[RFC] Reporting of relative device events

[Daniel Stone]

On Sat, May 24, 2008 at 05:41:51PM +0930, Peter Hutterer wrote:
> Right now, valuators reported in DeviceValuator events depend on the mode of
> the device. If the device is mode Absolute, the valuators are in absolute
> (device-specific) coordinates. If the device is mode Relative, the valuators
> are in relative (device-specific) coordinates. If I understand the specs
> correctly, this is in concordance with the XI v1.0 specs.
> 
> However, I don't have a good feeling about this. For example, I think a
> perfectly valid use-case may be to utilise a tablet in relative mode, but get
> absolute coordinates. Also, to drop the wretched DGA extension, relative
> coordinates may be desired by some clients even if the device is in absolute
> mode.
> 
> Instead of the current approach, it would be better to differ between
> DeviceMode and DeviceReportingMode, both independent of each other.

Yeah, so it just becomes an extra parameter to XSelectDeviceInput:
deviceid, wid, priority?, { ScreenAbs, DevAbs, Rel }; for this to be
useful though, we pretty much have to allow that in motion history, too,
which is going to be a hoot.

> The next question would then be - should this be implemented as a
> DeviceControl, thus globally. Or should it be implemented on a per-client
> basis?
> Looking at the source, both are feasable, although the latter requires
> additional requests to set and/or query the mode of the device for this
> client (and is generally nastier to implement).

I'd prefer it was per-input-selection.  Global controls for things like
this are the _suck_.

Cheers,
Daniel
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