frame method

@override String frame()

Implementation

@override
String frame() {
  const delimiter = '\n';
  final result = <String>[];
  for (int i = 0, j = 0; i < content.length; i++, j++) {
    if (j == width / 2) {
      result.add(delimiter);
      j = 0;
    }
    if (content[i] == 0) {
      result.add(' ');
    } else {
      result.add(String.fromCharCode(0x2800 + content[i]));
    }
  }
  result.add(delimiter);
  return result.join();
}