On Thu, Jan 06, 2011 at 10:55:21AM -0800, Ping Cheng wrote:
> On Wed, Jan 5, 2011 at 11:00 PM, Peter Hutterer
> <[email protected]> wrote:
> > Subtracting two values seems to be a far simpler way of calculating a delta.
> > This fixes the jumping strip on the I3 devices, at least for the vertical
> > one. Horizontal one untested for lack of device.
> >
> > Signed-off-by: Peter Hutterer <[email protected]>
> > ---
> > tbh, I did not figure out what the old code was supposed to do, but the data
> > my I3 gives me suggests a range of 0...4096 in bit-wise increments (i.e. 0,
> > 1,2 4, 8, 16, etc.). I guess this is where this code comes from, but since
> > we only care about value > 0 or < 0, this was a rather roundabout way.
>
> The idea was to get the actual scales a finger has moved over so we
> can speed up/slow down the corresponding events. Since we are not
> posting the event that way, it is fine to only check the difference.
does the strip have the resolution to make this worthwhile? I can only get a
few values on something that's hardly larger than my finger, so having
multiple scroll events depending on the finger speed seems a bit dangerous.
> > src/wcmCommon.c | 25 ++-----------------------
> > 1 files changed, 2 insertions(+), 23 deletions(-)
> >
> > diff --git a/src/wcmCommon.c b/src/wcmCommon.c
> > index bd1a198..8d138af 100644
> > --- a/src/wcmCommon.c
> > +++ b/src/wcmCommon.c
> > @@ -429,18 +429,7 @@ static int getWheelButton(InputInfoPtr pInfo, const
> > WacomDeviceState* ds,
> > /* emulate events for left strip */
> > if ( ds->stripx != priv->oldStripX )
> > {
> > - int temp = 0, n, i;
> > - for (i=1; i<14; i++)
> > - {
> > - n = 1 << (i-1);
> > - if ( ds->stripx & n )
> > - temp = i;
> > - if ( priv->oldStripX & n )
> > - value = i;
> > - if ( temp & value) break;
> > - }
> > -
> > - value -= temp;
> > + value = ds->stripx - priv->oldStripX;
> >
> > fakeButton = (value > 0) ? priv->striplup : priv->stripldn;
> > *fakeKey = (value > 0) ? priv->strip_keys[0] :
> > priv->strip_keys[1];
> > @@ -449,18 +438,8 @@ static int getWheelButton(InputInfoPtr pInfo, const
> > WacomDeviceState* ds,
> > /* emulate events for right strip */
> > if ( ds->stripy != priv->oldStripY )
> > {
> > - int temp = 0, n, i;
> > - for (i=1; i<14; i++)
> > - {
> > - n = 1 << (i-1);
> > - if ( ds->stripy & n )
> > - temp = i;
> > - if ( priv->oldStripY & n )
> > - value = i;
> > - if ( temp & value) break;
> > - }
> > + value = ds->stripy - priv->oldStripY;
> >
> > - value -= temp;
> > fakeButton = (value > 0) ? priv->striprup : priv->striprdn;
> > *fakeKey = (value > 0) ? priv->strip_keys[2] :
> > priv->strip_keys[2];
>
> As you've touched in the commit comments, value = 0 should not post an
> event. We need to update the above two lines accordingly.
All three (the scroll ring as well as the two strips) are guarded by
conditions like this:
if ( ds->stripy != priv->oldStripY )
so it's mathematically difficult to get a value of 0 :)
Cheers,
Peter
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