Creating New Item Presenter

In certain scenarios creating a new template is not sufficient. For example the case when you want to add an interactive control, such as Button in the Item's presenter and want to attach an event handler to this button so that you can perform specific action when it is pressed. In order to implement the above scenario, you have to derive from ItemPresenter and associate a custom template with the new class. For more information on how to create custom templates, check Creating New Item TemplateCreating New Item Template. Somewhere within the newly created template, there will be a button definition similar to the one below.

XAML

<Button x:Name="myButton" />

It is important to name the button so that it can be accessed in the template class.

The definition of the custom presenter class will look similar to the following.

C#

class MyPresenter : ItemPresenter
{
    public MyPresenter(Calendar calendar)
        : base(calendar)
    {
        this.DefaultStyleKey = typeof(MyPresenter);
    }
}

Visual Basic

Class MyPresenter
    Inherits ItemPresenter

    Public Sub New(ByVal calendar As Calendar)
        MyBase.New(calendar)

        Me.DefaultStyleKey = GetType(MyPresenter)

    End Sub

End Class

In order to attach an event handler to the button myButton, you have to override the OnApplyTemplate method, obtain a reference to the button through the GetTemplateChild method and attach an event handler to the button's Click event. Make sure to call the method of the base class in the OnApplyTemplate override. The following code illustrates how.

C#

public override void OnApplyTemplate()
{
    base.OnApplyTemplate();

    Button myButton = GetTemplateChild("myButton") as Button;
    if (myButton != null)
        myButton.Click += OnMyButtonClick;
}

...

void OnMyButtonClick(object sender, RoutedEventArgs e)
{
    // Perform the necessary actions here
}

Visual Basic

Public Overrides Sub OnApplyTemplate()

    MyBase.OnApplyTemplate()

    Dim myButton As Button = CType(GetTemplateChild("myButton"), Button)
    If Not myButton Is Nothing Then
        AddHandler myButton.Click, AddressOf OnMyButtonClick
    End If

End Sub

...

Sub OnMyButtonClick(ByVal sender As Object, ByVal e As RoutedEventArgs)

    ' Perform the necessary actions here

End Sub

Now that the custom presenter and its template are ready, you need to associate the presenter with an item. In order to do this, you have to define a new Item class and associate MyPresenter with it using the ItemPresenterAttribute. To see the new presenter in action, create an item of type MyAppointment and add it to the displayed schedule.

C#

[ItemPresenter(typeof(MyPresenter))]
public class MyAppointment : Appointment
{
    public MyAppointment()
    {
    }

    ...
}

Visual Basic

<ItemPresenter(GetType(MyAppointmentPresenter))> _
Public Class MyAppointment
    Inherits Appointment

    Public Sub New(ByVal calendar As calendar)

    End Sub

    ...

End Class

For an extensive example on how to create custom item presenters, check the new CustomItemTemplate sample.