属性换的不会执行

Question

我正在尝试以Windows表单实现MVP，我将所有控件都绑定到绑定源的相应属性，并且当用户更改某些内容并从控件中丢失焦点时，我希望将属性换的事件立即执行。 目前，只有当我输入主持人 - ＆gt;例如view.username =“ sosings”;但是我不想要这个。

public string Username
    {
        get { return txtUsername.Text; }
        set {
            var oldValue = txtUsername.Text;
            txtUsername.Text = value;
            NotifyPropertyChanged("Name", oldValue, value);
        }
    }




    public class PropertyChangedExtendedEventArgs : PropertyChangedEventArgs
{
    public virtual object OldValue { get; private set; }
    public virtual object NewValue { get; private set; }

    public PropertyChangedExtendedEventArgs(string propertyName, object oldValue,
           object newValue)
           : base(propertyName)
    {
        OldValue = oldValue;
        NewValue = newValue;
    }
}




public partial class MasterForm : Form, INotifyPropertyChanged
{
    public MasterForm()
    {
        InitializeComponent();
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void NotifyPropertyChanged(string propertyName, object oldvalue, object newvalue)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedExtendedEventArgs(propertyName, oldvalue, newvalue));
    }

    private void MasterForm_Load(object sender, EventArgs e)
    {
    }
}

Answer 1

您正在问当用户更改某些内容并因控件而失去焦点时，属性换事的事件将立即执行。

此代码显示了如何捕获UI控件的LostFocus事件以启动所需的事件。

public partial class MasterForm : Form , INotifyPropertyChanged
{
    public MasterForm ()
    {
        InitializeComponent();
    }

    protected override void OnHandleCreated(EventArgs e)
    {
        base.OnHandleCreated(e);
        // Subscribe to the event here
        textBoxUsername.LostFocus += onUsernameLostFocus;
    }

    // Handle the event here
    private void onUsernameLostFocus(object sender, EventArgs e)
    {
        OnPropertyChanged(nameof(Username));
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
    string _username = string.Empty;
    public string Username
    {
        get => _username;
        set
        {
            if (_username != value)
            {
                _username = value;
                OnPropertyChanged();
            }
        }
    }
}