PDF.js Previous/Next example

by spechackers

HTML

<script src="//mozilla.github.io/pdf.js/build/pdf.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.5.3/jspdf.min.js"></script>


<h1>PDF.js Previous/Next example</h1>

<div>
  <input type="button" id="addRectangle" value="Add Signature">

  <button id="prev">Previous</button>
  <button id="next">Next</button>
    <button id="byte">get byte array</button>

  &nbsp; &nbsp;
  <span>Page: <span id="page_num"></span> / <span id="page_count"></span></span>
</div>
<div id="generatePdf" style="display:none">
</div>
<canvas id="the-canvas"></canvas>

CSS

#the-canvas {
  border:1px solid black;
}

JavaScript

// If absolute URL from the remote server is provided, configure the CORS
// header on that server.
var url = 'https://raw.githubusercontent.com/mozilla/pdf.js/ba2edeae/web/compressed.tracemonkey-pldi-09.pdf';

// 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 = '//mozilla.github.io/pdf.js/build/pdf.worker.js';

var pdfDoc = null,
    pageNum = 1,
    prevPageNum = 1,
    pageRendering = false,
    pageNumPending = null,
    scale = 0.8,
    fCanvas = new fabric.Canvas("the-canvas", {
        selection: false
    }),
    pageHistoryCanvas = [],
    updatedPageHistory = [];
/**
 * Get page info from document, resize canvas accordingly, and render page.
 * @param num Page number.
 */
var pageHistory = {};

function getAllPdf() {
    var loadingTask = pdfjsLib.getDocument(url);
    loadingTask.promise.then(function(pdf) {
        var scale = 1.3;
        console.log("pdf 123", pdf)
        number_of_pages = pdf._pdfInfo.numPages;

        for (var i = 1; i <= pdf._pdfInfo.numPages; i++) {
            pdf.getPage(i).then(function(page) {
                var viewport = page.getViewport(scale);
                var canvas = document.createElement('canvas');
                //jspdf.addImage(imgData, 'PNG', 10, 10);
                document.getElementById('generatePdf').appendChild(canvas);
                
                canvas.className = 'pdf-canvas';
                canvas.height = viewport.height;
                canvas.width = viewport.width;

                context = canvas.getContext('2d');

                var renderContext = {
                    canvasContext: context,
                    viewport: viewport
                };
                var renderTask = page.render(renderContext);
                renderTask.then(function() {
                    $('.pdf-canvas').each(function(index, el) {
                ...