Question

I have a TextBlock which is bound to an Integer property of my model. The TextBlock int property increases its count from 0 to 99. I first show TextBlocks 0-9 in a ListView.

If there are more than 10 TextBlocks, I want the first 10 TextBlocks numbered 0-9 to show as 00, 01 , 02.. 09. I can use the string.Format method in WPF to achieve this behavior. But if there are fewer than 10 TextBlocks they should be numbered as 0, 1, 2 — 9.

How can I achieve this behaviour? Can I use MultiBinding Converter? If yes, help me with a sample.

Here is the code:

<ListView ItemsSource= "{Binding}"> <!-- Binding to a collection which has the Tag Id property -->
  <Grid x:Name="TagNum_grid" HorizontalAlignment="Right" VerticalAlignment="Bottom" Margin="1,3,0,0" Grid.Column="1" >
    <TextBlock x:Name="DefaultIDtextblock" Margin="1,0" Text="{Binding Path=TagID}" TextWrapping="Wrap" Foreground="#FFA0A0A0" />
  </Grid>
</ListView>

Answer 1

As you mentioned, you could use MultiBinding, where the first value is the tag id and the second is the number of elements.

First, define the value converter:

public class MyConverter : MarkupExtension, IMultiValueConverter
{
    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return this;
    }

    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        int tagId = (int)values[0];
        int itemCount = (int)values[1];

        if (itemCount >= 10 && tagId < 10)
        {
            return "0" + tagId;
        }

        return tagId;
    }
}

Then bind the values, using the above converter

<ListView ItemsSource="{Binding}">
    <Grid x:Name="TagNum_grid" HorizontalAlignment="Right" VerticalAlignment="Bottom" Margin="1,3,0,0" Grid.Column="1" >
        <TextBlock x:Name="DefaultIDtextblock" Margin="1,0" TextWrapping="Wrap" Foreground="#FFA0A0A0" >
            <TextBlock.Text>
                <MultiBinding Converter="{local:MyConverter}">
                    <Binding Path="TagID" />
                    <Binding Path="Items.Count" RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=ListView}" />
                </MultiBinding>
            </TextBlock.Text>
        </TextBlock>
    </Grid>
</ListView>