bug#51596: image-transform-resize has inconsistent semantics wrt scaling up/down

[Stefan Kangas <stefan@marxist.se>]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Stefan Kangas <stefan@marxist.se> writes:
>
>> "Fit height" and "fit width" both scales an image up or down, but "fit
>> height and width" only scales an image down.  Is that intentional?
>
> Yes, I think so?  The point of the latter is that too-big images are
> pretty useless -- you want to scale them down so that you can actually
> see them.  But it doesn't therefore follow that you want to scale tiny
> icons up to fill the screen.

Right, and that's a valid use case of course.  I still find the
interface inconsistent, as the naming scheme suggests that these three
options should behave similarly.

I made a quick review of other image viewers:

emacs                  gthumb          geeqie                eog
-----                  ------          ------                ---
fit height and width   Automatic       Zoom 1:1              Best fit
<missing>              Fit to window   Fit image to window   <missing>
fit to width           Fit to width    <missing>             <missing>
fit to height          Fit to height   <missing>             <missing>

How about renaming "fit height and width" to something that suggests
that it behaves differently from "fit to width" and "fit to height", and
then adding a new option "fit to window" that scales up or down as
needed?

Perhaps we could even have a "smart" option that only scales images up
larger than some height and width, and otherwise leaves them in their
original size.  That's probably the one I would like to use, now that I
think about it.  (I usually prefer to scale images up, but as you point
out it's pretty useless to scale small icons to fit the window.)