read method

@override Uint8List read(int offset, int count)

Reads an owned or immutable range without changing the source.

Implementation

@override
Uint8List read(int offset, int count) {
  if (_closed) {
    throw StateError('XCF input is closed');
  }
  if (offset < 0 || count < 0 || count > length - offset) {
    throw RangeError('XCF input range is outside the file');
  }
  if (offset >= _start && offset + count <= _start + _cache.length) {
    return Uint8List.sublistView(_cache, offset - _start, offset - _start + count);
  }
  _file.setPositionSync(offset);
  final int size = (count > cacheBytes ? count : cacheBytes).clamp(0, length - offset);
  final Uint8List bytes = _file.readSync(size);
  if (bytes.length != size) {
    throw const XcfFormatException('File changed or was truncated during XCF reading');
  }
  if (size <= cacheBytes) {
    _start = offset;
    _cache = bytes;
  }
  return Uint8List.sublistView(bytes, 0, count);
}