On Fri, 19 Sep 2014 14:24:50 -0400
Hongze Zhao <[email protected]> wrote:
> Hi All,
>
> I am using weston-1.5.X and I am curious about the which part of code that
> maintains the position of each surface.
>
> When multiple clients connects to the weston server and initializes its
> surface, the surfaces are not showed in the exactly same position
> initially, which means someone is maintaining the position of the
> each surfaces to avoid the newly created surfaces from being showed in the
> same position. I am wondering if anyone could give me some hint where I can
> look for the code doing this job.
It is not maintained in any single place.
- A wl_surface is usually bigger than appears on screen, because
windows may have shadows that add transparent margins. xdg-shell
defined "window geometry" which defines the extents of "the
window".
- weston_surface does not define a position at all, weston_view
does, and there can be several views for a surface. That means a
window may have multiple positions. It is up to the shell to
decide which one is "the" position.
- weston_view::geometry.x,y is the basic translation part, but the
matrices added to the transformation_list may also modify the
position.
- if weston_view::geometry.parent is set, the surface is positioned
relative to the parent, not in absolute coordinates. I forget if
the parent matrix is in the transformation_list.
If you want to find the position in absolute coordinates given a
weston_view, use weston_view_to_global_{float,fixed}() function on
all the corners of the window. It is not enough to inspect only the
top-left corner, as the window may be rotated. It is also usually
not useful to inspect the surface point (0,0) because of the
possible shadow margins - you should use the window geometry
instead.
You might inspect weston_view::transform.boundingbox, that will not
take the window geometry into account.
But like Jonas said, the desktop shell does not inspect any of
this. It just randomizes the initial positions.
Thanks,
pq
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