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Xiao Ling
Xiao Ling

Posted on • Edited on • Originally published at dynamsoft.com

How to Build Angular Barcode and QR Code Scanner Apps from Scratch

#angular #webdev #qrcode #typescript

Dynamsoft JavaScript barcode SDK is compatible with all mainstream web frameworks and web browsers. This article goes through the steps to build Angular barcode and QR code scanner apps with Dynamsoft JavaScript barcode SDK.

Development Environment

  • Node.js

  • Angular CLI v13.3.7

    npm install -g @angular/cli

ng --version

Angular CLI: 13.3.7
Node: 16.13.1
Package Manager: npm 8.1.2
OS: win32 x64

Angular: 13.3.10
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1303.7
@angular-devkit/build-angular   13.3.7
@angular-devkit/core            13.3.7
@angular-devkit/schematics      13.3.7
@angular/cli                    13.3.7
@schematics/angular             13.3.7
ng-packagr                      13.3.1
rxjs                            7.5.5
typescript                      4.6.4

  • Dynamsoft JavaScript Barcode SDK v9.0.2

To get started right away, you can visit the online project built on StackBlitz, which is a good place for editing and testing Angular code in the browser.

Steps to Create Angular App for Scanning Barcode and QR Code

Dynamsoft JavaScript barcode SDK provides two primary classes: BarcodeReader and BarcodeScanner. The BarcodeReader class supports reading barcode and QR code from static images, and the BarcodeScanner class supports scanning barcode and QR code from live video feeds. So in our Angular app, we will create two pages to demonstrate their functionalities respectively.

Scaffold and configure Angular project

We create a new Angular project named angular-barcode-qr-code-scanner in terminal:

ng new angular-barcode-qr-code-scanner
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Then install Dynamsoft JavaScript barcode SDK via npm command:

npm i dynamsoft-javascript-barcode
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Some resource (*.js, *.wasm) files must be copied to the assets folder in order to make the JS barcode SDK work. Let's open the angular.json file to add the configuration.


"build": 
{
  "builder": "@angular-devkit/build-angular:browser",
  "options": {
    ...
    "assets": [
      "src/favicon.ico",
      "src/assets",
      {
        "glob": "**/*",
        "input": "./node_modules/dynamsoft-javascript-barcode/dist",
        "output": "assets/dynamsoft-javascript-barcode"
      }
    ...
    ],
  },
  ...
},

"test": 
{
  "builder": "@angular-devkit/build-angular:karma",
  "options": {
    ...
    "assets": [
      "src/favicon.ico",
      "src/assets",
      {
        "glob": "**/*",
        "input": "./node_modules/dynamsoft-javascript-barcode/dist",
        "output": "assets/dynamsoft-javascript-barcode"
      }
    ],
    ...
  }
}
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In addition, the resource path has to be specified in TypeScript code. We create a products.ts file to set the license key and the resource path globally.

import { BarcodeReader } from 'dynamsoft-javascript-barcode';

BarcodeReader.license =
  'DLS2eyJoYW5kc2hha2VDb2RlIjoiMjAwMDAxLTE2NDk4Mjk3OTI2MzUiLCJvcmdhbml6YXRpb25JRCI6IjIwMDAwMSIsInNlc3Npb25QYXNzd29yZCI6IndTcGR6Vm05WDJrcEQ5YUoifQ==';

BarcodeReader.engineResourcePath = 'assets/dynamsoft-javascript-barcode/';

export interface Product {
  id: string;
  name: string;
  description: string;
}

export const products = [
  {
    id: 'reader',
    name: 'Barcode and QR Code Reader',
    description: 'Scan barcode and QR code from image files',
  },
  {
    id: 'scanner',
    name: 'Barcode and QR Code Scanner',
    description: 'Scan barcode and QR code from camera stream',
  },
];
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The products array will be used to create Angular components later.

List components and add navigation

In this section, we will create the homepage that contains a top bar and a component list.

