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I am opening WPF Window from Winforms application in manuItem_ClickedHandler.

Step 1:
In Constructor of ViewModel I am creating thread and doing some work. In callback event, Value of control is updated successfully.

Step 2:
I closes this WPF form and Re-Open the WPF Window. Thread again Runs and complete it work but this time Text on WPF GUI is not updated. Callback is called. but no Error and No GUI updated.

What I have tried:

View Model


C#
public class MyViewModel : BindableBase
{
    internal ThreadClass objThreadClass;
    string statusText = $"The Time is: {DateTime.Now}";
    public SynchronizationContext ViewContext;

    public string StatusText
    {
        get => statusText;
        set => SetProperty(ref statusText, value);
    }


    public MyViewModel()
    {
        objThreadClass = new ThreadClass();
        Events_Delegates.evDisplayStatus += Events_Delegates_evDisplayStatus;
    }

    void Events_Delegates_evDisplayStatus(int count)
    {
        ViewContext.Post(x => StatusText = $"Current Count is: {count}");
    }
}



//ThreadClass

//
C#
public class ThreadClass
{
    Thread objThread;
    Events_Delegates EvDel = new Events_Delegates();

    public ThreadClass()
    {
        objThread = new Thread(ExecuteMethod);
        objThread.Start();
    }

    void ExecuteMethod()
    {
        int i = 0;
        int j = 0;
        while (true)
        {
            while (i < 1000)
            {
                i++;
            }
            i = 0;
            j++;
            EvDel.DisplayStatus(j);
            Thread.Sleep(500);
        }
    }

}

public class Events_Delegates
{
    public delegate void dUpdateStatus(int count);
    public static event dUpdateStatus evDisplayStatus;

    public void DisplayStatus(int count)
    {
        evDisplayStatus(count);
    }


}


//View
HTML
<pre><Window x:Class="Abc.View.WinMultiThread"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Abc.View"
        xmlns:dc="clr-namespace:Abc.ViewModel"
        mc:Ignorable="d"
        Title="Multi Threading" Height="1200" Width="2000" WindowState="Maximized" >

    <Window.DataContext>
        <dc:My_ViewModel/>
    </Window.DataContext>

    <Grid>
 <Label Grid.Column="1" FontSize="18"  FontWeight="Bold" Foreground="White" Background="OrangeRed" VerticalAlignment="Center" Content="{Binding StatusText}" ></Label>
</Grid>
</Window>


//Code Behind

C#
public partial class WinMultiThread : Window
    {
        My_ViewModel dataContext = null; 
        public WinDashboard()
        {
            InitializeComponent();

            dataContext = (My_ViewModel)this.DataContext; 

            dataContext.ViewContext = SynchronizationContext.Current; //Assigning Context to update GUI that will be used in ViewModel
        }
}



//Code to Open Wpf Form from Winform Button
C#
Abc.View.WinMultiThread wpfwindow = new Abc.View.WinMultiThread();
ElementHost.EnableModelessKeyboardInterop(wpfwindow);
wpfwindow.Show();
Posted
Updated 21-Oct-20 15:22pm
v3
Comments
Gerry Schmitz 22-Oct-20 6:35am
   
I don't see any "On property changed" code. Invalid bindings can still work "once".
DoingWork 22-Oct-20 13:32pm
   
According to my knowledge, When Implementing BindableBase in View model then SetProperty(ref statusText, value); method in Setter calls On_property_changed in Background.
Richard Deeming 27-Oct-20 13:33pm
   
You have a memory leak in your application. The static evDisplayStatus field has a reference to your MyViewModel instance, which is never released when you close the window.

It's not clear why you're using that class at all, rather than raising an event directly from your ThreadClass class.

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