如何将datagrid列ActualWidth绑定到textbox MaxLength？

<DataGrid x:Name="datagrid">
    <DataGrid.Columns>
        <DataGridTemplateColumn>
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <Grid>
                        <TextBox Text="{Binding SomeText}" MaxLength="{Binding ColumnWidth, Mode=OneWay}" />
                    </Grid>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

<TextBox Text="{Binding SomeText}" MaxLength="{Binding ColumnWidth, Mode=OneWay}" />

public class ViewModel : INotifyPropertyChanged
{
    private double _columnWidth;

    public double ColumnWidth
    {
        get { return _columnWidth; }
        set
        {
            _columnWidth = value;
            OnPropertyChanged(nameof(ColumnWidth));
        }
    }

    // 其他属性和方法...

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

private void UpdateColumnWidth()
{
    // 获取datagrid列的ActualWidth
    double actualWidth = datagrid.Columns[0].ActualWidth;

    // 更新ColumnWidth属性的值
    ColumnWidth = actualWidth;
}