[PATCH 1/2] Treat all touch event valuators as absolute

[Peter Hutterer]

On Fri, Jan 20, 2012 at 05:51:33AM +0100, Chase Douglas wrote:
> On 01/20/2012 05:28 AM, Peter Hutterer wrote:
> > On Wed, Jan 18, 2012 at 07:09:20PM -0800, Chase Douglas wrote:
> >> An indirect touch device, such as a multitouch touchpad, has relative X
> >> and Y axes internally. These axes are in screen coordinates. However,
> >> the cooresponding axes for touch events are in absolute device
> >> coordinates.
> >>
> >> Signed-off-by: Chase Douglas <chase.douglas at canonical.com>
> >> ---
> >>  dix/getevents.c |   12 +++++++++---
> >>  1 files changed, 9 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/dix/getevents.c b/dix/getevents.c
> >> index 1547059..3e37910 100644
> >> --- a/dix/getevents.c
> >> +++ b/dix/getevents.c
> >> @@ -222,17 +222,23 @@ set_valuators(DeviceIntPtr dev, DeviceEvent* event, ValuatorMask *mask)
> >>      int i;
> >>  
> >>      /* Set the data to the previous value for unset absolute axes. The values
> >> -     * may be used when sent as part of an XI 1.x valuator event. */
> >> +     * may be used when sent as part of an XI 1.x valuator event.
> >> +     *
> >> +     * All touch event valuators are absolute, even if the corresponding pointer
> >> +     * valuator is relative. This is the case for indirect touch devices for the
> >> +     * X and Y axes. */
> >>      for (i = 0; i < valuator_mask_size(mask); i++)
> >>      {
> >>          if (valuator_mask_isset(mask, i))
> >>          {
> >>              SetBit(event->valuators.mask, i);
> >> -            if (valuator_get_mode(dev, i) == Absolute)
> >> +            if (IsTouchEvent((InternalEvent *)event) ||
> >> +                valuator_get_mode(dev, i) == Absolute)
> >>                  SetBit(event->valuators.mode, i);
> >>              event->valuators.data[i] = valuator_mask_get_double(mask, i);
> >>          }
> >> -        else if (valuator_get_mode(dev, i) == Absolute)
> >> +        else if (IsTouchEvent((InternalEvent *)event) ||
> >> +                 valuator_get_mode(dev, i) == Absolute)
> >>              event->valuators.data[i] = dev->valuator->axisVal[i];
> >>      }
> >>  }
> >> -- 
> >> 1.7.8.3
> > 
> > can we reshape this to pass in what the mode is for the valuators
> > instead of guessing based on the event type?
> 
> The purpose is to force absolute for all valuators if it's a touch
> event. We can add a parameter "Bool force_absolute", but that doesn't
> feel any less hackish to me. It also hides the details through a level
> of indirection, making us put a comment at the call into set_valuators
> instead of inside set_valuators. I understand what you see as being a
> bit obtuse in this implementation, but I'm not sure the alternative is
> better.

the current input API requires us to submit all valuators in one mode anyway
.  xf86PostMotionEvent takes only a single Relative/Absolute argument, so we
can carry that through. For touch events, we know that the values are always
absolute, so we can assume mode = Absolute in GetTouchEvents() and pass that
to set_valuators, no?

Cheers,
  Peter