Merge branch 'master' of github.com:nimiq-ux/qr-scanner

README.md

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+# qr-scanner
+
+Javascript QR Code Scanner based on [Lazar Lazslos javascript port](https://github.com/LazarSoft/jsqrcode) of [Googles ZXing library](https://github.com/zxing/zxing).
+
+In this library, several improvements have been applied over the original port:
+
+- This library uses an improved binarizer for transforming color input images into black and white images in the preprocessing step 
+which makes it more tolerant to shades and reflections on the screen.
+
+- The qr scanner can be configured for better performance on colored QR codes.
+
+- The scanner runs in a WebWorker which keeps the main / UI thread responsive.
+
+- The library was changed to be compatible with Googles closure compiler and compiled to just ~33.7 kb of javascript (~12 kb gzipped).
+
+- Work on higher resolution pictures by default.
+
+
+## Usage
+
+You can either use the ready to use UI (index.html + qr-scanner.js + qr-scanner-wroker.min.js, based on the lightweight [X-Element frontend framework](https://github.com/nimiq/x-element))
+or use just the qr-scanner-wroker.min.js Webworker as follows:
+
+Create a new Worker:
+```js
+const qrWorker = new Worker('/path/to/qr-scanner-worker.min.js');
+```
+
+Send [ImageData](https://developer.mozilla.org/en-US/docs/Web/API/ImageData) to the worker:
+```js
+qrWorker.postMessage({
+    type: 'decode',
+    data: imageData
+}, [imageData.data.buffer]);
+```
+
+Handle the result from the qr worker:
+```js
+qrWorker.addEventListener('message', event => {
+  const type = event.data.type;
+  const data = event.data.data;
+  if (type === 'qrResult') {
+      if (data !== null) {
+          alert(data);
+      }
+  }
+});
+```
+
+To enable debug mode:
+```js
+qrWorker.postMessage({
+    type: 'setDebug',
+    data: true
+});
+```
+
+To handle the debug image:
+```js
+qrWorker.addEventListener('message', event => {
+  const type = event.data.type;
+  const data = event.data.data;
+  if (type === 'debugImage') {
+      canvasContext.putImageData(data, 0, 0);
+  }
+});
+```
+
+## Building the project
+The project is prebuild in qr-scanner-worker.min.js. Building yourself is only neccessary if you wanna change the code in
+the /src folder. Nodejs and Java are required prequesites for building.
+
+Install required build packages:
+```batch
+npm install
+```
+
+Building:
+```batch
+gulp build
+```