Question

The purpose is set item’s style in tree view. Style choose depends on item’s property. I’ve tried two methods:

1. Switch item’s style from trigger in TreeView.ItemTemplate. Problem is that you can’t assign style from another style.

2. Switch item’s style from ItemContainerStyleSelector. Problem is that if item’s property updates (after form initializing), style does not update. (because StyleSelector.SelectStyle does not fire).

Answer 1

You can bind your Style-propery to the changing property of your object and then use a ValueConverter to return te correct style, e.g. when the property is a bool:

public class StyleSelectionConverter : IValueConverter
{
    public Style OnStyle { get; set; }
    public Style OffStyle { get; set; }

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        bool input = (bool)value;
        if (input)
        {
            return OnStyle;
        }
        else
        {
            return OffStyle;
        }
    }

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

Usage example:

<ListView.Resources>
    <Style x:Key="OnStyle" TargetType="{x:Type TextBlock}">
        <Setter Property="Background" Value="LightGreen"/>
        <Setter Property="Foreground" Value="Green"/>
    </Style>
    <Style x:Key="OffStyle" TargetType="{x:Type TextBlock}">
        <Setter Property="Background" Value="Pink"/>
        <Setter Property="Foreground" Value="DarkRed"/>
    </Style>
    <local:StyleSelectionConverter x:Key="StyleSelectionConverter"
                                   OnStyle="{StaticResource OnStyle}"
                                   OffStyle="{StaticResource OffStyle}"/>
</ListView.Resources>
...
<GridViewColumn Header="Is Active">
    <GridViewColumn.CellTemplate>
        <DataTemplate>
            <DataTemplate.Resources>
            </DataTemplate.Resources>
            <TextBlock Style="{Binding IsActive, Converter={StaticResource StyleSelectionConverter}}"
                       Text="{Binding IsActive}"/>
        </DataTemplate>
    </GridViewColumn.CellTemplate>
</GridViewColumn>