[RFC libinput] Add an API for touchpad gesture events

[Hans de Goede]

Hi,

On 23-01-15 09:51, Jonas Ådahl wrote:
> On Fri, Jan 23, 2015 at 09:38:06AM +0100, Hans de Goede wrote:
>> Hi,
>>
>> On 23-01-15 07:18, Jonas Ådahl wrote:

<snip>

>>>> As for 2 finger swipe at least: isn't that covered by scrolling? with the
>>>> caller deciding when a scroll event event is a swipe and when it is a scroll
>>>> event. It's the odd one out of course, but scrolling is a special case and
>>>> will be the odd one out anyway.
>>>
>>> Scrolling doesn't completely cover it because a user can disable
>>> 2-finger scroll for the whole session, and the application won't even
>>> see the scroll events. If an application wants to handle the 2-finger
>>> swipe no matter what configuration the user has chosen, then it'd
>>> probably have to come via something like a gesture API.
>>
>> AFAIK there is no such thing as a 2fg swipe on other platforms, why would
>> we make things difficult to try and support it in the first place ?
>
> Well, don't we already have it fully implemented except we call it
> scroll and only enable it if it (although by default) configured so? I
> agree though that its not very nice to send out duplicate events for the
> same gesture, but still, it feels some how wrong to not let applications
> depend on the most simple swipe (deliberately ignoring 1 finger swipe
> here) gesture.

Yes it is the most simple swipe gesture, but it is already taken for
scrolling and sending 2 events for the user doing a single thing just seems
very very wrong to me, and I really believe that that is something which
libinput should never ever do.

 > Also in click-to-scroll configurations, don't we disable 2 finger scroll?

We don't have click-to-scroll for touchpads, we've edge scrolling or
2 finger scrolling.

Regards,

Hans