Show/Hide RadRadialMenu When Used As a Context Menu In an MVVM Scenario

Environment

Product Version	2023.2.606
Product	RadRadialMenu for WPF

Description

Show or hide the RadRadialMenu control when it is used as a context menu for an element in an MVVM scenario.

Solution

1. Create a property of type bool inside your view model.

Creating a view model with a bool property

public class MainViewModel : ViewModelBase 
{ 
    private bool shouldOpenRadialMenu; 
 
    public bool ShouldOpenRadialMenu 
    { 
        get { return shouldOpenRadialMenu; } 
        set { shouldOpenRadialMenu = value; this.OnPropertyChanged(nameof(this.ShouldOpenRadialMenu)); } 
    } 
} 

Public Class MainViewModel 
    Inherits ViewModelBase 
 
    Private shouldOpenRadialMenu As Boolean 
 
    Public Property ShouldOpenRadialMenu As Boolean 
        Get 
            Return shouldOpenRadialMenu 
        End Get 
        Set(ByVal value As Boolean) 
            shouldOpenRadialMenu = value 
            Me.OnPropertyChanged(NameOf(Me.ShouldOpenRadialMenu)) 
        End Set 
    End Property 
End Class 

1. Create an attached property that will be bound to the bool property from the view model.

Creating an attached property

public class RadialMenuExtensions 
{ 
    public static int GetShouldOpenRadialMenu(DependencyObject obj) 
    { 
        return (int)obj.GetValue(ShouldOpenRadialMenuProperty); 
    } 
 
    public static void SetShouldOpenRadialMenu(DependencyObject obj, int value) 
    { 
        obj.SetValue(ShouldOpenRadialMenuProperty, value); 
    } 
 
    public static readonly DependencyProperty ShouldOpenRadialMenuProperty = 
        DependencyProperty.RegisterAttached("ShouldOpenRadialMenu", typeof(bool), typeof(RadialMenuExtensions), new PropertyMetadata(false, OnShouldOpenRadialMenuChanged)); 
 
    private static void OnShouldOpenRadialMenuChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
    { 
    } 
} 

Public Class RadialMenuExtensions 
    Public Shared Function GetShouldOpenRadialMenu(ByVal obj As DependencyObject) As Integer 
        Return CInt(obj.GetValue(ShouldOpenRadialMenuProperty)) 
    End Function 
 
    Public Shared Sub SetShouldOpenRadialMenu(ByVal obj As DependencyObject, ByVal value As Integer) 
        obj.SetValue(ShouldOpenRadialMenuProperty, value) 
    End Sub 
 
    Public Shared ReadOnly ShouldOpenRadialMenuProperty As DependencyProperty = DependencyProperty.RegisterAttached("ShouldOpenRadialMenu", GetType(Boolean), GetType(RadialMenuExtensions), New PropertyMetadata(False, AddressOf  OnShouldOpenRadialMenuChanged)) 
 
    Private Shared Sub OnShouldOpenRadialMenuChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs) 
    End Sub 
End Class 

1. Retrieve the RadRadialMenu instance that is set on the element as a context menu in the property callback method. To do so, use the RadRadialMenu.GetRadialContextMenu method. Depending on the value of the bool property from the view model, execute the RadRadialMenuCommands.Show and RadRadialMenuCommands.Hide commands.

Showing/Hiding the RadRadialMenu in the property callback method

private static void OnShouldOpenRadialMenuChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
{ 
    FrameworkElement frameworkElement = d as FrameworkElement; 
 
    if (frameworkElement != null) 
    { 
        RadRadialMenu radRadialMenu = RadRadialMenu.GetRadialContextMenu(frameworkElement); 
 
        if (radRadialMenu != null ) 
        { 
            bool shouldOpen = (bool)e.NewValue; 
 
            if (shouldOpen) 
            { 
                RadialMenuCommands.Show.Execute(null, frameworkElement); 
            } 
            else 
            { 
                RadialMenuCommands.Hide.Execute(null, frameworkElement); 
            } 
        } 
    } 
} 

Private Shared Sub OnShouldOpenRadialMenuChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs) 
    Dim frameworkElement As FrameworkElement = TryCast(d, FrameworkElement) 
 
    If frameworkElement IsNot Nothing Then 
        Dim radRadialMenu As RadRadialMenu = RadRadialMenu.GetRadialContextMenu(frameworkElement) 
 
        If radRadialMenu IsNot Nothing Then 
            Dim shouldOpen As Boolean = CBool(e.NewValue) 
 
            If shouldOpen Then 
                RadialMenuCommands.Show.Execute(Nothing, frameworkElement) 
            Else 
                RadialMenuCommands.Hide.Execute(Nothing, frameworkElement) 
            End If 
        End If 
    End If 
End Sub 

1. Set the attached property on the element that has the RadRadialMenu set as its context menu and bind it to the bool property from the view model.

The following example shows the RadRadialMenu control as a context menu for a TextBox element instance:

Binding the attached property

<Grid> 
    <Grid.DataContext> 
        <local:MainViewModel/> 
    </Grid.DataContext> 
    <TextBox local:RadialMenuExtensions.ShouldOpenRadialMenu="{Binding ShouldOpenRadialMenu, Mode=TwoWay}"> 
        <telerik:RadRadialMenu.RadialContextMenu> 
            <telerik:RadRadialMenu> 
                <telerik:RadRadialMenuItem Header="Item 1" /> 
                <telerik:RadRadialMenuItem Header="Item 2" /> 
                <telerik:RadRadialMenuItem Header="Item 3" /> 
            </telerik:RadRadialMenu> 
        </telerik:RadRadialMenu.RadialContextMenu> 
    </TextBox> 
</Grid>