How to implement OSD overlay in Wayland/Weston

[Guillermo Rodriguez]

Hello,

Indeed I looked into xdg-foreign but it does not seem to be supported in Weston.

Other ideas?

Guillermo

El mar., 19 nov. 2019 a las 10:21, Ilia Bozhinov (<ammen99 at gmail.com>) escribió:
>
> Hi,
>
> I am not entirely familiar with your setup, but you can try to use a combination of:
>
> 1. Setting your on-top window's input region to empty as you already have tried.
> 2. Use xdg-foreign protocol to set the main window as parent of your on-top window.
>>
> This will work on all compositors that support xdg-foreign, however I am not sure whether weston supports it.
>
> Regards,
> Ilia Bozhinov
>
> On Tue, 19 Nov 2019, 09:53 Guillermo Rodriguez, <guillerodriguez.dev at gmail.com> wrote:
>>
>> Hi all,
>>
>> This is a follow up to my earlier email "Let pointer events pass through".
>>
>> I have an use case where there is one full screen application (I'll
>> call this the "main" application) and I need to show a OSD overlay on
>> top of it. The OSD overlay is actually based on GStreamer (think PiP)
>> and is managed by a different process.
>> The OSD overlay should not handle pointer events; these should pass
>> through to the main application, which knows how to handle them.
>>
>> I am not sure how to approach this in Wayland/Weston. I have
>> considered the following:
>>
>> 1.
>> Use wl_surface::set_input_region so that pointer events are not
>> delivered to the OSD overlay, but instead pass through and are handled
>> by the main application.
>> This "almost" works, however when the main application receives the
>> event, Weston brings it on top, thus hiding the OSD overlay.
>> I searched for a way to specify that a given surface should always
>> stay "on top". This does not seem to be supported in Wayland.
>>
>> 2.
>> Setup things so that the OSD overlay is not an additional top level
>> surface, but a child surface owned by the main application.
>> This would mean having the main application create a child surface for
>> the OSD, and pass this surface to the OSD process.
>> In X this could be achieved by passing a Windows ID. In Wayland
>> apparently it is not possible to share surfaces between processes.
>>
>> 3.
>> Let the OSD overlay actually handle pointer events, but "send" them to
>> the main application.
>> In X this could be achieved with XSendEvent. In Wayland apparently it
>> is not possible to have one process send events to another process.
>>
>> Not sure what else to try.
>>
>> Any ideas? Either ways to make one of the above work, or new approaches...
>>
>> TIA,
>>
>> Guillermo Rodriguez
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