Chord source-edit helpers

Primitives for drag-to-reposition chord editing inside the rendered preview. <ChordSheet> / <RendererPreview> / renderChordproAst emit ChordRepositionEvent values through their onChordReposition callback; consumers feed them through applyChordReposition to compute the updated ChordPro source.

applyChordReposition

function applyChordReposition(
  source: string,
  event: ChordRepositionEvent,
): ChordRepositionResult;

Returns { nextSource, ok }. ok is false when the event refers to a chord position that no longer matches the source (e.g. the host's debounced state lagged behind a fast edit); nextSource is unchanged on failure.

import { ChordSheet, applyChordReposition } from '@chordsketch/react';

<ChordSheet
  source={source}
  onChordReposition={(event) => {
    const { nextSource, ok } = applyChordReposition(source, event);
    if (ok) setSource(nextSource);
  }}
/>

lyricsOffsetToSourceColumn

function lyricsOffsetToSourceColumn(line: string, lyricsOffset: number): number;

Helper used by applyChordReposition internally; exported for hosts that build their own drop handlers (e.g. a touch-aware gesture layer). Maps a 0-indexed offset in the rendered lyrics string to the 0-indexed column in the ChordPro source line.

ChordRepositionEvent

interface ChordRepositionEvent {
  /** 1-indexed source line carrying the chord that is being moved. */
  fromLine: number;
  /** 0-indexed source column where the chord currently lives. */
  fromColumn: number;
  /** 0-indexed offset in the rendered lyrics where the chord was dropped. */
  toLyricsOffset: number;
  /** The chord string itself, including brackets (e.g. `"[G]"`, `"[D/F#]"`). */
  chord: string;
}

The event shape is intentionally narrow — it describes a single chord move on a single line. Cross-line moves are not supported today (file an issue if your host needs them).