GridDesktop: invoke error

Aspose.Cells Product Family
1

We observe random exceptions like this in GridDesktop:

Exception-Type: System.InvalidOperationException
Message: Invoke oder BeginInvoke kann für ein Steuerelement erst aufgerufen werden, wenn das Fensterhandle erstellt wurde.
StackTrace:
   at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
   at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
   at Aspose.Cells.GridDesktop.GridDesktop.()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)

The message translates to “Invoke or BeginInvoke cannot be called on a control until the window handle has been created”.

We use the “GridDesktop” component in read only mode - this is the only code snippet that we invoke:

this.gridDesktop.ImportExcelFile("myfile.xslx", passwordtoOpen: null, passwordtoModify: null,
  openasReadOnly: true, runFormulas: true);

Unfortunately, we don’t have further details and cannot reproduce it, we just observed this error a few times in our azure cloud, but cannot see which program code lead to this error and have no user feedback.

There is something special in our app: we create a thread for each main form, and all dialogs that are shown from button clicks of this main form (like our GridDesktop viewer) run on the thread of the parent form. So, if you internally use components that cannot be reused across threads, this might be the reason for this error.

Do you have any idea about this? The obfuscated stack trace of your code makes it hard to see which code caused the error.

The error happened with version 24.8.0 and 25.1.0.

Best regards

Wolfgang

2

@wknauf

The error you are encountering, “Invoke or BeginInvoke cannot be called on a control until the window handle has been created,” typically occurs when trying to access a UI control from a thread that did not create that control. This is particularly relevant in your case since you mentioned that you create a thread for each main form, and the dialogs (including the GridDesktop viewer) run on the thread of the parent form.

Here are a few suggestions to help you troubleshoot and potentially resolve this issue:

  1. Ensure UI Thread Access: Make sure that any interaction with the GridDesktop control is done on the UI thread. You can use Invoke or BeginInvoke to marshal the call to the UI thread. For example:

    this.Invoke((MethodInvoker)delegate {
    this.gridDesktop.ImportExcelFile("myfile.xlsx", passwordtoOpen: null, passwordtoModify: null,
        openasReadOnly: true, runFormulas: true);
});

  2. Check Control Initialization: Ensure that the GridDesktop control is fully initialized before you attempt to call methods on it. You might want to check if the control’s handle is created by verifying this.gridDesktop.IsHandleCreated before invoking methods on it.

  3. Thread Management: Since you are using multiple threads, consider using a single thread for UI operations or ensure that all UI components are accessed from the same thread that created them. This can help avoid cross-thread operation issues.

  4. Error Logging: Since you mentioned that the error is sporadic and hard to reproduce, consider implementing more detailed logging around the areas where you interact with the GridDesktop control. This can help you identify patterns or specific conditions that lead to the error.

  5. Version Check: You are using versions 24.8.0 and 25.1.0. If possible, check if there are any updates or patches available for the Aspose.Cells library that might address this issue.

If the problem persists after trying these suggestions, you may want to reach out to Aspose support with detailed logs and the context of how the GridDesktop control is being used in your application.

Feel free to ask if you have any further questions or need additional assistance!

3

@wknauf,

It seems it is threading issue. The error System.InvalidOperationException appears to be .NET WinForms threading issue. It might occur when you try to call Invoke() or BeginInvoke() on a control before its handle (Handle) has been created, or from a non-UI thread. We appreciate if you could provide us a simulation test-case or sample app with resource file(s) which we can use to reproduce the issue on our end. To evaluate your issue thoroughly and to resolve it, we have to reproduce the issue in a sample .NET app on our end. By the way, did you try latest version/fix: Aspose.Cells.GridDesktop 25.4.2 if it makes any difference?

4

I tried to reproduce it in a small sample, but did not succeed up to now. At least I can reproduce it in our application at a customers site. I will come back with it if I can reproduce it.

Your latest version 24.5.2 is not bundled in our current release version of our application, so it will take some time until the package update makes it to our release.

I know the problems with “Invoke” or “BeginInvoke”, but for us it is not necessary here, as we load the excel file in the ui thread of the dialog.

5

@wknauf,

Please take your time to create a test case that reproduces the issue and share it with us. We will check your problem soon.

6

@wknauf

There is something special in our app: we create a thread for each main form, and all dialogs that are shown from button clicks of this main form (like our GridDesktop viewer) run on the thread of the parent form. So, if you internally use components that cannot be reused across threads, this might be the reason for this error.

We need a sample project to mimic and check how you call the GridDesktop.

my suggestion is : you can use the FinishLoadFile event
please check the below document

7

I still cannot reproduce it, but I hope I fixed the error on our side.

Before, I used this code sequence to load an excel file:

MyGridDesktopForm form = new MyGridDesktopForm();
form.LoadFile ("path\to\file.xlsx");
form.ShowDialog (this);

(where “LoadFile” calls “GridDesktop.ImportExcelFile”)

Loading the file before the dialog is shown probably causes the error. So I moved it to “OnLoad”:

public class MyGridDesktopForm  : Form
{
  public string File
  {
     get;
     set;
  }

  protected override void OnLoad(EventArgs e)
  {
    base.OnLoad(e);

    this.gridDesktop.ImportExcelFile(this.File, passwordtoOpen: null, passwordtoModify: null,
      openasReadOnly: true, runFormulas: true);
  }
}

And the call to load it is this:

MyGridDesktopForm form = new MyGridDesktopForm();
form.File = "path\to\file.xlsx";
form.ShowDialog (this);

So the issue is resolved now.

Thanks for your patience!

Wolfgang

8

@wknauf
Yes,fine, this is the better way.