Re: USPosition vs. PPosition with Virtual viewports

[Carsten Haitzler (The Rasterman) <raster rasterman com>]

On Tue, 25 Oct 2005 09:48:18 -0500 Sasha Vasko <sasha aftercode net> babbled:

> 
> 
> Carsten Haitzler (The Rasterman) wrote:
> 
> > On Mon, 24 Oct 2005 22:07:19 +0200 Lubos Lunak <l lunak suse cz> babbled:
> > 
> > 
> >>Dne čt 20. října 2005 03:29 Carsten Haitzler napsal(a):
> >>
> >>>On Wed, 19 Oct 2005 15:30:00 -0500 Sasha Vasko <sasha aftercode net> 
> >>
> >>babbled:
> >>
> >>>>There is a certain ambiguity in how geometry should be specified by
> >>>>user, when Window Manager is supporting virtual viewports. This surfaced
> >>>>  as the result of GIMP abuse of USPosition flag which is outlined here
> >>>>
> >>>>: http://bugzilla.gnome.org/show_bug.cgi?id=319099
> >>>>
> >>>>Basically, for user to be able to place , say, a term window into
> >>>>arbitrary viewport on the desktop, using just a command-line options -
> >>>>geometry must be specified in relation to the desktop origin, there is
> >>>>no other way around it. Therefore it is a duty of a Window Manager to
> >>>>always treat USPosition in relation to a desktop origin.
> >>>>
> >>>>On the other hand, as apps itself may not be aware of existence of
> >>>>virtual viewports, and even if they do - its not possible to reliably
> >>>>take it into consideration - PPosition must always be treated in
> >>>>relation to the current viewport's origin.
> >>>>
> >>>>Now this is not a transparent conclusion for anyone not involved with
> >>>>window management to a certain depth, and therefore I suggest that this
> >>>>should be clarified in specs under "Desktop/workspace model" subsection
> >>>>of Implementation notes.
> >>>>
> >>>>Anybody wants to comment on that ?
> >>>
> >>>this is a tough one. most existing apps will see BOTH USPosition and
> >>>PPosition as ROOT window relative co-ordinate hints (out of practicality
> >>>and a loong history). changing this will mean breakage of at least some
> >>>apps. but this also makes using a virtual desktop + movable viewport a bit
> >>>of a nightmare,as i assume you are discovering.
> >>>
> >>>basically a lot of wm's have ignored pposition in the past due to abuse by
> >>>apps (like netscape) and thus many aps have moved to abusing usposition
> >>>instead (though they do it better than netscape did). i know that
> >>>personally im gettigng to the point of encouraging users to use the lock
> >>>and override features of the wm to say "dont listen to the apps request for
> >>>position, size etc. use mine and ignore the app" as its geenralyl more
> >>>reliable :) thus in that scneario - the wm can choose to put the app where
> >>>it was last - relative to the virtual desktop co-ordinates, not the
> >>>viewport. :)
> >>
> >> Does somebody think it wouldn't be completely naive to try to fix this 
> >>USPosition/PPosition madness by adding some kind of I-do-it-properly
> >>property that both WMs and apps could set?
> >>
> >> Qt also sets both US and P positions, because of the reasons listed above,
> >>in order to work around broken old WMs and whatnot, and I've run already
> >>into this a couple of times with KWin. Qt e.g. always places dialogs, and
> >>although KWin has much better placement algorithm it's simply not of much
> >>use because of US and P position set. I even tried to actually ignore those
> >>flags in general for dialogs but that wasn't that good idea either :( . And
> >>having the user to manually set setting for every app is not really a
> >>solution.
> > 
> > 
> > agreed - for the aqverag user. power users when they get annoyed enough will
> > set it. :)
> > 
> > as for a new hint - i don't see this as a bad idea, but if we were to
> > propose such a hint - may i suggest we expand it a bit. we should:
> > 
> > 1. provide another client window id (that should be mapped at the time) to
> > place RELATIVE to. (if not provided root is assumed). 2. a flag to indicate
> > if the position is screen relative (viewport relative) or desktop relative.
> > 3. the ability to provide absoloute position offsets relative to the
> > top-left (or any other corner) but ALSO relative percentage offsets (as a
> > percentage of the relative window mentioned in 1. and its geometry at the
> > time the window is mapped.
> > 
> 
> Woa! Hold On! :)
> That's a whole different aspect you are bringing in here.
> As I see it we have two problems here now :
> 1) Let client apps know how Window Manager handles USPosition and PPosition
> 2) Possibly allow clients to request placement in relation to desktop
> origin or another window ( which is what you are bringin up ).

well i added the "relative to another window" thing as an answer for "kwin does
better placement than the apps" - often apps want their dialog up - but
centered on their OWN "main" window for example. this can be used in many ways
- wm's can still ignore it too, but it gives the app power to say more :)

> As to first problem I agree with Lubos, and here is what we could do :
> 
> _NET_PLACEMENT, ATOM[]/32
> 
> With possible atoms :
> 	_NET_PPOSITION
> 	_NET_USPOSITION
> 	_NET_USPOSITION_IS_DESKTOP_RELATIVE
> 
> For the second problem, I'd say it will be good enough if we'll allow
> clients to request position in relation to its other windows, but not
> root or viewport, as those should be dictated by window manager's own
> policy. Even that is to much IMHO. and I think we need to start a second
> thread for that discussion.

i definitely think the app NEEDs to be able to say if its requested position is
relative to the screen - the glass of the monitor, OR relative to a desktop.
often borderless windows like panels, and maybe temporary similar windows want
to position themselves relative to the SCREEN and possibly maintain that
positionr egardless where the virtual desktop viewport goes (ie sticky) - but
this is a different kind of sticky i guess. then there is requested position
but it may be relative to the overall massive desktop, or the currently visible
section. you could use sticky to try and indicate this - but i dones see any
harm in providing more information and allowing the wm to figure out what it
wants to do about it. :)

> 
> Sasha Vasko
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> 


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The Rasterman (Carsten Haitzler)    raster rasterman com
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