[PATCH evdev 1/2] Force x/y axes to exist on devices with any other axes (#44655)

[Chase Douglas]

On 01/13/2012 01:18 AM, Peter Hutterer wrote:
> Too much in the server relies on x/y to exist and to be axes 0 and 1. So if
> any relative axes exist, initialize REL_X/Y or ABS_X/Y as well.
> 
> For servers up to 1.11: a scrollwheel-only device now has relative axes
> where it only had buttons before.
> 
> For servers 1.12 or later: the device now has x/y in addition to the scroll
> axes.
> 
> X.Org Bug 44655 <http://bugs.freedesktop.org/show_bug.cgi?id=44655>
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  src/evdev.c |   43 +++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 43 insertions(+), 0 deletions(-)
> 
> diff --git a/src/evdev.c b/src/evdev.c
> index 989a255..68e3c75 100644
> --- a/src/evdev.c
> +++ b/src/evdev.c
> @@ -1958,6 +1958,38 @@ EvdevGrabDevice(InputInfoPtr pInfo, int grab, int ungrab)
>      return TRUE;
>  }
>  
> +/**
> + * Some devices only have other axes (e.g. wheels), but we
> + * still need x/y for these. The server relies on devices having
> + * x/y as axes 0/1 and core/XI 1.x clients expect it too (#44655)
> + */
> +static void
> +EvdevForceXY(InputInfoPtr pInfo, int mode)
> +{
> +    EvdevPtr pEvdev = pInfo->private;
> +
> +    xf86IDrvMsg(pInfo, X_INFO, "Forcing %s x/y axes to exist.\n",
> +                (mode == Relative) ? "relative" : "absolute");
> +
> +    if (mode == Relative)
> +    {
> +        EvdevSetBit(pEvdev->rel_bitmask, REL_X);
> +        EvdevSetBit(pEvdev->rel_bitmask, REL_Y);
> +    } else if (mode == Absolute)
> +    {
> +        EvdevSetBit(pEvdev->abs_bitmask, ABS_X);
> +        EvdevSetBit(pEvdev->abs_bitmask, ABS_Y);
> +        pEvdev->absinfo[ABS_X].minimum = 0;
> +        pEvdev->absinfo[ABS_X].maximum = 1000;
> +        pEvdev->absinfo[ABS_X].value = 0;
> +        pEvdev->absinfo[ABS_X].resolution = 0;
> +        pEvdev->absinfo[ABS_Y].minimum = 0;
> +        pEvdev->absinfo[ABS_Y].maximum = 1000;
> +        pEvdev->absinfo[ABS_Y].value = 0;
> +        pEvdev->absinfo[ABS_Y].resolution = 0;
> +    }
> +}
> +
>  static int
>  EvdevProbe(InputInfoPtr pInfo)
>  {
> @@ -2043,6 +2075,8 @@ EvdevProbe(InputInfoPtr pInfo)
>              pEvdev->num_buttons = num_buttons;
>          }
>  
> +        EvdevForceXY(pInfo, Relative);
> +
>          if (!ignore_rel)
>          {
>              xf86IDrvMsg(pInfo, X_PROBED, "Found relative axes\n");
> @@ -2116,7 +2150,16 @@ EvdevProbe(InputInfoPtr pInfo)
>                      pEvdev->flags |= EVDEV_TOUCHSCREEN;
>                      pEvdev->flags |= EVDEV_BUTTON_EVENTS;
>              }
> +        } else {
> +#ifdef MULTITOUCH
> +            if (!EvdevBitIsSet(pEvdev->abs_bitmask, ABS_MT_POSITION_X) ||
> +                !EvdevBitIsSet(pEvdev->abs_bitmask, ABS_MT_POSITION_Y))
> +#endif
> +                EvdevForceXY(pInfo, Absolute);
>          }
> +
> +
> +
>      }
>  
>      for (i = 0; i < BTN_MISC; i++) {

What ensures that the X and Y values of events are set for events? Or,
how are events delivered in the server if X and Y are always 0?

-- Chase