Re: [Lib2geom-devel] path::toPwSb for closed paths

[<J.B...@ew...>]

> -----Original Message-----
> From: njh [mailto:nj...@nj...] 
> Sent: woensdag 16 april 2008 18:55
> To: Engelen, J.B.C. (Johan)
> Cc: jf....@gm...; lib...@li...
> Subject: Re: path::toPwSb for closed paths
> 
> On Wed, 16 Apr 2008 J.B...@ew... wrote:
> 
> > Hi all,
> >
> > Have a look at rev. 1175. I think I made a mistake there. 
> Right now, the closing segment of a closed path is not added 
> to pwd2. So LPEs do not function correctly with closed paths.
> > I can't remember why I did rev. 1175; it does not say which 
> bug specifically it is supposed to fix.
> >
> > Do you guys think rev 1175 should be reverted?
> 
> Are you referring to
> Index: src/path.h
> ===================================================================
> --- src/path.h	(revision 1174)
> +++ src/path.h	(working copy)
> @@ -492,7 +492,8 @@
>       Piecewise<D2<SBasis> > ret;
>       ret.push_cut(0);
>       unsigned i = 1;
> -    for(const_iterator it = begin(); it != end_default(); 
> ++it, i++) {
> +    // ignore that path is closed or open. pw<d2<>> is always open.
> +    for(const_iterator it = begin(); it != end(); ++it, i++) {
>         ret.push(it->toSBasis(), i);
>       }
>       return ret;
> 
> We have argued endlessly about the semantics of closed and 
> open paths. 
> Paths have a flag to say whether they are open or closed, 
> whereas d2<pw> does not have that notion.  This is because 
> the correct behaviour when transforming a d2<pw> is not 
> always clear wrt the closing segment.  For example, the 
> closing segment is always a line, but if we have a transform 
> which does not preserve lines then should we transform that 
> last line?  I would argue yes in many cases.  Thus, we should 
> include the last line segment as a linear() in the d2.
> 
> Looking at the code, I would say that
> -    for(const_iterator it = begin(); it != end_default(); 
> ++it, i++) {
> is correct.  I don't know why you made the change - there 
> might be a bug elsewhere that this obscured (*gasp*).

I just changed it back. It fixes Inkscape's LPE bug.

Thanks,
Johan