Top bar

  1. Create a top-bar component:

    ng generate component top-bar

  2. Add the top-bar component to the app.component.html file.

    <app-top-bar></app-top-bar>
<div class="container">
  <router-outlet></router-outlet>
</div>

  3. Add the router link to the <H1> title in the top-bar.component.html.

    <a [routerLink]="['/']">
    <h1>Dynamsoft Barcode Reader and Scanner</h1>
  </a>

Product list

  1. Create a product-list component:

    ng generate component product-list

  2. Import pre-defined products to the product-list.components.ts file.

    import { Component } from '@angular/core';

import { products } from '../products';

@Component({
  selector: 'app-product-list',
  templateUrl: './product-list.component.html',
  styleUrls: ['./product-list.component.css'],
})
export class ProductListComponent {
  products = products;
}

  3. Dynamically create the product list with *ngFor and *ngIf in the product-list.component.html.

    
<h2>Examples</h2>
<div *ngFor="let product of products">
  <h3>
    <div *ngIf="product.id === 'reader'; else elseBlock">
      <a [title]="product.name + ' details'" [routerLink]="['/barcode-reader']"
        >>
        {{ product.name }}
      </a>
    </div>
    <ng-template #elseBlock
      ><a
        [title]="product.name + ' details'"
        [routerLink]="['/barcode-scanner']"
        >>
        {{ product.name }}
      </a></ng-template
    >
  </h3>

  <p *ngIf="product.description">Description: {{ product.description }}</p>
</div>

  4. Open the app-routing.module.ts file to configure the routes.

    import { ProductListComponent } from './product-list/product-list.component';
import { BarcodeReaderComponent } from './barcode-reader/barcode-reader.component';
import { BarcodeScannerComponent } from './barcode-scanner/barcode-scanner.component';

const routes: Routes = [
  { path: '', component: ProductListComponent },
      { path: 'barcode-reader', component: BarcodeReaderComponent },
      { path: 'barcode-scanner', component: BarcodeScannerComponent },
];

    Angular top bar component

    The ProductListComponent is configured as the homepage. We will create the BarcodeReaderComponent and BarcodeScannerComponent in the following paragraphs.

Create the Barcode Reader component

  1. Create the barcode-reader component.

    ng generate component barcode-reader

  2. Add HTMLInputElement, HTMLCanvasElement, and HTMLImageElement to the barcode-reader.component.html file.

    <span id="loading-status" style="font-size:x-large" [hidden]="isLoaded"
  >Loading Library...</span
>
<br />

<input type="file" id="file" accept="image/*" (change)="onChange($event)" />
<div>
  <a id="result"></a>
</div>

<div id="imageview">
  <img id="image" />
  <canvas id="overlay"></canvas>
</div>

    The change event is bound to the onChange method, which is defined in the barcode-reader.component.ts file.

  3. Initialize the BarcodeReader object in the barcode-reader.component.ts file.

    import { Component, OnInit } from '@angular/core';
import { BarcodeReader } from 'dynamsoft-javascript-barcode';

@Component({
  selector: 'app-barcode-reader',
  templateUrl: './barcode-reader.component.html',
  styleUrls: ['./barcode-reader.component.css'],
})
export class BarcodeReaderComponent implements OnInit {
  isLoaded = false;
  overlay: HTMLCanvasElement | undefined;
  context: CanvasRenderingContext2D | undefined;
  reader: BarcodeReader | undefined;

  constructor() {}

  ngOnInit(): void {
    this.initOverlay();
    (async () => {
      this.reader = await BarcodeReader.createInstance();
      this.isLoaded = true;
    })();
  }
}

  4. In the onChange method, we firstly load an image file with FileReader and then draw barcode and QR code results on the canvas which is above the image. The size of the canvas is determined by the image size.

    onChange(event: Event) {
    const element = event.currentTarget as HTMLInputElement;
    let fileList: FileList | null = element.files;
    if (fileList) {
      let file = fileList.item(0) as any;
      if (file) {
        let fr = new FileReader();
        fr.onload = (event: any) => {
          let image = document.getElementById('image') as HTMLImageElement;
          if (image) {
            image.src = event.target.result;
            const img = new Image();

            img.onload = (event: any) => {
              this.updateOverlay(img.width, img.height);
              if (this.reader) {
                this.reader.decode(file).then((results: any) => {
                  console.log(results);
                  let txts: any = [];
                  let elem = document.getElementById('result');
                  try {
                    let localization;
                    if (results.length > 0) {
                      for (var i = 0; i < results.length; ++i) {
                        txts.push(results[i].barcodeText);
                        localization = results[i].localizationResult;
                        this.drawOverlay(
                          localization,
                          results[i].barcodeText
                        );
                      }

                      if (elem) {
                        elem.innerHTML = txts.join(', ');
                      }
                    } else {
                      if (elem) {
                        elem.innerHTML = txts.join(', ');
                      }
                    }
                  } catch (e) {
                    alert(e);
                  }
                });
              }
            };
            img.src = event.target.result;
          }
        };
        fr.readAsDataURL(file);
      }
    }
  }

    Angular barcode and QR code reader

Create the Barcode Scanner component

  1. Create the barcode-scanner component:

    ng generate component barcode-scanner

  2. Add HTMLSelectElement and HTMLCanvasElement to the barcode-scanner.component.html file. Dynamsoft barcode scanner has encapsulated the video element. It simplifies the process of writing JavaScript code for camera control.

