Neat, there's a multi-user mode: http://jspaint.ml/#session:test
Try drawing programmatically:
tools[7].paint(ctx, x, y);
$canvas.trigger('change.session-hook');
undoable(function(){
for(var i = 0; i < 1; i += 1/10000){
var angle = i * 500;
var dist = i * 2;
var x = canvas.width * (1/2 + Math.cos(angle) * dist);
var y = canvas.height * (1/2 + Math.sin(angle) * dist);
tools[7].paint(ctx, x, y);
}
});