On Sun, 28 Apr 2019 21:52:34 +1200 Scott Anderson <scott.ander...@collabora.com> wrote:
> >>> This commit makes it so a wl_output.done event is guaranteed to be sent > >>> with a > >>> xdg_output.done event. > >> > >> Humm, I am not sure I like changing xdg-output to rely on another protocol > >> event, it's looks like a weird mixup to me... > > > > As noted below, this is idiomatic in the Wayland protocol. The > > wl_surface.commit request applies xdg_surface's state. > > Just to expand on this with my two-cents, many of the Wayland protocol > objects are conceptually extensions of other protocol objects. > xdg_surface extends wl_surface, xdg_toplevel extends xdg_surface, and if > we want to go cross-extension-protocol, xdg_toplevel_decoration extends > xdg_toplevel. > > While this is 4 protocol objects, we're conceptually just dealing with a > single surface's state. The protocol objects are simply adding new > interfaces to that surface and are meaningless on their own. We want to > keep that surface's state consistent, so they need to share the same > synchronisation to ensure atomicity, which includes wl_output.commit and *wl_surface.commit > xdg_surface.configure. > > So there is certainly precedence for relying on the events and requests > of other protocols. > > Now applying that to xdg_output, it's simply adding interfaces to an > wl_output object, and isn't meaningful on its own. It only makes sense > to synchronise it properly with wl_output. Hi, FWIW, I fully agree with Scott here. xdg_output may provide a super-set of properties, but it cannot exist without the base object wl_output, and the interpretation of xdg_output being an additional interface to what the wl_output originally represents is appropriate. Wayland core protocol (wl_output) cannot ever depend on an extension (xdg_output), so it does not make sense to say that wl_output property changes would emit an xdg_output.done event. Thanks, pq
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