CODEWITHSUNDEEP
c#wpfxaml
Nekeniehl
Nekeniehl

Reputation: 1691

Behaviour to un/hide Framework Element

I have created a custom TextBlock that changes the Visibility after some seconds specified by a DependencyProperty ShowTime:

<customUserControl:AutoHideTextBlock Text="AutoHideTextBlock" Visibility="{Binding IsVisibleEnabled, Converter={StaticResource BoolToVisConverter}}" ShowTime="3"/>

This is a nice solution and it works, the problem is that I have several other elements that needs the same behaviour and I cannot really make it a CustomUserControl for all of them, I have created the following class to help me with that:

public class AutoHideExtension
{
    public static readonly DependencyProperty VisibilityListenerProperty =
        DependencyProperty.RegisterAttached(
            "VisibilityListener",
            typeof(bool),
            typeof(AutoHideExtension),
            new PropertyMetadata(false, VisibilityChanged));

    public static double GetVisibilityListener(DependencyObject obj)
        => (double)obj.GetValue(VisibilityListenerProperty);

    public static void SetVisibilityListener(DependencyObject obj, double value)
        => obj.SetValue(VisibilityListenerProperty, value);

    private static void VisibilityChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var element = (FrameworkElement)d;

        if (element.Visibility == Visibility.Collapsed || !IsLoaded)
            {
                return;
            }

        DispatcherTimer timer = new DispatcherTimer(DispatcherPriority.Background)
                                    {
                                        Interval =
                                            new TimeSpan(
                                            0,
                                            0,
                                            ShowTime)
                                    };

        timer.Tick += (senderEvent, args) =>
            {
                element.Visibility = Visibility.Collapsed;
                timer.Stop();
            };

        timer.Start();
    }
}

The idea is that I can attach this new property to any element and change the visibility after the specified time, something like follows:

<TextBlock Text="TextToHide"
            helpers:AutoHideExtension.VisibilityListener="{Binding ChangesSavedEnabled}"/>

The problem is that I don't know how to specify the ShowTime as property in the extension class, and that this is simply not working since is not changing the Visibility.

Any Ideas or suggestions on how I can continue forward with this?

Thanks in advance!

Upvotes: 1

Views: 45

Answers (1)

mm8
mm8

Reputation: 169200

Your dependency property VisibilityListener should get and set a bool value:

public static bool GetVisibilityListener(DependencyObject obj)
    => (bool)obj.GetValue(VisibilityListenerProperty);

public static void SetVisibilityListener(DependencyObject obj, bool value)
    => obj.SetValue(VisibilityListenerProperty, value);

You could then define another attached property for the ShowTime, or you could define a Blend behaviour that contains two properties:

<TextBlock xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
          Text="TextToHide">
    <i:Interaction.Behaviors>
        <local:AutoHideExtensionBehavior VisibilityListener="{Binding ChangesSavedEnabled}" ShowTime="3" />
    </i:Interaction.Behaviors>
</TextBlock>

Upvotes: 1

Related Questions