mirror of
https://github.com/scratchfoundation/scratch-vm.git
synced 2024-12-26 07:52:50 -05:00
366 lines
11 KiB
JavaScript
366 lines
11 KiB
JavaScript
const log = require('../util/log');
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class Video {
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constructor (runtime) {
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/**
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* Reference to the owning Runtime.
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* @type{!Runtime}
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*/
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this.runtime = runtime;
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/**
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* Default value for mirrored frames.
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* @type boolean
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*/
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this.mirror = true;
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/**
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* Cache frames for this many ms.
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* @type number
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*/
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this._frameCacheTimeout = 16;
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/**
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* DOM Video element
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* @private
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*/
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this._video = null;
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/**
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* Usermedia stream track
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* @private
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*/
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this._track = null;
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/**
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* Stores some canvas/frame data per resolution/mirror states
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*/
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this._workspace = [];
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/**
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* Id representing a Scratch Renderer skin the video is rendered to for
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* previewing.
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* @type {number}
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*/
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this._skinId = -1;
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/**
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* The Scratch Renderer Skin object.
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* @type {Skin}
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*/
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this._skin = null;
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/**
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* Id for a drawable using the video's skin that will render as a video
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* preview.
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* @type {Drawable}
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*/
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this._drawable = -1;
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/**
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* Store the last state of the video transparency ghost effect
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* @type {number}
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*/
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this._ghost = 0;
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}
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static get FORMAT_IMAGE_DATA () {
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return 'image-data';
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}
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static get FORMAT_CANVAS () {
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return 'canvas';
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}
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/**
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* Dimensions the video stream is analyzed at after its rendered to the
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* sample canvas.
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* @type {Array.<number>}
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*/
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static get DIMENSIONS () {
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return [480, 360];
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}
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/**
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* Order preview drawable is inserted at in the renderer.
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* @type {number}
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*/
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static get ORDER () {
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return 1;
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}
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/**
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* Request video be enabled. Sets up video, creates video skin and enables preview.
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*
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* ioDevices.video.requestVideo()
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*
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* @return {Promise.<Video>} resolves a promise to this IO device when video is ready.
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*/
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enableVideo () {
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this.enabled = true;
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return this._setupVideo();
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}
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/**
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* Disable video stream (turn video off)
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*/
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disableVideo () {
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this.enabled = false;
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// If we have begun a setup process, call _teardown after it completes
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if (this._singleSetup) {
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this._singleSetup
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.then(this._teardown.bind(this))
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.catch(() => {});
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}
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}
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/**
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* async part of disableVideo
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* @private
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*/
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_teardown () {
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// we might be asked to re-enable before _teardown is called, just ignore it.
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if (this.enabled === false) {
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this._disablePreview();
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this._singleSetup = null;
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// by clearing refs to video and track, we should lose our hold over the camera
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this._video = null;
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if (this._track) {
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this._track.stop();
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}
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this._track = null;
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}
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}
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/**
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* Return frame data from the video feed in a specified dimensions, format, and mirroring.
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* @return {ArrayBuffer|Canvas|string|null} Frame data in requested format, null when errors.
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*/
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getFrame ({
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dimensions = Video.DIMENSIONS,
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mirror = this.mirror,
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format = Video.FORMAT_IMAGE_DATA,
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cacheTimeout = this._frameCacheTimeout
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}) {
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if (!this.videoReady) {
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return null;
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}
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const [width, height] = dimensions;
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const workspace = this._getWorkspace({dimensions, mirror: Boolean(mirror)});
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const {videoWidth, videoHeight} = this._video;
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const {canvas, context, lastUpdate, cacheData} = workspace;
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const now = Date.now();
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// if the canvas hasn't been updated...
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if (lastUpdate + cacheTimeout < now) {
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if (mirror) {
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context.scale(-1, 1);
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context.translate(width * -1, 0);
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}
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context.drawImage(this._video,
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// source x, y, width, height
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0, 0, videoWidth, videoHeight,
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// dest x, y, width, height
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0, 0, width, height
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);
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context.resetTransform();
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workspace.lastUpdate = now;
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}
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// each data type has it's own data cache, but the canvas is the same
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if (!cacheData[format]) {
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cacheData[format] = {lastUpdate: 0};
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}
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const formatCache = cacheData[format];
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if (formatCache.lastUpdate + cacheTimeout < now) {
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if (format === Video.FORMAT_IMAGE_DATA) {
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formatCache.lastData = context.getImageData(0, 0, width, height);
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} else if (format === Video.FORMAT_CANVAS) {
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// this will never change
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formatCache.lastUpdate = Infinity;
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formatCache.lastData = canvas;
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} else {
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log.error(`video io error - unimplemented format ${format}`);
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// cache the null result forever, don't log about it again..
