WPF Popup event handling - How to get triggered when Popup opens

Question

Hi,

I created a WPF Popup which contains a grid with border. There is some animation associated with the border which I want to be triggered every time the Popup opens.

Currently the code is like this

<Popup x:Name="myPopUp" >
  <Border x:Name="myBorder" >
    <Border.Triggers>
               <EventTrigger RoutedEvent="Popup.Loaded">
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation
                                    Storyboard.TargetName="myBorder" 
                                    Storyboard.TargetProperty="Height"
                                    From="10" To="255" Duration="0:0:0.20" />                      
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger>
     </Border.Triggers>
     <Grid />
   </Border>
</Popup>

As per the code the border shows up the animation for the first time the popup opens. What change do I need to make to trigger the border animation every time the Popup opens?

Answer 1

I'm not sure if the popup gets focus when it opens, but you could use the GotFocus event if it does. Alternatively, you could try using a datatrigger on the is IsOpen property. I think you'd have to put that in a style though instead of inline.

Answer 2

try changing your event trigger to

<EventTrigger RoutedEvent="Popup.Opened">

Answer 3

You can achieve this by listening to the IsOpen dependency property like

    public MainWindow()
    {
        InitializeComponent();

        //// Listening to the IsOpen dependency property of the Popup.
        this.SetBinding(PopupIsOpenProperty, new Binding() { Source = this.popupContainer, Path = new PropertyPath("IsOpen") });
    }

    /// <summary>
    /// Gets or sets a value indicating whether [popup is open].
    /// </summary>
    /// <value><c>true</c> if [popup is open]; otherwise, <c>false</c>.</value>
    public bool PopupIsOpen
    {
        get { return (bool)GetValue(PopupIsOpenProperty); }
        set { SetValue(PopupIsOpenProperty, value); }
    }

    // Using a DependencyProperty as the backing store for PopupIsOpen.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty PopupIsOpenProperty =
        DependencyProperty.Register("PopupIsOpen", typeof(bool), typeof(MainWindow), new PropertyMetadata(false, 
            (dependencyObject, e) =>
            {
                var mainWindow = (MainWindow)dependencyObject;

                if (mainWindow != null &&
                    (bool)e.NewValue == true)
                {
                    //// Raise your event here... like
                    //// mainWindow.RaisePopupOpened();
                    System.Diagnostics.Debug.WriteLine("Popup Open Triggered");
                }
            }));

    private void button_MouseLeave(object sender, MouseEventArgs e)
    {
        this.popupContainer.IsOpen = false;
    }

    private void button_MouseMove(object sender, MouseEventArgs e)
    {
        //// Setting the popup position
        var p = e.GetPosition(sender as UIElement);
        this.popupContainer.HorizontalOffset = p.X;
        this.popupContainer.VerticalOffset = p.Y;

        //// Enabling popup when it is hover on the button
        this.popupContainer.IsOpen = true;
    }


<!-- XAML Starts here-->
<Grid>
    <Button x:Name="button1" Content="This is a sample text" MouseMove="button_MouseMove" MouseLeave="button_MouseLeave" Width="100" Height="25" />
    <Popup x:Name="popupContainer" IsHitTestVisible="False" >
        <Grid Background="White">
            <TextBlock Text="{Binding Content, ElementName=button}" />
        </Grid>
    </Popup>
</Grid>

HTH