Question

I have a combobox filled with a list of Objects. I like to highlight an item in a combobox based on a IsHighlighted property of the Object.

I’ve tried writing my own style but no real success…

<Style x:Key="SimpleComboBoxItem" TargetType="ComboBoxItem">
        <Setter Property="FocusVisualStyle" Value="{x:Null}" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="ComboBoxItem">
                    <Border Name="Border" Padding="2" SnapsToDevicePixels="true">
                        <ContentPresenter x:Name="contentPresenter" />
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsSelected" Value="true">
                            <Setter TargetName="Border" Property="Background" Value="#FFCCCCCC"/>
                        </Trigger>
                        <Trigger Property="Tag" Value="Highlight" SourceName="contentPresenter">
                            <Setter Property="Background" TargetName="Border" Value="#FFAAF3A0"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

Thanx in advance

Answer 1

This should work fine with a simple DataTrigger.

Your Object Class:

public class TestObject
{
    public string Name { get; set; }

    public bool IsHighlighted { get; set; }

    public override string ToString()
    {
        return this.Name;
    }
}

Xaml:

<Window x:Class="TestWPF.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:TestWPF"
        Title="MainWindow">
    <Grid>
        <StackPanel>
            <ComboBox>
            <ComboBox.Resources>
                <Style TargetType="ComboBoxItem">
                    <Setter Property="FocusVisualStyle" Value="{x:Null}" />
                    <Setter Property="Background" Value="Gray" />
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding IsHighlighted}" Value="True">
                            <Setter Property="Background" Value="Red" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </ComboBox.Resources>
                <local:Employee Name="Nick" />
                <local:Employee Name="Bob" IsHighlighted="True" />
                <local:Employee Name="Fred" />
            </ComboBox>
        </StackPanel>
    </Grid>
</Window>

Note: Unlike the sample above, I’m guessing in your code you’re binding the combobox’s ItemsSource… which should work just the same. One thing to be careful of though, is if your object’s ‘IsHighlighted’ property can change, you should be implementing INotifyProperty changed to ensure that changing the value will notify the UI that the triggers should refresh.