[PATCH 14/19] present: Add window flip mode

[Roman Gilg]

It's because of what you made me aware of in the previous patch set:
the window original pixmap needs to have the updated content from the
flip Pixmap, otherwise for example screenshot applications won't work
anymore. I tested it with xwd.

I also tried to not copy, but set the window pixmap to the flip
pixmap. The problem I encountered here, is that the window original
pixmap can be controlled by the client. And when unflipping and
restoring the original pixmap, this already might have been deleted by
the client.

There might be ways to circumvent this problem, I have a few ideas,
but I decided to first go for a simple implementation by just copying
the pixmap content in order to decrease the overall complexity of the
patch set.

On Thu, Feb 1, 2018 at 4:33 PM, Michel Dänzer <michel at daenzer.net> wrote:
> On 2018-01-29 02:34 PM, Roman Gilg wrote:
>> In contrast to screen flip mode this mode currently:
>> * supports flips per windows (these windows need to have the same size
>>   as their parent windows with the same pixmap),
>> * always copies back to the original pixmap instead of pure flips, while
>>   giving the driver the flip pixmap provided by the application,
>
> What are the reasons for always copying back to the original pixmap? I
> don't think that should be necessary.
>
>
> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer