Robs Usability Development : Silverlight, ASP.NET, Ajax, Agile, MVC & Volta

In silverlight 1.1/2.0 alpha there are a lot of things that just do not work as us spoiled developers would expect.

One of these things is the fact that a normal Timer event cannot access the UI Thread. Meaning you cannot change any visual things with a normal timer.

There are some fixes around, I added some of them together in a simple class u can use as seen in the following example:

public partial class Page : Canvas
{
    UITimer _Timer;
    public void Page_Loaded(object o, EventArgs e)
    {
        // Create a new UITimer
        _Timer = new UITimer(this); 

        // With a 10 seconds interval
        _Timer.Duration = new TimeSpan(0, 0, 10); 

        // And call this delegate every 10 seconds
        _Timer.TimerEvent += new EventHandler(_Timer_TimerEvent);
    } 

    void _Timer_TimerEvent(object sender, EventArgs e)
    {
        // Do something in the UI
        // Fore example: Set the opacity of the page
        Opacity = 0.5;
    }
}

The class itself looks like this:

using System.Windows;
using System;
using System.Windows.Media.Animation; 

public class UITimer
{
    static int TimerCount = 0; 

    private bool _Active = false;
    public bool Active
    {
        get
        {
            return _Active;
        }
        set
        {
            if (_Active != value)
            {
                _Active = value;
                if (_Active)
                {
                    timer.Duration = _Duration;
                    timer.Begin();
                }
                else
                    timer.Stop();
            }
        }
    } 

    private Duration _Duration;
    public Duration Duration
    {
        get { return _Duration; }
        set
        {
            _Duration = value;
            timer.Duration = _Duration;
        }
    } 

    public event EventHandler TimerEvent;
    Storyboard timer; 

    public UITimer(FrameworkElement rootElement)
    {
        timer = (Storyboard)XamlReader.Load(String.Format(“<Storyboard xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml” x:Name=”UITimer_{0}” Duration=”00:00:00″ />”,UITimer.TimerCount));
        timer.Completed += new EventHandler(timer_Completed);
        rootElement.Resources.Add(timer);
        UITimer.TimerCount++;
    } 

    void timer_Completed(object sender, EventArgs e)
    {
        if (TimerEvent != null)
            TimerEvent(this, EventArgs.Empty);
    }
}

Source Code :  UITimer.zip

Light it up!

Robertjan Tuit