@undecaf/zbar-wasm
Advanced tools
This project was forked from ZBar.wasm, a WebAssembly build of the ZBar Bar Code Reader written in C/C++.
ImageData and
RGB/grayscale ArrayBuffer objects:warning: zbar-wasm versions 0.10 and above contain breaking changes with respect to version 0.9, please refer to section Bundling/deploying zbar-wasm.
A simple example: on GitHub (source code), on CodePen
A polyfill for the BarcodeDetector Web API:
on GitHub
(source code
with build scripts for Rollup and esbuild),
on CodePen
<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/tests/img/qr_code.png">
<pre id="result"></pre>
<script type="module">
import * as zbarWasm from 'https://cdn.jsdelivr.net/npm/@undecaf/zbar-wasm@0.11.0/dist/index.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>
<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@0.11.0/dist/index.js'
⁝
with
⁝
<script src="https://cdn.jsdelivr.net/npm/@undecaf/zbar-wasm@0.11.0/dist/index.js"></script>
<script>
⁝
Installing:
$ npm install @undecaf/zbar-wasm@0.11.0
or
$ yarn add @undecaf/zbar-wasm@0.11.0
Using:
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 ES module that scans a static image file:
import { createCanvas, loadImage } from 'canvas';
import { scanImageData } from '@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/tests/img/qr_code.png')
For a CommonJS module, just replace the first lines with
const { createCanvas, loadImage } = require('canvas');
const { scanImageData } = require('@undecaf/zbar-wasm');
Barcode scanning is always delegated to the WebAssembly code in file zbar.wasm.
zbar-wasm provides various functionally equivalent ESM and CommonJS modules for Node.js and for browsers
that differ in how zbar.wasm is to be provided at runtime:
zbar.wasm can be loaded from a CDN by browsers.zbar.wasm can be bundled as an asset. That asset should be served to browsers as application/wasm
so that it can be compiled in parallel with being received.zbar.wasm as inline data.The following overview shows the modules that are available in zbar-wasm. One of them needs to be bundled in your application.
| Path in package | Module type | Node core modules polyfilled (suitable for browsers) | zbar.wasm inlined |
|---|---|---|---|
/dist/index.mjs | ESM | :heavy_check_mark: | |
/dist/index.js | CommonJS | :heavy_check_mark: | |
/dist/main.mjs | ESM | ||
/dist/main.cjs | CommonJS | ||
/dist/inlined/index.mjs | ESM | :heavy_check_mark: | :heavy_check_mark: |
/dist/inlined/index.js | CommonJS | :heavy_check_mark: | :heavy_check_mark: |
/dist/inlined/main.mjs | ESM | :heavy_check_mark: | |
/dist/inlined/main.cjs | CommonJS | :heavy_check_mark: |
The package entry points of zbar-wasm have been chosen so that bundlers will emit the
appropriate module by default in most cases. However, zbar.wasm as inline data requires a suitable
export condition in the bundler configuration, typically 'zbar-inlined'.
Please refer to the exports section of package.json for details.
Building zbar-wasm includes testing the bundling process with Webpack, Rollup and
esbuild and also testing the resulting bundles. The bundler configuration files
tests/{webpack,rollup,esbuild}.config.js
may be used as a reference of how to achieve a particular bundling result. Each of them covers
the following combinations of platforms, module types and zbar.wasm provisioning for the
respective bundler:
zbar.wasm | Node module types | Browser module types |
|---|---|---|
| loaded from CDN | ESM, plain <script> | |
| bundled as asset | ESM, CommonJS | ESM |
| inlined in module | ESM, CommonJS | ESM, plain <script> |
zbar.wasm from a custom locationAs a last resort, if you cannot make your bundler place zbar.wasm where it can be located by the script,
you can specify an URL or path for that WASM file at runtime:
import { scanImageData, setModuleArgs } from '@undecaf/zbar-wasm';
⁝
// Call this function once at the beginning
setModuleArgs({
/**
* This function must return the URL or path of the WASM file.
*
* @param filename default WASM filename ('zbar.wasm')
* @param directory default WASM directory (URL or directory of the current script)
* @returns {string} URL or path of the WASM file
*/
locateFile: (filename, directory) => {
return 'file:///your/wasm/directory/zbar.wasm'
}
});
⁝
// Then use the scanner
const symbols = await scanImageData(...);
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 → ZBarScannerBarcodeDetector Web APIThe BarcodeDetector polyfill
package (in this repository, by the same author) is based on
zbar-wasm but provides a standardized, higher-level and more flexible API.
Prerequisites:
make, tar and curlTo build:
$ git clone https://github.com/undecaf/zbar-wasm
$ cd zbar-wasm
.testcaferc.json (supported browsers).tests/src/ports.js.EM_ENGINE = $(EM_DOCKER)
EM_ENGINE = $(EM_PODMAN)
Makefile.$ make
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 and in the selected browser(s) on the host machine.Software: LGPL-2.1
Documentation: CC-BY-SA 4.0
FAQs
A WebAssembly build of the C/C++ ZBar barcode reader
We found that @undecaf/zbar-wasm demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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