quaggaJS/README.md

quaggaJS
========

- [Changelog](#changelog) (2015-05-09)

## What is QuaggaJS?

QuaggaJS is a barcode-scanner entirely written in JavaScript supporting real-
time localization and decoding of various types of barcodes such as __EAN__,
__CODE 128__, __CODE 39__, __EAN 8__, __UPC-A__, __UPC-C__ and  __CODABAR__.
The library is also capable of using `getUserMedia` to get direct access to
the user's camera stream. Although the code relies on heavy image-processing
even recent smartphones are capable of locating and decoding barcodes in
real-time.

Try some [examples](http://serratus.github.io/quaggaJS/examples) and check out
the blog post ([How barcode-localization works in QuaggaJS][oberhofer_co_how])
if you want to dive deeper into this topic.

![teaser][teaser_left]![teaser][teaser_right]


## Yet another barcode library?

This is not yet another port of the great [zxing][zxing_github] library, but
more of an extension to it. This implementation features a barcode locator which
is capable of finding a barcode-like pattern in an image resulting in an
estimated bounding box including the rotation. Simply speaking, this reader is
invariant to scale and rotation, whereas other libraries require the barcode to
be aligned with the viewport.


## Requirements

In order to take full advantage of quaggaJS, the browser needs to support the
`getUserMedia` API which is already implemented in recent versions of Firefox,
Chrome and Opera. The API is also available on their mobile counterparts
installed on Android. Safari and IE do not allow the access to the camera yet,
neither on desktop, nor on mobile. You can check [caniuse][caniuse_getusermedia]
for updates.

In cases where real-time decoding is not needed, or the platform does not
support `getUserMedia` QuaggaJS is also capable of decoding image-files using
the File API or other URL sources.

## Getting Started

You can simply include `dist/quagga.min.js` in your project and you are ready
to go.

If you want to keep your project modular, you can also install QuaggaJS via npm:

```console
> npm install quagga
```

And then import it as dependency in your project:

```javascript
var quagga = require('quagga');
```

For starters, have a look at the [examples][github_examples] to get an idea
where to go from here.

## <a name="Building">Building</a>

You can build the library yourself by simply cloning the repo and typing:

```console
> npm install
> grunt dist
```

This grunt task builds a non optimized version `quagga.js` and a minified
version `quagga.min.js` and places both files in the `dist` folder.

## API

You can check out the [examples][github_examples] to get an idea of how to
use QuaggaJS. Basically the library exposes the following API:

### Quagga.init(config, callback)

This method initializes the library for a given configuration `config` (see
below) and invokes the `callback` when Quagga is ready to start. The
initialization process also requests for camera access if real-time detection is
configured.

```javascript
Quagga.init({
    inputStream : {
      name : "Live",
      type : "LiveStream"
    },
    decoder : {
      readers : ["code_128_reader"]
    }
  }, function() {
      console.log("Initialization finished. Ready to start");
      Quagga.start();
  });
```

### Quagga.start()

When the library is initialized, the `start()` method starts the video-stream
and begins locating and decoding the images.

### Quagga.stop()

If the decoder is currently running, after calling `stop()` the decoder does not
process any more images. Additionally, if a camera-stream was requested upon
initialization, this operation also disconnects the camera.

### Quagga.onProcessed(callback)

This method registers a `callback(data)` function that is called for each frame
after the processing is done. The `data` object contains detailed information
about the success/failure of the operation. The output varies, depending whether
the detection and/or decoding were successful or not.

### Quagga.onDetected(callback)

Registers a `callback(data)` function which is triggered whenever a barcode-
pattern has been located and decoded successfully. The passed `data` object
contains information about the decoding process including the detected code
which can be obtained by calling `data.codeResult.code`.

### Quagga.decodeSingle(config, callback)

In contrast to the calls described above, this method does not rely on
`getUserMedia` and operates on a single image instead. The provided callback
is the same as in `onDetected` and contains the result `data` object.

## <a name="resultobject">The result object</a>

The callbacks passed into `onProcessed`, `onDetected` and `decodeSingle`
receive a `data` object upon execution. The `data` object contains the following
information. Depending on the success, some fields may be `undefined` or just
empty.

```javascript
{
  "codeResult": {
    "code": "FANAVF1461710",
    "start": 355,
    "end": 26,
    "codeset": 100,
    "startInfo": {
      "error": 1.0000000000000002,
      "code": 104,
      "start": 21,
      "end": 41
    },
    "decodedCodes": [{
      "code": 104,
      "start": 21,
      "end": 41
    },
    // stripped for brevity
    {
      "error": 0.8888888888888893,
      "code": 106,
      "start": 328,
      "end": 350
    }],
    "endInfo": {
      "error": 0.8888888888888893,
      "code": 106,
      "start": 328,
      "end": 350
    },
    "direction": -1
  },
  "line": [{
    "x": 25.97278706156836,
    "y": 360.5616435369468
  }, {
    "x": 401.9220519377024,
    "y": 70.87524989906444
  }],
  "angle": -0.6565217179979483,
  "pattern": [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, /* ... */ 1],
  "box": [
    [77.4074243622672, 410.9288668804402],
    [0.050203235235130705, 310.53619724086366],
    [360.15706727788256, 33.05711026051813],
    [437.5142884049146, 133.44977990009465]
  ],
  "boxes": [
    [
      [77.4074243622672, 410.9288668804402],
      [0.050203235235130705, 310.53619724086366],
      [360.15706727788256, 33.05711026051813],
      [437.5142884049146, 133.44977990009465]
    ],
    [
      [248.90769330706507, 415.2041489551161],
      [198.9532321622869, 352.62160512937635],
      [339.546160777576, 240.3979259789976],
      [389.5006219223542, 302.98046980473737]
    ]
  ]
}
```

