[Interest] qt5 window setGeometry and move not work in wayland platform

Giulio Camuffo giuliocamuffo at gmail.com
Tue Aug 12 08:57:05 CEST 2014

2014-08-12 5:43 GMT+03:00 Steve (YiLiang) Zhou <szhou at telecomsys.com>:
> Thanks all you guys,
> So when it come to my issue, there is no way to adjust the position of
> my app which is developed with qt4 and upgraded to qt5 now ,right?
> Or can I create a wayland compositor and attach it to my qt window ?

No, there is no way.
Now the question is, what type of window is it? If it is a normal
application window you shouldn't try to place it automatically
anywhere, if it is something like a desktop panel we can work toward a
protocol for it.


> Thanks and Best Regards
> Steve Zhou
> -----Original Message-----
> From: Pekka Paalanen [mailto:ppaalanen at gmail.com]
> Sent: Tuesday, August 12, 2014 1:33 AM
> To: Nils Chr. Brause
> Cc: Giulio Camuffo; Rutledge Shawn; Steve (YiLiang) Zhou; Pier Luigi; Qt
> Project; wayland
> Subject: Re: [Interest] qt5 window setGeometry and move not work in
> wayland platform
> On Mon, 11 Aug 2014 18:49:50 +0200
> "Nils Chr. Brause" <nilschrbrause at gmail.com> wrote:
>> On Mon, Aug 11, 2014 at 12:57 PM, Giulio Camuffo
>> <giuliocamuffo at gmail.com>
>> wrote:
>> > The problem is that windows don't always have a meaningful position.
>> > If a window is shown on two outputs at the same time, maybe one of
>> > which a remote one, what is the window position? And what is the
>> > position of a window rotated 45 degrees?
>> >
>> Since the question about absolute positioning of windows comes up
>> every now and then (and probably will continue to do so for the next
>> few years), I thought about a possible way to fix this.
>> We could create a new interface, that puts an unrotated rectangle
>> around a window (which could be transformed in whatever way), that is
>> just big enough to fit in the whole window. The upper left corner of
>> this rectangle could then be defined as its "position", which could be
>> read and set by the user. The size of this rectangle could also be of
>> interest of the user, but of course not be set.
>> Since a window could be on multiple outputs, there would be the need
>> for one instance of this interface for every output and every window.
>> These could maybe be created and destroyed with events (whenever a
>> window appears or disappears on an output).
> Just... no.
> It is a very deliberate design choice to not expose window position.
> Your idea for a bounding box might seem like it could work at first, but
> what can an app actually do with it? The app won't have any idea of how
> the actual window is really mapped to an output. So far we are using
> rectangular outputs, but that does not need to be the case either.
> Window appearance is not limited to just one per output, in fact it has
> nothing to do with outputs at all. A window can appear any number of
> times anywhere, and with any transformation, if the compositor so
> decides. Any of these views may or may not allow user interaction, e.g.
> pointer input.
> You would have a lot of work communicating all that to the clients, even
> if you used the bounding box approach, and it would be full of races or
> round-trips, likely both.
> Yet another reason to not implement a coordinate based window
> positioning driven by clients is that clients do not know what else is
> on screen, what shape is the screen, etc.
> Just say no to all attempts for such generic positioning, and look at
> the actual use case behind it on *why* would this particular case want
> to do something like this, what is the real meaning behind it, and think
> how the compositor can do the job much better when it knows what the
> intention is.
> Thanks,
> pq
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