31:T81b,pdf_viewer_canvas = { var pdfDoc = null, pageNum = 1, pageRendering = false, pageNumPending = null, scale = 0.8, canvas = document.getElementById(canvas_id), ctx = canvas.getContext('2d'); /** * Get page info from document, resize canvas accordingly, and render page. * @param num Page number. */ function renderPage(num) { pageRendering = true; // Using promise to fetch the page pdfDoc.getPage(num).then(function(page) { var viewport = page.getViewport({scale: scale}); canvas.height = viewport.height; canvas.width = viewport.width; // Render PDF page into canvas context var renderContext = { canvasContext: ctx, viewport: viewport }; var renderTask = page.render(renderContext); // Wait for rendering to finish renderTask.promise.then(function() { pageRendering = false; if (pageNumPending !== null) { // New page rendering is pending renderPage(pageNumPending); pageNumPending = null; } }); }); // Update page counters document.getElementById('page_num').textContent = num; } /** * If another page rendering in progress, waits until the rendering is * finised. Otherwise, executes rendering immediately. */ function queueRenderPage(num) { if (pageRendering) { pageNumPending = num; } else { renderPage(num); } } /** * Displays previous page. */ function onPrevPage() { if (pageNum <= 1) { return; } pageNum--; queueRenderPage(pageNum); } document.getElementById('prev').addEventListener('click', onPrevPage); /** * Displays next page. */ function onNextPage() { if (pageNum >= pdfDoc.numPages) { return; } pageNum++; queueRenderPage(pageNum); } document.getElementById('next').addEventListener('click', onNextPage); /** * Asynchronously downloads PDF. */ pdfjsLib.getDocument(url_canvas).promise.then(function(pdfDoc_) { pdfDoc = pdfDoc_; document.getElementById('page_count').textContent = pdfDoc.numPages; // Initial/first page rendering renderPage(pageNum); }); }32:[] 2f:{"title":"PDF.js MultiPage Previous/Next","cells":[{"id":0,"value":"md`# PDF.js MultiPage Previous/Next`","pinned":false,"hidden":false,"mode":"ojs"},{"id":91,"value":"md`\nFrom [PDF.js | Hello World Walkthrough](https://mozilla.github.io/pdf.js/examples/).\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":67,"value":"md`\nThanks to [Fabian Iwand](https://observablehq.com/@mootari) for [getting this to work](https://observablehq.com/@mootari/hello-pdf-js)!\n\n\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":74,"value":"html`\n

\n \n \n \n Page: / \n

\n\n

\n\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":102,"value":"canvas_id = \"the-canvas\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":15,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":81,"value":"// Requires githack.com or a similar proxy for CORS headers.\nurl_canvas = 'https://raw.githubusercontent.com/mozilla/pdf.js/ba2edeae/web/compressed.tracemonkey-pldi-09.pdf'","pinned":false,"hidden":false,"mode":"ojs"},{"id":87,"value":"pdfjsLib = {\n const [pdfjs, workerSrc] = await Promise.all([\n require(\"pdfjs-dist@2\"),\n require.resolve(\"pdfjs-dist@2/build/pdf.worker.js\")\n ]);\n pdfjs.GlobalWorkerOptions.workerSrc = workerSrc; \n return pdfjs;\n}","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W32","stdlib":"1","titling":"auto"}