127 lines
3.2 KiB
JavaScript
127 lines
3.2 KiB
JavaScript
const Preloader = /** @constructor */ function () { // eslint-disable-line no-unused-vars
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const loadXHR = function (resolve, reject, file, tracker, attempts) {
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const xhr = new XMLHttpRequest();
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tracker[file] = {
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total: 0,
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loaded: 0,
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final: false,
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};
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xhr.onerror = function () {
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if (attempts <= 1) {
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reject(new Error(`Failed loading file '${file}'`));
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} else {
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setTimeout(function () {
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loadXHR(resolve, reject, file, tracker, attempts - 1);
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}, 1000);
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}
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};
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xhr.onabort = function () {
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tracker[file].final = true;
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reject(new Error(`Loading file '${file}' was aborted.`));
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};
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xhr.onloadstart = function (ev) {
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tracker[file].total = ev.total;
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tracker[file].loaded = ev.loaded;
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};
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xhr.onprogress = function (ev) {
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tracker[file].loaded = ev.loaded;
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tracker[file].total = ev.total;
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};
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xhr.onload = function () {
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if (xhr.status >= 400) {
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if (xhr.status < 500 || attempts <= 1) {
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reject(new Error(`Failed loading file '${file}': ${xhr.statusText}`));
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xhr.abort();
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} else {
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setTimeout(function () {
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loadXHR(resolve, reject, file, tracker, attempts - 1);
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}, 1000);
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}
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} else {
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tracker[file].final = true;
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resolve(xhr);
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}
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};
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// Make request.
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xhr.open('GET', file);
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if (!file.endsWith('.js')) {
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xhr.responseType = 'arraybuffer';
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}
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xhr.send();
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};
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const DOWNLOAD_ATTEMPTS_MAX = 4;
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const loadingFiles = {};
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const lastProgress = { loaded: 0, total: 0 };
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let progressFunc = null;
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const animateProgress = function () {
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let loaded = 0;
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let total = 0;
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let totalIsValid = true;
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let progressIsFinal = true;
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Object.keys(loadingFiles).forEach(function (file) {
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const stat = loadingFiles[file];
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if (!stat.final) {
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progressIsFinal = false;
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}
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if (!totalIsValid || stat.total === 0) {
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totalIsValid = false;
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total = 0;
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} else {
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total += stat.total;
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}
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loaded += stat.loaded;
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});
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if (loaded !== lastProgress.loaded || total !== lastProgress.total) {
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lastProgress.loaded = loaded;
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lastProgress.total = total;
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if (typeof progressFunc === 'function') {
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progressFunc(loaded, total);
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}
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}
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if (!progressIsFinal) {
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requestAnimationFrame(animateProgress);
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}
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};
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this.animateProgress = animateProgress;
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this.setProgressFunc = function (callback) {
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progressFunc = callback;
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};
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this.loadPromise = function (file) {
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return new Promise(function (resolve, reject) {
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loadXHR(resolve, reject, file, loadingFiles, DOWNLOAD_ATTEMPTS_MAX);
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});
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};
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this.preloadedFiles = [];
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this.preload = function (pathOrBuffer, destPath) {
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let buffer = null;
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if (typeof pathOrBuffer === 'string') {
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const me = this;
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return this.loadPromise(pathOrBuffer).then(function (xhr) {
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me.preloadedFiles.push({
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path: destPath || pathOrBuffer,
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buffer: xhr.response,
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});
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return Promise.resolve();
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});
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} else if (pathOrBuffer instanceof ArrayBuffer) {
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buffer = new Uint8Array(pathOrBuffer);
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} else if (ArrayBuffer.isView(pathOrBuffer)) {
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buffer = new Uint8Array(pathOrBuffer.buffer);
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}
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if (buffer) {
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this.preloadedFiles.push({
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path: destPath,
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buffer: pathOrBuffer,
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});
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return Promise.resolve();
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}
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return Promise.reject(new Error('Invalid object for preloading'));
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};
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};
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