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