@epicgames-ps/lib-pixelstreamingfrontend-ue5.4/src/DataChannel/DataChannelController.ts

Frontend library for Unreal Engine 5.4 Pixel Streaming

// Copyright Epic Games, Inc. All Rights Reserved.

import { Logger } from '../Logger/Logger';

/**
 * Handles the Sending and Receiving of messages to the UE Instance via the Data Channel
 */
export class DataChannelController {
    dataChannel: RTCDataChannel;
    peerConnection: RTCPeerConnection;
    datachannelOptions: RTCDataChannelInit;
    label: string;
    isReceivingFreezeFrame = false;

    /**
     * return the current state of a datachannel controller instance
     * @returns the current DataChannelController instance
     */
    getDataChannelInstance(): DataChannelController {
        return this;
    }

    /**
     * To Create and Set up a Data Channel
     * @param peerConnection - The RTC Peer Connection
     * @param label - Label of the Data Channel
     * @param datachannelOptions - Optional RTC DataChannel options
     */
    createDataChannel(
        peerConnection: RTCPeerConnection,
        label: string,
        datachannelOptions?: RTCDataChannelInit
    ) {
        this.peerConnection = peerConnection;
        this.label = label;
        this.datachannelOptions = datachannelOptions;
        if (datachannelOptions == null) {
            this.datachannelOptions = {} as RTCDataChannelInit;
            this.datachannelOptions.ordered = true;
        }

        this.dataChannel = this.peerConnection.createDataChannel(
            this.label,
            this.datachannelOptions
        );
        this.setupDataChannel();
    }

    setupDataChannel() {
        //We Want an Array Buffer not a blob
        this.dataChannel.binaryType = 'arraybuffer';
        this.dataChannel.onopen = (ev: Event) => this.handleOnOpen(ev);
        this.dataChannel.onclose = (ev: Event) => this.handleOnClose(ev);
        this.dataChannel.onmessage = (ev: MessageEvent) =>
            this.handleOnMessage(ev);
        this.dataChannel.onerror = (ev: MessageEvent) => this.handleOnError(ev);
    }

    /**
     * Handles when the Data Channel is opened
     */
    handleOnOpen(ev: Event) {
        Logger.Log(
            Logger.GetStackTrace(),
            `Data Channel (${this.label}) opened.`,
            7
        );
        this.onOpen(this.dataChannel?.label, ev);
    }

    /**
     * Handles when the Data Channel is closed
     */
    handleOnClose(ev: Event) {
        Logger.Log(
            Logger.GetStackTrace(),
            `Data Channel (${this.label}) closed.`,
            7
        );
        this.onClose(this.dataChannel?.label, ev);
    }

    /**
     * Handles when a message is received
     * @param event - Message Event
     */
    handleOnMessage(event: MessageEvent) {
        // Higher log level to prevent log spam with messages received
        Logger.Log(
            Logger.GetStackTrace(),
            `Data Channel (${this.label}) message: ${event}`,
            8
        );
    }

    /**
     * Handles when an error is thrown
     * @param event - Error Event
     */
    handleOnError(event: MessageEvent) {
        Logger.Log(
            Logger.GetStackTrace(),
            `Data Channel (${this.label}) error: ${event}`,
            7
        );
        this.onError(this.dataChannel?.label, event);
    }

    /**
     * Override to register onOpen handler
     * @param label Data channel label ("datachannel", "send-datachannel", "recv-datachannel")
     * @param ev event
     */
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    onOpen(label: string, ev: Event) {
        // empty default implementation
    }

    /**
     * Override to register onClose handler
     * @param label Data channel label ("datachannel", "send-datachannel", "recv-datachannel")
     * @param ev event
     */
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    onClose(label: string, ev: Event) {
        // empty default implementation
    }

    /**
     * Override to register onError handler
     * @param label Data channel label ("datachannel", "send-datachannel", "recv-datachannel")
     * @param ev event
     */
    // eslint-disable-next-line @typescript-eslint/no-unused-vars
    onError(label: string, ev: Event) {
        // empty default implementation
    }
}