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bwip-js // Barcode Writer in Pure JavaScript

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bwip-js bwip-js is a translation to native JavaScript of the amazing code provided in Barcode Writer in Pure PostScript. The translated code can run on any modern browser or JavaScript-based server framework.

The software has encoding modules for over 100 different barcode types and standards. All linear and two-dimensional barcodes in common use (and many uncommon ones) are available. An exhaustive list of supported barcode types can be found at the end of this document.

Version 2.0 introduces a new font rendering module based on the code at stb_truetype.h. This port was manually converted from the original C source and is both small and fast. It implements scalable, anti-aliased fonts and has been tuned to produce nearly identical character metrics as FreeType. The new library is usable in both Node.js and modern browsers.

The emscripten compiled freetype.js and the bitmapped fonts used in prior versions have been removed from this project. Likewise, the extra steps needed to get the bitmapped fonts to work in the browser have been eliminated.

To upgrade your code to the 2.0 release, you must make some minor changes. See Upgrading to 2.0.

Status

Supported Platforms

JavaScript Requirements

Emulating PostScript is non-trivial but most of the needed functionality is available in relatively modern JavaScript. The basic features required are:

If your JavaScript environment does not support those, there is no way to make this code work.

Installation

You can download the latest npm module using:

npm install bwip-js

Or the latest code from github:

https://github.com/metafloor/bwip-js

(The bwip-js master branch and the npm version are kept sync'd.)

Online Barcode Generator

An online barcode generator demonstrates all of the features of bwip-js. The app is also available in the root bwip-js directory. See Demo Apps.

Online Barcode API

A bwip-js barcode service is available online, ready to serve up barcode images on demand.

You can generate barcodes from anywhere on the web. Embed the URLs in your HTML documents or retrieve the barcode images directly from your non-JavaScript server. (JavaScript-based servers should use the bwip-js code directly - it will be a lot more performant.)

For details on how to use this service, see Online Barcode API.

Working With bwip-js Methods

Most of the public methods of the bwip-js export use an options object. Only two values are required:

All remaining options are optional, though you may find some quite useful.

The options values can be divided into two parts, bwip-js specific options and BWIPP options.

The bwip-js options are:

For the BWIPP specific options, you will need to consult the BWIPP documentation to determine what options are available for each barcode type.

Note that bwip-js normalizes the BWIPP width and height options to always be in millimeters. The resulting images are rendered at 72 dpi. To convert to pixels, use a factor of 2.835 px/mm (72 dpi / 25.4 mm/in). The bwip-js scale options multiply the width, height, and padding.

| :warning: An important note about the BWIPP width and height parameters. | |---------------|

Barcodes have the concept of module width (and height if a two-dimensional barcode). For linear barcodes, the module width is the width of the narrowest bar, and all other bar widths are a multiple of it. For 2D symbols, module width and height are the dimensions of the square or rectangle that defines the symbol's layout grid.

For a barcode to be "in spec", the individual module dimensions must be consistent throughout the symbol. With high resolution printing, you can add/subtract a dot to adjust the size of individual modules so the overall image meets the requested width or height, while still keeping the module size within spec. This is the intention behind BWIPP's width and height parameters.

bwip-js is designed for web usage, with a target display resolution of 72dpi. (All of BWIPP's internals are calculated in points and bwip-js just maps 1pt to 1px.) At that low resolution, it is not possible to add or subtract pixels without causing the symbol to go out of spec. Imagine a fairly common module width of 2px. If you add or subtract a pixel, you have changed the size by 50%. Typical barcode specs require module sizes to be within 5-10 pecent of nominal.

For this reason, bwip-js uses a constant module size so the resulting image is as large as possible, without exceeding the requested width or height. The design causes the rendered barcodes to grow in "quantums". An image will be X-pixels wide with a module with of 2px, and Y-pixels wide with a module width of 3px, and can not vary between those two sizes.

