btcpayserver/BTCPayServer/Views/Shared/CameraScanner.cshtml

@inject BTCPayServer.Security.ContentSecurityPolicies csp
@{
    csp.Add("worker-src", "blob:");
}

<template id="camera-qr-scanner-wrap">
	<div v-if="modalId" :id="modalId" class="modal fade" data-bs-backdrop="static">
		<div class="modal-dialog" role="document">
			<div class="modal-content">
				<div class="modal-header">
                    <h5 class="modal-title">
                        {{title}}
                    </h5>
                    <button type="button" class="btn-close" aria-label="Close" v-on:click="close">
                        <vc:icon symbol="close"/>
                    </button>
				</div>
				<div class="modal-body">
					<slot/>
				</div>
			</div>
		</div>
	</div>
	<div v-else>
		<slot></slot>
	</div>
</template>

<div id="camera-qr-scanner-modal-app" v-cloak class="only-for-js">
    <scanner-wrap v-bind="$data" v-on:close="close">
        <div class="d-flex justify-content-center align-items-center" :class="{'border border-secondary': !isModal}">
            <div class="spinner-border text-secondary position-absolute" role="status"></div>
            <qrcode-drop-zone v-on:decode="onDecode" v-on:init="logErrors">
                <qrcode-stream v-on:decode="onDecode" v-on:init="onInit" :camera="cameraOff? 'off': cameras[camera]" :device-id="cameras[camera]" :track="paint"/>
            </qrcode-drop-zone>
            <qrcode-capture v-if="noStreamApiSupport" v-on:decode="onDecode" :camera="cameraOff? 'off': cameras[camera]" :device-id="cameras[camera]"/>
        </div>
        <div v-if="isLoaded">
            <div v-if="errorMessage" class="alert alert-danger mt-3" role="alert">
                {{errorMessage}}
            </div>
            <div v-if="successMessage" class="alert alert-success mt-3" role="alert">
                {{successMessage}}
            </div>
            <div v-else-if="qrData" class="alert alert-info font-monospace text-truncate mt-3">
                {{qrData}}
            </div>
            <div v-else-if="decoder">
                <div class="my-3">BC UR: {{decoder.expectedPartCount()}} parts, {{decoder.getProgress() * 100}}% completed</div>
                <div class="progress">
                    <div class="progress-bar progress-bar-striped progress-bar-animated" role="progressbar" :style="{width: `${decoder.getProgress() * 100}%`}" id="progressbar"></div>
                </div>
            </div>
            <div class="mt-3 text-center">
                <button type="button" class="btn btn-primary me-1" v-if="qrData" v-on:click="submitData">Submit</button>
                <button type="button" class="btn btn-secondary me-1" v-if="qrData" v-on:click="retry">Retry</button>
                <button type="button" class="btn btn-secondary" v-if="requestInput && cameras.length > 2" v-on:click="nextCamera">Switch camera</button>
            </div>
        </div>
    </scanner-wrap>
</div>

<script>
function initCameraScanningApp(title, onDataSubmit, modalId, submitOnScan = false) {
	const isModal = !!modalId;

	Vue.component('scanner-wrap', {
		props: ["modalId", "title", "decoder"],
		template: "#camera-qr-scanner-wrap",
		methods: {
			close() {
				this.$emit('close');
			}
		}
  	});

    const app = new Vue({
		el: '#camera-qr-scanner-modal-app',
		data() {
			return {
				isModal,
				isLoaded: !isModal,
				title: title,
				modalId: modalId,
				noStreamApiSupport: false,
				qrData: null,
				decoder: null,
				errorMessage: null,
				successMessage: null,
				camera: 0,
				cameraOff: true,
				cameras: ["auto"],
				submitOnScan
			}
		},
		mounted() {
			if (this.isModal) {
				const modal = document.getElementById(this.modalId);
				modal.addEventListener('shown.bs.modal', () => { this.isLoaded = true; this.cameraOff = false; });
				modal.addEventListener('hide.bs.modal', () => { this.isLoaded = false; this.cameraOff = true; });
			} else {
				this.isLoaded = true;
				this.cameraOff = false;
			}
		},
		computed: {
			requestInput() {
				return !this.cameraOff && !this.errorMessage && !this.successMessage && !this.qrData;
			}
		},
		methods: {
		    nextCamera() {
		        if (this.camera === 0){
		            this.camera++;
		        } else if (this.camera === this.cameras.length - 1) {
		            this.camera = 0;
		        } else {
		            this.camera++;
		        }
		    },
			setQrData(qrData) {
				this.qrData = qrData;
				this.cameraOff = !!qrData;
                
