Show ContextMenu on Left Click using only XAML
Solution 1
What I would suggest doing is making a new static class with attached DependencyProperty. Call the class LeftClickContextMenu and the property Enabled (just ideas). When your registering the DependencyProperty add an on changed callback. Then in the property changed callback if Enabled is set to true then add a handler to the LeftMouseButtonDown event and do your stuff there. If Enabled is set to false remove the handler. This sould allow you to set it like a property on anything by simply using the following in your xaml.
<Border namespace:LeftClickContextMenu.Enabled="True" />
This technique is called an attached behavior and you can read more about it in this code project article: http://www.codeproject.com/KB/WPF/AttachedBehaviors.aspx
Solution 2
I've just written and tested this based on HK1's answer (you can also read about attached properties in Attached Properties Overview) :
public static class ContextMenuLeftClickBehavior
{
public static bool GetIsLeftClickEnabled(DependencyObject obj)
{
return (bool)obj.GetValue(IsLeftClickEnabledProperty);
}
public static void SetIsLeftClickEnabled(DependencyObject obj, bool value)
{
obj.SetValue(IsLeftClickEnabledProperty, value);
}
public static readonly DependencyProperty IsLeftClickEnabledProperty = DependencyProperty.RegisterAttached(
"IsLeftClickEnabled",
typeof(bool),
typeof(ContextMenuLeftClickBehavior),
new UIPropertyMetadata(false, OnIsLeftClickEnabledChanged));
private static void OnIsLeftClickEnabledChanged(object sender, DependencyPropertyChangedEventArgs e)
{
var uiElement = sender as UIElement;
if(uiElement != null)
{
bool IsEnabled = e.NewValue is bool && (bool) e.NewValue;
if(IsEnabled)
{
if(uiElement is ButtonBase)
((ButtonBase)uiElement).Click += OnMouseLeftButtonUp;
else
uiElement.MouseLeftButtonUp += OnMouseLeftButtonUp;
}
else
{
if(uiElement is ButtonBase)
((ButtonBase)uiElement).Click -= OnMouseLeftButtonUp;
else
uiElement.MouseLeftButtonUp -= OnMouseLeftButtonUp;
}
}
}
private static void OnMouseLeftButtonUp(object sender, RoutedEventArgs e)
{
Debug.Print("OnMouseLeftButtonUp");
var fe = sender as FrameworkElement;
if(fe != null)
{
// if we use binding in our context menu, then it's DataContext won't be set when we show the menu on left click
// (it seems setting DataContext for ContextMenu is hardcoded in WPF when user right clicks on a control, although I'm not sure)
// so we have to set up ContextMenu.DataContext manually here
if (fe.ContextMenu.DataContext == null)
{
fe.ContextMenu.SetBinding(FrameworkElement.DataContextProperty, new Binding { Source = fe.DataContext });
}
fe.ContextMenu.IsOpen = true;
}
}
}
...
<Button Content="Do All" local:ContextMenuLeftClickBehavior.IsLeftClickEnabled="True" >
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Make everything awesome" />
<MenuItem Header="Control the World" />
</ContextMenu>
</Button.ContextMenu>
</Button>
(note the comment inside the OnMouseLeftButtonUp() method)
Solution 3
While Caleb's answer is correct, it doesn't include working code. I setup an example using VB.NET (sorry) so I'm posting it here.
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:AttachedBehaviorTest.AttachedBehaviorTest"
Title="MainWindow" Height="350" Width="525">
<Grid>
<StackPanel>
<TextBlock local:ContextMenuLeftClickBehavior.IsLeftClickEnabled="True">Some Text Goes Here
<TextBlock.ContextMenu>
<ContextMenu>
<MenuItem Header="Test1" />
</ContextMenu>
</TextBlock.ContextMenu>
</TextBlock>
</StackPanel>
</Grid>
</Window>
Namespace AttachedBehaviorTest
Public NotInheritable Class ContextMenuLeftClickBehavior
Private Sub New()
End Sub
Public Shared Function GetIsLeftClickEnabled(obj As DependencyObject) As Boolean
Return CBool(obj.GetValue(IsLeftClickEnabled))
End Function
Public Shared Sub SetIsLeftClickEnabled(obj As DependencyObject, value As Boolean)
obj.SetValue(IsLeftClickEnabled, value)
End Sub
Public Shared ReadOnly IsLeftClickEnabled As DependencyProperty = _
DependencyProperty.RegisterAttached("IsLeftClickEnabled", GetType(Boolean), GetType(ContextMenuLeftClickBehavior), New UIPropertyMetadata(False, AddressOf OnIsLeftClickEnabled))
Private Shared Sub OnIsLeftClickEnabled(sender As Object, e As DependencyPropertyChangedEventArgs)
Dim fe As FrameworkElement = TryCast(sender, FrameworkElement)
If fe IsNot Nothing Then
Dim IsEnabled As Boolean = CBool(e.NewValue)
If IsEnabled = True Then
AddHandler fe.MouseLeftButtonUp, AddressOf OnMouseLeftButtonUp
Debug.Print("Added Handlers")
Else
RemoveHandler fe.MouseLeftButtonUp, AddressOf OnMouseLeftButtonUp
Debug.Print("RemovedHandlers")
End If
End If
End Sub
Private Shared Sub OnMouseLeftButtonUp(sender As Object, e As RoutedEventArgs)
Debug.Print("OnMouseLeftButtonUp")
Dim fe As FrameworkElement = TryCast(sender, FrameworkElement)
If fe IsNot Nothing Then
'Next Line is Needed if Context Menu items are Data Bound
'fe.ContextMenu.DataContext = fe.DataContext
fe.ContextMenu.IsOpen = True
End If
End Sub
End Class
End Namespace
Solution 4
This answer does exactly the same job as the answer from @nightcoder (thanks for the inspiration!). It uses a Blend-style behavior which is a more modern approach compared to an attached property.
using System;
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Interactivity;
/// <summary>
/// Add this to any button menu allow a left click to open the context menu as well as the right.
