Show calender on TextBox.GotFocus() event in MVVM

I have an application which is having TextBox. Upon getting the fo开发者_如何学Ccus, I need to show the Calendar as Popup.

My question is how to show subscribe the GotFocus event and show the calendar through view model?

It is fairly acceptable to write code-behind for view-specific tasks like this one, however if you insist to have clean code-behind files , do the following

you will need MvvmLight.Extras.WPF4.dll and System.Windows.Interactivity.dll, the second DLL comes mainly with blend , google the first and at any case you can find them both on the MVVMLight package.

reference them as follows:

xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.WPF4"

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

see your textBox

<TextBox>
<i:Interaction.Triggers>
 <i:EventTrigger EventName="GotFocus">
    <cmd:EventToCommand Command="{Binding showCalendar, Mode=OneWay}" MustToggleIsEnabledValue="True"/>
    </i:EventTrigger>
    </i:Interaction.Triggers>
</TextBox>

on your view model you should have a property that is bound to your Calendar Visibility property , change it to Visible inside the method invoked by the command.

You really don't need to go to the ViewModel for this - it can be done very simply in XAML. Use a BooleanToVisibilityConverter on a binding that is attached to the TextBox's IsFocused property.

            <TextBox x:Name="_textBox" Text="{Binding Text}" />
            <myNameSpace:Calendar Visibility="{Binding ElementName=_textBox, Path=IsFocused, Converter={x:Static _boolToVisibilityConverter}, Mode=OneWay}" />