Juergen
491 lines
15 KiB
JavaScript
491 lines
15 KiB
JavaScript
const MODULE_SELECTOR = '[data-pdf-flipbook-element="1"]';
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const PDF_MODULE_URL = '/bundles/flipbook/assets/vendor/pdf.min.mjs';
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const PDF_WORKER_URL = '/bundles/flipbook/assets/vendor/pdf.worker.min.mjs';
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const FLIPBOOK_MODULE_URL = '/bundles/flipbook/assets/vendor/flipbook.esm.min.js';
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const INIT_MARKER = 'pdfFlipbookInitialized';
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const BOOTSTRAP_MARKER = '__mummertPdfFlipbookBootstrapBound';
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let dependenciesPromise;
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let moduleCounter = 0;
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const loadDependencies = async () => {
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if (dependenciesPromise) {
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return dependenciesPromise;
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}
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dependenciesPromise = Promise.all([
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import(PDF_MODULE_URL),
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import(FLIPBOOK_MODULE_URL),
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]).then(([pdfjsLib, flipbookModule]) => {
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pdfjsLib.GlobalWorkerOptions.workerSrc = PDF_WORKER_URL;
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return {
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pdfjsLib,
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FlipBook: flipbookModule.default,
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};
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});
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return dependenciesPromise;
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};
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class PdfFlipbookModule {
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constructor(root, dependencies) {
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const parsedInitialPages = Number.parseInt(root.dataset.initialPages || '4', 10);
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this.root = root;
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this.dependencies = dependencies;
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this.pdfUrl = (root.dataset.pdfUrl || '').trim();
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this.initialPages = Number.isFinite(parsedInitialPages)
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? Math.min(4, Math.max(2, parsedInitialPages))
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: 4;
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this.showNavigation = root.dataset.showNavigation === '1';
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this.startMode = (root.dataset.startMode === 'spread' || root.dataset.startMode === 'cover')
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? 'spread'
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: 'center';
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this.loader = root.querySelector('[data-flipbook-loader="1"]');
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this.stage = root.querySelector('[data-flipbook-stage="1"]');
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this.bookElement = root.querySelector('[data-flipbook-book="1"]');
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this.nextButton = this.showNavigation ? root.querySelector('[data-flipbook-next="1"]') : null;
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this.prevButton = this.showNavigation ? root.querySelector('[data-flipbook-prev="1"]') : null;
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this.pdf = null;
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this.flipbook = null;
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this.pageElements = new Map();
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this.renderedPages = new Set();
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this.pendingPages = new Set();
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this.renderQueue = [];
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this.renderInProgress = false;
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this.resizeTimer = null;
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this.touchStart = null;
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this.aspectRatio = 1.4142;
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this.pageWidth = 0;
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this.pageHeight = 0;
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this.pageGap = 2;
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this.totalPages = 0;
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this.instanceId = `pdf-flipbook-${++moduleCounter}`;
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}
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async init() {
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if (!this.bookElement || !this.stage) {
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return;
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}
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if (!this.pdfUrl) {
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this.setStatus('Keine PDF-Datei gefunden.', true);
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return;
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}
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this.bookElement.id = this.instanceId;
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try {
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this.setStatus('PDF wird geladen ...');
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await this.loadPdf();
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await this.resolveInitialAspectRatio();
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this.buildPageSkeleton();
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this.updateLayout();
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await this.renderInitialPages();
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this.initializeFlipbook();
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this.bindKeyboard();
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this.bindTouchSwipe();
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this.bindResize();
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this.queuePages(this.getLazyCandidates());
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this.setStatus('');
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} catch {
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this.setStatus('PDF konnte nicht geladen werden.', true);
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}
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}
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async loadPdf() {
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const loadingTask = this.dependencies.pdfjsLib.getDocument({
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url: this.pdfUrl,
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useWorkerFetch: true,
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isEvalSupported: false,
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});
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this.pdf = await loadingTask.promise;
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this.totalPages = Number(this.pdf.numPages || 0);
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if (this.totalPages <= 0) {
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throw new Error('The selected PDF has no pages.');
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}
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}
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async resolveInitialAspectRatio() {
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const firstPage = await this.pdf.getPage(1);
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const viewport = firstPage.getViewport({ scale: 1 });
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if (viewport.width > 0 && viewport.height > 0) {
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this.aspectRatio = viewport.height / viewport.width;
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}
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}
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buildPageSkeleton() {
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const visualPageCount = this.totalPages % 2 === 0 ? this.totalPages : this.totalPages + 1;
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this.bookElement.innerHTML = '';
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this.pageElements.clear();
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for (let pageNumber = 1; pageNumber <= visualPageCount; pageNumber += 1) {
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const page = document.createElement('div');
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const loader = document.createElement('div');
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page.className = 'c-flipbook__page';
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page.dataset.pageNumber = String(pageNumber);
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loader.className = 'mod-pdf-flipbook__page-loader';
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loader.textContent = pageNumber <= this.totalPages ? `Seite ${pageNumber} wird gerendert ...` : 'Leere Seite';
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page.appendChild(loader);
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if (pageNumber > this.totalPages) {
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page.dataset.empty = '1';
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}
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this.bookElement.appendChild(page);
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if (pageNumber <= this.totalPages) {
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this.pageElements.set(pageNumber, page);
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}
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}
