[PATCH xf86-input-synaptics 00/12] Clickpad support

[Daniel Stone]

Hi,

On 11 February 2012 01:25, Chase Douglas <chase.douglas at canonical.com> wrote:
> On 02/11/2012 02:09 AM, Bryce Harrington wrote:
>> With the Clickpad property turned on with one of these dell netbooks,
>> when you touch the button surface with the second finger without pushing
>> the button it immediately interrupts and stops the pointer movement.  I
>> gather this is by design but it is a behavioral change that some might
>> find awkward.
>
> This is due to the previous patch set. The issue boils down to: when is
> it acceptable to send touch events? Peter, Daniel, and I had a couple
> long discussions about this on irc, and the result was that we can't
> send touch events whenever the input module is emitting other events
> derived from touches. For example, we can't emit touch events while
> performing a two-finger scroll.
>
> This means we also can't emit touch events while moving the cursor. I
> added a patch that ensures the cursor is only ever moved when one touch
> is on the device so we can emit touch events when two touches are on the
> device.

The click case in particular is a difficult one to solve correctly.  I
guess you ultimately don't want to crush any movement which is a
direct continuation of what came previously, but only new movement.
You do need to stop at least some movement though, since otherwise it
becomes near-impossible to click something accurately, as your finger
will invariably wiggle a bit while doing the physical click.

Cheers,
Daniel