Re: yank-media: allow users to limit image types that can be inserted

[Robert Pluim <rpluim@gmail.com>]

>>>>> On Mon, 23 Sep 2024 18:54:25 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Robert Pluim <rpluim@gmail.com>
    >> Cc: Visuwesh <visuweshm@gmail.com>,  pinmacs@cas.cat,  emacs-devel@gnu.org
    >> Date: Mon, 23 Sep 2024 17:09:03 +0200
    >> 
    Eli> IMO, for users we already have what is needed: when we detect several
    Eli> formats, we show them to the user and ask him/her to tell us which
    Eli> format he/she wants to use.
    >> 
    >> But that requires user interaction. I think the original request could
    >> be summed up as "if the list contains image/png, donʼt ask me, just
    >> insert the image".

    Eli> That's not how I understand the request.  It was not always PNG, it
    Eli> was "sometimes PNG, but if so-and-so-happens, the JPEG" etc.

Yes, but the "so-and-so" is determined by a user option. So

1. Always prefer "png" -> user option == "png"
2. Want to choose between "png" and "jpeg" -> user option == ("png"
"jpeg")
3. All of the formats -> user option == nil

    Eli> I'm okay with having C-y select one format, if we can come up with
    Eli> some reasonable default, but we need to discuss the algorithm to
    Eli> arrive at that default.  And if the suggestion is to let users write a
    Eli> function to make that decision, then I'm squarely against that,
    Eli> because providing such functions is the job of Lisp programs.

I donʼt think putting a single format on C-y works for case 2. I guess
we could pre-populate the future history with one or more formats, but
I think the user option would work better.

The algorithm would be 'select all the formats in the available list
that are in the user option. If that results in an empty list, offer
the original list. If it results in a list that has one element, use
it, else offer the shortened list'

    Eli> And no one has explained yet why I would prefer PNG to JPEG or vice
    Eli> versa, btw.  The usual choices I'm familiar with is whether or not to
    Eli> preserve typefaces, colors, and other fancy attributes; regarding
    Eli> images, there's just a decision whether you want to paste the material
    Eli> as a picture or as some kind of text, whether rich or not.  So the
    Eli> background and the context for this request is still not clear to me.

I can definitely see a use for case 1 above: "donʼt bother asking me,
if png is available just use that".

Robert
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