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How to run background process in C# WPF

I am completely new to WPF.
I am writing a simple ui for patient monitoring. In the main screen, I have 3 beds i.e. 3 Buttons
I want to run some background process which basically change the background color of each of the button based on some condition. Each button will have its own process before it updates the color.

Multithreading is a large beast to tackle and even more difficult to debug if you don't fully understand the characteristics of multi threaded environments. Be careful of deadlocks, inadvertently overwriting data in a different thread, and race conditions. With this said I would suggests 2 things to first explore when writing multithreaded applications.
background workers and async functions.
I would start with the background worker and try to send it generics and such, but keep in mind that any changes to the GUI must be done on the same thread that created the GUI (main thread). So callbacks must be in place which the on completed event of the background worker will allow you to do.

Creating wpf controls in background thread

I have to render about 10'000 wpf controls, and I don't want to freeze my application during this action. Is it possible to do it in another thread?
I tried to use
myStackPanel.Dispatcher.BeginInvoke(
System.Windows.Threading.DispatcherPriority.SystemIdle,
new NextPrimeDelegate(this.AddButton));
and another variants of Dispatcher. But it always freeze my application. I'd like to show animated waiting screen during creating hundred controls, but it's always freeze, because it's dispatcher's thread.
thanks for help
Andrew.

WPF controls must be created on the thread associated with the dispatcher where they will be presented. The call to Dispatcher.BeginInvoke schedules the specified action to run on the dispatcher thread at a later time, not on a background thread.
If you have a lot of UI controls to create and want to display an animation during their creation, then you will need to segment the work to be done into small units that can be quickly processed. You can then call BeginInvoke at a priority lower than normal to process each unit of work group individually.
The fact that you need to create 10,000 controls is extreme and you should probably investigate virtualizing the controls.

How to show progress status for a long-time-consuming function?

I have a windows form simply like this: 1) a button when clicked will perform an operation taking a long time to complete, 2) a label showing how much percentage of the progress is going on.
In the long operation I mentioned, I write the code to update the Text property of the label but it doesn't work!
Please help me to show the progress status correctly.

You can take a look at the BackgroundWorker class (see the MSDN overview). It allows you to run some long-running operation in background and report progress updates (percentage) and completion from the background task to the user interface. Note that you'll need to calculate the progress percentage yourself.
However, the BackgroundWorker class takes care of other tricky aspects, such as sending your progress reports to the main GUI thread (where you can safely update the user interface).

Your going to want to create a worker thread that performs the task and occasionally reports its update to the form thread. If you do all of your work in the UI thread, your UI will be locked and won't update the progress/label correctly.
Before you start the worker thread, calculate the total number of steps you believe the process will take. Start the worker thread. After each unit of work, you Invoke an update method on the UI thread to increment the process.
You'll want to look at the BackgroundWorker class.
If your application will have several of these, I recommend creating a process interface (e.g. IProgressProcess). This interface will contain methods for executing a process and reporting updates. You will create all of your process classes by implementing from this interface. Write a control that contains a progress bar and accepts an IProgressProcess through a constructor or property. It can then use your custom process to execute and move along the progress bar. Then you can have your custom progress control send events when the process is complete or canceled.

This usually happens if you try to update the UI on the same thread where the operation is occurring. There are a couple of different ways that you could accomplish this.
You can update the UI with the BeginInvoke method.
You can use a BackgroundWorker component.

The reason that you don't see any change, is that the change causes a message to redraw the label, but the main thread is busy working so it doesn't respond to the message.
The simplest solution would be to just call the Application.DoEvents after updating the label. That works as a quick fix for your immediate problem, but it still will leave the application unresponsive in any other way.
The good solution would to start the operation in a separate thread. That way your main thread is free to handle messages while the operation is running. However working in a separate thread means a litte more work when communicating with the UI. If you want to update controls, you have to use the Invoke method to start a method that runs in the main thread so that it has access to the controls. Alternatively you can just update a variable in the thread, and have a timer control that periodically checks for changes in the variable and updates the label accordingly.

Use the UI thread of a WPF application to do a long processing task on a UI element, but also update a progress bar on the same window

My program consists of a large graphing UI control that I need to spend about 15 seconds re-loading every once in a while. Because the updating code works primarily with the UI control (maybe 90% of it actually sets properties on the control), it would make sense to me to actually let the UI thread handle that. I really don't want the control to visually re-paint while it is loading in a separate thread from the UI.
I also want a progress bar to update as well that lives in the status bar of the same application window. Is there a way to break the rule in this case and re-paint only the progress bar, or should I just open a new application window for the progress bar to live in?
What would you do in this particular case?

If you can break your primary task (ie. updating the graph) in many steps, you can perform each step as a separate dispatcher message. This will allow other messages to be processed, including giving you the ability to update progress information.
The basic pattern is:
Invoke your primary task, passing in zero for the step.
Perform the step.
If there are more steps, queue another message, passing in step + 1.
You can then add in progress updates at the appropriate points in your code.
PS. Not saying this is your best option - hard to tell without knowing all the details. But this is an option.

