从WinForm调用对象事件

Question

I need to raise objects event in WinForm. Need to change control state (in UI) when object property has been changed. How can I raise objects event in UI?

EDIT: On form i have 2 drop downs binded to object properties. I need to disable second drop down when selection on first one is false.

Answer 1

You can't raise object's event. Only object can raise it's event. You can only subscribe to object's event. Why? Because event is actually a pair of methods for adding and removing handlers. It's not same as property of delegate type, which you can invoke from any place.

So, you should do something which will cause object to raise that event. There is no way to raise event directly.

---

Here is sample of INotifyPropertyChanged usage:

// your object
public class Foo : INotifyPropertyChanged
{
    private bool _bar;

    public bool Bar
    {
        get { return _bar; }
        set { 
            if (_bar == value)
                return;

            _bar = value;
            OnPropertyChanged("Bar");
        }
    }

    protected virtual void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

And bind your control to this object:

yourControl.DataBindings.Add("Enabled", foo, "Bar");

When Bar property will be changed, foo object will raise event, and your control will handle that event.

Answer 2

If you object already implements INotifyPropertyChanged , you can do the following inside your WinForm class:

yourObject.PropertyChanged += (s, e) =>
    {
        if (e.PropertyName == "Name") {
            //Check the value of the property here, etc...
            button1.Enabled = false;
        }
    };

In that example, Name is the property you want to monitorize.