Question

I am writing a custom user control, called MyUserControl. I have many DependecyProperties for it, which I use in the MainWindow where several MyUserControl are defined multiple times. What I would like to know is how can I create custom Properties that the Triggers/Properties for a style would fire?

For example, if I have a custom property BOOL IsGoing and a custom property MyBackgroung(the background of the UserControl), both defined as :

public bool IsGoing
    {
        get { return (bool)this.GetValue(IsGoingProperty); }
        set { this.SetValue(IsGoingProperty, value); }
    }
    public static readonly DependencyProperty IsGoingProperty = DependencyProperty.RegisterAttached(
        "IsGoing", typeof(bool), typeof(MyUserControl), new PropertyMetadata(false));  

public Brush MyBackground
    {
        get { return (Brush)this.GetValue(MyBackgroundProperty); }
        set { this.SetValue(MyBackgroundProperty, value); }
    }
    public static readonly DependencyProperty MyBackgroundProperty = DependencyProperty.Register(
            "MyBackground", typeof(Brush), typeof(MyUserControl), new PropertyMetadata(Brushes.Red));

and if I define my UserControl in MainWindow.xaml, how can I access the Triggers and set MyBackground, depending on whether or not the IsGoing property is true/false?
I tried many things, but in essence, I’m trying to achieve something like:

<custom:MyUserControl MyBackground="Green" x:Name="myUC1" Margin="120.433,0,0,65.5" Height="50" Width="250" VerticalAlignment="Bottom" HorizontalAlignment="Left"  >
        <Style>
            <Style.Triggers>
                <Trigger Property="IsGoing" Value="True">
                    <Setter Property="MyBackground" Value="Yellow"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </custom:MyUserControl>

I hope my explanation is good enough for you to understand. I’ve been working on this for a couple of days now, and I can’t seem to find the solution.
Thanks for the help!!!

Adrian

Answer 1

Your style should just need to be used as UserControl.Style and have the correct TargetType, also default values you intend to change via trigger need to be moved into the style due to precedence:

<custom:MyUserControl.Style>
    <Style TargetType="custom:MyUserControl">
        <Setter Property="MyBackground" Value="Green"/>
        <Style.Triggers>
            <Trigger Property="IsGoing" Value="True">
                <Setter Property="MyBackground" Value="Yellow"/>
            </Trigger>
        </Style.Triggers>
    </Style>
</custom:MyUserControl.Style>

Whether this actually does anything depends on how you use the properties in the control definition.