如何将组合框绑定到 wpf 中的组合框

Question

I have two Combobox

<ComboBox x:Name="sourceNumber">
    <ComboBoxItem Content="1"/>
    <ComboBoxItem Content="2"/>
    <ComboBoxItem Content="3"/>
    <ComboBoxItem Content="4"/>
    <ComboBoxItem Content="5"/>

and

<ComboBox x:Name=destinationNumber ItemsSource="{Binding Source={sourceNumber.SelectedIndex}"/>

When I select sourceNumber = 3 (1,2,3) will be added to destinationNumber
When I select sourceNumber = 5 (1,2,3,4,5) will be added to destinationNumber

How can I do it ? Thanks for helps .

Answer 1

You can use converter to solve this problem.

public class ComboBoxItemsSourceConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if(value != null && value is int)
            {
                int max = (int)value;
                if (max == -1) return null;
                return Enumerable.Range(1, max + 1);
            }
            else
                return null;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

And you must slightly change your XAML code:

<ComboBox x:Name="destinationNumber" 
                  ItemsSource="{Binding Path=SelectedIndex, ElementName=sourceNumber, Converter={StaticResource myConverter}}"/>

Where myConverter is:

<local:ComboBoxItemsSourceConverter x:Key="myConverter" />