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How to invoke into message loop after Application.Run()

How can I invoke into the message loop of the tread/form after calling Application.Run() without a dialog? The reason is that I want to prepare (and later show) a dialog that is clickable even if a modal dialog is shown in the main application.
static Form1 dialog;
private static void CreateDialog(object obj)
{
dialog = new Form1();
Application.Run();
}
static void Main(string[] args)
{
var thread = new Thread(CreateDialog);
thread.Start();
Thread.Sleep(2000); //only for demonstration
dialog.Invoke((Action)dialog.Show); //InvalidOperationException: need window handle first
}

I found the solution here: https://stackoverflow.com/a/4411493/1520078
I just have to access the Handle property of the Form to be able to invoke it from now on.
private static void CreateDialog(object obj)
{
dialog = new Form1();
_ = dialog.Handle;
Application.Run();
}
Now this does not throw any more:
dialog.Invoke((Action)dialog.Show);

Update a form after Application.Run()

Here is what i want to do
// pseudo code
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Form1 myForm = new Form1();
Application.Run(myForm);
while(true)
{
string a = readline();
}
form1.show(a)
In other words , I need the form always show the input. but the code above will stop after 'Application.Run(myForm);'. The reason I don't write such code in the form1 class is the main part of code is run on a machine learning engine written in F#, and because F# doesn't have a good visual designer. So I am trying to create a simple form1.dll, and use it to plot the result over time.
So my problem is I only can initialise the form, but I can't update it over time.
Any hints will be appreciated.

You're trying to do 2 things at the same time, so your application should reflect that by using 2 threads. Next, the Form's Show() method does not accept a string, so you need to implement your own method.
Here's a C# 2.0 WinForms solution. The program runs the thread and processes the console input:
static class Program
{
[STAThread]
private static void Main()
{
// Run form in separate thread
var runner = new FormRunner();
var thread = new Thread(runner.Start) {IsBackground = false};
thread.Start();
// Process console input
while (true)
{
string a = Console.ReadLine();
runner.Display(a);
if (a.Equals("exit")) break;
}
runner.Stop();
}
}
The FormRunner takes care about thread invocation:
internal class FormRunner
{
internal Form1 form = new Form1();
internal void Start()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(form);
}
private delegate void StopDelegate();
public void Stop()
{
if (form.InvokeRequired)
{
form.Invoke(new StopDelegate(Stop));
return;
}
form.Close();
}
private delegate void DisplayDelegate(string s);
public void Display(string s)
{
if (form.InvokeRequired)
{
form.Invoke(new DisplayDelegate(form.Display), new[] {s});
}
}
}
And Form1 just needs something to display:
public void Display(string s)
{
textBox1.Multiline = true;
textBox1.Text += s;
textBox1.Text += Environment.NewLine;
}

Problems with Windows Forms

I have the following C# code:
using System;
using System.Windows.Forms;
namespace WinFormErrorExample
{
public partial class Form1 : Form
{
public static Form1 Instance;
public Form1()
{
Instance = this;
InitializeComponent();
}
public void ChangeLabel1Text(String msg)
{
if (InvokeRequired)
Invoke(new Action<String>(m => label1.Text = m), new object[] {msg});
else
label1.Text = msg;
}
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
Instance.ChangeLabel1Text("cool");
}
}
}
}
When i'm calling the Instance.ChangeLabel1Text("cool"); nothing is happening in the GUI.
This is a small program i constructed to show my problem in a larger program.
Why is the GUI not being updated?

The call to
Application.Run(new Form1());
is blocking your application until the Form1 closes. So your subsequent line is not executed until you try to close
Of course, if you just want to test the functionality of the Instance call then remove that line after the Application.Run. Instead you need to create a separate thread that tries to call that method on the Form1 current instance

The Application.Run(new Form1()); method call performs running a standard application message loop on the current thread. So, this line Instance.ChangeLabel1Text("cool"); will be executed when the application is closed.
Why not change the text of the label inside the constructor? No static variables needed.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
ChangeLabel1Text("Hello!");
}
}

This would do,
First set the text to textbox control and then Run()
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Form1 form = new Form1();
form.Controls["ChangeLabel1Text"].Text = "cool";
Application.Run(form);

Closing a form that is created in another thread

I have been searching for an answer to my particular problem for a while with no success.
I have a task in my program that takes a few seconds and I want to show a new form while that task is being done. The new form has a loadingbar and some text.
I need to show the new form parallel to the task otherwise the task will not start untill I close the new form.
This is the solution I have now:
private void loadingBar()
{
frmLoading frm = new frmLoading("Please wait while the database is being backed up", "This might take several days.");
frm.ShowDialog();
}
public void Backup()
{
Thread load = new Thread(new ThreadStart(loadingBar));
load.Start();
///Execute a task.
load.Abort();
}
So, this works OK but my question is: Wouldn't it be better to close the the form "frm" in the load-thread to make it stop?

You could do this a few ways...
1 - You could do as BendEg suggested and invoke you frmClose once you are ready
Something like;
Invoke(new Action(Close));
or
Invoke(new Action(() => frmMain.Close()));
2 - Or you could simply use a background worker;
The simplest way to demonstrate this would be to add a BackgroundWorker to your form, and use the events provided;
public Form1()
{
InitializeComponent();
backgroundWorker1.RunWorkerAsync();
MessageBox.Show(#"Please wait while the database is being backed up", #"This might take several days.");
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
Debug.WriteLine("Running"); //Execute a task
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
Debug.WriteLine("Ended"); //Dispose of any objects you'd like (close yor form etc.)
}
I hope this helps.

