PDF.js Previous/Next example

by magikMaker

HTML

<script src="//mozilla.github.io/pdf.js/build/pdf.js"></script>

<header>
  <button id="prev">Previous</button>
  <button id="next">Next</button>
  &nbsp; &nbsp;
  <span>Page: <span id="page_num"></span> / <span id="page_count"></span></span>
</header>

<div class="container">
  <canvas id="canvas-page-a"></canvas>
  <canvas id="canvas-page-b"></canvas>
</div>

CSS

*,
*::after,
*::before {
  box-sizing: border-box;
}

body,
html {
  background-color: #aaa;
  height: 100%;
  padding: 0;
  margin: 0;
}

button {
  background-color: #369;
  border-radius: 5px;
  color: #eee;
  font-weight: bolder;
  outline: none;
  padding: 2em;
}

header {
  background-color: #eee;
  border: 1px solid #333;
  margin-bottom: 1em;
  padding: 1em;
}

.container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-evenly;
}

canvas {
  background-color: #eee;
  border: 1px solid #333;
  box-shadow: 3px 3px 3px 0px rgba(33, 33, 33, 0.75);
  height: 50vw;
  min-width: 200px;
  width: 40vw;
  
}

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,
    pageRendering = false,
    pageNumPending = null,
    scale = 0.8,
    canvas = document.getElementById('canvas-page-b'),
    canvasA = document.getElementById('canvas-page-a'),
    ctxA = canvasA.getContext('2d'),
    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;
      } else {
      renderPageA(num - 1);
      }
    });
  });

  // Update page counters
  document.getElementById('page_num').textContent = num;
}

function renderPageA(num){
	if(num < 1) {
  	return false;
  }
  
  console.log('render page A', num);
  
  pdfDoc.getPage(num).then(function(page) {
    var viewport = page.getViewport({scale: scale});
    canvasA.height = viewport.height;
    canvasA.width = viewport.width;

    //...