## <a name="configobject">Config</a>

The default `config` object is set as followed:

```javascript
{
  inputStream: { name: "Live",
       type: "LiveStream",
       constraints: {
         width: 640,
         height: 480,
         facing: "environment"
       }
  },
  tracking: false,
  debug: false,
  controls: false,
  locate: true,
  numOfWorkers: 4,
  visual: {
    show: true
  },
  decoder:{
    drawBoundingBox: false,
    showFrequency: false,
    drawScanline: true,
    showPattern: false,
    readers: [
      'code_128_reader'
    ]
  },
  locator: {
    halfSample: true,
    patchSize: "medium", // x-small, small, medium, large, x-large
    showCanvas: false,
    showPatches: false,
    showFoundPatches: false,
    showSkeleton: false,
    showLabels: false,
    showPatchLabels: false,
    showRemainingPatchLabels: false,
    boxFromPatches: {
      showTransformed: false,
      showTransformedBox: false,
      showBB: false
    }
  }
}
```

## Examples

The following example takes an image `src` as input and prints the result on the
console. The decoder is configured to detect _Code128_ barcodes and enables the
locating-mechanism for more robust results.

```javascript
Quagga.decodeSingle({
  readers: ['code_128_reader'],
  locate: true, // try to locate the barcode in the image
  src: '/test/fixtures/code_128/image-001.jpg' // or 'data:image/jpg;base64,' + data
}, function(result){
  console.log(result);
});
```

## Tests

Unit Tests can be run with [Karma][karmaUrl] and written using
[Mocha][mochaUrl], [Chai][chaiUrl] and [SinonJS][sinonUrl]. Coverage reports are
automatically generated in the coverage/ folder.

```console
> npm install
> grunt test
```
## Image Debugging

In case you want to take a deeper dive into the inner workings of Quagga, get to
know the _debugging_ capabilities of the current implementation. The various
flags exposed through the `config` object give you the abilily to visualize
almost every step in the processing. Because of the introduction of the
web-workers, and their restriction not to have access to the DOM, the
configuration must be explicitly set to `config.numOfWorkers = 0` in order to
work.

## <a name="changelog">Changelog</a>

### 2015-05-09
- Improvements
  - Odd image dimensions no longer cause problems

### 2015-04-30
- Features
  - Added support for [UPC-A and UPC-E][upc_wiki] barcodes
  - Added support for [EAN-8][ean_8_wiki] barcodes
- Improvements
  - Added extended configuration to the live-video example
  - Releasing resources when calling ``Quagga.stop()``

### 2015-04-25
- Improvements
  - Added extended configuration to the file-input example
  - Configurable ``patchSize`` for better adjustment to small/medium/large
      barcodes

### 2015-04-16
- Features
  - Added support for [Codabar][codabar_wiki] barcodes

### 2015-03-16
- Improvements
  - now includes minified version (23.3KB gzipped)
  - No need for configuration of script-name any more

### 2015-03-12
- Improvements
  - removed dependency on async.js

### 2015-03-04
- Features
  - Added support for [Code 39][code39_wiki] barcodes

### 2015-01-21
- Features
  - Added support for web-worker (using 4 workers as default, can be changed
  through `config.numOfWorkers`)
  - Due to the way how web-workers are created, the name of the script file
  (`config.scriptName`) should be kept in sync with your actual filename
  - Removed canvas-overlay for decoding (boxes & scanline) which can now be
  easily implemented using the existing API (see example)
- API Changes
In the course of implementing web-workers some breaking changes were
introduced to the API.
  - The `Quagga.init` function no longer receives the callback as part of the
   config but rather as a second argument: `Quagga.init(config, cb)`
  - The callback to `Quagga.onDetected` now receives an object containing
  much more information in addition to the decoded code.(see
  [data](#resultobject))
  - Added `Quagga.onProcessed(callback)` which provides a way to get information
  for each image processed. The callback receives the same `data` object as
  `Quagga.onDetected` does. Depending on the success of the process the `data`
  object might not contain any `resultCode` and/or `box` properties.

[zxing_github]: https://github.com/zxing/zxing
[teaser_left]: https://raw.githubusercontent.com/serratus/quaggaJS/master/doc/img/mobile-located.png
[teaser_right]: https://raw.githubusercontent.com/serratus/quaggaJS/master/doc/img/mobile-detected.png
[caniuse_getusermedia]: http://caniuse.com/#feat=stream
[sinonUrl]: http://sinonjs.org/
[chaiUrl]: http://chaijs.com/
[mochaUrl]: https://github.com/mochajs/mocha
[karmaUrl]: http://karma-runner.github.io/
[code39_wiki]: http://en.wikipedia.org/wiki/Code_39
[codabar_wiki]: http://en.wikipedia.org/wiki/Codabar
[upc_wiki]: http://en.wikipedia.org/wiki/Universal_Product_Code
[ean_8_wiki]: http://en.wikipedia.org/wiki/EAN-8
[oberhofer_co_how]: http://www.oberhofer.co/how-barcode-localization-works-in-quaggajs/
[github_examples]: http://serratus.github.io/quaggaJS/examples