Wayland Relative Pointer API Progress

[Hans de Goede]

Hi,

On 17-04-15 13:17, Michal Suchanek wrote:
> On 17 April 2015 at 12:52, Hans de Goede <hdegoede at redhat.com> wrote:
>> Hi,
>>
>>
>> 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.
>>
>
> Do you mean that the absolute trackpoint excentricity is somehow
> translated to relative motion delta in hardware so that it does look
> like a mouse although it is in fact a joystick?

Yes.

Also have you ever used a trackpoint it is really nothing like a joystick,
with a joystick you move the stick and then it stays in position (there
are springs to center the stick when you let go, but you can remove those
and everything will still work just fine).

Where as a trackpoint is more of a presure sensor which senses how much you
push against it in a certain direction, it does not actually move.

They are really just completely different beasts.

Regards,

Hans