How To Read QR Codes In Angular ? |

In a previous tutorial we covered how to generate QR Codes in Angular applications .In this tutorial we ae going to see how we can read them by building a simple Angular 4 demo application which you can find from the link .

Now lets get started by generating a new Angular application using the Angular CLI new command .

Open your terminal or command prompt ,depending on your operating system,then run :

ng new qrcode-reader

Next navigate inside the root directory of your project :

cd qrcode-reader

We'll be using An Angular component from npm for reading QR Codes so lets first install it .

npm install ng2-qrcode-reader --save

Head over to your project app/app.module.ts then import NgQRCodeReaderModule

import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { MaterialModule } from '@angular/material';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { FlexLayoutModule } from '@angular/flex-layout';

import { AppComponent } from './app.component';
import { NgQRCodeReaderModule } from 'ng2-qrcode-reader';

Then add it imports

@NgModule({
declarations: [
    AppComponent
],
imports: [
    BrowserModule,
    FormsModule,
    NgQRCodeReaderModule,
    MaterialModule,
    BrowserAnimationsModule,
    FlexLayoutModule,
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }

Now you can use ng2-qrcode-reader component to read QR Codes via URLs ,DATA URLs or Canvas .

Open app/app.component.ts then copy and paste :

import { Component , ElementRef ,ViewChild ,Renderer2} from '@angular/core';

@Component({
selector: 'app-root',
template: `
<div fxLayout="column" fxFlexAlign="center">
    <div  fxFlex="20" fxFill>
    <md-input-container fxFill><textarea fxFill mdInput placeholder="qrr-value (URL or DATA URL)" [(ngModel)]="value"></textarea></md-input-container>
    <br/>

    </div>
    <div  fxFlex="60" fxFill>
    <ng2-qrcode-reader (result)="render($event)" [qrr-show]="showQRCode" [qrr-value]="value" [qrr-type]="elementType"></ng2-qrcode-reader>
    </div>
    <p>Result</p>
    <div #result  fxFlex="20" fxFill>
    </div>
    </div>

`,
styles: []
})
export class AppComponent {
elementType = 'url';
value = 'https://assets.econsultancy.com/images/resized/0002/4236/qr_code-blog-third.png';
@ViewChild('result') resultElement: ElementRef;
showQRCode : boolean = true;
constructor(private renderer: Renderer2) { 

}   
render(e){
    console.log(e.result);
    let element :Element = this.renderer.createElement('p');
    element.innerHTML = e.result;
    this.renderElement(element);    
}

renderElement(element){
    for (let node of this.resultElement.nativeElement.childNodes) {
            this.renderer.removeChild(this.resultElement.nativeElement, node);
    }            
    this.renderer.appendChild(this.resultElement.nativeElement, element);
}  

}

So to get the result of our QR Code reading we need to bind a method to result custom component event .