readPage method
Implementation
Future<Uint8List> readPage(int pageId) async {
await _file.setPosition(pageId * pageSize);
final data = await _file.read(pageSize);
if (data.length < pageSize) {
// Partial read (file smaller than expected) → zero-fill
final buf = Uint8List(pageSize);
buf.setAll(0, data);
return buf;
}
return Uint8List.fromList(data);
}