I've recently taken over the documentation for some of the Silverlight controls, and one of the controls I now own is Popup. One of the first things I do when preparing to document a control is play around with it in code. Using the Popup control is pretty straightforward, but I wanted to share the basics, particularly since we didn't get the documentation in for Beta1 (see Margaret's post; we are a bit understaffed) Popup is useful for hosting content, particularly a UserControl, in a new "popup" on top of the existing Silverlight content.

To get started, I created a Silverlight application project and added a user control named MyControl to the project.

Following is the code for my user control. It's a control that contains a button which, when clicked, causes the pop-up to disappear. (It's basic--I don't want to detract from the main point of this post). First the code in MyControl.xaml:

<UserControl x:Class="PopupEx.MyControl"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="150" Height="80">
    <Border BorderThickness="5" BorderBrush="Black">
    <StackPanel x:Name="LayoutRoot" Background="White">
       <TextBlock Margin="5" Text="See the popup?" />
        <Button Width=" 50" Content="Yes" Click="Button_Click"/>
    </StackPanel>
    </Border>
</UserControl>

Here's the click event handler for MyControl.xaml.cs. The event-handler simply sets the Visibility property to Visibility.Collapsed, to remove it from the layout.

private void Button_Click(object sender, RoutedEventArgs e)
{
       // Remove the control from the layout.
       this.Visibility = Visibility.Collapsed;
}

Next I'll add a button to Page.xaml for my main Silverlight control, which when clicked, shows my user control. Paste this into the existing Grid in Page.xaml:

<Button Width="100" Height="50" x:Name="showPopup" Click="showPopup_Click"
        Content="Show Popup" />

My next task is to handle the click event for the ShowPopup button. I'll need to add a using statement for System.Windows.Controls.Primitives to Page.xaml.cs, because Popup is in the Primitives namespace:

using System.Windows.Controls.Primitives;

Now I need to handle the Click event and show my user control. I'll create a new Popup object and set its Child property to my user control. I can optionally tweak where the popup shows up on the screen with VerticalOffset and HorizontalOffset. Finally, I'll show the popup by setting its IsOpen property to true.

// Declare the popup object.
Popup p;
private void showPopup_Click(object sender, RoutedEventArgs e)
{
    // Create a popup.
    p = new Popup();

    // Set the Child property of Popup to an instance of MyControl.
    p.Child = new MyControl();

    // Set where the popup will show up on the screen.
    p.VerticalOffset = 200;
    p.HorizontalOffset = 200;

    // Open the popup.
    p.IsOpen = true;
}