Function wrapTextToLines

packages/core/src/layout/textMeasure.ts:495–560

(text: string, maxWidth: number)

 * - Hard-breaks overlong tokens at grapheme boundaries
 */
export function wrapTextToLines(text: string, maxWidth: number): readonly string[] {
  if (text.length === 0 || maxWidth <= 0) return Object.freeze([]);

  const lines: string[] = [];
  const paragraphs = text.split("\n");
  for (let p = 0; p < paragraphs.length; p++) {
    const paragraph = paragraphs[p] ?? "";
    if (paragraph.length === 0) {
      lines.push("");
      continue;
    }

    const tokens = paragraph.match(/[^\s]+|\s+/g);
    if (!tokens || tokens.length === 0) {
      lines.push("");
      continue;
    }

    let line = "";
    let lineWidth = 0;

    for (let i = 0; i < tokens.length; i++) {
      const token = tokens[i] ?? "";
      const tokenWidth = measureTextCells(token);

      if (lineWidth + tokenWidth <= maxWidth) {
        line += token;
        lineWidth += tokenWidth;
        continue;
      }

      if (tokenWidth <= maxWidth) {
        if (lineWidth > 0 || line.length > 0) lines.push(line);
        line = token;
        lineWidth = tokenWidth;
        continue;
      }

      if (lineWidth > 0 || line.length > 0) {
        lines.push(line);
        line = "";
        lineWidth = 0;
      }

      const chunks = splitWordByWidth(token, maxWidth);
      for (let j = 0; j < chunks.length; j++) {
        const chunk = chunks[j] ?? "";
        const chunkWidth = measureTextCells(chunk);
        if (lineWidth + chunkWidth <= maxWidth) {
          line += chunk;
          lineWidth += chunkWidth;
          continue;
        }
        if (lineWidth > 0 || line.length > 0) lines.push(line);
        line = chunk;
        lineWidth = chunkWidth;
      }
    }