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<!--
SPDX-License-Identifier: MIT
This shortcut was originally taken from: https://github.com/anvithks/hugo-embed-pdf-shortcode,
where it is available under the MIT License, where it was originally created by https://github.com/anvithks
Since the project seems discontinued, it has been re-created here
-->
<!-- Load the PDF-JS from the local folder (should be updated over time) -->
<script src= '/js/pdf-js/build/pdf.js'></script>
<!-- Set the navigation menu -->
<div id="paginator">
<button id="prev">Previous</button>
<button id="next">Next</button>
<span>Page: <span id="page_num"></span> / <span id="page_count"></span></span>
</div>
<!-- And the canvas where the PDF will load -->
<div id="embed-pdf-container">
<div id="loadingWrapper">
<div id="loading"></div>
</div>
<canvas id="the-canvas"></canvas>
</div>
<!-- This script gets the PDF, sets it and passes it on to the already-loaded pdf-js -->
<script type="text/javascript">
window.onload = function() {
// If absolute URL from the remote server is provided, configure the CORS
// header on that server.
var url = "{{.Site.BaseURL}}" + '{{ .Get "src" }}';
var hidePaginator = "{{ .Get "hidePaginator" }}" === "true";
var hideLoader = "{{ .Get "hideLoader" }}" === "true";
var selectedPageNum = parseInt("{{ .Get "renderPageNum" }}") || 1;
// Loaded via <script> tag, create shortcut to access PDF.js exports.
var pdfjsLib = window['pdfjs-dist/build/pdf'];
// The workerSrc property shall be specified.
pdfjsLib.GlobalWorkerOptions.workerSrc = "{{.Site.BaseURL}}" + '/js/pdf-js/build/pdf.worker.js';
// Change the Scale value for lower or higher resolution.
var pdfDoc = null,
pageNum = selectedPageNum,
pageRendering = false,
pageNumPending = null,
scale = 3,
canvas = document.getElementById('the-canvas'),
ctx = canvas.getContext('2d'),
paginator = document.getElementById("paginator"),
loadingWrapper = document.getElementById('loadingWrapper');
// Attempt to show paginator and loader if enabled
showPaginator();
showLoader();
/**
* 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;
showContent();
if (pageNumPending !== null) {
// New page rendering is pending
renderPage(pageNumPending);
pageNumPending = null;
}
});
});
// Update page counters
document.getElementById('page_num').textContent = num;
}
/**
* Hides loader and shows canvas
*/
function showContent() {
loadingWrapper.style.display = 'none';
canvas.style.display = 'block';
}
/**
* If we haven't disabled the loader, show loader and hide canvas
*/
function showLoader() {
if(hideLoader) return
loadingWrapper.style.display = 'flex';
canvas.style.display = 'none';
}
/**
* If we haven't disabled the paginator, show paginator
*/
function showPaginator() {
if(hidePaginator) return
paginator.style.display = 'block';
}
/**
* If another page rendering in progress, waits until the rendering is
* finished. 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).promise.then(function(pdfDoc_) {
pdfDoc = pdfDoc_;
var numPages = pdfDoc.numPages;
document.getElementById('page_count').textContent = numPages;
// If the user passed in a number that is out of range, render the last page.
if(pageNum > numPages) {
pageNum = numPages
}
// Initial/first page rendering
renderPage(pageNum);
});
}
</script>
<!-- Finally, make the canvas more beautiful -->
<style>
#the-canvas {
border: 1px solid black;
direction: ltr;
width: 100%;
height: auto;
display: none;
}
#paginator {
display: none;
text-align: center;
margin-bottom: 10px;
}
#loadingWrapper {
display: none;
justify-content: center;
align-items: center;
width: 100%;
height: 350px;
}
#loading {
display: inline-block;
width: 50px;
height: 50px;
border: 3px solid #d2d0d0;;
border-radius: 50%;
border-top-color: #383838;
animation: spin 1s ease-in-out infinite;
-webkit-animation: spin 1s ease-in-out infinite;
}
@keyframes spin {
to { -webkit-transform: rotate(360deg); }
}
@-webkit-keyframes spin {
to { -webkit-transform: rotate(360deg); }
}
</style>
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