Attaching a custom DependencyProperty to a StackPanel in WPF? - wpf

Question

I'm trying to make a mouse over for a stack panel in WPF using a custom DependencyProperty (StackPanels do not handle the MouseEnter event).
I've created a class for the DependencyProperty like so:
Public Class MouseEnterBehavior
Public Shared Property MouseEnterProperty As DependencyProperty =
DependencyProperty.RegisterAttached("MouseEnter",
GetType(ICommand),
GetType(MouseEnterBehavior),
New PropertyMetadata(Nothing, AddressOf MouseEnterChanged))
Public Shared Function GetMouseEnter(ByVal obj As DependencyObject) As ICommand
Return CType(obj.GetValue(MouseEnterProperty), ICommand)
End Function
Public Shared Sub SetMouseEnter(ByVal obj As DependencyObject, ByVal value As ICommand)
obj.SetValue(MouseEnterProperty, value)
End Sub
Public Shared Sub MouseEnterChanged(ByVal obj As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
Dim element As UIElement = TryCast(obj, UIElement)
If element IsNot Nothing Then
AddHandler element.MouseEnter, AddressOf uiElement_MouseEnter
End If
End Sub
Public Shared Sub uiElement_MouseEnter(ByVal sender As Object, ByVal e As EventArgs)
Dim uiElement As UIElement = TryCast(sender, UIElement)
Dim command As ICommand = GetMouseEnter(uiElement)
If command IsNot Nothing And command.CanExecute(uiElement) Then
command.Execute(uiElement)
End If
End Sub
End Class
My View looks like this:
<Window x:Class="MainWindowView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:WpfApplication1"
Title="MainWindow" Height="350" Width="525">
<Grid>
<StackPanel Height="76" vm:MouseEnterBehavior.MouseEnterCommand="{Binding MouseEnteredCommand}" HorizontalAlignment="Left" Margin="212,117,0,0" VerticalAlignment="Top" Width="88" Background="#72000000" />
</Grid>
</Window>
And my ViewModel looks like this:
Public Class MainWindowViewModel
Inherits ViewModelBase
Implements INotifyPropertyChanged
Private cmdMouseCommand As RelayCommand
Public ReadOnly Property MouseEnteredCommand As ICommand
Get
If cmdMouseCommand Is Nothing Then
cmdMouseCommand = New RelayCommand(AddressOf OnMouseEnterCommand)
End If
Return cmdMouseCommand
End Get
End Property
Private Sub OnMouseEnterCommand(ByVal obj As Object)
''//Do something
End Sub
End Class
Update
I was able to get the code to compile and run, however the binding doesn't occur. I can't seem to figure out why.

Answer 1

You've registered the dependency property as MouseEnteredCommand, but try to bind to MouseEnterCommand.
On a side note, the binding won't set your DependencyProperty using the Set call you've provided; it will call SetValue directly. You'll need to pass a callback into the RegisterAttached so that you'll be notified.

Answer 2

I do believe that this is your problem:
DependencyProperty.RegisterAttached("MouseEnteredCommand",
GetType(ICommand),
GetType(MainWindowViewModel)
the first GetType should be the type of the property ( you are OK here )
the second GetType shuold be the type of the containing class, in your case "MouseEnterBehavior"