lib-jitsi-meet/modules/RTC/JitsiTrack.js

var RTCBrowserType = require("./RTCBrowserType");
var JitsiTrackEvents = require("../../JitsiTrackEvents");
var EventEmitter = require("events");

/**
 * This implements 'onended' callback normally fired by WebRTC after the stream
 * is stopped. There is no such behaviour yet in FF, so we have to add it.
 * @param jitsiTrack our track object holding the original WebRTC stream object
 * to which 'onended' handling will be added.
 */
function implementOnEndedHandling(jitsiTrack) {
    var stream = jitsiTrack.getOriginalStream();
    var originalStop = stream.stop;
    stream.stop = function () {
        originalStop.apply(stream);
        if (jitsiTrack.isActive()) {
            stream.onended();
        }
    };
}

/**
 * Adds onended/oninactive handler to a MediaStream.
 * @param mediaStream a MediaStream to attach onended/oninactive handler
 * @param handler the handler
 */
function addMediaStreamInactiveHandler(mediaStream, handler) {
    if(RTCBrowserType.isTemasysPluginUsed()) {
        // themasys
        mediaStream.attachEvent('ended', function () {
            handler(mediaStream);
        });
    }
    else {
        if(typeof mediaStream.active !== "undefined")
            mediaStream.oninactive = handler;
        else
            mediaStream.onended = handler;
    }
}

/**
 * Represents a single media track (either audio or video).
 * @constructor
 * @param rtc the rtc instance
 * @param stream the stream
 * @param streamInactiveHandler the function that will handle
 *        onended/oninactive events of the stream.
 */
function JitsiTrack(rtc, stream, streamInactiveHandler)
{
    /**
     * Array with the HTML elements that are displaying the streams.
     * @type {Array}
     */
    this.containers = [];
    this.rtc = rtc;
    this.stream = stream;
    this.eventEmitter = new EventEmitter();
    this.audioLevel = -1;
    this.type = (this.stream.getVideoTracks().length > 0)?
        JitsiTrack.VIDEO : JitsiTrack.AUDIO;
    if(this.type == "audio") {
        this._getTracks = function () {
            return this.stream.getAudioTracks();
        }.bind(this);
    } else {
        this._getTracks = function () {
            return this.stream.getVideoTracks();
        }.bind(this);
    }
    if (RTCBrowserType.isFirefox() && this.stream) {
        implementOnEndedHandling(this);
    }

    if(stream)
        addMediaStreamInactiveHandler(stream, streamInactiveHandler);
}

/**
 * JitsiTrack video type.
 * @type {string}
 */
JitsiTrack.VIDEO = "video";

/**
 * JitsiTrack audio type.
 * @type {string}
 */
JitsiTrack.AUDIO = "audio";

/**
 * Returns the type (audio or video) of this track.
 */
JitsiTrack.prototype.getType = function() {
    return this.type;
};

/**
 * Returns the RTCMediaStream from the browser (?).
 */
JitsiTrack.prototype.getOriginalStream = function() {
    return this.stream;
}

/**
 * Mutes the track.
 */
JitsiTrack.prototype.mute = function () {
    this._setMute(true);
}

/**
 * Unmutes the stream.
 */
JitsiTrack.prototype.unmute = function () {
    this._setMute(false);
}

/**
 * Attaches the MediaStream of this track to an HTML container (?).
 * Adds the container to the list of containers that are displaying the track.
 * @param container the HTML container
 */
JitsiTrack.prototype.attach = function (container) {
    if(this.stream)
        require("./RTCUtils").attachMediaStream(container, this.stream);
    this.containers.push(container);
}

/**
 * Removes the track from the passed HTML container.
 * @param container the HTML container. If <tt>null</tt> all containers are removed.
 */
JitsiTrack.prototype.detach = function (container) {
    for(var i = 0; i < this.containers.length; i++)
    {
        if(this.containers[i].is(container))
        {
            this.containers.splice(i,1);
        }
        if(!container)
        {
            this.containers[i].find(">video").remove();
        }
    }
    if(container)
        $(container).find(">video").remove();

}

/**
 * Stops sending the media track. And removes it from the HTML.
 * NOTE: Works for local tracks only.
 */
JitsiTrack.prototype.stop = function () {
}

/**
 * Returns true if this is a video track and the source of the video is a
 * screen capture as opposed to a camera.
 */
JitsiTrack.prototype.isScreenSharing = function(){

}

/**
 * Returns id of the track.
 * @returns {string} id of the track or null if this is fake track.
 */
JitsiTrack.prototype.getId = function () {
    var tracks = this.stream.getTracks();
    if(!tracks || tracks.length === 0)
        return null;
    return tracks[0].id;
};

/**
 * Checks whether the MediaStream is avtive/not ended.
 * When there is no check for active we don't have information and so
 * will return that stream is active (in case of FF).
 * @returns {boolean} whether MediaStream is active.
 */
JitsiTrack.prototype.isActive = function () {
    if((typeof this.stream.active !== "undefined"))
        return this.stream.active;
    else
        return true;
};

/**
 * Attaches a handler for events(For example - "audio level changed".).
 * All possible event are defined in JitsiTrackEvents.
 * @param eventId the event ID.
 * @param handler handler for the event.
 */
JitsiTrack.prototype.on = function (eventId, handler) {
    if(this.eventEmitter)
        this.eventEmitter.on(eventId, handler);
}

/**
 * Removes event listener
 * @param eventId the event ID.
 * @param [handler] optional, the specific handler to unbind
 */
JitsiTrack.prototype.off = function (eventId, handler) {
    if(this.eventEmitter)
        this.eventEmitter.removeListener(eventId, handler);
}

// Common aliases for event emitter
JitsiTrack.prototype.addEventListener = JitsiTrack.prototype.on;
JitsiTrack.prototype.removeEventListener = JitsiTrack.prototype.off;


/**
 * Sets the audio level for the stream
 * @param audioLevel the new audio level
 */
JitsiTrack.prototype.setAudioLevel = function (audioLevel) {
    if(this.audioLevel !== audioLevel) {
        this.eventEmitter.emit(JitsiTrackEvents.TRACK_AUDIO_LEVEL_CHANGED,
            audioLevel);
        this.audioLevel = audioLevel;
    }
 }

module.exports = JitsiTrack;