dispose method

void dispose()

Implementation

void dispose() {
  if (_disposed) return;
  _disposed = true;
  if (_attached) {
    if (!chartController.isDisposed) {
      chartController.removeListener(_onChartControllerChange);
    }
    if (!zoomController.isDisposed) {
      zoomController.removeListener(_onZoomControllerChange);
    }
    _attached = false;
  }
}