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webcamContentCheck: check that webcam videos are changing by computing

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a hash of their entire contents, rather than checking a single pixel
This commit is contained in:
Brent Baccala 2022-05-23 21:30:30 +00:00
parent 7d6fe7b03c
commit 776fd9f024
1 changed files with 32 additions and 7 deletions
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39
bigbluebutton-tests/playwright/webcam/util.js
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@ -2,6 +2,10 @@ const e = require('../core/elements');
const { sleep } = require('../core/helpers');
const { LOOP_INTERVAL, ELEMENT_WAIT_LONGER_TIME } = require('../core/constants');
// loop 5 times, every LOOP_INTERVAL milliseconds, and check that all
// videos displayed are changing by comparing a hash of their
// displayed contents
async function webcamContentCheck(test) {
await test.waitForSelector(e.webcamVideoItem);
await test.wasRemoved(e.webcamConnecting, ELEMENT_WAIT_LONGER_TIME);
@ -11,23 +15,44 @@ async function webcamContentCheck(test) {
console.log(`loop ${i}`);
const checkCameras = () => {
const videos = document.querySelectorAll('video');
const lastVideoColor = document.lastVideoColor || {};
document.lastVideoColor = lastVideoColor;
const lastVideoHash = document.lastVideoHash || {};
document.lastVideoHash = lastVideoHash;
// If this code was running in the playwright test harness, we
// could just require('sha1'), but it's running in the test
// browser via test.page.evaluate, and I'm not sure how to get a
// node module (like sha1) into the test browser. So I just
// found a nice hash function on the Internet. -bwb
// public domain code from https://stackoverflow.com/a/52171480/1493790
// and/or https://github.com/bryc/code/blob/master/jshash/experimental/cyrb53.js
const cyrb53 = function(array, seed = 0) {
let h1 = 0xdeadbeef ^ seed, h2 = 0x41c6ce57 ^ seed;
for (let i = 0, ch; i < array.length; i++) {
ch = array[i];
h1 = Math.imul(h1 ^ ch, 2654435761);
h2 = Math.imul(h2 ^ ch, 1597334677);
}
h1 = Math.imul(h1 ^ (h1>>>16), 2246822507) ^ Math.imul(h2 ^ (h2>>>13), 3266489909);
h2 = Math.imul(h2 ^ (h2>>>16), 2246822507) ^ Math.imul(h1 ^ (h1>>>13), 3266489909);
return 4294967296 * (2097151 & h2) + (h1>>>0);
};
for (let v = 0; v < videos.length; v++) {
const video = videos[v];
const canvas = document.createElement('canvas');
const context = canvas.getContext('2d');
context.drawImage(video, 0, 0, video.videoWidth, video.videoHeight);
const pixel = context.getImageData(0, 0, 1, 1).data;
const pixelString = new Array(pixel).join(' ').toString();
const pixel = context.getImageData(0, 0, video.videoWidth, video.videoHeight).data;
const pixelHash = cyrb53(pixel);
if (lastVideoColor[v]) {
if (lastVideoColor[v] == pixelString) {
if (lastVideoHash[v]) {
if (lastVideoHash[v] == pixelHash) {
return false;
}
}
lastVideoColor[v] = pixelString;
lastVideoHash[v] = pixelHash;
}
return true;
};