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How can Load my UserControl using different threads?

I'm using .NET C# and trying to load a UserControl that contains three tabs. What I want to do is, to load the first Tab make it visible and responsive and then load the other two tabs in a background thread (or worker or task).
I've tried to do so using a thread, a task, a backgroundworker but always have the same exception "The calling thread cannot access this object because a different thread owns it."
here some code samples I used:
BackgroundWorker bw = new BackgroundWorker();
bw.DoWork += new DoWorkEventHandler(bw_DoWork);
bw.RunWorkerAsync();
in the bw_DoWork I put all the work I need to do that involves UI updates
Task t1 = new Task(DoWork);
t1.Start();
in the DoWork I do the same( some code with UI update)
Thanks for the help.
Oussema

This is not impossible, but it is a bad idea - it's very tricky to get right.
Instead, you want to separate the business logic from the UI, so that you can do the logic in the background, while the UI is still on the UI thread. The key is that you must not modify the UI controls from the background thread - instead, you first load whatever data you need, and then either use Invoke or ReportProgress to marshal it back on the UI thread, where you can update the UI.
If creating the controls themselves is taking too long, you might want to look at some options at increasing the performance there. For example, using BeginUpdate and friends to avoid unnecessary redraws and layouting while you're still filling in the data, or creating the controls on demand (as they are about to be visible), rather than all upfront.
A simple example using await (using Windows Forms, but the basic idea works everywhere):
tabSlow.Enabled = false;
try
{
var data = await Database.LoadDataAsync();
dataGrid.DataSource = data;
}
finally
{
tabSlow.Enabled = true;
}
The database operation is done in the background, and when it's done, the UI update is performed back on the UI thread. If you need to do some expensive calculations, rather than I/O, you'd simply use await Task.Run(...) instead - just make sure that the task itself doesn't update any UI; it should just return the data you need to update the UI.

WPF does not allow you to change UI from the background thread. Only ONE SINGLE thread can handle UI thread. Instead, you should calculate your data in the background thread, and then call Application.Current.Dispatcher.Invoke(...) method to update the UI. For example:
Application.Current.Dispatcher.Invoke(() => textBoxTab2.Text = "changing UI from the background thread");

Properly use Background Worker in a WPF application

i'm stuck in using properly the background worker, the app needs to communicate with the database, so it takes a bit longer and the UI freezes for a while, i need to create a function that does the database things and wait until the work is finished, for this time, i want to display a kind of window that inform the user about the app state (Loading, busy, Downloading).
My code
i didn't write any code yet, but here're what i need:
//instructions
InitializeComponent();
//do this in background and wait until it finnishes
GetEntitiesFromDatabase();
entitiesListView.ItemSource = someList; (GetEntitiesFromDatabase will initialize this list)
//....
How can i proceed, i know that this question might be already asked in the forum but i'm desperate by searching for an answer, if this can be done other way please help me, thanks in advance.

If you are going to directly manipulate the UI like that, you need to use Dispatcher.BeginInvoke when you aren't on the UI thread (read, in the BackgroundWorker).
Dispatcher.BeginInvoke(new Action(() =>
{
entitiesListView.ItemSource = someList;
}), null);
You could also bind that items source to your view model (a much better idea) and the framework will marshal the change to the bound property for you.
Basically, either use Dispatcher.BeginInvoke or switch to MVVM (which WPF was meant to use anyways).

Creating heavy user controls in WPF

I know that I cannot spawn different threads and put it in the UI thread to add it in the Visual Tree as it will throw an exception that it cannot access that object because a different thread owns it.
My current scenario is that I am heavily creating UI controls runtime, say like 200 (FrameworkContentElement) controls and add it to the DockWindow. Is it possible for me not to freeze the UI while creating this and try to load them to the UI thread? I cannot even show a progress dialog because that will use the UI thread while showing the dialog while doing work on another thread, that is okay if what I need to handle is data and put it in the UI but this time I need to create these UI controls.
One approach I've thought is create the UI controls and serialize them into MemoryStream and load them to the UI thread, one problem in here is that I have to re-attach the DataContext to the controls but that is fine, at that moment I can delegate it to another thread. Problem still is that is this feasible to do?
I tried mixing Task and Thread object to make the ApartmentState to STA but still no luck.
public static Task<T> StartSTATask<T>(Func<T> func)
{
var tcs = new TaskCompletionSource<T>();
Thread thread = new Thread(() =>
{
try
{
tcs.SetResult(func());
}
catch (Exception e)
{
tcs.SetException(e);
}
});
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
return tcs.Task;
}
EDIT: These controls again are FrameworkContentElement, virtualizing controls in this scenario won't help. This is with FlowDocument controls creating the controls in runtime. Say, Runs, Tables, Paragraphs, etc.. Therefore, ListBox, TreeViews, etc are not applicable in this scenario.

200 controls shouldn't pose that big of a problem to render WPF on a decent machine can take a few thousand primitives.
You can show a progress bar while loading your data and while parsing it. Then you can throttle creating the UI elements if needed by having and off-UI-thread process loop over your data and call UI thread to instantiate controls. You can even separate instantiations by a small sleep to let the screen render, but only use this for VERY heavy UI...
... that being said - if your UI is so heavy you're probably designing it wrong. The question should not be
"how many UI elements can I put before my UI slows down to a drag?"
but
"what's the smallest number of active UI elements that can do the job?".
The word "active" refers to the approach taken by listviews where the actual items are virtualized - they are only created as needed and disposed if not visible. So instead of a DockPanel consider using a virtualizing container, such as a ListView, if your UI allows for it;
I can elaborate further if you can provide an example of your specific UI elements.

