Re: Backend and non-backend (was Re: Stencil bounding box)

[David Feuer]

On 5/2/06, Johannes Schindelin <address@hidden> wrote:
> If you have two different versions of LilyPond, the same object could be
> subtly moved between the two. But if you measure the area of the overlap
> area between old and new bbox, you have a pretty good idea how much the
> result deviates from the original.
>
> And if somebody wants to try a super-cool idea, that measure will not only
> tell how much the output has changed, but also where to look for the
> largest effect.

Got it.  I was mostly thinking about how to match up elements that are
supposed to correspond if the structure of the stencils changes even a
little: for instance, if ((a b) c) becomes (a (b c)).  Once the
elements are matched up, we can measure the differences between them
in various ways.  Han-Wen's method won't necessarily notice if
elements get larger (e.g., stems get longer).  A more sensitive
measure might use both the area of the intersection and the area of
the union.

David