From 947bfb7a118f3743e50fa2dd3c83e75d38c9207a Mon Sep 17 00:00:00 2001
From: David Walsh <davidwalsh83@gmail.com>
Date: Wed, 14 Oct 2020 16:48:09 -0500
Subject: [PATCH] Fix #9043 - Ensure QR code scanner works

---
 .../modals/qr-scanner/qr-scanner.component.js | 21 +++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/ui/app/components/app/modals/qr-scanner/qr-scanner.component.js b/ui/app/components/app/modals/qr-scanner/qr-scanner.component.js
index d78db3d14..330bd3fa4 100644
--- a/ui/app/components/app/modals/qr-scanner/qr-scanner.component.js
+++ b/ui/app/components/app/modals/qr-scanner/qr-scanner.component.js
@@ -104,15 +104,28 @@ export default class QrScanner extends Component {
   componentWillUnmount () {
     this.mounted = false
     clearTimeout(this.permissionChecker)
-    if (this.codeReader) {
-      this.codeReader.reset()
+    this.teardownCodeReader();
+  }
+
+  teardownCodeReader() {
+    if(this.codeReader) {
+      this.codeReader.reset();
+      this.codeReader.stop();
+      this.codeReader = null;
     }
   }
 
   initCamera = async () => {
+    // The `decodeFromInputVideoDevice` call prompts the browser to show
+    // the user the camera permission request.  We must then call it again
+    // once we receive permission so that the video displays.
+    // Removing this teardown will create 2 video streams in Firefox, one
+    // of which the user will not be able to remove without refreshing the page.
+    this.teardownCodeReader();
     this.codeReader = new BrowserQRCodeReader()
     try {
       await this.codeReader.getVideoInputDevices()
+      this.checkPermissions();
       const content = await this.codeReader.decodeFromInputVideoDevice(undefined, 'video')
       const result = this.parseContent(content.text)
       if (!this.mounted) {
@@ -162,7 +175,7 @@ export default class QrScanner extends Component {
 
   stopAndClose = () => {
     if (this.codeReader) {
-      this.codeReader.reset()
+      this.teardownCodeReader();
     }
     this.props.hideModal()
   }
@@ -170,7 +183,7 @@ export default class QrScanner extends Component {
   tryAgain = () => {
     clearTimeout(this.permissionChecker)
     if (this.codeReader) {
-      this.codeReader.reset()
+      this.teardownCodeReader()
     }
     this.setState(this.getInitialState(), () => {
       this.checkEnvironment()