finalizing the Iterator API

Roger Larsson roger.larsson at
Fri Jul 9 02:03:20 CEST 2004

On Wednesday 07 July 2004 11.23, Casper Boemann wrote:
> > > And as Boudewijn said up,down.left,right might be nice functions,
> however
> > > they don't make sense for a PathIterator. I have had this idea myself,
> but
> > > on reflection: when would they really be used.
> >
> > Edge detection, for instance.
> good point, question is if we should make a special WalkerIterator for this
> or just provide those functions in general.

(Better to call "mkbitmap" and "potrace" on a temporary image...)

You might end up moving around _a lot_... (how to follow a edge? - you need
to check neighbors to know that you still are on a edge).
And for each movement you need to check that the iterator is still in
selection or in image...

It might be better to move around a AreaIterator instead...
And wouldn't that be the same as a selector?

What about providing direct pixel access within the selector?
* Iterate over all within the selector to get average.

   When the selection size increases it is better to use two selectors
    one to add new pixel values, the other to subtract old

	for fit in front_selector:
		acc += *fit;
	for eit in end_selector:
		acc = *eit;
	average = acc / size(total_selector);



Roger Larsson

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