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

[Peter Hutterer]

On 13/01/12 18:00 , Chase Douglas wrote:
> 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?

unless we have a bug in the server, we can handle events without x/y 
set. if none are ever sent, last.valuators is taken from the sprite 
position on the device changed event handling (and rescaled into device 
range). root x/y is taken from those then.

so in this case, since the valuator mask should never have 0/1 set, 
we're fine.

Cheers,
   Peter