107 lines
2.6 KiB
JavaScript
107 lines
2.6 KiB
JavaScript
const pdfjsLib = await import('./pdf/pdf.mjs');
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const pdfjsWorker = await import('./pdf/pdf.worker.mjs');
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// The workerSrc property shall be specified.
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pdfjsLib.GlobalWorkerOptions.workerSrc = pdfjsWorker;
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export function displayPdf(options) {
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var pdfDoc = null,
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pageNum = 1,
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pageRendering = false,
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pageNumPending = null,
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ctx = options.canvas.getContext('2d');
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/**
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* Get page info from document, resize canvas accordingly, and render page.
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* @param num Page number.
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*/
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function renderPage(num) {
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pageRendering = true;
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// Using promise to fetch the page
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pdfDoc.getPage(num).then(function(page) {
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var canvasWidth = options.canvas.getBoundingClientRect().width,
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pageWidth = page.getViewport({scale: 1.0}).width,
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scale = canvasWidth/pageWidth,
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viewport = page.getViewport({scale: scale});
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options.canvas.height = viewport.height;
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options.canvas.width = viewport.width;
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// Render PDF page into canvas context
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var renderContext = {
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canvasContext: ctx,
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viewport: viewport
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};
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var renderTask = page.render(renderContext);
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// Wait for rendering to finish
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renderTask.promise.then(function() {
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pageRendering = false;
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if (pageNumPending !== null) {
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// New page rendering is pending
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renderPage(pageNumPending);
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pageNumPending = null;
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}
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});
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});
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// Update page counters
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options.pageNum.textContent = num;
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}
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/**
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* If another page rendering in progress, waits until the rendering is
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* finised. Otherwise, executes rendering immediately.
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*/
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function queueRenderPage(num) {
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if (pageRendering) {
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pageNumPending = num;
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} else {
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renderPage(num);
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}
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}
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/**
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* Re-render page (e.g. on resize)
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*/
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function reRender() {
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queueRenderPage(pageNum);
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}
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document.defaultView.addEventListener('resize', reRender)
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/**
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* Displays previous page.
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*/
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function onPrevPage() {
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if (pageNum <= 1) {
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return;
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}
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pageNum--;
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queueRenderPage(pageNum);
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}
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options.prevPage.addEventListener('click', onPrevPage);
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/**
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* Displays next page.
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*/
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function onNextPage() {
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if (pageNum >= pdfDoc.numPages) {
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return;
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}
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pageNum++;
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queueRenderPage(pageNum);
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}
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options.nextPage.addEventListener('click', onNextPage);
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/**
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* Asynchronously downloads PDF.
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*/
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pdfjsLib.getDocument(options.url).promise.then(function(pdfDoc_) {
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pdfDoc = pdfDoc_;
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options.pageCount.textContent = pdfDoc.numPages;
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// Initial/first page rendering
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renderPage(pageNum);
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});
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}
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