Support rounding for `.wkt_string()`

[IndigoCurnick]

Hi! A feature I'd really like is supporting rounding to X decimal places in the .wkt_string() function.

For example I can force the output to be POINT (2.32 5.45).

Maybe a second function like wkt_string_rounded(prec: i32)?

I'm happy to work on this myself and PR but wanted to check if this would be something of interest first that would get merged in! Thanks!

[lnicola]

Note that this can turn valid polygons into invalid ones (with self-intersections). As prior art, PostGIS has a maxdecimaldigits parameter, but suggets using ST_ReducePrecision first, which calls GEOSGeom_setPrecision.

[frewsxcv]

Another option could be a builder pattern:

wkt::Formatter::new()
   .with_pretty_print()
   .with_max_decimal_digits(5)
   .format(my_wkt)

[IndigoCurnick]

@lnicola Yes, I see the problem with just rounding naively, has georust already implemented something like ST_ReducePrecision? I haven't been able to find it yet if it has

@frewsxcv I think a builder is actually a much more sensible idea for this interface!

[urschrei]

@lnicola Yes, I see the problem with just rounding naively, has georust already implemented something like ST_ReducePrecision? I haven't been able to find it yet if it has

No, and my understanding is that its implementation is non-trivial so it's unlikely to be available in the short term (but PRs are very welcome)