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

[Adam Jackson]

On Tue, 2018-02-06 at 12:21 +0100, Michel Dänzer wrote:
> On 2018-02-05 09:08 PM, Adam Jackson wrote:
> > On Mon, 2018-02-05 at 12:53 +0100, Michel Dänzer wrote:
> > 
> > > > > The inability to queue a presentation to the next MSC is more of a step
> > > > > back compared to the status quo.
> > > > 
> > > > I'm about to go write up some ideas I'm working on that will make it
> > > > possible to more regularly display redirected windows at the target MSC,
> > > > and to reliably report which MSC the window contents were displayed at.
> > > > 
> > > > I mention this because I think there are some parallels between that
> > > > work and this.
> > > 
> > > Not really seeing that. Composite isn't involved with Xwayland.
> > 
> > This is not entirely true, I don't think. In rootless mode you only get
> > a wl_surface for manually-redirected windows; if you don't have a
> > compositing window manager running, you don't get X windows.
> 
> Oh, I wasn't aware of that, thanks.
> 
> Still, the Xwayland DDX pushes window contents to the Wayland compositor
> directly, without a round-trip to the compositing manager, right?

Right. The subwindow redirection in the Xwayland display is just to get
the windows into their own pixmaps, which Xwayland backs with wayland
surfaces. The compositor doesn't need to bother with glXBindTexImage or
even CompositeNameWindowPixmap, it's already got a wayland handle.

- ajax