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

[Visuwesh <visuweshm@gmail.com>]

[திங்கள் செப்டம்பர் 23, 2024] Eli Zaretskii wrote:

>> Date: Mon, 23 Sep 2024 15:00:54 -0300
>> Cc: visuweshm@gmail.com, emacs-devel@gnu.org
>> From: pinmacs <pinmacs@cas.cat>
>> 
>> Before yank-media, I was using org-download [1], so I got used to just 
>> insert a screenshot with no question to answer (such as the type of the 
>> image).
>> 
>> Recently, I moved to yank-media, but to have the same functionality, I 
>> had to tweak it a little bit, full detail here [2].
>> 
>> I see utility on asking for the image/png and image/jpeg and here you 
>> have details why you would care about [3].
>
> This just says that PNG is always preferable to JPEG if both are
> available.  As I already said, I'm okay with the idea of having C-y or
> similar key to decide which format to use, and so what you are saying
> (and I agree) that it should always choose PNG if Emacs supports it.
>
> What I still do not understand is what would be the reason for the
> user to prefer JPEG over PNG.  More generally, if Emacs can support N
> formats out of those available in the clipboard, why would the user
> want to be shown only 1 < M < N out of them?

[ The more I think about this, the more I believe the choice of
  "preferred formats" will change depending on the scenario where
  yank-media is used.  In Org, I could see "don't bother asking me, just
  use PNG if available" could be useful.  But somewhere in HTML mode,
  "always ask me" could be the right choice.  ]

> Furthermore, your request was even more broad and general: it asked
> for some filtering infrastructure, and I'm still trying to understand
> why that would be needed.  The discussion to which you point on the
> Org list doesn't explain the rationale, either.
>
> Bottom line: I'm okay with offering two yank-media alternatives:
>
> (1) via a command that selects a single most appropriate format based
> on some (yet to be defined) algorithm; and

What about a user option yank-media-preferred-mimetypes which is a list
of mimetypes that the user would like to always opt for, given the
choice?

. If there is only mimetype available, then we simply choose that type's
  handler without consulting the user option.

. If there are more than one mimetype available, we pick those mimetypes
  that are in the user option.

    . If more than one mimetype from the user option is matched, we ask
      the user what format, among the matched, they want to use.
    . If none of the mimetypes available match those in the user option,
      we again ask the user to choose from all available formats (we
      delegate to option (2) below)


> (2) via showing the list of all the formats that the running Emacs
> supports and asking the user to choose one.

This is what we already have so nothing to be changed.

> If we can agree on this, we should now discuss those algorithms for
> selecting a single media type.
>
> Thanks.