feat: add barcode reader

src/app/types/globalThis.d.ts

@@ -0,0 +1,22 @@
+type ImageBitmapSource = HTMLImageElement | SVGImageElement | HTMLVideoElement | HTMLCanvasElement | ImageBitmap | OffscreenCanvas | VideoFrame | Blob | ImageData
+
+export type BarcodeDetectorOptions = {
+  formats: string[]
+}
+
+export type DetectedBarcode = {
+  boundingBox: DOMRectReadOnly;
+  cornerPoints: coords[];
+  format: string[];
+  rawValue: string;
+}
+
+declare global {
+  var BarcodeDetector: BarcodeDetector;
+}
+
+declare type BarcodeDetector =  {
+    new (formats?: {formats: string[]}): BarcodeDetector;
+    static getSupportedFormats(): Promise<string[]>;
+    detect(imageBitmapSource: ImageBitmapSource): Promise<DetectedBarcode[]>;
+}

src/app/web-components/barcode-reader.ts

@@ -0,0 +1,192 @@
+import type { BarcodeDetector, DetectedBarcode } from '../types/globalThis';
+
+export class BarcodeReader extends HTMLElement {
+  animationFrameId = null;
+  constraints = {
+    audio: false,
+    video: {
+      facingMode: 'environment',
+    },
+  };
+  container = document.createElement('div');
+  video = document.createElement('video');
+  dataCanvas = document.createElement('canvas');
+  dataCtx: CanvasRenderingContext2D | null | undefined;
+  detector: BarcodeDetector | null = null;
+  code: DetectedBarcode | null = null;
+  stream: MediaStream | null = null;
+  scanId = -1;
+  frame = document.createElement('div');
+
+  constructor() {
+    super();
+    const link = document.createElement('link');
+    link.rel = 'stylesheet';
+    link.href = '/barcode-reader/barcode-reader.css';
+    this.container.setAttribute('id', 'container');
+    const videoContainer = document.createElement('div');
+    videoContainer.setAttribute('id', 'video-container');
+    this.container.appendChild(videoContainer);
+
+    const overlay = document.createElement('div');
+    overlay.classList.add('overlay');
+    this.video.setAttribute('autoplay', '');
+    this.video.setAttribute('playsinline', '');
+    this.dataCanvas.setAttribute('id', 'data-canvas');
+
+    this.frame.setAttribute('id', 'frame');
+    this.frame.style.display = 'none';
+    for (let el of ['top-left', 'top-right', 'bottom-right', 'bottom-left']) {
+      const div = document.createElement('div');
+      div.classList.add('corner', el);
+      this.frame.appendChild(div);
+    }
+    videoContainer.appendChild(overlay);
+    videoContainer.appendChild(this.dataCanvas);
+    videoContainer.appendChild(this.video);
+    videoContainer.appendChild(this.frame);
+
+    const shadowRoot = this.attachShadow({ mode: 'open' });
+    shadowRoot.appendChild(link);
+    shadowRoot.appendChild(this.container);
+    this.capturing = false;
+
+    this.dataCtx = this.dataCanvas.getContext('2d', { willReadFrequently: true, alpha: false });
+  }
+
+  get capturing() {
+    return this.hasAttribute('capturing');
+  }
+
+  set capturing(isCapturing) {
+    if (isCapturing) {
+      this.setAttribute('capturing', '');
+    } else {
+      this.removeAttribute('capturing');
+    }
+  }
+
+  async connectedCallback() {
+    this.detector = await this.getDetector();
+    this.video.onplaying = async () => {
+      if (this.dataCanvas) {
+        this.dataCanvas.width = this.dataCanvas.offsetWidth;
+        this.dataCanvas.height = this.dataCanvas.offsetHeight;
+        this.getResults();
+      }
+    };
+  }
+
+  async getDetector(): Promise<BarcodeDetector | null> {
+    if (globalThis.BarcodeDetector) {
+      const formats = await BarcodeDetector.getSupportedFormats();
+      return new BarcodeDetector({ formats });
+    }
+    return null;
+  }
+
+  async scan() {
+    this.showContainer(true);
+
+    try {
+      this.capturing = true;
+      this.code = null;
+
+      if (this.stream instanceof MediaStream) {
+        await this.getResults();
+      } else {
+        this.dispatchEvent(new CustomEvent('scan-status', { detail: { state: 'loading' } }));
+        this.stream = await navigator.mediaDevices.getUserMedia(this.constraints);
+        this.startVideo();
+        this.showFrame();
+        this.dispatchEvent(new CustomEvent('scan-status', { detail: { state: 'started' } }));
+        this.dispatchEvent(new CustomEvent('scan-start'));
+      }
+    } catch (e) {
+      console.log(e);
+      this.showContainer(false);
+      this.dispatchEvent(new CustomEvent('scan-status', { detail: { state: 'stopped' } }));
+      this.dispatchEvent(new CustomEvent('scan-permission-denied'));
+      this.capturing = false;
+    }
+  }
+
+  stopScan() {
+    clearTimeout(this.scanId);
+    if (this.stream) {
+      this.capturing = false;
+      this.stream.getTracks().forEach((track) => track.stop());
+      this.stream = null;
+      this.video.srcObject = null;
+      this.dispatchEvent(new CustomEvent('scan-stop'));
+      this.dispatchEvent(new CustomEvent('scan-status', { detail: { state: 'stopped' } }));
+      this.hideFrame();
+      this.showContainer(false);
+    }
+  }
+
+  startVideo() {
+    if (this.video) this.video.srcObject = this.stream;
+  }
+
+  parseResults(results: DetectedBarcode[]) {
+    const code = results.length > 0 ? results[0] : undefined;
+    if (code && code.rawValue !== '') {
+      clearTimeout(this.scanId);
+      this.code = code;
+      this.capturing = false;
+
+      setTimeout(() => {
+        this.dispatchEvent(
+          new CustomEvent('result', {
+            detail: { code },
+          })
+        );
+        this.stopScan();
+      }, 300);
+    } else {
+      this.scanId = setTimeout(this.getResults.bind(this), 300);
+    }
+  }
+
+  async getResults() {
+    if (this.code) {
+      clearTimeout(this.scanId);
+      return false;
+    }
+
+    try {
+      if (this.video && this.detector) {
+        let imgData: ImageData | null = this.getImageData(this.video);
+        if (imgData) {
+          const results = await this.detector.detect(imgData);
+          imgData = null;
+          this.parseResults(results);
+        }
+      }
+    } catch (e) {
+      console.log('error', e);
+    }
+    return undefined;
+  }
+
+  getImageData(source: HTMLVideoElement) {
+    if (this.dataCtx) {
+      this.dataCtx.drawImage(source, 0, 0, this.dataCanvas.width, this.dataCanvas.height);
+      return this.dataCtx.getImageData(0, 0, this.dataCanvas.width, this.dataCanvas.height);
+    }
+    return null;
+  }
+
+  showContainer(show: boolean) {
+    this.container.style.display = show ? 'block' : 'none';
+  }
+
+  showFrame() {
+    this.frame.style.display = 'block';
+  }
+
+  hideFrame() {
+    this.frame.style.display = 'none';
+  }
+}

src/main.ts

@@ -1,6 +1,8 @@
 import { bootstrapApplication } from '@angular/platform-browser';
 import { appConfig } from './app/app.config';
 import { App } from './app/app';
+import { BarcodeReader } from './app/web-components/barcode-reader';
 
 bootstrapApplication(App, appConfig)
+  .then(() => customElements.define('barcode-reader', BarcodeReader))
   .catch((err) => console.error(err));