FormatNumber.h File Reference

#include <string>

Include dependency graph for FormatNumber.h:

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Namespaces
namespace	donner
	Top-level Donner namespace, which is split into different sub-namespaces such as donner::svg and donner::css.

Functions
std::string	donner::detail::FormatNumberForSVG (double value)
	Format a single double into the minimum-length round-trippable decimal form.

Function Documentation

FormatNumberForSVG()

std::string donner::detail::FormatNumberForSVG

(

double

value

)

Format a single double into the minimum-length round-trippable decimal form.

• Integer-valued finite doubles (e.g. 10.0, -3.0) are cast to int64_t and formatted without a decimal point or scientific notation.
• All other doubles use std::format's {} default specifier, which per C++20 [format.string.std] emits the shortest decimal representation that round-trips through std::from_chars. The {:g} specifier was tried and rejected - it defaults to 6-significant-digit precision, which drops accuracy for values like tan(π/6) = 0.57735026918962562.

Defined out-of-line in FormatNumber.cc: this header is included nearly everywhere (via Length.h and Transform.h), and an inline definition instantiates the std::format machinery in every including translation unit.

Used by toSVGTransformString, Path::toSVGPathData, and Length::toRcString().