insert method
Inserts a new Line into the paragraph.
Implementation
void insert(Line line) {
if (_sealed) {
throw StateError(
'Element of type ${line.runtimeType} cannot be inserted when $runtimeType is sealed');
}
if (last != null && !last!.isSealed && last!.isEmpty && line.isNotEmpty) {
for (final TextFragment frag in line.fragments) {
_lines.last.addFragment(frag);
}
return;
}
_lines.add(line);
}