You can declare the form on Class-Level and later close it with an invoke.
MSDN-Windows Forms Invoke
Like this:
public class Class1
{
private Form myForm;
public Class1()
{
myForm = new Form();
}
public void DoSomeWork()
{
// ===================================================
// Do Some Work...
// ===================================================
myForm.Invoke(new MethodInvoker(this.Hide));
}
public void Hide()
{
myForm.Hide();
}
public void Backup()
{
myForm.ShowDialog();
Thread load = new Thread(new ThreadStart(DoSomeWork));
load.Start();
}
}

I think this can work for you.
void YourMethod()
{
WaitForm wf = new WaitForm();
Invoke(new PleaseWaitDelegate(Launch),wf);
bool val = BoolMethodDoWork();
Invoke(new PleaseWaitDelegate(Close), wf);
if(val)
{
MessageBox.Show("Success!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
return;
}
MessageBox.Show("Damn!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
}
delegate void PleaseWaitDelegate(Form form);
void Launch(Form form)
{
new System.Threading.Thread(()=> form. ShowDialog()).Start();
}
void Close(Form form)
{
form.Close();
}

I think this will help you (if i understood you right):
Parallel.Invoke(() => somemethod(), () =>
{
someothertaskmethod();
});
I placed methods as example to demonstrate 2 tasks running.
You nee to use the proper using statement using System.Threading.Tasks;

TPL Equivalent of Thread Class 'Splash-Type' Screen

Given the class below, to launch a splash screen on an alternate thread:
public partial class SplashForm : Form
{
private static Thread _splashThread;
private static SplashForm _splashForm;
public SplashForm()
{
InitializeComponent();
}
// Show the Splash Screen (Loading...)
public static void ShowSplash()
{
if (_splashThread == null)
{
// Show the form in a new thread.
_splashThread = new Thread(new ThreadStart(DoShowSplash));
_splashThread.IsBackground = true;
_splashThread.Start();
}
}
// Called by the thread.
private static void DoShowSplash()
{
if (_splashForm == null)
_splashForm = new SplashForm();
// Create a new message pump on this thread (started from ShowSplash).
Application.Run(_splashForm);
}
// Close the splash (Loading...) screen.
public static void CloseSplash()
{
// Need to call on the thread that launched this splash.
if (_splashForm.InvokeRequired)
_splashForm.Invoke(new MethodInvoker(CloseSplash));
else
Application.ExitThread();
}
}
This is called and closed with the following respective commands
SplashForm.ShowSplash();
SplashForm.CloseSplash();
Fine.
I am not exactly new to the TPL, of course we can show the form on another thread using something as simple as:
Task task = Task.Factory.StartNew(() =>
{
SomeForm someForm = new SomeForm();
someForm.ShowDialog();
};
My issue is closing this SomeForm down when you are ready. There must be a better way than creating a public static method in the SomeForm class like
private static SomeForm _someForm;
public static void CloseSomeForm()
{
if (_someForm.InvokeRequired)
_someForm.Invoke(new MethodInvoker(CloseSomeForm));
}
My question is, what is the best way to do the same thing as shown using the SplashForm class above using the Task Parrallel Library (TPL)? Specifically, the best way to close the form invoked on another thread from the UI.

Your question does not seem to be so much about a difference between Thread and Task because what you want is to get rid of the "dirty" static state. I suggest you encapsulate it into a class:
class SplashController
{
public void Run() {
_someForm = new SomeForm();
someForm.ShowDialog();
}
private SomeForm _someForm;
public void CloseSomeForm()
{
if (_someForm.InvokeRequired)
_someForm.Invoke(new MethodInvoker(CloseSomeForm));
}
}
You can call Run using whatever threading mechanism you like. CloseSomeForm does not use threading so it is independent of this problem.
You can now store a reference to an instance of SplashController wherever you like. In local variables or indeed in a static variable. The latter makes sense because there is exactly one splash screen.
Because the static state is now well encapsulated I don't see any problem with it being statically held.

You probably shouldn't do something like this
Task task = Task.Factory.StartNew(() =>
{
SomeForm someForm = new SomeForm();
someForm.ShowDialog();
};
because it would require a message loop to be present on the exact thread that creates the Form, which is a ThreadPool thread. But I haven't tested this.
You could try this:
public static Task<SplashForm> ShowSplash()
{
var tcs = new TaskCompletionSource<SplashForm>();
// Show the form in a new thread.
_splashThread = new Thread(() =>
{
var splashForm = new SplashForm();
tcs.SetResult(_splashForm);
// Create a new message pump on this thread (started from ShowSplash).
Application.Run(splashForm);
});
_splashThread.IsBackground = true;
_splashThread.Start();
}
this would allow you to remove the static modifier from CloseSplash:
// Close the splash (Loading...) screen.
public void CloseSplash()
{
// Need to call on the thread that launched this splash.
if (this.InvokeRequired)
this.Invoke(new MethodInvoker(CloseSplash));
else
Application.ExitThread();
}
May be used like this:
var form = await SplashForm.ShowSplash();
form.CloseSplash();