With bwip-js, the scale parameters can be thought of as requesting a particular module width. scale=1 maps to a 1px module. scale=2 is a 2px module. Etc.

When you specify width, you are effectively changing the scale of the final image. Internally, bwip-js calcuates the requested width x scale, then divides by the number of modules the symbol requires. The floor of that value is the module width (scale) of the rendered barcode.

Browser Usage

To use within a browser, add the following to the head of your page:

<script type="text/javascript" src="file-or-url-path-to/bwip-js/dist/bwip-js-min.js"></script>

When developing your code, you may want to use dist/bwip-js.js to get better stack traces.

If you are using RequireJS or another module/packaging utility, the bwip-js script is structured as a UMD and should work with your environment.

The script adds a single bwipjs global object. To draw a barcode to a canvas:

try {
    // The return value is the canvas element
    let canvas = bwipjs.toCanvas('mycanvas', {
            bcid:        'code128',       // Barcode type
            text:        '0123456789',    // Text to encode
            scale:       3,               // 3x scaling factor
            height:      10,              // Bar height, in millimeters
            includetext: true,            // Show human-readable text
            textxalign:  'center',        // Always good to set this
        });
} catch (e) {
    // `e` may be a string or Error object
}

The bwipjs.toCanvas() method takes two parameters:

On return from toCanvas(), the barcode image will have been fully rendered to the canvas.

If you would prefer to display the barcode using an <img> tag or with CSS background-image, pass in a detached or hidden canvas, and use the canvas method HTMLCanvasElement.toDataURL to get a data URL. For example:

let canvas = document.createElement('canvas');
try {
    bwipjs.toCanvas(canvas, options);
    document.getElementById(myimg).src = canvas.toDataURL('image/png');
} catch (e) {
    // `e` may be a string or Error object
}

React Usage

The following is a minimal example of using bwip-js in a React app. It is based on the default App.js file generated by create-react-app.

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';
import bwipjs from 'bwip-js';

class App extends Component {
  componentDidMount() {
    try {
      // The return value is the canvas element
      let canvas = bwipjs.toCanvas('mycanvas', {
                bcid:        'code128',       // Barcode type
                text:        '0123456789',    // Text to encode
                scale:       3,               // 3x scaling factor
                height:      10,              // Bar height, in millimeters
                includetext: true,            // Show human-readable text
                textxalign:  'center',        // Always good to set this
            });
    } catch (e) {
        // `e` may be a string or Error object
    }
  }
  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        </div>
        <canvas id="mycanvas"></canvas>
      </div>
    );
  }
}
export default App;

See the Browser Usage section for details on the toCanvas() method.

Node.js Request Handler

The online barcode API is implemented as a Node.js application. See the Online Barcode API for details on how the URL query parameters must be structured.

A working, minimal example of how to use the request handler can be found in server.js:

// Simple HTTP server that renders barcode images using bwip-js.
const http   = require('http');
const bwipjs = require('bwip-js');

// This shows how to load the Inconsolata font, supplied with the bwip-js distribution.
// The path to your fonts will be different.
//bwipjs.loadFont('Inconsolata', 100,
//      require('fs').readFileSync('./fonts/Inconsolata.otf', 'binary'));

http.createServer(function(req, res) {
    // If the url does not begin /?bcid= then 404.  Otherwise, we end up
    // returning 400 on requests like favicon.ico.
    if (req.url.indexOf('/?bcid=') != 0) {
        res.writeHead(404, { 'Content-Type':'text/plain' });
        res.end('BWIPJS: Unknown request format.', 'utf8');
    } else {
        bwipjs.request(req, res); // Executes asynchronously
    }

}).listen(3030);

If you run the above code on your local machine, you can test with the following URL:

http://localhost:3030/?bcid=isbn&text=978-1-56581-231-4+52250&includetext&guardwhitespace

The bwip-js request handler only operates on the URL query parameters and ignores all path information. Your application is free to structure the URL path as needed to implement the desired HTTP request routing.

