jitsi_app_c0/react/features/video-layout/middleware.web.js

import VideoLayout from '../../../modules/UI/videolayout/VideoLayout.js';

import { DOMINANT_SPEAKER_CHANGED } from '../base/participants';
import { MiddlewareRegistry } from '../base/redux';

/**
 * Middleware which intercepts actions and updates the legacy component
 * {@code VideoLayout} as needed. The purpose of this middleware is to redux-ify
 * {@code VideoLayout} without having to simultaneously react-ifying it.
 *
 * @param {Store} store - The redux store.
 * @returns {Function}
 */
// eslint-disable-next-line no-unused-vars
MiddlewareRegistry.register(store => next => action => {
    const result = next(action);

    switch (action.type) {
    case DOMINANT_SPEAKER_CHANGED:
        VideoLayout.onDominantSpeakerChanged(action.participant.id);
        break;
    }

    return result;
});