All files / music-core/utils KeyUtils.ts

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/**
 * @file 调号工具函数
 * @description 提供调号相关的计算和转换
 */
 
import { StepName, KeyMode } from '../models/types';
import { getKeyTonic, getKeyAlterations, getMidiPitch } from './PitchUtils';
 
/**
 * 调号信息
 */
export interface KeyInfo {
  /** 五度圈位置 */
  fifths: number;
  /** 调式 */
  mode: KeyMode;
  /** 主音 */
  tonic: { step: StepName; alter?: number };
  /** 调号中的升降音 */
  alterations: { step: StepName; alter: number }[];
  /** 调号名称(中文) */
  name: string;
  /** 关系大小调 */
  relative?: { fifths: number; mode: KeyMode };
}
 
/**
 * 大调名称映射
 */
const MAJOR_KEY_NAMES: Record<number, string> = {
  [-7]: 'Cb大调', [-6]: 'Gb大调', [-5]: 'Db大调', [-4]: 'Ab大调',
  [-3]: 'Eb大调', [-2]: 'Bb大调', [-1]: 'F大调', [0]: 'C大调',
  [1]: 'G大调', [2]: 'D大调', [3]: 'A大调', [4]: 'E大调',
  [5]: 'B大调', [6]: 'F#大调', [7]: 'C#大调'
};
 
/**
 * 小调名称映射
 */
const MINOR_KEY_NAMES: Record<number, string> = {
  [-7]: 'ab小调', [-6]: 'eb小调', [-5]: 'bb小调', [-4]: 'f小调',
  [-3]: 'c小调', [-2]: 'g小调', [-1]: 'd小调', [0]: 'a小调',
  [1]: 'e小调', [2]: 'b小调', [3]: 'f#小调', [4]: 'c#小调',
  [5]: 'g#小调', [6]: 'd#小调', [7]: 'a#小调'
};
 
/**
 * 简谱调号名称(1=X)
 */
const JIANPU_KEY_NAMES: Record<number, string> = {
  [-7]: '1=Cb', [-6]: '1=Gb', [-5]: '1=Db', [-4]: '1=Ab',
  [-3]: '1=bE', [-2]: '1=bB', [-1]: '1=F', [0]: '1=C',
  [1]: '1=G', [2]: '1=D', [3]: '1=A', [4]: '1=E',
  [5]: '1=B', [6]: '1=#F', [7]: '1=#C'
};
 
/**
 * 获取调号的完整信息
 * @param fifths 五度圈位置
 * @param mode 调式(默认大调)
 * @returns 调号信息
 */
export function getKeyInfo(fifths: number, mode: KeyMode = 'major'): KeyInfo {
  const tonic = getKeyTonic(fifths);
  const alterations = getKeyAlterations(fifths);
  
  let name: string;
  let relative: { fifths: number; mode: KeyMode } | undefined;
  
  if (mode === 'major') {
    name = MAJOR_KEY_NAMES[fifths] ?? `${fifths}个升降号大调`;
    relative = { fifths, mode: 'minor' }; // 关系小调
  } else if (mode === 'minor') {
    name = MINOR_KEY_NAMES[fifths] ?? `${fifths}个升降号小调`;
    relative = { fifths, mode: 'major' }; // 关系大调
  } else {
    // 其他调式
    name = `${tonic.step}${tonic.alter === 1 ? '#' : tonic.alter === -1 ? 'b' : ''} ${mode}`;
  }
  
  return {
    fifths,
    mode,
    tonic,
    alterations,
    name,
    relative
  };
}
 
/**
 * 获取简谱调号标记
 * @param fifths 五度圈位置
 * @returns 如 "1=C", "1=G", "1=bB"
 */
export function getJianpuKeyName(fifths: number): string {
  return JIANPU_KEY_NAMES[fifths] ?? `1=${getKeyTonic(fifths).step}`;
}
 
/**
 * 从调名获取五度圈位置
 * @param keyName 调名(如 "C", "G", "Bb", "F#")
 * @param mode 调式
 * @returns 五度圈位置
 */
export function getKeyFifths(keyName: string, mode: KeyMode = 'major'): number {
  // 解析调名
  const match = keyName.match(/^([A-G])([#b])?$/i);
  if (!match) {
    throw new Error(`Invalid key name: ${keyName}`);
  }
  
  const step = match[1].toUpperCase() as StepName;
  const alter = match[2] === '#' ? 1 : match[2] === 'b' ? -1 : 0;
  
  // 根据主音找五度圈位置
  for (let fifths = -7; fifths <= 7; fifths++) {
    const tonic = getKeyTonic(fifths);
    if (tonic.step === step && (tonic.alter ?? 0) === alter) {
      return fifths;
    }
  }
  
  throw new Error(`Key not found: ${keyName}`);
}
 
/**
 * 获取调内音阶(大调)
 * @param fifths 五度圈位置
 * @param octave 起始八度
 * @returns 音阶音符数组
 */
export function getMajorScale(
  fifths: number, 
  octave: number
): { step: StepName; octave: number; alter: number }[] {
  const scale: { step: StepName; octave: number; alter: number }[] = [];
  const tonic = getKeyTonic(fifths);
  const alterations = getKeyAlterations(fifths);
  const alterMap = new Map(alterations.map(a => [a.step, a.alter]));
  
