CODEWITHSUNDEEP
c#wpfmultithreadingdata-binding
konrad
konrad

Reputation: 3716

cannot update wpf control from non UI thread

I know this was answered but i can't get it to work. can someone be kind enough to help me figure this out

Here's my xaml class:

namespace Windamow
{
/// <summary>
/// Interaction logic for DynamoWindow.xaml
/// </summary>
public partial class DynamoWindow : Window
{
    public DynamoWindow()
    {
        InitializeComponent();
    }
    public void setBrowserURL(string URL)
    {
        browser.Source = new Uri(URL);
    }
    public void setBrowserFromString(string HTMLString)
    {
        browser.NavigateToString(HTMLString);
    }
}
}

I then try to update the html string that gets displayed like this:

namespace Windamow
{
public class Windamow
{

    private DynamoWindow window;

    internal void ThreadProc()
    {
        window = new DynamoWindow();

        window.ShowDialog();
    }

    internal Windamow()
    {
        Thread t = new Thread(ThreadProc);
        t.SetApartmentState(ApartmentState.STA);
        t.Start();
    }

    public static DynamoWindow MakeWindow(bool launch, string html)
    {
        if (launch)
        {
            Windamow mow = new Windamow();

            var action = new Action(() => mow.window.setBrowserFromString(html));
            Application.Current.Dispatcher.BeginInvoke(
            DispatcherPriority.Input,
            action);

            return mow.window;
        }
        else
        {
            return null;
        }
    }
}
}

xaml:

<Window x:Class="Windamow.DynamoWindow"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
<Grid>
    <WebBrowser x:Name="browser" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</Grid>

Error message:

The calling thread cannot access this object because a different thread owns it.

Upvotes: 1

Views: 117

Answers (1)

Pragmateek
Pragmateek

Reputation: 13408

The issue is here:

var action = new Action(() => mow.window.setBrowserFromString(html));

This code will try to access the window object from the main UI thread whereas it has been created on and associated to another thread, the one you create yourself t.

Depending on your use case you may simply try something like:

public DynamoWindow(string html)
{
    InitializeComponent();

    setBrowserFromString(html);
}
...
if (launch)
{
    Windamow mow = new Windamow(html);

    return mow.window;
}

(not tested but you get the idea)

Upvotes: 1

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