[RFC] XI2 draft protocol specification (v 0.1)

[Peter Hutterer]

On Tue, Mar 10, 2009 at 11:53:58AM +0100, Simon Thum wrote:
> Peter Hutterer wrote:
> > yeah, of course. sorry. what I meant was that the value x is sent as x * (1 <<
> > 16). A little test program for random values between 0 and 0xFFFF showed an
> > average rounding error of 0x000008.
> I can't judge whether that is good or bad :)
> IMO for the protocol, definition is more important than impl. 1<<16
> should be valid, one can work out rounding later.

that should read "rounding error of 0.000008" of course. 8 millionth of a
pixel rounding error should be within reasonable margin of error for most
applications.

anyway, I finally wrote that code and decided for INT16.CARD16 as wire format.

Cheers,
  Peter

> > tbh. I am also contemplating to just send IEEE floats/doubles over the wire
> > and get on with life.
> I'm not really against it, but that's essentially wasting the exponent
> bits. I'd say fixed is a better match, although I'd prefer 24.8 for
> on-screen coords. I don't think we have information beyond n.4 in any case.