    <span id="loading-status" style="font-size:x-large" [hidden]="isLoaded"
  >Loading Library...</span
>
<br />

<div class="select">
  <label for="videoSource">Video source: </label>
  <select id="videoSource" (change)="openCamera()"></select>
</div>

<div id="videoview">
  <div class="dce-video-container" id="videoContainer"></div>
  <canvas id="overlay"></canvas>
</div>

  3. Initialize the BarcodeScanner object in the barcode-scanner.component.ts file.

    import { Component, OnInit } from '@angular/core';
import { BarcodeScanner } from 'dynamsoft-javascript-barcode';

@Component({
  selector: 'app-barcode-scanner',
  templateUrl: './barcode-scanner.component.html',
  styleUrls: ['./barcode-scanner.component.css'],
})
export class BarcodeScannerComponent implements OnInit {
  isLoaded = false;
  overlay: HTMLCanvasElement | undefined;
  context: CanvasRenderingContext2D | undefined;
  scanner: BarcodeScanner | undefined;
  cameraInfo: any = {};
  videoSelect: HTMLSelectElement | undefined;

  constructor() { }

  ngOnInit(): void {
    this.videoSelect = document.querySelector('select#videoSource') as HTMLSelectElement;
    this.initOverlay();
    (async () => {
      await this.initBarcodeScanner();
    })();
  }

    async initBarcodeScanner(): Promise<void> {
        this.scanner = await BarcodeScanner.createInstance();
        this.isLoaded = true;
        await this.scanner.updateRuntimeSettings("speed");
        let uiElement = document.getElementById('videoContainer');
        if (uiElement) {
          await this.scanner.setUIElement(uiElement);
          let cameras = await this.scanner.getAllCameras();
          this.listCameras(cameras);
          await this.openCamera();
          this.scanner.onFrameRead = results => {
            this.clearOverlay();

            let txts = [];
            let resultElement = document.getElementById('result');
            try {
              let localization;
              if (results.length > 0) {
                for (var i = 0; i < results.length; ++i) {
                  txts.push(results[i].barcodeText);
                  localization = results[i].localizationResult;
                  this.drawOverlay(localization, results[i].barcodeText);
                }
                if (resultElement) {
                  resultElement.innerHTML = txts.join(', ');
                }
              }
              else {
                if (resultElement) {
                  resultElement.innerHTML = "No barcode found";
                }
              }

            } catch (e) {
              alert(e);
            }
          };
          this.scanner.onPlayed = () => {
            this.updateResolution();
          }
          await this.scanner.show();
        }
      }

    We can get the barcode and QR code results by registering the onFrameRead event. The onFrameRead event is triggered when the barcode and QR code results are ready.

    Angular barcode and QR code scanner

Run the Angular project with SSL

Web camera access requires HTTPS protocol. Therefore, we use the ng serve --ssl command to run the Angular project. Without ssl, the NotAllowedError: Permission denied error is thrown:

Angular camera permission error

GitHub Page Deployment

After pushing the source code to GitHub, we can deploy the Angular project to GitHub pages with GitHub actions.

Here are the steps:

  1. Create a custom workflow file including Angular Deploy gh-pages Actions:

    name: Build and Deploy
on:
  push:
    branches:
      - main
jobs:
  build:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2
    - name: All things angular
      uses: AhsanAyaz/angular-deploy-gh-pages-actions@v1.3.2
      with:
        github_access_token: ${{ secrets.GITHUB_TOKEN }} 
        build_configuration: production 
        base_href: /angular-barcode-qr-code-scanner/   
        deploy_branch: gh-pages 
        angular_dist_build_folder: dist/angular-barcode-qr-code-scanner

    You need to replace angular-barcode-qr-code-scanner with your project name.

  2. Go to Your GitHub repository > Settings > Pages to launch the GtiHub page with the gh-pages branch. The sample project page is available at https://yushulx.me/angular-barcode-mrz-document-scanner/.

Source Code

https://github.com/yushulx/angular-barcode-mrz-document-scanner

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