Add a soprano recorder tab converter as a Linux AppImage.

The app turns a lead line into Baroque fingering tabs with rhythm kept, ships Twinkle and Ode to Joy, and reads photos locally with oemer when the bundled Python is present.

Co-authored-by: catpersonisme <catpersonisme@gmail.com>

src/lib/score.ts

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+import { formatQuarterLengths, quartersMatch } from "@/lib/duration";
+
+export type TimeSignature = {
+  beats: number;
+  beatType: number;
+};
+
+export type ScoreEvent = {
+  id: string;
+  kind: "note" | "rest";
+  pitch: string | null;
+  quarters: number;
+  label: string;
+  tied: boolean;
+};
+
+export type Measure = {
+  id: string;
+  events: ScoreEvent[];
+};
+
+export type ScoreOrigin = "sample" | "upload" | "blank";
+
+export type Score = {
+  title: string;
+  attribution: string;
+  timeSignature: TimeSignature;
+  measures: Measure[];
+  origin: ScoreOrigin;
+};
+
+export const TIME_SIGNATURES: TimeSignature[] = [
+  { beats: 2, beatType: 4 },
+  { beats: 3, beatType: 4 },
+  { beats: 4, beatType: 4 },
+  { beats: 6, beatType: 8 },
+  { beats: 3, beatType: 8 },
+  { beats: 2, beatType: 2 },
+];
+
+export function newId(prefix: string): string {
+  return `${prefix}-${Math.random().toString(36).slice(2, 10)}`;
+}
+
+export function signatureKey(timeSignature: TimeSignature): string {
+  return `${timeSignature.beats}/${timeSignature.beatType}`;
+}
+
+export function parseSignature(key: string): TimeSignature {
+  const [beats, beatType] = key.split("/").map(Number);
+  return { beats, beatType };
+}
+
+export function expectedQuarters(timeSignature: TimeSignature): number {
+  return (timeSignature.beats * 4) / timeSignature.beatType;
+}
+
+export function barStatus(
+  measure: Measure,
+  timeSignature: TimeSignature,
+): { ok: boolean; text: string } {
+  const sum = measure.events.reduce((total, event) => total + event.quarters, 0);
+  const expected = expectedQuarters(timeSignature);
+  const signature = signatureKey(timeSignature);
+  if (quartersMatch(sum, expected)) {
+    return { ok: true, text: `${signature} · ${formatQuarterLengths(sum)}` };
+  }
+  return {
+    ok: false,
+    text: `${formatQuarterLengths(sum)} in this bar; ${signature} holds ${formatQuarterLengths(expected)}.`,
+  };
+}
+
+export function startBeats(events: ScoreEvent[], timeSignature: TimeSignature): number[] {
+  const quartersPerBeat = 4 / timeSignature.beatType;
+  let cursor = 0;
+  return events.map((event) => {
+    const beat = cursor / quartersPerBeat + 1;
+    cursor += event.quarters;
+    return beat;
+  });
+}
+
+export function formatBeat(beat: number): string {
+  const rounded = Math.round(beat * 100) / 100;
+  return Number.isInteger(rounded) ? String(rounded) : String(rounded);
+}
+
+export function blankScore(): Score {
+  return {
+    title: "Untitled line",
+    attribution: "Hand-entered lead line. Add notes, then read the tabs.",
+    timeSignature: { beats: 4, beatType: 4 },
+    origin: "blank",
+    measures: [{ id: newId("m"), events: [] }],
+  };
+}