A few observations from a newcomer

[Libretti]

I've just started experimenting with Clipper2, and it's glorious. Here are some quick suggestions. If any have already been implemented and I just haven't found them, or if any are nonsensical, I'd appreciate a push in the right direction.

1. A length() function for computing the lengths of lines in every type of shape.
2. An area() function for polytrees.
3. The ability to pass a polytree to SvgWriter.
4. Make all operations equally capable of accepting objects in "D" or "64" coordinates.
5. Looking at the DistanceSqr() function, some quick tests show that using std::pow() to compute the square of the difference of two numbers is about six times slower than (x-y)*(x-y), and (z=(x-y))*z is probably faster still if a bit harder to read.

[Libretti]

Regarding my last point, you'll always want to cast your values to type "double" before squaring if integer overflow is an issue, which I assume it is. For example, if your 64-bit integer is 0x20000000000001 and you square it, you won't get the right answer. Casting it to a double causes loss of precision, but as a double multiplying 0x20000000000001 by itself gives the same result, and faster, than using std::pow().

[AngusJohnson]

Thanks Michael, helpful suggestions which I've included in the latest update.

3. The ability to pass a polytree to SvgWriter.

However, I'm not persuaded to do this. 😁
IMHO the added complexity isn't justifed given that you can easily use the PolyTreeToPaths() function.

[Libretti]

Yes, that's exactly what I did, although it took me a while to locate that function. A laudable goal would be for as many functions as possible to accepts as many inputs as possible, where it's reasonable to do so. As another example, in my version of Clipper2 the Execute function did not operate equally on "D" and "64" inputs, and I finally gave up on "D" and did my tests in "64" coordinates. Don't forget that some of us are new to Clipper2, and when a function isn't available we're apt to think that such an operation shouldn't be done, not that we should do our own conversions.