3.6 KiB
quaggaJS
QuaggaJS is a barcode-scanner entirely written in JavaScript supporting real-time localization and decoding of various types of barcodes such as EAN and CODE128. The library is also configured to use getUserMedia to get direct access to the user's camera stream. Although the code contains some heavy image-processing parts even recent smartphones are capable of locating and decoding barcodes in real-time.
Yet another barcode library?
This is not yet another port of the great zxing 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 rotation. Simply speaking, this reader is invariant in 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 by the 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 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.
Usage
Just download the pre-built version quagga.min.js from the dist folder and include in your project.
The library exposes the following API
quagga.init(config, callback)
This method initializes the library for a given configuration and a function which is called when the loading-process has finished. The initialization process also requests for camera access if real-time detection is configured.
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.
onDetected(callback)
Registeres a callback function which is triggered whenever a barcode-pattern has been located and decoded successfully. The callback function is called with the decoded data as the first parameter.
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 decoded data as first parameter.
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.
quagga.decodeSingle({
readers: [quagga.Reader.Code128Reader],
locate: true, // try to locate the barcode in the image
src: src //'data:image/jpg;base64,' + data
}, function(result){
console.log(result);
});
Build it yourself
In case you want to build the library directly from the source code, just run npm install follewed by the grunt task. This places two files in the dist folder, of which quagga.min.js is the minified version.