[Mono-list] Mono, Windows Forms, and Headless operation

Mladen Mihajlovic mmihajlovic at gmail.com
Sun Jan 10 06:34:33 UTC 2016 

Hey George

In a couple of places you mention you don't want to see the GUI and only
needed background workers? u think using normal threads will do the trick.
You can do everything and more that the background wonder does. Check
http://www.albahari.com/threading/ for more help.

Cheers
Mladen

On Saturday, 9 January 2016, George, Glover E ERDC-RDE-ITL-MS <
Glover.E.George at erdc.dren.mil> wrote:

> Thanks Jordan.
>
> It turns out, I may have been conflating two problems into one.  The fact
> that I needed to show the windows form was because I needed a message loop
> to process the BackgroundWorker¹s events.  Turns out I can just call
> Application.Run() with no parameter, and it will cause the UI thread to
> start a message loop that works fine.
>
> The real problem is that it still seems as though mono requires X11 for
> Windows Forms apps.  So I created a new project from scratch to test this
> theory.  It is a very simple app.  It¹s a simple form with a button
> (runButton) and a progress bar (progressBar1) (Designer code is left out
> due to space).
>
> PROGRAM.CS
> static class Program
>     {
>         /// <summary>
>         /// The main entry point for the application.
>         /// </summary>
>   [STAThread]
>   static void Main()
>   {
>     // Instantiate the Main Form
>     Form frm = new Form1();
>     Application.Run();
>   }
>     }
>
>
> #FORM1.cs
> public partial class Form1 : Form
>     {
>   public Form1()
>   {
>     InitializeComponent();
>     runButton_Click(this,null);
>   }
>
>   private void runButton_Click(object sender, EventArgs e)
>   {
>     BackgroundWorker worker = new BackgroundWorker();
>     worker.WorkerReportsProgress = true;
>     worker.DoWork += DoWork;
>     worker.ProgressChanged += ProgressChanged;
>     worker.RunWorkerCompleted += WorkerCompleted;
>     worker.RunWorkerAsync(worker);
>   }
>
>   public void DoWork(object sender, EventArgs e)
>   {
>     var worker = sender as BackgroundWorker;
>     for (int i = 0; i < 100; i++)
>     {
>       Thread.Sleep(100);
>       worker.ReportProgress(i);
>     }
>   }
>
>   public void ProgressChanged(object sender, ProgressChangedEventArgs e)
>   {
>     progressBar1.Value = e.ProgressPercentage;
>   }
>
>   public void WorkerCompleted(object sender, EventArgs e)
>   {
>     MessageBox.Show("I'm done!!!");
>     Application.Exit();
>   }
> }
>
>
> This program runs perfectly well without displaying anything so long as
> DISPLAY is set to a valid X11 Display (:0).  However, if I unset DISPLAY
> (export DISPLAY=), then I get the following error.  Note, this is similar
> to the error I previously posted, but the stack trace and error message is
> a bit more detailed (don¹t know why yet):
>
>
> Unhandled Exception:
> System.TypeInitializationException: The type initializer for
> 'System.Windows.Forms.WindowsFormsSynchronizationContext' threw an
> exception. ---> System.TypeInitializationException: The type initializer
> for 'System.Windows.Forms.XplatUI' threw an exception. --->
> System.ArgumentNullException: Could not open display (X-Server required.
> Check your DISPLAY environment variable)
> Parameter name: Display
>   at System.Windows.Forms.XplatUIX11.SetDisplay (IntPtr display_handle)
> <0x4100b560 + 0x00b9b> in <filename unknown>:0
>   at System.Windows.Forms.XplatUIX11..ctor () <0x41009890 + 0x001df> in
> <filename unknown>:0
>   at System.Windows.Forms.XplatUIX11.GetInstance () <0x410096c0 + 0x0005b>
> in <filename unknown>:0
>   at System.Windows.Forms.XplatUI..cctor () <0x41009390 + 0x00137> in
> <filename unknown>:0
>   --- End of inner exception stack trace ---
>   at System.Windows.Forms.Theme.get_MenuAccessKeysUnderlined ()
> <0x41009340 + 0x0000b> in <filename unknown>:0
>   at System.Windows.Forms.SystemInformation.get_MenuAccessKeysUnderlined
> () <0x41004790 + 0x00017> in <filename unknown>:0
>   at System.Windows.Forms.Control..ctor () <0x410033b0 + 0x00243> in
> <filename unknown>:0
>   at (wrapper remoting-invoke-with-check)
> System.Windows.Forms.Control:.ctor ()
>   at System.Windows.Forms.WindowsFormsSynchronizationContext..cctor ()
> <0x410046c0 + 0x0001f> in <filename unknown>:0
>   --- End of inner exception stack trace ---
>   at System.Windows.Forms.Control..ctor () <0x410033b0 + 0x00053> in
> <filename unknown>:0
>   at System.Windows.Forms.ScrollableControl..ctor () <0x41002e40 +
> 0x0000f> in <filename unknown>:0
>   at System.Windows.Forms.ContainerControl..ctor () <0x41002cb0 + 0x00027>
> in <filename unknown>:0
>   at System.Windows.Forms.Form..ctor () <0x41002430 + 0x000bb> in
> <filename unknown>:0
>   at test2.Form1..ctor () <0x40ffff90 + 0x0001f> in <filename unknown>:0
>   at (wrapper remoting-invoke-with-check) test2.Form1:.ctor ()
