private async void ConvertToText()
        {
            VisualStateManager.GoToElementState(GridMain, "TextShown", false);

            TextConverter converter = new TextConverter(CreateOptions());

            try
            {
                Progress <double> progress = new Progress <double>(UpdateProgress);
                TbAscii.Text = await converter.ConvertAsync(_source, progress);
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message, "Operation failed!");
            }
        }