truncateTo method
Clamps the reveal when the source shrank to a prefix of itself.
The surviving prefix keeps its stamps, so text that merely restyled — a construct claiming characters the tail had already shown — carries on its entrance instead of starting over.
Implementation
void truncateTo(int length) {
if (_revealed > length) {
_revealed = length.toDouble();
}
if (_settledBelow > length) {
_settledBelow = length;
}
}