Enum Fidelity 

pub enum Fidelity {
    Ansi16,
    Ansi256,
    TrueColor,
}

How many colours the terminal can actually show.

Only Fidelity::Ansi16 changes what this crate draws. Above it, colour separates a raised surface from a well on every shipped theme, and the glyph fallback below never fires. Recorded rather than inferred, because a caller that quantised its palette knows the answer and this crate cannot recover it from the colours afterwards.

Variants

Ansi16

Sixteen colours. Depth cannot be carried by colour: a well collapses onto its face on 18 of 31 themes and a bevel loses an edge on all 31.

Ansi256

The 6x6x6 cube and the grey ramp. Enough on 27 of 31 themes.

TrueColor

24-bit. The only failures left belong to the theme, not the terminal.

Implementations

impl Fidelity

pub fn detect() -> Self

Read the terminal’s own claim, from COLORTERM then TERM.

Deliberately credulous, and the fall-through is where that is decided. An unrecognised TERM is assumed capable, because the two wrong answers do not cost the same: guessing TrueColor on a limited terminal costs some fidelity, and guessing Ansi16 on a capable one throws away colour the user paid for — and, for a caller that quantises its palette off this answer, throws away the whole theme. COLORTERM is routinely stripped by ssh and by multiplexers, so an unrecognised name is the common case rather than the exotic one: foot, xterm and screen all land here.

So sixteen colours is reached by naming the terminals that really have them. The list is short and it does not grow: these are the fixed consoles, and TERM=linux is the case this exists for — the Linux virtual console, which is what an installer and a machine with no desktop draw on.

pub fn from_env(colorterm: &str, term: &str) -> Self

detect with the environment passed in, so the decision can be tested without mutating a process-wide variable from a parallel test.

pub const fn separates_depth(self) -> bool

Whether colour alone can tell a raised surface from a well here.

Trait Implementations

impl Clone for Fidelity

fn clone(&self) -> Fidelity

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Fidelity

impl Debug for Fidelity

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

Formats the value using the given formatter.

impl Default for Fidelity

fn default() -> Fidelity

Returns the “default value” for a type.

impl Eq for Fidelity

impl PartialEq for Fidelity

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Fidelity