Function wrapLabelToWidth

pj_widgets/src/MessageBox.cpp:54–78

Greedy word-wrap: insert '\n' so no single rendered line exceeds max_width. Returns text unchanged when it already fits on one line (the common case for short labels, which then render exactly as before). A single word wider than max_width is kept on its own line rather than dropped or split mid-word.

// short labels, which then render exactly as before). A single word wider than
// max_width is kept on its own line rather than dropped or split mid-word.
QString wrapLabelToWidth(const QString& text, const QFontMetrics& fm, int max_width) {
  if (max_width <= 0 || fm.horizontalAdvance(text) <= max_width) {
    return text;
  }
  const QStringList words = text.split(QLatin1Char(' '), Qt::SkipEmptyParts);
  if (words.isEmpty()) {
    return text;
  }
  // Greedily pack words onto the current line; start a new line when the next
  // word would overflow. A single word wider than max_width still gets its own
  // line (it just can't be packed with anything).
  QStringList lines;
  QString line = words.first();
  for (int i = 1; i < words.size(); ++i) {
    const QString candidate = line + QLatin1Char(' ') + words[i];
    if (fm.horizontalAdvance(candidate) <= max_width) {
      line = candidate;
    } else {
      lines.append(line);
      line = words[i];
    }
  }
  lines.append(line);
  return lines.join(QLatin1Char('\n'));
}

}  // namespace