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}
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updateLayout() {
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const stageWidth = Math.max(this.stage.clientWidth || 0, 282);
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this.pageWidth = Math.max(Math.floor((stageWidth - this.pageGap) / 2), 140);
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this.pageHeight = Math.max(Math.floor(this.pageWidth * this.aspectRatio), 180);
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this.stage.style.height = `${this.pageHeight}px`;
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this.bookElement.style.height = `${this.pageHeight}px`;
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this.pageElements.forEach((pageElement) => {
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pageElement.style.width = `${this.pageWidth}px`;
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pageElement.style.height = `${this.pageHeight}px`;
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});
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}
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async renderInitialPages() {
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const limit = Math.min(this.initialPages, this.totalPages);
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for (let pageNumber = 1; pageNumber <= limit; pageNumber += 1) {
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await this.renderPage(pageNumber);
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}
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}
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initializeFlipbook() {
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const startsWithDoubleSpread = this.startMode === 'spread';
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this.flipbook = new this.dependencies.FlipBook(this.bookElement, {
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nextButton: this.nextButton,
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previousButton: this.prevButton,
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canClose: !startsWithDoubleSpread,
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arrowKeys: false,
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initialActivePage: 0,
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initialCall: false,
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width: '100%',
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height: `${this.pageHeight}px`,
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onPageTurn: () => {
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this.queuePages(this.getLazyCandidates());
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},
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});
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}
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bindKeyboard() {
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this.root.addEventListener('pointerdown', () => {
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this.root.focus();
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});
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this.root.addEventListener('keydown', (event) => {
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if (!this.flipbook) {
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return;
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}
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if (event.key === 'ArrowRight') {
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this.flipbook.turnPage('forward');
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event.preventDefault();
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}
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if (event.key === 'ArrowLeft') {
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this.flipbook.turnPage('back');
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event.preventDefault();
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}
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});
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}
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bindTouchSwipe() {
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this.bookElement.addEventListener('touchstart', (event) => {
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const touch = event.changedTouches && event.changedTouches[0];
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if (!touch) {
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return;
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}
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this.touchStart = {
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x: touch.clientX,
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y: touch.clientY,
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};
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}, { passive: true });
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this.bookElement.addEventListener('touchend', (event) => {
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if (!this.flipbook || !this.touchStart) {
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this.touchStart = null;
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return;
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}
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const touch = event.changedTouches && event.changedTouches[0];
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if (!touch) {
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this.touchStart = null;
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return;
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}
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const deltaX = touch.clientX - this.touchStart.x;
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const deltaY = touch.clientY - this.touchStart.y;
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const horizontalThreshold = 40;
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const verticalLimit = 60;
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if (Math.abs(deltaX) >= horizontalThreshold && Math.abs(deltaY) < verticalLimit) {
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if (deltaX < 0) {
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this.flipbook.turnPage('forward');
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} else {
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this.flipbook.turnPage('back');
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}
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}
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this.touchStart = null;
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}, { passive: true });
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}
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bindResize() {
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const onResize = () => {
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window.clearTimeout(this.resizeTimer);
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this.resizeTimer = window.setTimeout(() => {
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if (!this.pdf) {
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return;
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}
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const previousHeight = this.pageHeight;
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this.updateLayout();
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if (Math.abs(previousHeight - this.pageHeight) < 2) {
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return;
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}
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this.bookElement.style.height = `${this.pageHeight}px`;
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const rerender = Array.from(this.renderedPages);
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this.renderedPages.clear();
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rerender.forEach((pageNumber) => {
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const page = this.pageElements.get(pageNumber);
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if (page) {
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const oldCanvas = page.querySelector('canvas');
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if (oldCanvas) {
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oldCanvas.remove();
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}
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}
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});
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this.queuePages(rerender, true);
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}, 120);
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};
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if ('ResizeObserver' in window) {
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const observer = new ResizeObserver(onResize);
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observer.observe(this.stage);
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} else {
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window.addEventListener('resize', onResize, { passive: true });
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}
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}
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getLazyCandidates() {
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const activePages = Array.from(this.bookElement.querySelectorAll('.c-flipbook__page.is-active'));
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const candidates = new Set();
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if (activePages.length === 0) {
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const fallbackFrom = Math.min(this.initialPages + 1, this.totalPages);
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const fallbackTo = Math.min(fallbackFrom + 2, this.totalPages);
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for (let pageNumber = fallbackFrom; pageNumber <= fallbackTo; pageNumber += 1) {
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candidates.add(pageNumber);
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}
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return Array.from(candidates);
