Question : C# Updating WPF with from Thread

Hi,

I am trying to figure out how to tell the main window thread to update the textbox from the thread I generated. I've read all over google about it and I just don't understand it. The examples vary a lot in structure so it's difficult to learn it when it's all different.

I get the following error when running this program:
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System.InvalidOperationException was unhandled
Message=The calling thread cannot access this object because a different thread owns it.
Source=WindowsBase
StackTrace:
at System.Windows.Threading.Dispatcher.VerifyAccess()
at System.Windows.Threading.Dispatcher.DisableProcessing()
at System.Windows.Documents.TextContainer.BeginChange(Boolean undo)
at System.Windows.Documents.TextContainer.System.Windows.Documents.ITextContainer.BeginChange()
at System.Windows.Documents.TextRangeBase.BeginChangeWorker(ITextRange thisRange, String description)
at System.Windows.Documents.TextRangeBase.SetText(ITextRange thisRange, String textData)
at System.Windows.Documents.TextRange.System.Windows.Documents.ITextRange.set_Text(String value)
at System.Windows.Controls.Primitives.TextBoxBase.AppendText(String textData)
at WpfApplication7.MainWindow.appendToLog() in c:\users\user\documents\visual studio 2010\Projects\WpfApplication7\WpfApplication7\MainWindow.xaml.cs:line 41
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:
/////////////////////////////////////////////////////////////////////////////////

Here is the program:
/////////////////////////////////////////////////////////////////////////////////
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel;
using System.Threading;

namespace WpfApplication7
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private Thread t;
private string myMessage;

public MainWindow()
{
InitializeComponent();

myMessage = "Thread me...\n";

t = new Thread(appendToLog);
t.Start();
}

private void appendToLog()
{
for (int i = 0; i < 10; i++)
{
tbLog.AppendText(myMessage);
Thread.Sleep(1000);
}
}
}
}
/////////////////////////////////////////////////////////////////////////////////

Thank you for any help!

Answer : C# Updating WPF with from Thread

There are many ways to do it...here's one:

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    public partial class MainWindow : Window
    {

        private Thread t;
        private delegate void UpdateLog(string msg);

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_ContentRendered(object sender, EventArgs e)
        {
            t = new Thread(appendToLog);
            t.IsBackground = true;
            t.Start();
        }

        private void appendToLog()
        {
            for (int i = 0; i < 10; i++)
            {
                Dispatcher.Invoke(new UpdateLog(UpdateLogMethod), new object[] { "Message #" + i.ToString() + Environment.NewLine});
                Thread.Sleep(1000);
            }
        }

        private void UpdateLogMethod(string msg)
        {
            tbLog.AppendText(msg);
        }

    }