Re: [RFC] _NET_WORKAREA and Xinerama

[Sasha Vasko <sasha aftercode net>]

Havoc Pennington wrote:
> On Fri, Mar 14, 2003 at 09:27:57PM -0800, Rob Adams wrote:
>
> > I'm working on an implementation of this in metacity.  The thing that
> > worries me right now is the "sqeeze play".
> >
> > Two corner panels on opposite corners.  Put a window between them.  Then
> > grow the corner panels until they meet in the middle.
> >
> > I'm thinking that perhaps when two struts get two close to each other,
> > the WM should merge them together.  This would result in the window
> > "squirting" out when the struts are merged into one strut.  Is this the
> > sort of behavior people had envisioned with regard to partial-width
> > struts?


> I'd envision that the window squirts out as soon as a strut overlaps
> it.

Consider this scenario: You open a new window, and that increases the 
size of the panel, which should increase the size of the strut and 
relocate windows to make space for newly sized panel. Then you close 
this window and that reduces the size of the panel. Should you relocate 
windows back where they were prior to increase in size of the panel ?

It might not be a good idea to sqeeze out windows upon the change in 
strut size. In fact it may be a better approach to apply new strut size 
only when windows are moved/resized, new window is getting placed or 
window is maximized.


> i.e. the constraint on the window top is that it may not cross a strut. so
> say we have:
>
> ======================================================== screen top
>
>   strut A
> ----------        strut B
>                  -------          strut C
>                               --------------
>
>              ----------------------
>             |    top of window     |
>             |                      |
>
> I'm not sure what the right algorithm is. It is especially scary in
> light of constraints.c already being scary. ;-)
>
> The thing is that here the width and position of the window affects
> what the constraints are. If the window is just moved straight up,
> then it's constrained by the lowermost strut it overlaps, strut
> C. However, if you move it left a bit OR resize it narrower, it would
> ignore strut C.

Very simple: compute a set of rectangles that are suitable for placing 
window in them and then select one using best-fit criteria, such as:
1) if window is being relocated without user interaction - then select 
rectangle to minimize distance between new and old window location
2) if window is relocated by user - then select rectangle that minimizes 
distance between new position and user requested position.

Also since we are talking about extending struts protocol, maybe its 
better to go all the way and make strut to be a rectangle, and not just 
a portion on the side of the screen?


Sasha