How to connect MouseDoubleClick to ViewModel in an Attached Behavior? - wpf

Question

I am trying to implement Attached Behaviors functionality in the MVVM pattern. I have a Calendar control and would like to handle the MouseDoubleClick event. I was doing that using System.Windows.Interactivity and Interaction.Triggers. However, I am also using BlackoutDates in the Calendar and double-clicking on a Blackout Date results in the last valid selected date being passed to the MouseDoubleClick method, not the date clicked on.
So I am now targeting the CalendarDayButton, which will get me the date clicked on, but CDB doesn't have Commands, so I need to use an Attached Behavior. But I'm still not understanding how to get the MouseDoubleClick handler info into the ViewModel. My current code:
View
<Calendar HorizontalAlignment="Left" VerticalAlignment="Top" Margin="20,48,0,0"
SelectedDate="{Binding ReportDate, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
DisplayDateStart="{Binding ReportDateStart, Mode=OneTime}"
DisplayDateEnd="{Binding ReportDateEnd, Mode=OneTime}"
local:AttachedProperties.RegisterBlackoutDates="{Binding NoProdDates, Mode=OneWay}">
<Calendar.CalendarDayButtonStyle>
<Style TargetType="CalendarDayButton">
<Setter Property="local:AttachedBehaviors.IsValidDateSelected"
Value="{Binding ValidDateSelected, Mode=TwoWay}"/>
</Style>
</Calendar.CalendarDayButtonStyle>
</Calendar>
ViewModel
...
private bool validDateSelected;
public bool ValidDateSelected
{
get { return validDateSelected; }
set
{
if (validDateSelected != value)
{
validDateSelected = value;
RaisePropertyChanged("ValidDateSelected");
}
}
}
...
Attached Behaviors class
using System.Windows;
using System.Windows.Controls.Primitives;
using System.Windows.Input;
namespace MDOD
{
public class AttachedBehaviors : DependencyObject
{
public static readonly DependencyProperty IsValidDateSelectedProperty =
DependencyProperty.RegisterAttached("IsValidDateSelected", typeof(bool), typeof(AttachedBehaviors),
new UIPropertyMetadata(false, OnIsValidDateSelectedChanged));
public static bool GetIsValidDateSelected(DependencyObject obj)
{
return (bool)obj.GetValue(IsValidDateSelectedProperty);
}
public static void SetIsValidDateSelected(DependencyObject obj, bool value)
{
obj.SetValue(IsValidDateSelectedProperty, value);
}
private static void OnIsValidDateSelectedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
CalendarDayButton cdb = d as CalendarDayButton;
if (cdb != null)
{
if ((bool)e.NewValue)
{
cdb.MouseDoubleClick += cdb_MouseDoubleClick;
}
else
{
cdb.MouseDoubleClick -= cdb_MouseDoubleClick;
}
}
}
private static void cdb_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{
// How do I get this info to the ViewModel?
}
}
}