Printing with only pdf.js (without the viewer) - pdf.js

Question

There are already two questions about this, but the specific question remains unanswered.
I have a multipage pdf document. I have successfully used pdf.js core to write a page to a canvas. Soon I'm sure I'll have prev / next paging functions so I can see each page. See my existing code at bottom. The reason I am not using the viewer is because my boss doesn't like it. He wants a totally different interface that is extremely minimal and simple, and I have successfully built that minus the full print, ala:
Please note that there is no url to a pdf document. I get the data from a api call that returns base64 data. My code loads the data from an array into the pdf.
My current print function seems like a hack, and I know it isn't how the pdf.js viewer does it. I want to print the pdf as the pdf.js viewer does; meaning, true to form. I'm not sure if converting each page to an image gets it done, but I remain open to suggestions.
The problems are: extra margin not in the original document, and headers / footers. Not to mention pdf documents actually can contain different page layouts and sizes for each page and throwing an image tag into a new window completely ignores that.
I did check the pdf.js examples on Github. None of them are print and they say that using the pdf.js without the viewer is not supported and we are on our own if we do that (is that right?). Anyway, nothing on Google that I could find.
var pdfDocument;
var canvas;
// load from base64 data
loadPdfDocument(file.Content);
function print() {
var doc = document.getElementById('document');
var html = doc.innerHTML;
if (canvas)
html = "<img src='" + canvas.toDataURL() + "'";
var win = window.open('', '', '');
win.document.write(html);
win.document.close();
win.focus();
win.print();
win.close();
};
function loadPdfDocument(base64Data) {
PDFJS.disableWorker = true;
var pdfData = base64ToUint8Array(base64Data);
PDFJS.getDocument(pdfData).then(function(pdf) {
canvas = document.getElementById('pdfPage');
pdfDocument = pdf;
loadPdfPage(1);
});
}
function base64ToUint8Array(base64) {
var raw = atob(base64); // convert base 64 string to raw string
var uint8Array = new Uint8Array(raw.length);
for (var i = 0; i < raw.length; i++) {
uint8Array[i] = raw.charCodeAt(i);
}
return uint8Array;
}
function loadPdfPage(pageIndex) {
pdfDocument.getPage(pageIndex).then(function(page) {
var scale = 1;
var viewport = page.getViewport(scale);
var context = canvas.getContext('2d');
canvas.height = viewport.height;
canvas.width = viewport.width;
page.render({
canvasContext: context,
viewport: viewport
});
});
}
<div id="document">
<canvas id="pdfPage" />
</div>