[PATCH] xdg-shell: add set_max_size request

[Carsten Haitzler (The Rasterman)]

On Mon, 04 Apr 2016 19:44:58 +0000 "Jasper St. Pierre" <jstpierre at mecheye.net>
said:

> I think min/max hints are acceptable in xdg-shell.

i agree. they are realistic things a apps have as constraints on their content.
knowing in advance what those constraints might be can make life for a
compositor much easier.

eg. if you set max size and its < screen size (or whatever size a maximized
window might be in the wm) the em/compositor can disable the maximize action
entirely.

already pointed out - tiling wms can alter their layout policy for content eg
placing content that has a small max height along the bottom or top of your
screen.

yes - asking for max size opens up min size too.

i would argue size stepping is kind of needed too - the case of a tiling wm
with eg:

+---+---+
| 1 | 2 |
+---+---+
| 3 | 4 |
+---+---+

if all the windows are terminals whose content is only correct at "size units"
(because otherwise the terminal pads out N pixels without expanding the
terminal grid there just wasting space), then when resizing the dividers across
the middle of the screen -0 dragging them up/down or left/right a wm might want
to limit the sizing to steps of N pixels assuming all clients involved share a
common size step (the implied default is 1 pixel). without this hint a wm is
unable to do anything sensible here.

i am not saying the wm MUST follow the hints. there are impossible cases. one
window (1) uses size step 10x10, and (2) uses 9x9... there are very few points
where they "agree". (at 0x0 +base, 90x90 + base , 180x180 + base etc.) so as a
wm i would assume it would only follow stepping if all steps are multiples of
each other eg 3x3, 6x6, 9x9 or 2x2, 4x4, 6x6, 8x8 etc. ... (or are the same).
clients still have to deal with arbitrary sizing in some sensible way.

aspect hints tho are rather painful. they assume a single piece of content that
has to retain aspect (eg 1 movie). i'd personally not want to go this far. :)

> On Mon, Apr 4, 2016, 12:33 PM Mike Blumenkrantz <
> michael.blumenkrantz at gmail.com> wrote:
> 
> > On Mon, Apr 4, 2016 at 3:30 PM Olivier Fourdan <ofourdan at redhat.com>
> > wrote:
> >
> >>
> >> Hi Mike,
> >>
> >> ----- Original Message -----
> >> > [...]
> >> >
> >> > Yes, I know you are not currently advocating for it, but you've proved
> >> my
> >> > point--others will see this go in and then they will push for it. Adding
> >> > any form of size hints is a slipper slope which leads to more size hints
> >> > imo.
> >>
> >> My turn to play the Devil's advocate then :-)
> >>
> >> And even if we end with more hints eventually, what is wrong with that?
> >>
> >> I reckon if we had hints in X11, it's also because people have had a need
> >> for such a mechanism...
> >>
> >> Cheers,
> >> Olivier
> >>
> >
> > Sure, and as I said, I have no issues with that if a separate (optional)
> > protocol  is created for it. I just don't think that the best place for it
> > is in xdg-shell, which is supposed to be just a small core set of features
> > that are absolutely required in order to create a usable desktop
> > environment.
> > _______________________________________________
> > wayland-devel mailing list
> > wayland-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/wayland-devel
> >


-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at rasterman.com