How do I make an ellipse blink?

Question

I am trying to make a custom control in WPF. I want it to simulate the behavior of a LED that can blink.

There are three states to the control: On, Off, and Blinkin

Answer 1

You can do this with an animation that auto-reverses and repeats (this is for Silverlight):

and then start the animation when the control loads or when a property is set - you don't need a dependency property unless you

private bool blinking;
public bool IsBlinking
{
    get
    {
       return blinking;
    }
    set
    {
        if (value)
        {
             this.Blink.Begin();
        }
        else
        {
             this.Blink.Stop();
        }

        this.blinking = value;
    }
}

or on startup:

private void UserControl_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
    this.Blink.Begin();
}

Here is another way to do it in WPF - using the VisualStateManager - that will also work in Silverlight:

and then have the IsBlinking property switch the visual state:

namespace BlinkerApp
{
    using System.Windows;
    using System.Windows.Controls;

/// 

/// Interaction logic for Blinker.xaml
/// 
public partial class Blinker : UserControl
{
    private bool blinking;

    public Blinker()
    {
        this.InitializeComponent();
    }

    public bool IsBlinking
    {    
        get    
        {       
            return blinking;    
        }    

        set    
        {        
            if (value)        
            {
                VisualStateManager.GoToState(this, "Blinking", true);
            }        
            else        
            {
                VisualStateManager.GoToState(this, "Stopped", true);
            }        

            this.blinking = value;    
        }
    }       
}
}