Node.js Image Generator

You can use bwip-js to generate PNG images directly.

const bwipjs = require('bwip-js');

bwipjs.toBuffer({
        bcid:        'code128',       // Barcode type
        text:        '0123456789',    // Text to encode
        scale:       3,               // 3x scaling factor
        height:      10,              // Bar height, in millimeters
        includetext: true,            // Show human-readable text
        textxalign:  'center',        // Always good to set this
    }, function (err, png) {
        if (err) {
            // `err` may be a string or Error object
        } else {
            // `png` is a Buffer
            // png.length           : PNG file length
            // png.readUInt32BE(16) : PNG image width
            // png.readUInt32BE(20) : PNG image height
        }
    });

If you would prefer to work with Promises, omit the callback function and toBuffer() will return a Promise:

bwipjs.toBuffer({
        bcid:        'code128',       // Barcode type
        text:        '0123456789',    // Text to encode
        scale:       3,               // 3x scaling factor
        height:      10,              // Bar height, in millimeters
        includetext: true,            // Show human-readable text
        textxalign:  'center',        // Always good to set this
    })
    .then(png => {
        // `png` is a Buffer as in the example above
    })
    .catch(err => {
        // `err` may be a string or Error object
    });

Electron Example

There has been some changes to the Electron bundler, and it may pull in either the nodejs or browser module, depending on your version of Electron. The example below shows using the nodejs module.

If you try this example and get the error bwipjs.toBuffer is not a function, the Electron bundler grabbed the browser module. See the Browser Usage section above and draw to a canvas instead.

If you happen to know how the Electron bundler changed its behavior and how to fix it in a project's package.json, please raise an issue at github issues page.

This is an example index.html file for a basic, single window app:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Hello World!</title>
  </head>
  <body>
    Node.js <script>document.write(process.versions.node)</script>,
    Chromium <script>document.write(process.versions.chrome)</script>,
    Electron <script>document.write(process.versions.electron)</script>,
    bwip-js <script>document.write(bwipjs.VERSION)</script>,
    and BWIPP <script>document.write(bwipjs.BWIPP.VERSION)</script>.
    <br><br><img id="myimg">
    <pre id="output"></pre>
  </body>

  <script>
    var bwipjs = require('bwip-js');
    bwipjs.toBuffer({ bcid:'qrcode', text:'0123456789' }, function (err, png) {
        if (err) {
          document.getElementById('output').textContent = err;
        } else {
          document.getElementById('myimg').src = 'data:image/png;base64,' +
                                                 png.toString('base64');
        }
      });
  </script>
</html>

Command Line Interface

bwip-js can be used as a command line tool.

$ npm install -g bwip-js
$ bwip-js
Usage: bwip-js symbol-name text [options...] png-file
       bwip-js --bcid=symbol-name --text=text [options...] png-file

Example:
       bwip-js code128 012345678 includetext textcolor=ff0000 my-code128.png

Try 'bwip-js --help' for more information.
Try 'bwip-js --symbols' for a list of supported barcode symbols.

To use a custom font with the command line utility, use the --loadfont option. It takes one of three formats:

--loadfont=font-name,y-mult,x-mult,path-to-font-file
--loadfont=font-name,size-mult,path-to-font-file
--loadfont=font-name,path-to-font-file

For example:

$ bwip-js code128 12345678 includetext textfont=CONS textxalign=center \
  loadfont=CONS,250,100,../fonts/Inconsolata.otf /tmp/code128.png

The above demonstrates how to maniplulate the font metrics so the characters appear tall and narrow.

Demo HTML App

demo.html located in the root bwip-js directory is a full featured demonstation of bwip-js barcode rendering. It uses bwip-js' built-in graphics to draw to a canvas. The images produced will match pixel-for-pixel with the images produced by the same nodejs usage.

Examples

There are example html and node apps provided with the project including how to write your own drawing interface, generating SVG barcode images, and adding scalable barcodes to a pdfkit document.

See the examples README for more details.