A WebAssembly build of the ZBar Bar Code Reader
This project was forked from ZBar.wasm, a WebAssembly build of the ZBar Bar Code Reader written in C/C++.
Features
- Provided as minified ES module, CommonJS module and plain script
- Runs in modern browsers, in Node.js and also in workers
- Supports Code-39, Code-93, Code-128, Codabar, Databar/Expanded, EAN/GTIN-5/8/13, ISBN-10/13, ISBN-13+2, ISBN-13+5, ITF (Interleaved 2 of 5), QR Code, UPC-A/E.
- Detects multiple barcodes per frame, also with different types
- Barcodes may be oriented horizontally or vertically
- Scans
ImageDataand RGB/grayscaleArrayBufferobjects - Outperforms pure JavaScript barcode scanners
Examples based on zbar-wasm
-
A simple example: on GitHub (source code), on CodePen
-
A polyfill for the
BarcodeDetectorWeb API: on GitHub (source code with build scripts for Rollup and esbuild), on CodePen
Getting started
Using zbar-wasm as <script type="module">
An example that scans a static image file:
<!DOCTYPE html>
<html>
<body>
<img id="img" crossorigin="anonymous" src="https://raw.githubusercontent.com/undecaf/zbar-wasm/master/test/img/qr_code.png">
<pre id="result"></pre>
<script type="module">
import * as zbarWasm from 'https://cdn.jsdelivr.net/npm/@undecaf/zbar-wasm/dist/main.js'
(async () => {
const
img = document.getElementById('img'),
result = document.getElementById('result'),
canvas = document.createElement('canvas'),
context = canvas.getContext('2d');
await img.decode()
canvas.width = img.naturalWidth
canvas.height = img.naturalHeight
context.drawImage(img, 0, 0)
const
imageData = context.getImageData(0, 0, canvas.width, canvas.height),
symbols = await zbarWasm.scanImageData(imageData);
symbols.forEach(s => s.rawData = s.decode())
result.innerText = JSON.stringify(symbols, null, 2)
})()
</script>
</body>
</html>Using zbar-wasm as plain <script>
Almost identical to the snippet above, just replace the lines
⁝
<script type="module">
import * as zbarWasm from 'https://cdn.jsdelivr.net/npm/@undecaf/zbar-wasm/dist/main.js'
⁝with
⁝
<script src="https://cdn.jsdelivr.net/npm/@undecaf/zbar-wasm/dist/index.js"></script>
<script>
⁝Including zbar-wasm as ESM or as CommonJS module
Installing:
$ npm install @undecaf/zbar-wasm
or
$ yarn add @undecaf/zbar-wasmUsing:
import ... from '@undecaf/zbar-wasm' pulls the ES module from the package,
require('@undecaf/zbar-wasm') pulls the CommonJS module.
Please refer to the API documentation for what can be imported/required.
A simple Node.js example that scans a static image file:
const { createCanvas, loadImage } = require('canvas');
const { scanImageData } = require('@undecaf/zbar-wasm');
(async (url) => {
const
img = await loadImage(url),
canvas = createCanvas(img.width, img.height),
ctx = canvas.getContext('2d');
ctx.drawImage(img, 0, 0);
const
imageData = ctx.getImageData(0, 0, img.width, img.height),
symbols = await scanImageData(imageData);
console.log(symbols[0].typeName, symbols[0].decode());
}) ('https://raw.githubusercontent.com/undecaf/zbar-wasm/master/test/img/qr_code.png');Bundling/deploying zbar-wasm
zbar-wasm loads the WebAssembly file zbar.wasm at runtime. zbar.wasm must be located in the same directory
as the zbar-wasm <script> or module, be it on a file system or at a remote endpoint.
This must be observed when bundling zbar-wasm or deploying it to a server:
@undecaf/zbar-wasm/dist/zbar.wasmmust be copied as-is (e.g. usingcopy-webpack-plugin,rollup-plugin-copy,esbuild-plugin-copyor similar).zbar.wasmmust be copied to the directory where the zbar-wasm module/the bundle containing that module is located.- It should be served as
application/wasmso that it can be compiled in parallel with being received by the browser.
Licensing considerations
Please note that zbar-wasm is licensed under the LGPL because it is derived from an LGPL-licensed work. Therefore, bundling zbar-wasm imposes the LGPL on the bundles, too.
If you need a more liberal license for your work then the BarcodeDetector polyfill package might be an option. It does not bundle zbar-wasm but loads it at runtime (as a library), and it is under the MIT license. As an additional benefit it provides a simpler and more flexible API than zbar-wasm.
API documentation
Owing to the predecessor of this project, samsam2310/zbar.wasm, a wiki and an extensive API Reference are already available. Many thanks to the author!
Please note that a few classes have been renamed compared to the documentation in order to avoid conflicts with built-in JavaScript class names:
Symbol→ZBarSymbolImage→ZBarImageImageScanner→ZBarScanner
Building zbar-wasm from source
Prerequisites:
To build:
$ git clone https://github.com/undecaf/zbar-wasm
$ cd zbar-wasm
$ makeThe make command runs emscripten in a container, compiling the C/C++
sources of the ZBar Bar Code Reader
to WebAssembly. It also compiles and bundles the TypeScript glue code
and runs the tests in Node.js on the host machine.
If you prefer Podman as container engine then the provided Makefile need
to be edited before running make: replace the line
EM_ENGINE = $(EM_DOCKER)
with
EM_ENGINE = $(EM_PODMAN)
Credits to ...
- samsam2310 for providing invaluable information in his zbar.wasm repository
- mchehab for maintaining zbar
- the emscripten folks for their compiler toolchain
License
Software: LGPL-2.1
Documentation: CC-BY-SA 4.0