Question

After I google so much and I still cant understand how does the delegate and event works.

What I want to achieve is:
Class 1 will be playing animation, when the animation END, it will pass the delegate/event to the Class 2 so that Class 2 will do something on the animation END.

I wonder how can I code the above behavior?

Answer 1

Very basic event implementation…

public delegate void Class1AnimationCompletedHandler(object sender, EventArgs e);

public class Class1
{
    public event Class1AnimationCompletedHandler AnimationCompleted;

    private void OnAnimationCompleted(EventArgs e)
    {
        if (this.AnimationCompleted != null)
        {
            // raises the AnimationCompleted event
            this.AnimationCompleted(this, e);
        }
    }

    public void Animate()
    {
        // do your animation steps here

        this.OnAnimationCompleted(new EventArgs());
    }
}

public class Class2
{
    private Class1 c1;

    public Class2()
    {
        // initialize the class
        c1 = new Class1();

        // attach this.Class1_AnimationCompleted to the AnimationCompleted event;
        c1.AnimationCompleted += new Class1AnimationCompletedHandler(this.Class1_AnimationCompleted);
    }

    private void Class1_AnimationCompleted(object sender, EventArgs e)
    {
        // do your post-animation stuff here
    }

}

This link provides a good quick example on how to create events. It’s targeted for VS 2003, but is still applicable.