How to implement uploading files to a site with location spoofing?

Question

Browsers

I am filling my site with goods now and I needed an addition of such a plan (google did not give a result, maybe I was looking for it in the wrong way):

There is a site with an ecwid admin panel, but this should also be relevant for the admin panels of other sites, this is for the future. In general, the point is to load the products of any admin panel with any photo engine using links to sites, and not from a local source. The problem here is that not every engine, especially self-written, will allow you to complete the download directly from links from the Internet.

That is, you need such an add-on for ff or another browser that would replace or emulate downloading from a local source for downloading from a link to a file on the Internet.
Roughly speaking, the problem comes down to replacing the dialog box for opening a file with a window with inserting a link to download a photo from the Internet from the link, or something like that. Just download the pictures to the local machine, then upload them again from the local disk to the site, well, this is not ice ... when there should be an option for direct upload via a link directly to the site.
Perhaps someone faced a similar problem and can tell something on the topic.

Thank you very much for your help.

PS Posted at the request of one person

Answer 1

Now I will tell you one secret, only to anyone!
In the dialog for selecting a file to upload, which opens the browser in the path bar, you can write the URL of the remote file. And everything will load itself :)

Answer 2

The scooter is not mine!!! I just posted an ANNOUNCEMENT!
The browser plugin will not be able to emulate the data. you will need to first download the image from the source, encode it, and only then attach it to the POST request. the same as the option to download and save by hand, only the process will go in the background. fiddle more with the plugin itself.
And to finish the engine is not so much.
Detect if it's a url
Set curl on the link
Resume the normal work of the image processing script (crop, scale, compress)