Canvas, disable image download [duplicate]

Answer 1

This code may help:

document.body.addEventListener('contextmenu', function(e) {
  e.preventDefault();
});

This will disable context menu on a page. Instead of document.body you can write your canvas element:

document.getElementById('map_element').addEventListener('contextmenu', function(e) {
  e.preventDefault();
});

where map_element is ID of the canvas element

UPDATE:

but even this protection might be broken by executing in browser console:

document.getElementById('map_element').toDataURL('image/jpeg');

I think the right decision is to download from server small regions of the map part by part