Ionic cordova-plugin-qrscanner has no camera preview

Question

I run a simple demo to use cordova-plugin-qrscanner, it can scan qrcode but no camera preview.

qrscannerDemo on Github

Related code blow:

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';


import { AndroidPermissions } from '@ionic-native/android-permissions';
import { QRScanner, QRScannerStatus } from '@ionic-native/qr-scanner';

@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {

  constructor(public navCtrl: NavController,
              public androidPermissions: AndroidPermissions,
              public qrScanner: QRScanner) {

  }

  qrscanner() {

    // Optionally request the permission early
    this.qrScanner.prepare()
      .then((status: QRScannerStatus) => {
        if (status.authorized) {
          // camera permission was granted
          alert('authorized');

          // start scanning
          let scanSub = this.qrScanner.scan().subscribe((text: string) => {
            console.log('Scanned something', text);
            alert(text);
            this.qrScanner.hide(); // hide camera preview
            scanSub.unsubscribe(); // stop scanning
          });

          this.qrScanner.resumePreview();

          // show camera preview
          this.qrScanner.show();

          // wait for user to scan something, then the observable callback will be called

        } else if (status.denied) {
          alert('denied');
          // camera permission was permanently denied
          // you must use QRScanner.openSettings() method to guide the user to the settings page
          // then they can grant the permission from there
        } else {
          // permission was denied, but not permanently. You can ask for permission again at a later time.
          alert('else');
        }
      })
      .catch((e: any) => {
        alert('Error is' + e);
      });

  }

}

<ion-header>
  <ion-navbar transparent>
    <ion-title>
      Ionic Blank
    </ion-title>
  </ion-navbar>
</ion-header> 

 <ion-content padding style="background: none transparent;">
  <button ion-button (click)="qrscanner()">qrscanner</button>
</ion-content>  

I run the ionic project on android then click the button but nothing happened and no camera preview show.

I test the project again and find it can scan qrcode and get the result test, but no camera preview.

I search the problem, someone says should to set the body and any elements transparent. I try but does not work.

Android. Nothing appears on screen. #35

AnyOne help?

Answer 1

In top level index.html:

<ion-app style="background: none transparent;"></ion-app>

In camera display page html file:

<ion-content style="background: none transparent;">