fs.writeFile("output"+i+".png", outputImages[i], function (error) {
          if (error) { console.error("Error: " + error); }
        });
    });

It's a lot easier and cleaner to implement inside an async function using await:

(async function () {
  pdfArray = await pdf2img.convert('http://www.example.com/pdf_online.pdf');
  console.log("saving");
  for (i = 0; i < pdfArray.length; i++){
    fs.writeFile("output"+i+".png", pdfArray[i], function (error) {
      if (error) { console.error("Error: " + error); }
    }); //writeFile
  } // for
})();

There is also an optional second conversion_config argument which accepts an object like this:

{
  width: 100 //Number in px
  height: 100 // Number in px
  page_numbers: [1, 2, 3] // A list of pages to render instead of all of them
  base64: True,
  scale: 2.0
}

(Any of these attributes can be omitted from the object - they're all optional)

• width or height control the scale of the output images - One or the other, it ignores height if width is supplied too.

• page_numbers controls which pages are rendered - pages are 1-indexed.

• base64 should be set to true if a base64-encoded image output is required. Otherwise it'll just output an array of Uint8Arrays.

• scale is the viewport scale ratio, which defaults to 1 (original width and height).

Contributing

If you'd like to contribute, please do submit a pull request!

Once you've finalised your changes, please include a summary of these changes under the [Unreleased] section of CHANGELOG.md in this format.