From 3c5c82f9799503890cbe5b937c2a0eee21723acb Mon Sep 17 00:00:00 2001
From: Christoph Reiter <reiter.christoph@gmail.com>
Date: Tue, 20 Oct 2020 16:14:30 +0200
Subject: [PATCH] Properly cancel all queued callbacks when stopping
---
packages/qr-code-scanner/src/qr-code-scanner.js | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/packages/qr-code-scanner/src/qr-code-scanner.js b/packages/qr-code-scanner/src/qr-code-scanner.js
index 642fef71..e9d814f2 100644
--- a/packages/qr-code-scanner/src/qr-code-scanner.js
+++ b/packages/qr-code-scanner/src/qr-code-scanner.js
@@ -86,6 +86,7 @@ export class QrCodeScanner extends ScopedElementsMixin(DBPLitElement) {
this.clipMask = false;
this._devices = new Map();
+ this._frameRequestID = null;
}
static get scopedElements() {
@@ -192,13 +193,15 @@ export class QrCodeScanner extends ScopedElementsMixin(DBPLitElement) {
video.play();
that.videoRunning = true;
qrContainer.scrollIntoView({ behavior: 'smooth', block: 'start' });
- requestAnimationFrame(tick);
+ that._frameRequestID = requestAnimationFrame(tick);
}).catch((e) => { console.log(e); that.askPermission = true;});
let lastVideoTime = -1;
let lastCode = null;
function tick() {
+ that._frameRequestID = null;
+
if (that.sourceChanged) {
video.srcObject.getTracks().forEach(function(track) {
track.stop();
@@ -340,7 +343,7 @@ export class QrCodeScanner extends ScopedElementsMixin(DBPLitElement) {
qrContainer.scrollIntoView({ behavior: 'smooth', block: 'start' });
scroll = true;
}
- requestAnimationFrame(tick);
+ that._frameRequestID = requestAnimationFrame(tick);
}
}
@@ -359,6 +362,11 @@ export class QrCodeScanner extends ScopedElementsMixin(DBPLitElement) {
*
*/
stopScanning() {
+ if (this._frameRequestID !== null) {
+ cancelAnimationFrame(this._frameRequestID);
+ this._frameRequestID = null;
+ }
+
this.askPermission = false;
this.videoRunning = false;
}
--
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