CODEWITHSUNDEEP
c#wpfcomboboxdatatrigger
SelfBiased_Resistor
SelfBiased_Resistor

Reputation: 43

ComboBox: Style content depending on property state

There are some posts that might point to my problem, but then again I get stuck by other problems when I try to apply their solution to my task.

So, I want a ComboBox to show a number (PathID) from my Path-class. Path has a property called PathState, which is an enum that can be PathState.red, PathState.blue, PathState.green, indicating a color.

I'd like to create a simple hardcoded list of type Path, just for learning, and then populate the ComboBox. I'd like to create three Path-objects with increasing ID, giving each a distinct color by asigning the PathState property.

By starting the app, the ComboBox should consist of the numbers 1, 2, and 3, whereas 1 is red, 2 is green, 3 is blue.

I know I need to get to it via ComboBox.ItemTemplate, DataTemplate, and DataTrigger - I just don't know where to start.

public class Path
{
  public int PathID {get;set;}
  public PathState PathState { get; set;}
}

public enum PathState
{
   red = 0,
   green = 1,
   blue = 2
}

EDIT: OK, I've made some effort, but are stuck on the DataTrigger-Part: here is my code:

<ComboBox Name="cmbTest" ItemsSource="{Binding MyPaths}" Grid.Column="1" Grid.Row="1"  VerticalContentAlignment="Center" HorizontalContentAlignment="Center">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock x:Name="cmbText"  Text="{Binding PathId}" Foreground="Red"/>
            </DataTemplate>                
        </ComboBox.ItemTemplate>
        <Style>
            <Style.Triggers>
                <DataTrigger Binding="{Binding Path=MyPaths}" Value="MyPaths.PathState">
                     <!-- Actually, I don't know how to continue beyond this point) -->
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ComboBox>

Upvotes: 2

Views: 358

Answers (1)

grek40
grek40

Reputation: 13438

You should write a IValueConverter that converts from your PathState to the corresponding System.Windows.Media.Brush. Use predefined Brushes(https://learn.microsoft.com/de-de/dotnet/api/system.windows.media.brushes?view=netframework-4.8) unless you need something special.

Then instantiate the value converter somewhere in your resources (could be at any parent level, I put it in ComboBox only for this example. Then use the converter to bind your color to display properties.

If you want the Background, do it within ItemContainerStyle. If you want Foreground put it wherever its needed. Beware: my example puts Foreground=Background, you won't see much.

<ComboBox>
    <ComboBox.Resources>
        <local:MyColorConverter x:Key="colorConverter"/>
    </ComboBox.Resources>
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding PathID}" Foreground="{Binding PathState,Converter={StaticResource colorConverter}}"/>
        </DataTemplate>
    </ComboBox.ItemTemplate>
    <ComboBox.ItemContainerStyle>
        <Style TargetType="ComboBoxItem">
            <Setter Property="Background" Value="{Binding PathState,Converter={StaticResource colorConverter}}"/>
        </Style>
    </ComboBox.ItemContainerStyle>
</ComboBox>

Upvotes: 1

Related Questions