/// </summary>
public class ContextMenuLeftClickBehavior : Behavior<ButtonBase>
{
protected override void OnAttached()
{
base.OnAttached();
this.AssociatedObject.Loaded += this.OnWindowLoaded;
this.AssociatedObject.Unloaded += this.OnWindowUnloaded;
}
private void OnWindowLoaded(object sender, RoutedEventArgs e)
{
this.AssociatedObject.Click += OnMouseLeftButtonUp;
}
private void OnWindowUnloaded(object sender, RoutedEventArgs e)
{
this.AssociatedObject.Click -= OnMouseLeftButtonUp; // Cannot override OnDetached(), as this is not called on Dispose. Known issue in WPF.
}
private static void OnMouseLeftButtonUp(object sender, RoutedEventArgs e)
{
if (sender is ButtonBase fe && fe.ContextMenu != null)
{
if (fe.ContextMenu != null)
{
// If we use binding in our context menu, then it's DataContext won't be set when we show the menu on left click. It
// seems setting DataContext for ContextMenu is hardcoded in WPF when user right clicks on a control? So we have to set
// up ContextMenu.DataContext manually here.
if (fe.ContextMenu?.DataContext == null)
{
fe.ContextMenu?.SetBinding(FrameworkElement.DataContextProperty, new Binding { Source = fe.DataContext });
}
fe.ContextMenu.IsOpen = true;
}
}
}
}
Then add the behavior to the button:
<Button>
<i:Interaction.Behaviors>
<attachedProperties:ContextMenuLeftClickBehavior/>
</i:Interaction.Behaviors>
<Button>
Elements such as an Ellipse or a Rectangle do not have an OnClick
event, which means nothing really works very well for anything interactive. So wrap everything in a button to get that OnClick
event. Might as well hint that the area is clickable by changing the mouse cursor to a hand on mouseover.
<Button.Style>
<Style TargetType="{x:Type Button}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Ellipse Fill="{TemplateBinding Background}" Width="16" Height="16"/>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<!-- Bind to custom color in ViewModel -->
<Setter Property="Background" Value="{Binding CustomBrush}"/>
<Setter Property="Cursor" Value="Hand"/>
</Trigger>
</Style.Triggers>
</Style>
</Button.Style>
yurnero
A .NET developer that is currently working on a real-time financial application built in WPF at his job. In my spare time, I mess with all kinds of other stuff.
Updated on July 28, 2022Comments
-
yurnero almost 2 years
The default behavior of a WPF
ContextMenu
is to display it when the user right-clicks. I want theContextMenu
to show when the user left-clicks. It seems like this should be a simple property onContextMenu
, but it is not.I rigged it, so that I handle the
LeftMouseButtonDown
event in the code-behind and then display the context menu.I'm using MVVM in my project which means I'm using
DataTemplate
s for the items that have the context menus. It would be much more elegant to get rid of the code-behind and find a way to display the context menu using triggers or properties in the XAML.Any ideas or solutions to this issue?
-
Sonhja over 11 yearsI think this solution is easier: uxpassion.com/blog/old-blog/…
-
Caleb Vear over 11 yearsIt is definitely an easier approach and if you only need it one spot I would recommend just putting the code in the code behind. However if you need this behaviour in a few places the attached behavior method I have suggested is nicer IMO.
-
Caleb Vear over 11 yearsOh and if you wanted an even easier solution with a button you can just use a ToggleButton and bind it's IsChecked property to the context menu's IsOpen property.
-
DoubleJ about 8 yearsExcellent solution, to solve the binding issue referenced in your comments, you can set the placement target:
fe.ContextMenu.PlacementTarget = fe
thenDataContext="{Binding Path=PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
You can then use the ContextMenuService properties like Placement and Horizontal/VerticalOffset to position it. -
Admin almost 5 yearsI did not want it to open again when clicking the button while the contextmenu was already shown. So below IsOpen=true I added these 2 lines:
fe.ContextMenu.Closed += ((s, a) => { fe.IsEnabled = true; }); fe.IsEnabled = false;
-
Charles A. over 2 yearsThis works for me, but some things have changed since this answer was posted.
System.Windows.Interactivity
no longer seems to exist andBehavior
is now part of theMicrosoft.Xaml.Behaviors
namespace in the NuGet packageMicrosoft.Xaml.Behaviors.WPF
(there are other packages for other frameworks). Also worth noting is that theattachedProperties
namespace is aclr-namespace
pointing to the namespace that contains the behavior subclass. In my case I already had a local namespace in my XAML for this, so it was just<local:ContextMenuLeftClickBehavior/>
. -
CodingNinja over 2 years@user1552075 It is recommended to add
ContextMenuService.IsEnabled="false"
to xaml to avoid the need for an extra click to switch operation whenIsOpen=True
.