jiti-meet/react/features/stream-effects/presenter/JitsiStreamPresenterEffect.js

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// @flow
import {
CLEAR_INTERVAL,
INTERVAL_TIMEOUT,
SET_INTERVAL,
timerWorkerScript
} from './TimeWorker';
/**
* Represents a modified MediaStream that adds video as pip on a desktop stream.
* <tt>JitsiStreamPresenterEffect</tt> does the processing of the original
* desktop stream.
*/
export default class JitsiStreamPresenterEffect {
_canvas: HTMLCanvasElement;
_ctx: CanvasRenderingContext2D;
_desktopElement: HTMLVideoElement;
_desktopStream: MediaStream;
_frameRate: number;
_onVideoFrameTimer: Function;
_onVideoFrameTimerWorker: Function;
_renderVideo: Function;
_videoFrameTimerWorker: Worker;
_videoElement: HTMLVideoElement;
isEnabled: Function;
startEffect: Function;
stopEffect: Function;
/**
* Represents a modified MediaStream that adds a camera track at the
* bottom right corner of the desktop track using a HTML canvas.
* <tt>JitsiStreamPresenterEffect</tt> does the processing of the original
* video stream.
*
* @param {MediaStream} videoStream - The video stream which is user for
* creating the canvas.
*/
constructor(videoStream: MediaStream) {
const videoDiv = document.createElement('div');
const firstVideoTrack = videoStream.getVideoTracks()[0];
const { height, width, frameRate } = firstVideoTrack.getSettings() ?? firstVideoTrack.getConstraints();
this._canvas = document.createElement('canvas');
this._ctx = this._canvas.getContext('2d');
this._desktopElement = document.createElement('video');
this._videoElement = document.createElement('video');
videoDiv.appendChild(this._videoElement);
videoDiv.appendChild(this._desktopElement);
if (document.body !== null) {
document.body.appendChild(videoDiv);
}
// Set the video element properties
this._frameRate = parseInt(frameRate, 10);
this._videoElement.width = parseInt(width, 10);
this._videoElement.height = parseInt(height, 10);
this._videoElement.autoplay = true;
this._videoElement.srcObject = videoStream;
// set the style attribute of the div to make it invisible
videoDiv.style.display = 'none';
// Bind event handler so it is only bound once for every instance.
this._onVideoFrameTimer = this._onVideoFrameTimer.bind(this);
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this._videoFrameTimerWorker = new Worker(timerWorkerScript, { name: 'Presenter effect worker' });
this._videoFrameTimerWorker.onmessage = this._onVideoFrameTimer;
}
/**
* EventHandler onmessage for the videoFrameTimerWorker WebWorker.
*
* @private
* @param {EventHandler} response - The onmessage EventHandler parameter.
* @returns {void}
*/
_onVideoFrameTimer(response) {
if (response.data.id === INTERVAL_TIMEOUT) {
this._renderVideo();
}
}
/**
* Loop function to render the video frame input and draw presenter effect.
*
* @private
* @returns {void}
*/
_renderVideo() {
// adjust the canvas width/height on every frame incase the window has been resized.
const [ track ] = this._desktopStream.getVideoTracks();
const { height, width } = track.getSettings() ?? track.getConstraints();
this._canvas.width = parseInt(width, 10);
this._canvas.height = parseInt(height, 10);
this._ctx.drawImage(this._desktopElement, 0, 0, this._canvas.width, this._canvas.height);
this._ctx.drawImage(this._videoElement, this._canvas.width - this._videoElement.width, this._canvas.height
- this._videoElement.height, this._videoElement.width, this._videoElement.height);
// draw a border around the video element.
this._ctx.beginPath();
this._ctx.lineWidth = 2;
this._ctx.strokeStyle = '#A9A9A9'; // dark grey
this._ctx.rect(this._canvas.width - this._videoElement.width, this._canvas.height - this._videoElement.height,
this._videoElement.width, this._videoElement.height);
this._ctx.stroke();
}
/**
* Checks if the local track supports this effect.
*
* @param {JitsiLocalTrack} jitsiLocalTrack - Track to apply effect.
* @returns {boolean} - Returns true if this effect can run on the
* specified track, false otherwise.
*/
isEnabled(jitsiLocalTrack: Object) {
return jitsiLocalTrack.isVideoTrack() && jitsiLocalTrack.videoType === 'desktop';
}
/**
* Starts loop to capture video frame and render presenter effect.
*
* @param {MediaStream} desktopStream - Stream to be used for processing.
* @returns {MediaStream} - The stream with the applied effect.
*/
startEffect(desktopStream: MediaStream) {
const firstVideoTrack = desktopStream.getVideoTracks()[0];
const { height, width } = firstVideoTrack.getSettings() ?? firstVideoTrack.getConstraints();
// set the desktop element properties.
this._desktopStream = desktopStream;
this._desktopElement.width = parseInt(width, 10);
this._desktopElement.height = parseInt(height, 10);
this._desktopElement.autoplay = true;
this._desktopElement.srcObject = desktopStream;
this._canvas.width = parseInt(width, 10);
this._canvas.height = parseInt(height, 10);
this._videoFrameTimerWorker.postMessage({
id: SET_INTERVAL,
timeMs: 1000 / this._frameRate
});
return this._canvas.captureStream(this._frameRate);
}
/**
* Stops the capture and render loop.
*
* @returns {void}
*/
stopEffect() {
this._videoFrameTimerWorker.postMessage({
id: CLEAR_INTERVAL
});
}
}