Coordinate precision controls?

[veltman]

What are your thoughts on allowing user control over the precision of generated coordinates from methods like line() and area()?

I'm thinking of two reasons why this is potentially useful:

1. Any kind of non-browser static rendering where file size is a consideration.
2. I've run into a few browser-specific SVG rendering bugs that are precision-dependent, where coordinates with many significant digits can lead to weird problems (e.g. https://bugzilla.mozilla.org/show_bug.cgi?id=1507603).

2 has only come up on rare occasions for me, but 1 has come up more often.

I could imagine two versions:

Specify a number to round each coordinate to:

d3.line()
  .precision(1e-3);

Or instead update d3-path directly to take an optional precision argument that gets applied in the toString() method, and then someone could pass one as a custom context.

d3.line()
  .context(d3.path(1e-3));

// or...

d3.line()
  .context(d3.path().precision(1e-3));

Any thoughts on the merit of incorporating this? The latter approach would avoid cluttering the main API but still provide a low-level outlet for interested users.

[veltman]

Oops, I just realized this has already been discussed over at d3/d3-path#10, I'll chime in there.