C# - Cross-thread operation - Create Control in thread, add to main form

I have an older form that I really don't want to rewrite at this point, so what I'm doing is loading the form and then adding it to a panel in the new UI form. This is working fine, but it's slow. The old form does a lot of loading and gathering of data and it's not very efficient. So as a result larger records take up to 30 seconds to load. As you know, creating the form then "locks up" the main UI for about 30 seconds while it loads the old form. This is the action I'm trying to prevent. I want to load the new form, display a "Loading" gif in the blank panel, and then once the old form is loaded remove the "Loading" image and add the form as a control.
And here starts the problem.
I've tried creating a Background Worker but this causes a STA error (old form has a few threaded data loadings of it's own), and since I can't change the worker to STA I stopped trying.
I've tried to create an Invoke (and BeginInvoke) and while this works, it doesn't really load the old form in the thread. It simply sends it back to the UI thread and does the work there. Again this hangs the UI. I.E.: Not what I want.
I've tried to create a delegate and trigger it as an event in the thread, but I get the same results as below...
I've created a thread, set STA on it, started it and then did a while loop with a DoEvents waiting on it to finish. Of course this all seems to work up to the point of accually adding the form to the panel, and then I get the "Control 'ChartForm' accesses from a thread other than the thread it was created on". In this error 'ChartForm' is the old chart that was loaded in the thread.
I've tried the above method, but I instead used a private static field to hold the creating of the old form, and then adding it to the panel once the thread is completed. This is in the method that created the thread, just after the while loop. Same error.
So, I've used the above method in other places with DataTables and didn't have any issue getting the data back to the main thread for use with DataBinding. I know that this is a little different but I didn't think that it would be this hard to do.
Below is the code that I have tried to use that seems to be the closest to what I want.
private static _ChartForm;
private void LoadPatientChart()
{
ClearMainPanel(); // Removes any loaded ChartForms from Panel
if (_Patient == null) // Test to make sure a patient is loaded
return;
loadingPanel.Visible = true; // Displays the "Loading" gif
Thread thread = new Thread(new ThreadStart(this.GetChartForm));
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
while (thread.ThreadState != ThreadState.Stopped)
Application.DoEvents(); // Keeps the UI active and waits for the form to load
this.ChartPanel.Controls.Add(_ChartForm); // This is where the error is
loadingPanel.Visible = false; // Hide the "Loading" gif
}
private void GetChartForm()
{
ChartForm chartForm = new ChartForm(_Patient.AcctNum.ToString(), false);
chartForm.TopLevel = false;
chartForm.FormBorderStyle = FormBorderStyle.None;
chartForm.Dock = DockStyle.Fill;
chartForm.Visible = true;
_ChartForm = chartForm;
}

It's really not a good idea to create UI controls on any other thread than the UI thread. It is technically possible, but it's difficult to manage, especially if the new thread is a "temporary" one.
What you really need to do is refactor out the work that the ChartForm is doing (on construction it appears?) and do that work on a background thread, and then return it to your UI thread and then create your ChartForm passing in the results of that work. IMHO this is a better design anyways; although it may be a lot of work for you.

I don't think what you want is possible without refactoring this "old form". There is only one UI thread, and all UI elements must be created on that thread to be displayed to the user.
I would suggest refactoring the form to display initially without any data (or maybe with a loading image), and then have the form start a background task using BackgroundWorker to perform the long running tasks that are not UI related (going to a database, etc.) Once the worker is complete, then you can run the code that initializes the Form's data elements. This will keep the UI responsive for as long as possible while the blocking tasks are performed.

I've tried to create an Invoke (and BeginInvoke) and while this works,
it doesn't really load the old form in the thread. It simply sends it
back to the UI thread and does the work there. Again this hangs the
UI. I.E.: Not what I want.
You must update the user interface on the main thread, you do not have any choice, if its still hanging then your doing the calculations in the wrong thread.

C# how to implement a class that works with controls and enable threading?

I have written a class that fills a treeview for me. IN my project I need this treeview several times and I don;t want to copy paste my code, so I decided to create a class that fills the treeview for me.
On some forms I want to use a thread to fill the treeview. This is because sometimes it can take some time to load the data and fill the treeview.
In my treeview-class I pass the treeview in the constructor. At the moment I want to fill the treeview, I call the LoadTreeview() method.
I'd like to call the LoadTreeview method on a thread, but when I do this I get the exception that the treeview is created on another thread. Which is logic off course. But I was wondering, what is the best way to create a custom class that works with controls and you want to use this class in a thread?
Do I need to write this code on every 'GUI-action'?
treeview.Invoke((MethodInvoker)delegate
{
treeview.Nodes.Add(MyNode);
})
Or are there other (smarter) ways?

Both your and Levisaxos' solutions will prevent the crash but you should really benchmark the runtime performance of this. The problem is that if you insert lots of nodes to the treeview and each node is inserted through Control.Invoke your code will not be doing much but synchronizing to the UI thread. If this is the case you should consider to separate loading the data that is needed to create the nodes for the treeview from the actual insertion of the nodes. Instead load the data asynchronously and then synchronously insert all nodes at once.

public delegate TreeView updateLabelDelegate(TreeView view);
private TreeView InvokeTreeView(TreeView view)
{
if (view.InvokeRequired)
{
view.Invoke(new updateLabelDelegate(InvokeTreeView), new object[] { view });
return null;
}
else
{
return view;
}
}
I hope this helps you. This is how I am handeling Async operations.
[edit]
Depending on how you want to use it.
In a thread:
public TreeView thistreeviewsucks;
void SomeThread()
{
TreeView tv = new TreeView();
tv.Items.Add("something");
//upon completion
this.thistreeviewsucks = InvokeTreeView(tv);
}
As far as I know this will work.