Tuesday, January 08, 2013

Visibility Hidden Behavior for WinRT

In my last post, I lamented the loss of the Hidden in the Windows.UI.Xaml.Visibility enumeration. Here’s an ultra-simple attached property that simulates Hidden by changing the opacity and hit testability of the element:

using Windows.UI.Xaml;

namespace Blog.VisibilityHiddenDemo
{
    public class VisibilityHiddenBehavior : DependencyObject
    {
        public static readonly DependencyProperty IsVisibleProperty = 
            DependencyProperty.RegisterAttached("IsVisible", typeof(bool), typeof(VisibilityHiddenBehavior),
                new PropertyMetadata(true, OnIsVisibleChanged));

        public static bool GetIsVisible(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsVisibleProperty);
        }

        public static void SetIsVisible(DependencyObject obj, bool value)
        {
            obj.SetValue(IsVisibleProperty, value);
        }

        private static void OnIsVisibleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var element = d as FrameworkElement;
            if (element != null)
            {
                var visible = (bool)e.NewValue;
                element.Opacity = visible ? 1 : 0;
                element.IsHitTestVisible = visible;
            }
        }        
    }
}

Free as in beer.

Happy coding.

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