[libcamera-devel] Compound libcamera controls?

[Naushir Patuck]

Hi,

I've been looking to add some controls related to returning out focus
statistics via libcamera controls.  The simplest way to do this would
be to return a single numeric value to indicate the "sharpness" or
"contrast" of the image.

However, I got thinking a bit more and ideally, we would like to
return a numeric metric for a number of zones or regions around the
image.  Of course, these zones could be setup by the user, so there
needs to be a libcamera control to setup regions.  One way to do this
would be to have another libcamera control to set a list of focus
regions.  However, as we know, libcamera controls only accept either
singular values or arrays, and that could be cumbersome for specifying
regions.  Ideally, we would want to specify a region as a struct with
{x, y, width, height}, and have the control accept an array of these
structs, together with the number of regions to be used.

Is there any plans to extend libcamera::controls to allow compound
types for such use cases.  If no, any suggestions what the most
convenient way to specify a number of zones would be?

Regards,
Naush