[Development] Moving QDesktopServices from Gui to Core?

[Marc Mutz]

Hi,

Juha is currently improving the OAuth implementation in QtNetworkAuth. 
The protocol involves launching the system browser to get an access 
code, in turn used to get access tokens with which services can then be 
accessed.

OAuth therefore requires a UI to run the browser in, but not necessarily 
a _G_UI (the system browser could be lynx). Even if a CLI tool like a 
mail fetcher, backup program, or VPN client will eventually launch 
Firefox or Chrome, I think it's too much to ask to link to QtGui just to 
do the equivalent of exec xdf-open <url>.

I've looked at the implementation of openUrl(), and the only 
Gui-dependency is on the platform helpers. The handler registration is 
only using Core functionality.

I would therefore propose to move the services code from Gui to Core 
(QTBUG-125085), so QtNetworkAuth can access it w/o incurring a Gui 
dependency.

After a quick look, I can see two ways to do that:
- keep the platform handling code in the platform helpers, incl. Gui 
dependency, and only move the handler registration to Core
- move the platform url handlers out of the platform helpers into (a 
plugin for) Core

The first would enable users to write their own handlers w/o Gui 
dependency, but has the disadvantage that the code behaves differently, 
depending on whether QtGui is loaded or not.

The second would be more work, but with consistently better user experience.

Is there a reason other than history for the openUrl handlers to be in 
the platform handlers? We have XDG-code in QtCore already (mime types), 
so we should have all the information in Core already to implement the 
functionality, should we not?

Thanks,
Marc

-- 
Marc Mutz <marc.mutz at qt.io> (he/his)
Principal Software Engineer

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