Enum ColorDepth 

pub enum ColorDepth {
    Truecolor,
    Color256,
    Color16,
}

Color depth rung used by the SGR emitters and the Figlet render path.

Ordering: Truecolor > Color256 > Color16. ColorDepth::detect returns the highest rung the current terminal advertises. resolve_depth downgrades a requested rung to the detected rung when the terminal cannot honor it, emitting a fixed warning unless suppressed.

Variants

Truecolor

24-bit truecolor (\x1b[38;2;R;G;Bm). Advertised by COLORTERM=truecolor or COLORTERM=24bit. Highest rung.

Color256

256-color indexed palette (\x1b[38;5;Nm). Middle rung.

Color16

16-color ANSI named palette (\x1b[30m..37m, \x1b[90m..97m). Lowest rung; always available on any ANSI-compatible terminal.

Implementations

impl ColorDepth

pub fn detect() -> Self

Detect the highest color depth the current terminal advertises.

Cache contract (FR-031)

This function is intended to be called once at builder time (FigletBuilder::build); the result is cached on the crate::Figlet renderer for its lifetime. The render path NEVER calls detect — invalidation is caller-driven only via crate::Figlet::set_color_depth. Calling detect is O(1) + one syscall (isatty) + one env-var read.

Detection rules (per spec Edge Cases + FR-010):

1. If COLORTERM is set to "truecolor" or "24bit" (case-sensitive, matching the upstream toilet convention), return Self::Truecolor.
2. Otherwise return Self::Color16 — the safe lowest-common-denominator rung that any ANSI-compatible terminal honors.

256-color is NOT auto-detected because no portable environment variable reliably signals 256-color support — TERM=xterm-256color is a hint but not a contract. Callers who want 256-color SHOULD pass it explicitly via resolve_depth.

The isatty probe is performed only when std::io::IsTerminal is available; non-TTY stdout (e.g., piped to a file) returns Self::Color16 regardless of COLORTERM so redirected output is not polluted with 24-bit escapes that the consuming program won’t strip.

Trait Implementations

impl Clone for ColorDepth

fn clone(&self) -> ColorDepth

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ColorDepth

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ColorDepth

fn default() -> ColorDepth

Returns the “default value” for a type.

impl Hash for ColorDepth

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ColorDepth

fn eq(&self, other: &ColorDepth) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for ColorDepth

impl Eq for ColorDepth

impl StructuralPartialEq for ColorDepth