Achieving Integer Scaling through GPU composition

[Pekka Paalanen]

On Tue, 21 Jan 2020 14:16:09 +0200
Pekka Paalanen <ppaalanen at gmail.com> wrote:

> On Tue, 21 Jan 2020 16:53:51 +0530
> uday kiran pichika <udaykiran.pichika at gmail.com> wrote:
> 
> > What is present in Weston currently ?
> > 
> >  I know that there is scaling logic already present in the Weston
> > compositor in GL composition path.
> > 
> > *But just wanted to know whether it is Integer scaling as mentioned above ?
> > If not, does it possible to implement Integer Scaling in the compositor ?*  
> 
> Hi,
> 
> yeah, Weston's GL-renderer does pick between NEAREST and LINEAR sampling
> filters, but I think the conditions do not detect an integer factor,
> only unity factor, so you probably get NEAREST only without any
> scaling. This is something that could be fixed, but doing it properly
> will take effort.

I found some related issues filed:

- for computing an end-to-end transformation matrix for analysis so
  that decision between NEAREST and LINEAR takes all combinations into
  account: https://gitlab.freedesktop.org/wayland/weston/issues/47

- but since that is a high risk change, we need screenshooting based
  tests in the test suite:
  https://gitlab.freedesktop.org/wayland/weston/issues/52

The latter I have finally started on, now that
https://gitlab.freedesktop.org/wayland/weston/merge_requests/344 is
more or less done except for one Mesa bug. This depends on
https://gitlab.freedesktop.org/wayland/weston/merge_requests/287 which
should be ready to merge as soon as the release freeze is lifted.

However, we probably should write screenshooting tests for wp_viewport
first, as well.


Thanks,
pq
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