Use-case for CTRC background color?

Harish Krupo harish.krupo.kps at
Fri Nov 16 08:31:06 UTC 2018

Hi Emre,

Thanks for replying.

Ucan, Emre (ADITG/ESB) <eucan at> writes:

> Hi,
> Clients should not control a property of a wl_output directly.
> You can add a new property to the weston-config for output section, so that weston can enable a specific color for an output at startup.

Sorry, I should have been specific. The user would set the color here
[1]. The desktop client would then check if the output (output wrapper)
has advertised the background color capability. If so, it would then set
the color using a different request as compared the the set_background
request which already exists in weston-desktop-shell. This interface
would take R, G, B colors instead of a buffer.

Thank you
Harish Krupo


>> -----Original Message-----
>> From: wayland-devel <wayland-devel-bounces at> On
>> Behalf Of Harish Krupo
>> Sent: Freitag, 16. November 2018 04:57
>> To: wayland-devel at
>> Cc: pekka.paalanen at; daniels at
>> Subject: Use-case for CTRC background color?
>> Hi,
>> This patch [1] introduces the background crtc color property. This
>> property is available on some display controlers and allows setting a
>> non-black colors for pixels not covered by any plane (or pixels covered
>> by the transparent regions of higher planes). I would like to implement
>> a userspace consumer of this propery in weston.
>> The primary use case for this property is for compositors to set the
>> background color. I am planning on implementing it as follows:
>> * The desktop client would bind to the weston-desktop-shell protocol.
>> * The weston-desktop-shell would have a wrapper for the wl_output
>> object.
>> * The client would create a wrapper for wl_output (maybe called
>> weston_desktop_shell_output).
>> * This output interface will have an event to advertise its capability
>> to set the background color directly.
>> * Once the capability is found and if the client wishes to set the
>> background color, it would use the set_background_color request in the
>> weston_desktop_shell_ouput interface to set the color by providing the
>> r,g,b primaries.
>> I have not completely thought this through, so I am sure this is
>> incomplete and will require modification. I would like to know your
>> comments and suggestions on the above method (or even if we could use
>> this property differently) before I begin the implementation.
>> Thank you
>> Regards
>> Harish Krupo
>> [1]
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