>   at test2.Program.Main () <0x40fffd90 + 0x0001b> in <filename unknown>:0
> [ERROR] FATAL UNHANDLED EXCEPTION: System.TypeInitializationException: The
> type initializer for
> 'System.Windows.Forms.WindowsFormsSynchronizationContext' threw an
> exception. ---> System.TypeInitializationException: The type initializer
> for 'System.Windows.Forms.XplatUI' threw an exception. --->
> System.ArgumentNullException: Could not open display (X-Server required.
> Check your DISPLAY environment variable)
> Parameter name: Display
>   at System.Windows.Forms.XplatUIX11.SetDisplay (IntPtr display_handle)
> <0x4100b560 + 0x00b9b> in <filename unknown>:0
>   at System.Windows.Forms.XplatUIX11..ctor () <0x41009890 + 0x001df> in
> <filename unknown>:0
>   at System.Windows.Forms.XplatUIX11.GetInstance () <0x410096c0 + 0x0005b>
> in <filename unknown>:0
>   at System.Windows.Forms.XplatUI..cctor () <0x41009390 + 0x00137> in
> <filename unknown>:0
>   --- End of inner exception stack trace ---
>   at System.Windows.Forms.Theme.get_MenuAccessKeysUnderlined ()
> <0x41009340 + 0x0000b> in <filename unknown>:0
>   at System.Windows.Forms.SystemInformation.get_MenuAccessKeysUnderlined
> () <0x41004790 + 0x00017> in <filename unknown>:0
>   at System.Windows.Forms.Control..ctor () <0x410033b0 + 0x00243> in
> <filename unknown>:0
>   at (wrapper remoting-invoke-with-check)
> System.Windows.Forms.Control:.ctor ()
>   at System.Windows.Forms.WindowsFormsSynchronizationContext..cctor ()
> <0x410046c0 + 0x0001f> in <filename unknown>:0
>   --- End of inner exception stack trace ---
>   at System.Windows.Forms.Control..ctor () <0x410033b0 + 0x00053> in
> <filename unknown>:0
>   at System.Windows.Forms.ScrollableControl..ctor () <0x41002e40 +
> 0x0000f> in <filename unknown>:0
>   at System.Windows.Forms.ContainerControl..ctor () <0x41002cb0 + 0x00027>
> in <filename unknown>:0
>   at System.Windows.Forms.Form..ctor () <0x41002430 + 0x000bb> in
> <filename unknown>:0
>   at test2.Form1..ctor () <0x40ffff90 + 0x0001f> in <filename unknown>:0
>   at (wrapper remoting-invoke-with-check) test2.Form1:.ctor ()
>   at test2.Program.Main () <0x40fffd90 + 0x0001b> in <filename unknown>:0
>
>
>
> From the looks of that error message, is X truly a requirement for any app
> that is calling Windows Forms controls?  Also note, the project type for
> this project is Console App.  It appears that by dynamically loading (or
> is it the link?) anything from System.Windows.Forms causes mono to require
> X.
> ‹ ‹ ‹
>
> Glover E. George
> Computer Scientist
> Information Technology Laboratory
> US Army Engineer Research and Development Center
> Vicksburg, MS 39180
> 601-634-4730
>
>
>
>
>
> On 1/8/16, 10:29 AM, "mono-list-bounces at lists.ximian.com <javascript:;>
> on behalf of
> Robert Jordan" <mono-list-bounces at lists.ximian.com <javascript:;> on
> behalf of
> robertj at gmx.net <javascript:;>> wrote:
>
> >On 07.01.2016 22:24, George, Glover E ERDC-RDE-ITL-MS wrote:
> >> Hi all,
> >>
> >> We¹re currently porting a Windows Forms Application to Mono, and have
> >> generally had great success.  However, we have now hit a critical
> >> decision point, and were hoping for some guidance on the best route
> >> forward.   If we don¹t have X11, mono fails to run Windows Forms code
> >> with the following error:
> >>
> >> From: System.Windows.Forms, at: Void .ctor(), Error Message: The type
> >> initializer for
> >> 'System.Windows.Forms.WindowsFormsSynchronizationContext' threw an
> >> exception.
> >>
> >> Question First: The main question I had for the Mono list is this.
> >> Is it possible to have mono run Windows Forms code without trying to
> >> open X11 (I.e. headless mode)?  What triggers mono to request an X11
> >> display? Is it the project type?  Is it the call to an object that
> >> inherits from a Windows Forms control?  I don¹t need to see the form,
> >> but if I¹m using BackgroundWorkers, I need the form's event handler,
> >> don¹t I?
> >
> >
> >BackgroundWorker does not depend upon System.Windows.Forms, i.e.
> >it can use it headless.
> >
> >The exception you're experiencing is caused by the synchronization
> >context set and used by WinForms.
> >
> >Supposing that you don't need any kind of synchronization, you
> >may want to replace the synchronization context with a simple
> >one.
> >
> >I don't know if the most simple one
> >(System.Threading.SynchronizationContext)
> >would be enough or if you have to subclass it. Have a look
> >at its sources and at
> >System.Windows.Forms.WindowsFormsSynchronizationContext.
> >
> >Robert
> >
> >_______________________________________________
> >Mono-list maillist  -  Mono-list at lists.ximian.com <javascript:;>
> >Blockedhttp://lists.ximian.com/mailman/listinfo/mono-listBlocked
> >
>
> _______________________________________________
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