[PATCH] xdg-shell: add set_max_size request

Tue Apr 5 12:58:29 UTC 2016

On Mon, 4 Apr 2016 22:40:10 -0700 Bill Spitzak <spitzak at gmail.com> said:

> I think sending stepping size or aspect is not needed, but steps will 
> work only if the client can add a constant. Ie the width can be n*A+B 
> where A and B are specified by the client. The X11 version did not allow 
> a client to add a border that was not a multiple of the steps thick, 
> which made it pretty much impossible.

yes the x11 version DId allow this. that's what base size was. stepping was to
be done as base size + integer * step. read icccm.

of course when i mention stepping i do mean base + size in integer multiples
of a step as that is what icccm did and what existing apps have come to support
and use and... what is necessary.

> Aspect also needs the ability for the client to add a constant so a 
> frame can be put around the fixed-content area.

aspect does this too. in fact it was min and max aspect .... accounting for
base size too:

http://www.x.org/releases/X11R7.6/doc/xorg-docs/specs/ICCCM/icccm.html

x11 did get this right. aspect was really minimally useful. stepping was useful
for just about every terminal and min/max have been widely used by apps.

> Both of these I think are better handled by the client doing the resize 
> however, so only min/max should be sent.
> 
> On 04/04/2016 07:20 PM, Carsten Haitzler (The Rasterman) wrote:
> > 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
> >>>
> >
> >
> 
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-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at rasterman.com