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?
You just need to toggle the ion-app display between "none" and "block" if the status is authorized.
const ionApp = <HTMLElement>document.getElementsByTagName("ion-app")[0];
// start scanning
const scanSub = this.qrScanner.scan().subscribe((link: string) => {
ionApp.style.display = "block";
this.qrScanner.hide(); // hide camera preview
scanSub.unsubscribe(); // stop scanning
});
ionApp.style.display = "none";
this.qrScanner.show();
After some research even i found the answer and surely this works fantastic for all ,but @nokeieng answer helped me too..
1) First, make a new component for qrscanner
. In ionic
there is a lifecycle in ionic so go according to that after entering the component this event trigger ionViewDidEnter()
.In this event the camera opens and let you scan.
ionViewDidEnter(){
this.qrScanner.prepare()
.then((status: QRScannerStatus) => {
if (status.authorized) {
// camera permission was granted
var camtoast = this.toastCtrl.create({
message: 'camera permission granted',
duration: 1000
});
camtoast.present();
// start scanning
this.qrScanner.show()
window.document.querySelector('ion-app').classList.add('cameraView');
let scanSub = this.qrScanner.scan().subscribe((text: string) => {
console.log('Scanned something', text);
window.document.querySelector('ion-app').classList.remove('cameraView');
this.qrScanner.hide(); // hide camera preview
const toast = this.toastCtrl.create({
message: 'You scanned text is this :'+text,
duration: 6000
});
toast.present();
scanSub.unsubscribe(); // stop scanning
});
} else if (status.denied) {
const toast = this.toastCtrl.create({
message: 'camera permission was denied',
duration: 3000
});
toast.present();
// 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 {
const toast = this.toastCtrl.create({
message: 'You can ask for permission again at a later time.',
duration: 3000
});
toast.present();
// permission was denied, but not permanently. You can ask for permission again at a later time.
}
})
.catch((e: any) => console.log('Error is', e));
}
2) After this remove the camera
class when back button is pressed for that add this code.
ionViewWillLeave()
will triggers when component is destroyed or left.
ionViewWillLeave(){
window.document.querySelector('ion-app').classList.remove('cameraView');
}
3) We are done with .ts file. Now we have to make the component and the main element i.e ion-app
transparent so that we can see the camera for that we add this css inside theme/variables.scss
ion-app.cameraView ion-nav{opacity:0}
and
ion-app.cameraView,ion-app.cameraView ion-content,ion-app.cameraView .nav-decor,{
background: transparent url("../../assets/imgs/camera_overlay.png") !important;
background-size: 100% 100% !important;}
4) As you can see I have given a background image so that we get a camera overlay preview
and you are done with the code just run this command in terminal to see live changes in ionic
ionic cordova run android --livereload
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;">
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