Re: layout.cc: do not draw empty boxes (issue 6450113)

[k-ohara5a5a]

On 2012/09/03 22:54:24, joeneeman wrote:
> > On 2012/09/03 07:25:53, Keith wrote:
> > > It is arguably valid to request a box running from right to left,
> > > for which length() returns zero.

> I argue that it is invalid. If you interpret a "right-to-left box"
> as being non-empty, then the implementation of Box needs to be
> rewritten, since functions such as add_point and widen don't act
> as expected.

Surprisingly, only 'draw-thick-zero-fret tried to draw a box using an
Interval with negative length.  Since Intervals with negative length are
regarded as "empty" in LilyPond, we could refuse to draw them, but warn
if they are non-infinite, that is, something somebody might have wanted
to draw.

New patch up.

http://codereview.appspot.com/6450113/