Define Custom Trigger Behavior

You can use a custom behavior that will perform additional logic when attaching the RadRadialMenu to the target element. You have to create a class that inherits from the RadialMenuTriggerBehavior class and override its methods to implement custom logic defining where and when the context menu will appear/diappears. The RadRadialMenu is attached/detached to the target element by calling the AttachToTargetElement/DetachToTargetElement method.

This example demonstrates how you can display the context menu when the text in a TextBox is changed and hide it when the Esc button is pressed.

First, create a class that inherits from the RadialMenuTriggerBehavior class. You can override its SubscribeToTargetEvents and UnsubscribeFromTargetEvents methods to implement your custom logic for triggering the appearance of the menu.

Example 1: Custom RadialMenuTriggerBehavior

• XAML

public class CustomTriggerBehavior : RadialMenuTriggerBehavior 
{ 
    public CustomTriggerBehavior() 
    { 
        this.AttachTriggers = RadialMenuAttachTriggers.None; 
    } 
 
    protected override void SubscribeToTargetEvents(FrameworkElement element) 
    { 
        base.SubscribeToTargetEvents(element); 
 
        var textBox = element as TextBox; 
        textBox.TextChanged += TextBoxTextChanged; 
        textBox.KeyDown += TextBoxKeyDown; 
    } 
 
    void TextBoxKeyDown(object sender, KeyRoutedEventArgs e) 
    { 
        if (e.Key == VirtualKey.Escape) 
        { 
            this.DetachFromTargetElement(); 
        } 
    } 
 
    void TextBoxTextChanged(object sender, TextChangedEventArgs e) 
    { 
        this.AttachToTargetElement(); 
    } 
 
    protected override void UnsubscribeFromTargetEvents(FrameworkElement element) 
    { 
        var textBox = element as TextBox; 
        textBox.TextChanged -= TextBoxTextChanged; 
        textBox.KeyDown -= TextBoxKeyDown; 
 
        base.UnsubscribeFromTargetEvents(element); 
    } 
} 

Then set the attached RadRadialContextMenu properties to the target element.

Example 2: Set the Behavior Property

• XAML

<TextBox Width="200"> 
    <navigation:RadRadialContextMenu.Behavior> 
        <local:CustomTriggerBehavior/> 
    </navigation:RadRadialContextMenu.Behavior> 
    <navigation:RadRadialContextMenu.Menu> 
        <navigation:RadRadialMenu/> 
    </navigation:RadRadialContextMenu.Menu> 
</TextBox>