[Gimp-developer] preview window does not work

[gg at catking.net]

On Wed, 07 Mar 2007 10:02:38 +0100, Sven Neumann <sven at gimp.org> wrote:

> Hi,
>
> On Wed, 2007-03-07 at 09:55 +0100, gg at catking.net wrote:
>
>> How is it a problem that there are these small and varying offsets all  
>> the
>> way through gimp?
>>
>> I suspect this is not so much a bug in the example code, which as you  
>> say
>> is just an example, but in gimp itself.
>
> If you can point out how this can be a bug in gimp itself, I would love
> to hear about it. We have several hundreds of plug-ins that work
> correctly so it is rather unlikely that there's a bug in the core or
> libgimp that would be responsible for this offset.

OK, then you're probably right , it's a buggy eg. and it would be best to  
give examples the work correcly to get ppl off to a good start.

>
> The fact that there's an offset here and a drift in the transform code
> in the core is pure coincidence. I wonder what makes you think that
> there's a relation. Off-by-one and rounding errors are not uncommon and
> they happen all over the place.
>
>
> Sven

Obviously rounding errors are unavoidable when doing everything in integer  
arithmatic although I think quite a bit could be done to reduce the  
accumulation of errors.

However I was seeing a more significant offset on NONE that I detailed  
when I split the "lancos offset" bug (principally for this reason).

gg