Mail Archives: geda-user/2011/10/01/19:48:10
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On Sat, 2011-10-01 at 18:56 -0400, Dave McGuire wrote:
> > You might even be able to set the gains to negateive of their normal
> > numbers to enable a kind of "natural scrolling" feature - I believe tha=
t
> > is common on Mac?
>=20
> If that means "smooth scrolling" rather than "jumping in chunks", yes.
Smooth scrolling is different to what I meant. I'm not familiar enough
with GTK on OS-X to know whether we can get high precision scroll events
from the "mouse".
On Win32 (where I'm most familiar with the problems with the scroll
wheel), there is a message parameter with the scroll event which tells
you how many units the wheel has moved. When smooth scrolling is enabled
(not sure how that happens), Windows will send you more messages.
On X11 (and the Mac OS X version of PCB uses X11 of course), the wheel
events are translated into button presses - not a valuator. This seems
to imply that unless there is an API for getting at the high-res "wheel"
data, we would have to fake the smooth scrolling - meaning things would
still move in quanta - just that we might be able to animate it a bit.
Another technique associated with smooth scrolling is "kinetic
scrolling", where you assign some notional mass to the object being
scrolled, and use that to implement accelerations and decelerations of
the scroll animation. When this is got right, it works amazingly. It can
be very infuriating when its got wrong though. (And on Apple's platform,
where they put a lot of effort into getting these things right - we will
have a high standard to keep up to!)
> > Try (scrollpan-steps -8) if you want that, the code comments seem to
> > suggest this is possible.
>
> I tried that; I was expecting smaller steps to the scrolling, but it=
=20
> didn't seem to have any effect. I'd dearly love a less "jumpy"=20
> scrolling action. But frankly, having two-axis scrolling as above is a=
=20
> huge deal in itself!
If you increase the magnitude of the number, the scroll quanta will get
smaller. (Sign sets the direction). But unless we can get more events
from the input device. this will mean you scroll gets slower as well as
less jumpy.
--=20
Peter Clifton
Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA
Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)
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