jiti-meet/react/features/screenshot-capture/ScreenshotCaptureSummary.js

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// @flow
import resemble from 'resemblejs';
import 'image-capture';
import './createImageBitmap';
import { createScreensharingCaptureTakenEvent, sendAnalytics } from '../analytics';
import { getCurrentConference } from '../base/conference';
import { getRemoteParticipants } from '../base/participants';
import { extractFqnFromPath } from '../dynamic-branding';
import {
CLEAR_INTERVAL,
INTERVAL_TIMEOUT,
PERCENTAGE_LOWER_BOUND,
POLL_INTERVAL,
SET_INTERVAL
} from './constants';
import { getParticipantJid } from './functions';
import { processScreenshot } from './processScreenshot';
import { timerWorkerScript } from './worker';
declare var interfaceConfig: Object;
declare var ImageCapture: any;
/**
* Effect that wraps {@code MediaStream} adding periodic screenshot captures.
* Manipulates the original desktop stream and performs custom processing operations, if implemented.
*/
export default class ScreenshotCaptureSummary {
_state: Object;
_currentCanvas: HTMLCanvasElement;
_currentCanvasContext: CanvasRenderingContext2D;
_handleWorkerAction: Function;
_initScreenshotCapture: Function;
_imageCapture: any;
_streamWorker: Worker;
_streamHeight: any;
_streamWidth: any;
_storedImageData: ImageData;
/**
* Initializes a new {@code ScreenshotCaptureEffect} instance.
*
* @param {Object} state - The redux state.
*/
constructor(state: Object) {
this._state = state;
this._currentCanvas = document.createElement('canvas');
this._currentCanvasContext = this._currentCanvas.getContext('2d');
// Bind handlers such that they access the same instance.
this._handleWorkerAction = this._handleWorkerAction.bind(this);
this._initScreenshotCapture = this._initScreenshotCapture.bind(this);
this._streamWorker = new Worker(timerWorkerScript, { name: 'Screenshot capture worker' });
this._streamWorker.onmessage = this._handleWorkerAction;
}
/**
* Starts the screenshot capture event on a loop.
*
* @param {Track} track - The track that contains the stream from which screenshots are to be sent.
* @returns {Promise} - Promise that resolves once effect has started or rejects if the
* videoType parameter is not desktop.
*/
start(track: Object) {
const { videoType } = track;
const stream = track.getOriginalStream();
if (videoType !== 'desktop') {
return;
}
const desktopTrack = stream.getVideoTracks()[0];
const { height, width }
= desktopTrack.getSettings() ?? desktopTrack.getConstraints();
this._streamHeight = height;
this._streamWidth = width;
this._currentCanvas.height = parseInt(height, 10);
this._currentCanvas.width = parseInt(width, 10);
this._imageCapture = new ImageCapture(desktopTrack);
this._initScreenshotCapture();
}
/**
* Stops the ongoing {@code ScreenshotCaptureEffect} by clearing the {@code Worker} interval.
*
* @returns {void}
*/
stop() {
this._streamWorker.postMessage({ id: CLEAR_INTERVAL });
}
/**
* Method that is called as soon as the first frame of the video loads from stream.
* The method is used to store the {@code ImageData} object from the first frames
* in order to use it for future comparisons based on which we can process only certain
* screenshots.
*
* @private
* @returns {void}
*/
async _initScreenshotCapture() {
const imageBitmap = await this._imageCapture.grabFrame();
this._currentCanvasContext.drawImage(imageBitmap, 0, 0, this._streamWidth, this._streamHeight);
const imageData = this._currentCanvasContext.getImageData(0, 0, this._streamWidth, this._streamHeight);
this._storedImageData = imageData;
this._streamWorker.postMessage({
id: SET_INTERVAL,
timeMs: POLL_INTERVAL
});
}
/**
* Handler of the {@code EventHandler} message that calls the appropriate method based on the parameter's id.
*
* @private
* @param {EventHandler} message - Message received from the Worker.
* @returns {void}
*/
_handleWorkerAction(message: Object) {
return message.data.id === INTERVAL_TIMEOUT && this._handleScreenshot();
}
/**
* Method that processes the screenshot.
*
* @private
* @param {ImageData} imageData - The image data of the new screenshot.
* @returns {void}
*/
_doProcessScreenshot(imageData) {
sendAnalytics(createScreensharingCaptureTakenEvent());
const conference = getCurrentConference(this._state);
const sessionId = conference.getMeetingUniqueId();
const { connection } = this._state['features/base/connection'];
const jid = connection.getJid();
const timestamp = Date.now();
const { jwt } = this._state['features/base/jwt'];
const meetingFqn = extractFqnFromPath();
const remoteParticipants = getRemoteParticipants(this._state);
const participants = [];
remoteParticipants.forEach(p => participants.push(
getParticipantJid(this._state, p.id)
));
this._storedImageData = imageData;
processScreenshot(this._currentCanvas, {
jid,
jwt,
sessionId,
timestamp,
meetingFqn,
participants
});
}
/**
* Screenshot handler.
*
* @private
* @returns {void}
*/
async _handleScreenshot() {
const imageBitmap = await this._imageCapture.grabFrame();
this._currentCanvasContext.drawImage(imageBitmap, 0, 0, this._streamWidth, this._streamHeight);
const imageData = this._currentCanvasContext.getImageData(0, 0, this._streamWidth, this._streamHeight);
resemble(imageData)
.compareTo(this._storedImageData)
.setReturnEarlyThreshold(PERCENTAGE_LOWER_BOUND)
.onComplete(resultData => {
if (resultData.rawMisMatchPercentage > PERCENTAGE_LOWER_BOUND) {
this._doProcessScreenshot(imageData);
}
});
}
}