  // 大调音阶:全全半全全全半
  const steps: StepName[] = ['C', 'D', 'E', 'F', 'G', 'A', 'B'];
  const tonicIndex = steps.indexOf(tonic.step);
  
  let currentOctave = octave;
  for (let i = 0; i < 8; i++) {
    const stepIndex = (tonicIndex + i) % 7;
    const step = steps[stepIndex];
    
    if (i > 0 && stepIndex === 0) {
      currentOctave++;
    }
    
    const alter = alterMap.get(step) ?? 0;
    scale.push({ step, octave: currentOctave, alter });
  }
  
  return scale;
}
 
/**
 * 获取调内音阶(自然小调)
 * @param fifths 五度圈位置
 * @param octave 起始八度
 * @returns 音阶音符数组
 */
export function getNaturalMinorScale(
  fifths: number,
  octave: number
): { step: StepName; octave: number; alter: number }[] {
  // 自然小调 = 关系大调从第6级开始
  const scale = getMajorScale(fifths, octave);
  
  // 重新排列,从第6级开始(la = 6)
  const minorScale = [];
  for (let i = 5; i < 5 + 8; i++) {
    const note = scale[i % 7];
    minorScale.push({
      ...note,
      octave: note.octave + (i >= 7 ? 1 : 0)
    });
  }
  
  return minorScale;
}
 
/**
 * 判断两个调是否为关系大小调
 * @param fifths1 调1的五度圈位置
 * @param mode1 调1的调式
 * @param fifths2 调2的五度圈位置
 * @param mode2 调2的调式
 * @returns 是否为关系大小调
 */
export function areRelativeKeys(
  fifths1: number, mode1: KeyMode,
  fifths2: number, mode2: KeyMode
): boolean {
  // 关系大小调有相同的五度圈位置,但调式不同
  return fifths1 === fifths2 && mode1 !== mode2 && 
         ((mode1 === 'major' && mode2 === 'minor') || 
          (mode1 === 'minor' && mode2 === 'major'));
}
 
/**
 * 判断两个调是否为同主音大小调
 * @param fifths1 调1的五度圈位置
 * @param mode1 调1的调式
 * @param fifths2 调2的五度圈位置
 * @param mode2 调2的调式
 * @returns 是否为同主音大小调
 */
export function areParallelKeys(
  fifths1: number, mode1: KeyMode,
  fifths2: number, mode2: KeyMode
): boolean {
  // 同主音大小调有相同的主音,但调式不同
  const tonic1 = getKeyTonic(fifths1);
  const tonic2 = getKeyTonic(fifths2);
  
  return tonic1.step === tonic2.step && 
         (tonic1.alter ?? 0) === (tonic2.alter ?? 0) &&
         mode1 !== mode2;
}
 
/**
 * 计算两个调之间的转调关系
 * @param fromFifths 起始调
 * @param toFifths 目标调
 * @returns 转调信息
 */
export function getModulationInfo(
  fromFifths: number,
  toFifths: number
): { distance: number; direction: 'sharp' | 'flat' | 'none'; isNear: boolean } {
  const distance = toFifths - fromFifths;
  const direction = distance > 0 ? 'sharp' : distance < 0 ? 'flat' : 'none';
  
  // 近关系调:五度圈上相差 ±1
  const isNear = Math.abs(distance) <= 1;
  
  return { distance, direction, isNear };
}
 
/**
 * 获取调内和弦(大调)
 * @param fifths 五度圈位置
 * @returns 级数和弦数组
 */
export function getDiatonicChords(fifths: number): {
  degree: number;
  root: { step: StepName; alter: number };
  quality: 'major' | 'minor' | 'diminished';
  romanNumeral: string;
}[] {
  const scale = getMajorScale(fifths, 4);
  const qualities: ('major' | 'minor' | 'diminished')[] = 
    ['major', 'minor', 'minor', 'major', 'major', 'minor', 'diminished'];
  const romanNumerals = ['I', 'ii', 'iii', 'IV', 'V', 'vi', 'vii°'];
  
  return scale.slice(0, 7).map((note, i) => ({
    degree: i + 1,
    root: { step: note.step, alter: note.alter },
    quality: qualities[i],
    romanNumeral: romanNumerals[i]
  }));
}
 
/**
 * 检查音符是否需要临时记号
 * @param step 音名
 * @param alter 升降
 * @param fifths 调号
 * @returns 是否需要临时记号
 */
export function needsAccidental(step: StepName, alter: number, fifths: number): boolean {
  const keyAlterations = getKeyAlterations(fifths);
  const keyAlterMap = new Map(keyAlterations.map(a => [a.step, a.alter]));
  const expectedAlter = keyAlterMap.get(step) ?? 0;
  return alter !== expectedAlter;
}
 
/**
 * 获取移调后的调号
 * @param fifths 原调号
 * @param semitones 移调半音数
 * @returns 新调号的五度圈位置
 */
export function transposeKey(fifths: number, semitones: number): number {
  // 半音与五度圈的关系:每上升7个半音 = 五度圈+1
  // 简化:半音数 % 12,然后找对应的五度圈变化
  const semitoneToFifths: Record<number, number> = {
    0: 0, 1: 7, 2: 2, 3: -3, 4: 4, 5: -1,
    6: 6, 7: 1, 8: -4, 9: 3, 10: -2, 11: 5
  };
  
  const normalizedSemitones = ((semitones % 12) + 12) % 12;
  const fifthsChange = semitoneToFifths[normalizedSemitones];
  
  let newFifths = fifths + fifthsChange;
  
  // 保持在 -7 到 +7 范围内
  while (newFifths > 7) newFifths -= 12;
  while (newFifths < -7) newFifths += 12;
  
  return newFifths;
}