Re: Image-conversion shims

[Eli Zaretskii]

> From: Lars Ingebrigtsen <address@hidden>
> Cc: address@hidden,  address@hidden
> Date: Mon, 30 Sep 2019 06:12:03 +0200
> 
> > Actually, why not simply add the relevant extensions to
> > auto-mode-alist, causing them to invoke image-mode?
> 
> But when do we do that?  To determine what the list of supported formats
> is, we have to run `image-converter--probe' (etc).  But we don't know
> whether we need to do that until we know that we're going to load an
> unsupported image format.  :-/
> 
> I.e., we want ("*.webp" . image-mode) in auto-mode-alist, but we can't
> put it there before we've called "gm convert -list format"

I don't think I understand why we can't put the association in
auto-mode-alist before running "gm convert".  Please elaborate why.

> Uhm.  Perhaps map .wepb etc to a new image-mode-external that should
> just be a mode that inherits from image-mode, but would do nothing if
> the image-external-converter-mode has been toggled off?

Not "do nothing", but display an error message saying this image
format is unsupported, IMO.