It is not really true that there is only one UI thread in an application, it is just that most windows applications only ever create UI objects in one thread so this thread becomes "the" UI thread in the application. It is easy to understand why - this makes the code simpler to understand, and protects us from implicit thread binding issues between controls.
This suggests a possible idea, should it prove impossible to improve the speed of updating the control (which is what I would suggest to do first). Create the UI control on a separate thread. You need to make sure that the thread is suitable for UI, that is to say the threading model is STA, and that it will pump messages and not die before the control is destroyed. I don't know if you need to create the parent window in the UI thread as well, or just the control but it may be worth experimenting here.

Find a graphing UI control that is more efficient. Unless the UI thread yields to the message loop any other updates won't happen (and it will slow down your graph control's updates).

I would suggest using a progressbar in a new window (without the form headers). Make it paint the progress bar by reading the shared properties of a graph control. this way you can avoid the thread blocking (sluggish loading).. And it gives you good visual experience (progressive painting on both the controls).

C# Winforms How to update toolStrip in function

I'm building a UI for a program, and I can't figure out why my progress bar won't become visible after the convert button is clicked.
private void convertButton_Click(object sender, EventArgs e)
{
toolStripProgressBar.Visible = true;
...
toolStripProgressBar.Visible = false;
}
I ran into a similar problem with tkinter in Python, and I had to call a function to update the idle tasks. Is there a way to do this with windows forms without using threads?
Edit: On a side note, this is a progress bar in a toolStrip that also contains a label that gets updated with status bar text. Is there any way to get the label on the left side and the progress bar on the other instead of right next to each other on the left?

Well, there is a way to do this without using threads (Application.DoEvents) but I strongly recommend against you using it. Re-entrancy is nasty, and you really don't want the UI thread tied up at all.
Use BackgroundWorker instead - it's easy, and it's pretty much designed for progress bars. It takes the hassle out of using a separate thread and reporting progress back to the UI thread. No need for Control.Invoke etc - it takes care of that for you.
There are lots of tutorials for BackgroundWorker - it shouldn't take you too long to get going with it.

Per the question you asked for the way to do this WITHOUT threads, that is to do it with Application.DoEvents();. (Just add that call right after setting the progress bar as visible.)
Now I do agree with Jon Skeet though that BackgroundWorker is a better way of doing this, but it does use a separate thread.

You need to execute your process in a thread separate from the UI thread, and then have it periodically report back to the UI thread with it's progress. If your convert operation is working inside the UI thread, it will simply go unresponsive until the operation is complete.

The progress bar can only become visible when it is allowed to paint which occurs during the processing of messages. Message processing cannot normally happen while you are in the middle of an event handler. If you want the progress bar to show up you will have to set the visiblitity to true, start a background thread to complete the work and return from the handler.

I'm guessing the problem is that the "..." in your code is a long-running process. UI updates are not instantaneous, but must run through the message queue in windows and then be painted to the screen. The queue is pumped and painting takes place in the same thread as your events.
As a result, any long-running tasks need to be moved to a different thread. More than that, your line line of code needs to called after that thread terminates. Otherwise you set the progress bar and then immediately turn it off again.
One way to do that is with a BackgroundWorker control.

Here go two links trying to explain you how things work:
(1) (2)
Now, I will try to explain it as shortly as I can. Most of what happens inside a windows forms application happens in a single thread, usually the same thread Main() runs in. If you open Program.cs, you will see that Main() has a line that looks like the following:
Application.Run(new Form1());
If you debug the application at any moment and examine the call stack, you will see it will trace back to that Run method. This means that a Windows Forms application is in fact a continuous run of the Run method. So, what is Run doing? Run is eating a message queue through which Windows sends messages to it. Run then dispatches those messages to the correct controls, which themselves do things like add text which corresponds to the key being pressed, redraw themselves, etc. Notice that all this happens during and endless loop running alongside a single thread, so weather you are typing or simply moving the window around, loads of those messages are being passed onto the application, which in turn is processing them and reacting accordingly, all in that single thread. Controls can also send messages to themselves through the queue and even you can place messages in the pump via Control.BeginInvoke. One of the things those controls do is to raise events according to what happens. So, if you click a button, the code you've written to handle that click will ultimately and indirectly be run by the Application.Run method.
Now, what is happening with your code is that even though you are changing the visible status of your progress bar to visible and then updating its Value, you are then changing its visibility to false, all in the same method. This means that only after you leave the method, will Application.Run() be able to continue iterating and consuming the message queue, effectively asking the progress bar to update its display. When that happens, you've already left the progress bar's visibility to false, the last thing you did before exiting the method. DoEvents() is a quick and dirty workaround to your problem as it reads the messages in the queue and processes them. I don't really feel comfortable using it as it can bring reentrancy problems.
Using threads is a good solution, but I would recommend using a ThreadPool thread instead of a custom thread in this kind of situation, as I tend to use custom threads only in cases where I have a limited number of long lived threads and I need to control their life cycles. The easiest and most practical way to use threads is to use the BackgroundWorker component, even though I would recommend going through the pains of understanding how to do Windows Forms multithreading with delegates if you want to really understand what is going on.

My solution is to call refresh on the status strip.
I believe this causes the UI thread to repaint the status strip.
toolStripStatusBar1.PerformStep();
statusStrip1.Refresh();
This is for .NET 4.0. Even though this question is old it was the first I found on googling this issue.