如何在WPF中使隐藏的窗口在背景中存活？

Question

How can I keep a window alive when it is hidden, I'm trying this code out ..

Win1 : Contains Current time and date. ON Button Click the win2 window opens and win1 Hides.

Win2 : In win2 window i have passed the value of the win1 textbox using property.

But in win2 the time is not getting updated .. this means the win1 is not alive anymore

Any suggestions?

{
    public win1()
    {
        InitializeComponent();

        DispatcherTimer timer = new DispatcherTimer(new TimeSpan(0,0,1), DispatcherPriority.Normal, delegate
        {
            this.textb.Text = DateTime.Now.ToString("HH:mm:ss tt");
        }, this.Dispatcher);
    }

    private void Grid_Loaded(object sender, RoutedEventArgs e)
    {

    }

    private void but_send_Click(object sender, RoutedEventArgs e)
    {
        win2 w2 = new win2();
        w2.passval = textb.Text;
        this.Hide();
        w2.ShowDialog();
    }
}

and this is my second window win2.xaml.cs

{
    private string nm;

    public string passval
    {
        get { return nm; }
        set { nm = value;}
    }     

    public win2()
    {
        InitializeComponent();

    }

    private void Grid_Loaded(object sender, RoutedEventArgs e)
    {
        lbl1.Content = "Time " + nm;
    }    
}

Answer 1

The problem is that you are updating Win1's TextBox . The following line copies the string located in textb.Text into w2.passval :

w2.passval = textb.Text;

But that's it: further updates to textb.Text has no effect on the w2.passval property.

Furthermore, keeping a reference to w2 in Win1 and directly updating w2.passval from your delegate, would also not update the contents of lbl1 since your are only updating its value when the Grid is loaded. Therefore you'll need to:

1. Update w2.passval from the delegate in Win1 . For instance:

    public win1() { InitializeComponent(); DispatcherTimer timer = new DispatcherTimer(new TimeSpan(0,0,1), DispatcherPriority.Normal, delegate { this.textb.Text = DateTime.Now.ToString("HH:mm:ss tt"); if (_w2 != null) _w2.passval = textb.Text; }, this.Dispatcher); } private win2 _w2 = null; // Reference to your Win2 private void but_send_Click(object sender, RoutedEventArgs e) { _w2 = new win2(); _w2.passval = textb.Text; this.Hide(); w2.ShowDialog(); } 

2. Update the Label in Win2 . For instance:

    private string nm; public string passval { get { return nm; } set { nm = value; // This should rather be done somewhere else, not in the setter lbl1.Content = "Time " + nm; } }