Support for AbsInfo

[BrendanBall]

Hi
I'm busy looking at using uinput from rust. At the moment I'm specifically trying to implement absolute positioning pointers. This high level crate doesn't seem to support this right now. Is this crate considered unmaintained seen as it hasn't been worked on in quite a while?

[BrendanBall]

Ok, I've found it does currently support it, but using an old deprecated method, which is why my search didn't find what I was looking for. see torvalds/linux@052876f

[meh]

It's not unmaintained, I'm just depressed. Is there documentation on how to use the non-deprecated one?

[BrendanBall]

Sorry man :( .
I mostly figured it out between the comments at uinput.h and the uinput relative mouse example and created a c prototype example for abs mouse which you can see here.

I can create a PR in the rust-uinput-sys crate as it's currently missing some structs and things, but I think this high level api should likely change, e.g. in .event(Absolute(Position(X))) Absolute should probably take in an AbsInfo because it doesn't work without any configuration (by work I mean the device doesn't end up doing anything even if you create events, at minimum it needs a maximum > 0) as in my c prototype.

One important thing to note regarding the API design taken from the commit that changed this:

These ioctls support all features of the old method, plus a "resolution" field
for absinfo. Furthermore, it's properly forward-compatible to new ABS codes
and a growing "struct input_absinfo" structure.

So ideally this high level api should also be forward compatible to adding more fields to that struct.

The uinput docs do mention though that

UI_ABS_SETUP - Set absolute axis information for the device to setup
----
 This ioctl can be called multiple times and will overwrite previous values.
 If this ioctl fails with -EINVAL, it is recommended to use the old
 "uinput_user_dev" method via write() as a fallback, in case you run on an
 old kernel that does not support this ioctl."

I'm not exactly sure which kernel version this was deprecated at, and how much you want to support old kernels in this crate.