PDF.js Previous/Next example

by Miguel Roman

HTML

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

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

<div>
  <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>
  &nbsp; &nbsp;
  <button id="add">
    Add signature
  </button>
</div>

<canvas id="the-canvas"></canvas>

CSS

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

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('the-canvas'),
    ctx = canvas.getContext('2d'),
    rect = {},
    drag = false,
    drawing = false;

canvas.addEventListener('mousedown', mouseDown, false);
canvas.addEventListener('mouseup', mouseUp, false);
canvas.addEventListener('mousemove', mouseMove, false);
document.getElementById('add').addEventListener('click', addSignature);

function addSignature(e) {
	drawing = true;
  document.getElementById('add').disabled = true;
}

function mouseDown(e) {
	if (!drawing) return;
  rect.startX = e.pageX - this.offsetLeft;
  rect.startY = e.pageY - this.offsetTop;
  drag = true;
}

function mouseUp() {
	if (!drawing) return;
  drag = false;
}

function mouseMove(e) {
	if (!drawing) return;
  if (drag) {
    rect.w = (e.pageX - this.offsetLeft) - rect.startX;
    rect.h = (e.pageY - this.offsetTop) - rect.startY ;
  	ctx.beginPath();
    ctx.rect(rect.startX, rect.startY, rect.w, rect.h);
    ctx.stroke();
  }
}


/**
 * 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:...