New `MimeType` fields in .desktop

[Bollinger, John C]

On Wednesday, February 17, 2021 6:30 AM, Thomas Kluyver <thomas at kluyver.me.uk> wrote:

On Tue, 16 Feb 2021, at 23:04, Bollinger, John C wrote:
But that does not imply that some applications should be able to claim to be more equal than others with respect to particular file types.

I think Jehan's idea is that applications should be able to claim to be *less* equal than others for a given mimetype, i.e. that GIMP could declare 'I can open JPEGs, but you should probably use something else by default'. Obviously, if the user explicitly set GIMP as the default handler for image/jpeg, it would override this priority.

Ok, on re-reading I can see that, but it is even less the GIMP's role to say "you should prefer other applications for opening JPEGs" than it is to say "you should prefer me for opening XCFs".  Desktop files still are not the right place to express policy.  The MIME Applications specification still describes the right place(s).

If neither the user nor the system has explicitly configured any default application for a given MIME type then it is not reasonable for the user to expect the default application for that type to be stable.  If that presents a problem for the user then XDG already has a solution: configure their preferred default explicitly.  If doing so is unreasonably difficult in some XDG-based environment then what is needed is better tools for that environment, not changes to the desktop file specification (and all the tools based on it).

Distinguishing things like 'native' and 'equivalent intent' filetypes seems tempting, but I suspect it would end up with a lot of awkward grey areas. If this is a problem worth solving, I'd be more inclined to make a numeric priority scale, something like the shared-mime-info database uses for assigning mimetypes to files (which allows e.g. ODT files to be recognised as ODT rather than general zip files).

The problem here is that the application to be used to open files of a particular type is not an inherent characteristic of the file type, nor of the set of available applications that can handle that type.  That's why the user has no good reason to expect stability of default application where no specific one is configured.  And it's also why the user is mischaracterizing the problem if they claim that the GIMP has taken over file associations for a given file type -- installing a desktop file simply does not do that, because desktop files express no policy.

Another approach to the stability issue (e.g. GIMP 'taking over' the JPEG mimetype) is for the desktop to fix it: if you open a JPEG file and there isn't already a default application for that, store whatever it uses as the default application, so it won't change unless the user manually changes the association or uninstalls that application. I think that could be done without changing any specs.

Yes.  This would be a manifestation of "better tools" such as I suggested above.  It would be an appropriate way to address the issue from the XDG side.


John


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From: xdg <xdg-bounces at lists.freedesktop.org> on behalf of Thomas Kluyver <thomas at kluyver.me.uk>
Sent: Wednesday, February 17, 2021 6:30 AM
To: xdg <xdg at lists.freedesktop.org>
Subject: Re: New `MimeType` fields in .desktop

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On Tue, 16 Feb 2021, at 23:04, Bollinger, John C wrote:
But that does not imply that some applications should be able to claim to be more equal than others with respect to particular file types.

I think Jehan's idea is that applications should be able to claim to be *less* equal than others for a given mimetype, i.e. that GIMP could declare 'I can open JPEGs, but you should probably use something else by default'. Obviously, if the user explicitly set GIMP as the default handler for image/jpeg, it would override this priority.

Distinguishing things like 'native' and 'equivalent intent' filetypes seems tempting, but I suspect it would end up with a lot of awkward grey areas. If this is a problem worth solving, I'd be more inclined to make a numeric priority scale, something like the shared-mime-info database uses for assigning mimetypes to files (which allows e.g. ODT files to be recognised as ODT rather than general zip files).

Another approach to the stability issue (e.g. GIMP 'taking over' the JPEG mimetype) is for the desktop to fix it: if you open a JPEG file and there isn't already a default application for that, store whatever it uses as the default application, so it won't change unless the user manually changes the association or uninstalls that application. I think that could be done without changing any specs.

Thomas

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