Generating thumbnail of a pdf using PDF.js
I figured it out, the scale is not a parameter. The parameters are an object with field of scale that needed to be set.
function makeThumb(page) {
// draw page to fit into 96x96 canvas
var vp = page.getViewport({ scale: 1, });
var canvas = document.createElement("canvas");
var scalesize = 1;
canvas.width = vp.width * scalesize;
canvas.height = vp.height * scalesize;
var scale = Math.min(canvas.width / vp.width, canvas.height / vp.height);
console.log(vp.width, vp.height, scale);
return page.render({ canvasContext: canvas.getContext("2d"), viewport: page.getViewport({ scale: scale }) }).promise.then(function () {
return canvas;
});
}
Based on helloworld example:
function makeThumb(page) {
// draw page to fit into 96x96 canvas
var vp = page.getViewport(1);
var canvas = document.createElement("canvas");
canvas.width = canvas.height = 96;
var scale = Math.min(canvas.width / vp.width, canvas.height / vp.height);
return page.render({canvasContext: canvas.getContext("2d"), viewport: page.getViewport(scale)}).promise.then(function () {
return canvas;
});
}
pdfjsLib.getDocument("https://raw.githubusercontent.com/mozilla/pdf.js/ba2edeae/web/compressed.tracemonkey-pldi-09.pdf").promise.then(function (doc) {
var pages = []; while (pages.length < doc.numPages) pages.push(pages.length + 1);
return Promise.all(pages.map(function (num) {
// create a div for each page and build a small canvas for it
var div = document.createElement("div");
document.body.appendChild(div);
return doc.getPage(num).then(makeThumb)
.then(function (canvas) {
div.appendChild(canvas);
});
}));
}).catch(console.error);<script src="//npmcdn.com/pdfjs-dist/build/pdf.js"></script>