[PATCH] dix: undo transformation for missing valuators (#49347)

[Chase Douglas]

On 05/14/2012 04:52 PM, Peter Hutterer wrote:
> last.valuators contains the transformed valuators of the device. If the
> device submits events with x/y missing, we need to get that from
> last.valuators and undo the transformation to that axis.
> 
> X.Org Bug 49347 <http://bugs.freedesktop.org/show_bug.cgi?id=49347>
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  dix/getevents.c |   18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/dix/getevents.c b/dix/getevents.c
> index c960d44..d466ebb 100644
> --- a/dix/getevents.c
> +++ b/dix/getevents.c
> @@ -1167,15 +1167,25 @@ transformAbsolute(DeviceIntPtr dev, ValuatorMask *mask)
>  {
>      double x, y, ox, oy;
>  
> +    if (!valuator_mask_isset(mask, 0) || !valuator_mask_isset(mask, 1)) {
> +        struct pixman_f_transform invert;
> +
> +        /* undo transformation from last event */
> +        ox = dev->last.valuators[0];
> +        oy = dev->last.valuators[1];
> +
> +        pixman_f_transform_invert(&invert, &dev->transform);
> +        transform(&invert, &ox, &oy);
> +
> +        x = ox;
> +        y = oy;
> +    }
> +
>      if (valuator_mask_isset(mask, 0))
>          ox = x = valuator_mask_get_double(mask, 0);
> -    else
> -        ox = x = dev->last.valuators[0];
>  
>      if (valuator_mask_isset(mask, 1))
>          oy = y = valuator_mask_get_double(mask, 1);
> -    else
> -        oy = y = dev->last.valuators[1];
>  
>      transform(&dev->transform, &x, &y);
>  

This all looks like a no-op if neither X nor Y are set in the passed-in
mask. Why not just return early? I suppose ox != x and/or oy != y after
the transformation, so we'll always be setting the values in the mask,
but is that necessary since they haven't changed?

-- Chase