yes, I know, that’s what I observed initially and what the code shows.
I just wrote what I expected as an unbiased user, and I still wonder why the page URL isn’t derived from $_SERVER[‘HTTP_REFERER’] if urlref is not empty - I don’t see the connection between url and urlref.
As I wrote initially, I can easily pass the referrer when I construct the piwik image url e.g. with php, and it would be nice it Piwik would guess the page URL if I don’t pass it.
But - as I wrote also - there might be reasons against it. IOW reasons for the code checking both url and urlref for “empty”. Maybe it is a good idea to put this reason in the existing comment in the code.