Key

Key signatures, keys in the seven diatonic modes and spelling in a key. More...

Collaboration diagram for Key:

Classes
class	MCC::Key
	A tonic and a diatonic mode, with the key signature they imply. More...
class	MCC::KeySignature
	Key signature: zero to seven sharps or flats (SPEC-KEY-1). More...

Enumerations
enum class	MCC::KeyMode : uint8_t {   Lydian = 0 , Major , Mixolydian , Dorian ,   Minor , Phrygian , Locrian }
	Diatonic mode of a key, ordered from brightest to darkest.

Detailed Description

Key signatures, keys in the seven diatonic modes and spelling in a key.

MCC::KeySignature stores zero to seven sharps or flats as a position on the circle of fifths. MCC::Key pairs a tonic with an MCC::KeyMode and derives its signature, so E minor has one sharp and D Dorian has none; Key::FromSignature() goes the other way. Key::Spell() writes a pitch class, or a sounding chromatic index, in the key's context: diatonic notes use the key's letters, and chromatic notes are raised in sharp keys and lowered in flat keys. See Music-Domain Specification (SPEC-KEY-*).

const MCC::Key key(MCC::NoteName(MCC::Letter::E), MCC::KeyMode::Minor);
key.Signature().Sharps();                 // 1
key.Spell(MCC::PitchClass(3));            // D#  (sharp key)
MCC::Key(MCC::NoteName(MCC::Letter::F), MCC::KeyMode::Major)
    .Spell(MCC::PitchClass(3));           // Eb  (flat key)

Available when MCC_KEY is defined. Requires the Scale module.