Wayland Relative Pointer API Progress

Hans de Goede hdegoede at redhat.com
Fri Apr 17 03:52:33 PDT 2015


On 17-04-15 11:47, Michal Suchanek wrote:
> On 17 April 2015 at 09:11, Pekka Paalanen <ppaalanen at gmail.com> wrote:
>> On Fri, 17 Apr 2015 13:43:11 +0900
>> x414e54 <x414e54 at linux.com> wrote:
>>> Thank you for the comments.
>>> I do have a few counterpoints but I will leave after that.
>>>> Not sure an IR/laser/wii mote pointer should even be considered a
>>>> "relative" pointer since they operate in absolute coordinates. Given
>>>> this, there is no "set position" hint to consider. Transmitting
>>>> acceleramoter data via a "relative pointer" doesn't sound reasonable.
>>> I think this is the issue right here. Pointers are not relative, mice
>>> are not pointers.
>> What definition of a "pointer" are you using?
>> The definition Wayland uses for a wl_pointer is a device that:
>> - requires a cursor image on screen to be usable
>> - the physical input is relative, not absolute
>> This definition is inspired by mice, and mice have been called pointer
>> devices, so we picked the well-known name "pointer" for mice-like
>> devices.
>> Specifically, a pointer is *not* a device where you directly point a
>> location on screen, like a touchscreen for example. For touchscreens,
>> there is a separate protocol wl_touch.
>> For drawing tablets, there will be yet another procotol.
>> Joysticks or gamepads fit into none of the above. For the rest of the
>> conversation, you should probably look up the long gamepad protocol
>> discussions from the wayland-devel mailing list archives.
> And how is a joystick different from a trackpoint, exactly?
> It uses different hardware interface and later different software
> interface but for no good reason. It's just 2 axis relative input
> device with buttons. Sure, the big joystick, gamepad directional cap
> and trackpoint are at a different place of the stick size scale and
> might have different hardware sensors which should be reflected with
> different acceleration settings but ultimately it's the same kind of
> device.

Actually joystick analog inputs are absolute not relative. They give a value
for exactly how much the "stick" has moved from the center.

Except for dpads which are really buttons not relative axis, so joysticks
really are pretty much not like trackpoints in anyway.



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