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}
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activePages.forEach((activePage) => {
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const currentPage = Number(activePage.dataset.pageNumber || 0);
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for (let offset = -1; offset <= 3; offset += 1) {
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const pageNumber = currentPage + offset;
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if (pageNumber >= 1 && pageNumber <= this.totalPages) {
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candidates.add(pageNumber);
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}
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}
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});
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return Array.from(candidates);
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}
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queuePages(pageNumbers, prioritize = false) {
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for (const pageNumber of pageNumbers) {
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if (!Number.isInteger(pageNumber) || pageNumber < 1 || pageNumber > this.totalPages) {
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continue;
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}
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if (this.renderedPages.has(pageNumber) || this.pendingPages.has(pageNumber)) {
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continue;
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}
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this.pendingPages.add(pageNumber);
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if (prioritize) {
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this.renderQueue.unshift(pageNumber);
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} else {
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this.renderQueue.push(pageNumber);
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}
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}
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this.processRenderQueue();
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}
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async processRenderQueue() {
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if (this.renderInProgress) {
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return;
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}
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this.renderInProgress = true;
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while (this.renderQueue.length > 0) {
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const pageNumber = this.renderQueue.shift();
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if (!pageNumber) {
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continue;
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}
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this.pendingPages.delete(pageNumber);
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try {
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await this.renderPage(pageNumber);
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} catch {
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continue;
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}
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}
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this.renderInProgress = false;
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}
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async renderPage(pageNumber) {
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if (this.renderedPages.has(pageNumber)) {
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return;
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}
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const pageElement = this.pageElements.get(pageNumber);
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if (!pageElement) {
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return;
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}
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const page = await this.pdf.getPage(pageNumber);
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const viewportAtScale1 = page.getViewport({ scale: 1 });
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const scale = this.pageWidth / viewportAtScale1.width;
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const viewport = page.getViewport({ scale });
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const devicePixelRatio = window.devicePixelRatio || 1;
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const outputScale = Math.max(1, devicePixelRatio);
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const existingCanvas = pageElement.querySelector('canvas');
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if (existingCanvas) {
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existingCanvas.remove();
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}
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const canvas = document.createElement('canvas');
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const context = canvas.getContext('2d', { alpha: false });
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if (!context) {
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throw new Error('Could not create canvas 2D context.');
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}
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canvas.width = Math.floor(viewport.width * outputScale);
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canvas.height = Math.floor(viewport.height * outputScale);
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canvas.style.width = `${Math.floor(viewport.width)}px`;
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canvas.style.height = `${Math.floor(viewport.height)}px`;
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const renderTask = page.render({
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canvasContext: context,
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viewport,
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transform: outputScale === 1 ? null : [outputScale, 0, 0, outputScale, 0, 0],
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intent: 'display',
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});
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await renderTask.promise;
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const loader = pageElement.querySelector('.mod-pdf-flipbook__page-loader');
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if (loader) {
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loader.remove();
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}
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pageElement.appendChild(canvas);
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this.renderedPages.add(pageNumber);
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}
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setStatus(message, isError = false) {
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if (!this.loader) {
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return;
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}
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if (!message) {
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this.loader.classList.add('is-hidden');
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this.loader.classList.remove('is-error');
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this.loader.textContent = '';
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return;
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}
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this.loader.classList.remove('is-hidden');
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this.loader.classList.toggle('is-error', isError);
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this.loader.textContent = message;
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}
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}
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const run = async () => {
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const modules = Array.from(document.querySelectorAll(MODULE_SELECTOR))
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.filter((moduleElement) => moduleElement.dataset[INIT_MARKER] !== '1');
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if (modules.length === 0) {
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return;
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}
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const dependencies = await loadDependencies();
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await Promise.all(modules.map(async (moduleElement) => {
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moduleElement.dataset[INIT_MARKER] = '1';
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const module = new PdfFlipbookModule(moduleElement, dependencies);
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await module.init();
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}));
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};
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if (window[BOOTSTRAP_MARKER]) {
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run().catch(() => {
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});
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} else {
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window[BOOTSTRAP_MARKER] = true;
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if (document.readyState === 'loading') {
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document.addEventListener('DOMContentLoaded', () => {
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run().catch(() => {
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});
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}, { once: true });
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} else {
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run().catch(() => {
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});
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}
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}
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