UI Freezes When Try to Update textbox in wpf - wpf

Question

I have a code that has a text box and a button, when i press the button, the code update the text box and after words sleep for 5 seconds, in those seconds the ui is freezing
I tried with delegates, and threading but nothing works
This is the code with delegates:
MainWindow.vb
Class MainWindow
Delegate Sub MySubDelegate(ByVal x As String)
Private m_engine As Engine
Public Sub New()
m_engine = New Engine(AddressOf WriteToLog)
InitializeComponent()
Me.DataContext = m_engine.GetViewModel()
End Sub
Public Sub WriteToLog(str As String)
Dim vv As ViewModel = CType(DataContext, ViewModel)
vv.Log = str
End Sub
Private Sub clicked(sender As Object, e As RoutedEventArgs)
m_engine.TimingRecord()
End Sub
End Class
Engine.vb
Private m_viewModel As New ViewModel
Private _msd As MainWindow.MySubDelegate
Public Sub New()
End Sub
Sub New(msd As MainWindow.MySubDelegate)
_msd = msd
End Sub
Public Function GetViewModel() As ViewModel
Return m_viewModel
End Function
Public Sub TimingRecord()
_msd("aaaaa")
SetText()
End Sub
Public Sub SetText()
Thread.Sleep(5000)
End Sub
viewModel.vb
Public Class ViewModel
Implements INotifyPropertyChanged
Private m_log As String
Public Property Log As String
Get
Return m_log
End Get
Set(value As String)
m_log = value
End Set
End Property
Public Event PropertyChanged(sender As Object, e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged
Private Sub NotifyPropertyChanged(Optional ByVal propertyName As String = Nothing)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
End Sub
End Class
This is the code with thread:
MainWindow.vb
Delegate Sub MySubDelegate(ByVal x As String)
Private m_engine As Engine
Public Sub New()
m_engine = New Engine(AddressOf WriteToLog)
InitializeComponent()
Me.DataContext = m_engine.GetViewModel()
End Sub
Public Sub WriteToLog(str As String)
Me.Dispatcher.Invoke(Sub() CType(DataContext, ViewModel).Log = str)
'Dim vv As ViewModel = CType(DataContext, ViewModel)
'vv.Log = str
End Sub
Private Sub clicked(sender As Object, e As RoutedEventArgs)
m_engine.TimingRecord()
End Sub
Engine.vb
Public Class Engine
Private m_viewModel As New ViewModel
Private m_thread As Thread
Private _msd As MainWindow.MySubDelegate
Public Sub New(msd As MainWindow.MySubDelegate)
_msd = msd
End Sub
Public Function GetViewModel() As ViewModel
Return m_viewModel
End Function
Public Sub TimingRecord()
m_thread = New Thread(AddressOf DoRecordThread)
m_thread.IsBackground = True
m_thread.Start("aa")
SetText()
End Sub
Public Sub SetText()
Thread.Sleep(5000)
End Sub
Private Sub DoRecordThread(str As String)
_msd(str)
'm_viewModel.Log = str
End Sub
End Class
The ViewModel Stay The same. I'm using wpf so i bind the Log into the textbox and with simple code it works.
Thank you all in advance.

Answer 1

Thread.Sleep causing the issue. It blocks the UI thread that makes the UI frozen.
Have the long running task in different thread and once completed Update the UI(TextBox) with Application.Current.Dispatcher.
Sample Code to update the UI from background thread with Dispatcher :
Application.Current.Dispatcher.Invoke(new Action(() => { Textbox1.Text = result; }))
This is not a right way but I hope this is what you are looking for.
Update
Also, there is another way, you can use builtin BackgroundWorker.
//Add the namespace
using System.ComponentModel;
//Declare
private readonly BackgroundWorker worker = new BackgroundWorker();
//Initialize
worker.DoWork += worker_DoWork;
worker.ProgressChanged += worker_ProgressChanged;
worker.RunWorkerCompleted += worker_RunWorkerCompleted;
//method declaration
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
worker.ReportProgress(0, "Process started");
// run all background tasks here
}
private void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//Progress update with e.UserState.ToString();
}
private void worker_RunWorkerCompleted(object sender,
RunWorkerCompletedEventArgs e)
{
//update ui once worker complete his work
}
//Invoke
worker.RunWorkerAsync();

Answer 2

The problem solved by put the thread.sleep but very foolish of me in the viewmodel class i accidently delete the property changed now it is working perfectly thank you all for helping