                if (this.qrData && this.submitOnScan) {
                    this.submitData();
                }
			},
			retry() {
				this.cameraOff = true;
				this.$nextTick(this.reset);
			},
			reset() {
				this.setQrData(null);
                this.successMessage = null;
				this.errorMessage = null;
                this.decoder = null;
			},
			close() {
				if (this.modalId) {
					const modal = bootstrap.Modal.getInstance(document.getElementById(this.modalId));
					modal.hide();
				}
				this.reset();
			},
			onDecode(content) {
				if (this.qrData) return;
                const isUR = content.toLowerCase().startsWith("ur:");
                console.debug(1, content);
                
                try {
                    if (!isUR) {
                        this.setQrData(content);
                    } else {
                        this.decoder = this.decoder || new window.URlib.URRegistryDecoder();
                        if (this.decoder.receivePart(content)) {
                            if (this.decoder.isComplete()) {
                                if (this.decoder.isSuccess()) {
                                    const ur = this.decoder.resultUR();
                                    this.setQrData(ur);
                                    this.successMessage = `UR ${ur.type} decoded`;
                                } else if (this.decoder.isError()) {
                                    this.errorMessage = this.decoder.resultError();
                                }
                            }
                        }
				    }
                } catch (error) {
                    console.error(error);
                    this.errorMessage = error.message;
                }
			},
			submitData() {
                if (onDataSubmit) {
                    onDataSubmit(this.qrData);
                }
                this.close();
            },
			logErrors(promise) {
				promise.catch(console.error)
			},
			paint(detectedCodes, ctx) {
				for (const detectedCode of detectedCodes) {
                    const [ firstPoint, ...otherPoints ] = detectedCode.cornerPoints
                    ctx.strokeStyle = "#51b13e";
                    ctx.beginPath();
                    ctx.moveTo(firstPoint.x, firstPoint.y);
                    for (const { x, y } of otherPoints) {
                      ctx.lineTo(x, y);
                    }
                    ctx.lineTo(firstPoint.x, firstPoint.y);
                    ctx.closePath();
                    ctx.stroke();
                }
			},
			onInit(promise) {
				promise.then(() => {
					if (app.cameras.length === 1) {
                        navigator.mediaDevices.enumerateDevices().then(devices => {
                            for (const device of devices) {
                                if (device.kind === "videoinput"){
                                   app.cameras.push( device.deviceId)
                                }
                            }
                        });
                    }					 
				}).catch(error => {
					if (error.name === 'StreamApiNotSupportedError') {
						this.noStreamApiSupport = true;
					} else if (error.name === 'NotAllowedError') {
						this.errorMessage = 'A permission to the camera is needed to scan the QR code. Please grant the browser access and then retry.'
					} else if (error.name === 'NotFoundError') {
						this.errorMessage = 'A camera was not detected on your device.'
					} else if (error.name === 'NotSupportedError') {
						this.errorMessage = 'This page is served in non-secure context (HTTPS, localhost or file://)'
					} else if (error.name === 'NotReadableError') {
						this.errorMessage = 'Couldn\'t access your camera. Is it already in use?'
					} else if (error.name === 'OverconstrainedError') {
						this.errorMessage = 'Constraints don\'t match any installed camera.'
					} else {
						this.errorMessage = 'UNKNOWN ERROR: ' + error.message
					}
				})
			}
		}
	});
}
</script>