I'm looking for way to change foreground color for top 3 Lables in my listview. I have working code depends on value using ObservableCollection, but looking for way to change only color for top 3 lables.

Code in my ProductItem(theme)

<Label Content="{Binding Tonnes}"
       FontWeight="Bold"
       HorizontalAlignment="Center"
       Padding="0,0,0,0"
       FontSize="16"
       Foreground="{Binding Tonnes, Converter={StaticResource ColorConverter}}"/> 

ColorCoverter

  public class ColorConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            decimal tempValue = decimal.Parse(value.ToString());
            string tempString = "Red";
            if (tempValue >= 0 && tempValue <= 1)
                tempString = "Red";

            if (tempValue > 1 && tempValue <= 2)
                tempString = "#EDDF00";

            if (tempValue > 2 && tempValue <= 5)
                tempString = "Green";

            SolidColorBrush brush = new SolidColorBrush();
            BrushConverter conv = new BrushConverter();
            brush = conv.ConvertFromString(tempString) as SolidColorBrush;
            return brush;
        }

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

CodePudding user response：

You can make use of index number of ListViewItem which hosts the Label. Let's say, you want to change Foreground of top 3 items to orange, modify the converter for MultiBinding.

public class ColorConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        if ((values is { Length: 2 }) &&
            (values[0] is decimal tempValue) &&
            (values[1] is ListViewItem listViewItem))
        {
            ListView listView = (ListView)ItemsControl.ItemsControlFromItemContainer(listViewItem);
            int index = listView.ItemContainerGenerator.IndexFromContainer(listViewItem);
            if (index <= 2)
                return Brushes.Orange; // Brush for top 3 items

            // Do the conversion for other items.
        }
        return DependencyProperty.UnsetValue;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

Then modify the binding of Foreground property.

<Label Content="{Binding Tonnes}">
    <Label.Foreground>
        <MultiBinding Converter="{StaticResource ColorConverter}">
            <Binding Path="Tonnes"/>
            <Binding RelativeSource="{RelativeSource AncestorType={x:Type ListViewItem}}"/>
        </MultiBinding>
    </Label.Foreground>
</Label>