renderAnsi function

String renderAnsi(List<List<ThemedToken>> lines, SyntaxTheme theme, { bool background = false, })

Renders highlighted lines with 24-bit ANSI escape codes, for terminals. Set background to paint the theme's background across each full row.

Control characters in the code, other than tab, are replaced with U+FFFD, so the code cannot emit its own escape sequences.

Implementation

String renderAnsi(
  List<List<ThemedToken>> lines,
  SyntaxTheme theme, {
  bool background = false,
}) {
  final out = StringBuffer();
  final bg = background ? _sgrColor(48, theme.background) : '';
  for (var i = 0; i < lines.length; i++) {
    if (i > 0) out.write('\n');
    // Erase to the end of the row in the background color.
    if (background) out.write('\x1B[0m$bg\x1B[K');
    for (final token in lines[i]) {
      final style = token.style;
      out
        ..write('\x1B[0m')
        ..write(bg)
        ..write(_sgrColor(38, style.foreground));
      if (style.background != null) out.write(_sgrColor(48, style.background!));
      if (style.bold) out.write('\x1B[1m');
      if (style.italic) out.write('\x1B[3m');
      if (style.underline) out.write('\x1B[4m');
      if (style.strikethrough) out.write('\x1B[9m');
      out.write(token.text.replaceAll(_controlChars, '\uFFFD'));
    }
    out.write('\x1B[0m');
  }
  return out.toString();
}