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formatCache.lastUpdate = Infinity;
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formatCache.lastData = null;
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}
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// rather than set to now, this data is as stale as it's canvas is
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formatCache.lastUpdate = Math.max(workspace.lastUpdate, formatCache.lastUpdate);
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}
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return formatCache.lastData;
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}
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/**
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* Set the preview ghost effect
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* @param {number} ghost from 0 (visible) to 100 (invisible) - ghost effect
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*/
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setPreviewGhost (ghost) {
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this._ghost = ghost;
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if (this._drawable) {
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this.runtime.renderer.updateDrawableProperties(this._drawable, {ghost});
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}
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}
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/**
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* Create a video stream.
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* Should probably be moved to -render or somewhere similar later
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* @private
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* @return {Promise} When video has been received, rejected if video is not received
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*/
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_setupVideo () {
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// We cache the result of this setup so that we can only ever have a single
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// video/getUserMedia request happen at a time.
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if (this._singleSetup) {
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return this._singleSetup;
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}
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this._singleSetup = new Promise((resolve, reject) => {
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navigator.getUserMedia({
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audio: false,
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video: {
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width: {min: 480, ideal: 640},
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height: {min: 360, ideal: 480}
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}
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}, resolve, reject);
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})
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.then(stream => {
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this._video = document.createElement('video');
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this._video.src = window.URL.createObjectURL(stream);
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// Hint to the stream that it should load. A standard way to do this
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// is add the video tag to the DOM. Since this extension wants to
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// hide the video tag and instead render a sample of the stream into
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// the webgl rendered Scratch canvas, another hint like this one is
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// needed.
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this._track = stream.getTracks()[0];
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this._setupPreview();
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return this;
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})
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.catch(err => {
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this._singleSetup = null;
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if (this.onError) {
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this.onError(err);
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} else {
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log.error(`Unhandled io device error`, err);
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}
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});
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return this._singleSetup;
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}
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_disablePreview () {
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if (this._skin) {
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this._skin.clear();
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this.runtime.renderer.updateDrawableProperties(this._drawable, {visible: false});
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}
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this._renderPreviewFrame = null;
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}
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_setupPreview () {
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const {renderer} = this.runtime;
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if (!renderer) return;
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if (this._skinId === -1 && this._skin === null && this._drawable === -1) {
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this._skinId = renderer.createPenSkin();
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this._skin = renderer._allSkins[this._skinId];
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this._drawable = renderer.createDrawable();
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renderer.setDrawableOrder(
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this._drawable,
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Video.ORDER
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);
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renderer.updateDrawableProperties(this._drawable, {
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skinId: this._skinId
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});
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}
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// if we haven't already created and started a preview frame render loop, do so
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if (!this._renderPreviewFrame) {
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renderer.updateDrawableProperties(this._drawable, {
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ghost: this._ghost,
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visible: true
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});
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this._renderPreviewFrame = () => {
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clearTimeout(this._renderPreviewTimeout);
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if (!this._renderPreviewFrame) {
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return;
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}
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this._renderPreviewTimeout = setTimeout(this._renderPreviewFrame, this.runtime.currentStepTime);
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const canvas = this.getFrame({format: Video.FORMAT_CANVAS});
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if (!canvas) {
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this._skin.clear();
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return;
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}
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const xOffset = Video.DIMENSIONS[0] / -2;
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const yOffset = Video.DIMENSIONS[1] / 2;
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this._skin.drawStamp(canvas, xOffset, yOffset);
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this.runtime.requestRedraw();
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};
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this._renderPreviewFrame();
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}
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}
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get videoReady () {
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if (!this.enabled) {
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return false;
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}
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if (!this._video) {
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return false;
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}
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if (!this._track) {
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return false;
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}
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const {videoWidth, videoHeight} = this._video;
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if (typeof videoWidth !== 'number' || typeof videoHeight !== 'number') {
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return false;
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}
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if (videoWidth === 0 || videoHeight === 0) {
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return false;
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}
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return true;
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}
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/**
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* get an internal workspace for canvas/context/caches
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* this uses some document stuff to create a canvas and what not, probably needs abstraction
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* into the renderer layer?
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* @private
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* @return {object} A workspace for canvas/data storage. Internal format not documented intentionally
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*/
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_getWorkspace ({dimensions, mirror}) {
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let workspace = this._workspace.find(space => (
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space.dimensions.join('-') === dimensions.join('-') &&
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space.mirror === mirror
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));
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if (!workspace) {
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workspace = {
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dimensions,
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mirror,
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canvas: document.createElement('canvas'),
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lastUpdate: 0,
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cacheData: {}
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};
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workspace.canvas.width = dimensions[0];
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workspace.canvas.height = dimensions[1];
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workspace.context = workspace.canvas.getContext('2d');
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this._workspace.push(workspace);
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}
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return workspace;
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}
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}
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module.exports = Video;
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