CODEWITHSUNDEEP
wpfmfc
Anthony
Anthony

Reputation: 21

WPF User Control On MFC Dialog Showing Hidden Every Once and a While

I am running into a very strange problem that I wanted to see if anyone else has seen. I have a C++ application (compile with CLR support) that has a MFC dialog which hosts a WPF user control. Every once and a while, the WPF user control will not appear when the dialog opens. The control is there as I can press a button on that user control. Obviously, I cannot see it, but the button still responds to a click event if I click the area where the button is supposed to be.

The strange part in all this is how sporadic it happens. Sometimes it happens the first time the user goes into the dialog after starting the application. Other times, it will happen after successfully going into the dialog a few times. We have deinitely not found any pattern to when it will happen. It just happens once and a while. Also, we have seen this across all different operating systems - XP, Vista and Win7.

To correct the problem, simply closing the application and relaunching it norally cures it.

In terms of the code, the standard approach for WPF user controls on MFC dialogs is being used:

    // Create the initial object
    System::Windows::Interop::HwndSourceParameters^ sourceParams = gcnew System::Windows::Interop::HwndSourceParameters ("BatchSelectionContainer");
    sourceParams->PositionX = x;
    sourceParams->PositionY = y;
    sourceParams->Height = height;
    sourceParams->Width = width;
    sourceParams->ParentWindow = System::IntPtr(parent);
    sourceParams->WindowStyle = WS_VISIBLE | WS_CHILD;
    BatchSelectionDialogGlobals::gHwndSource = gcnew System::Windows::Interop::HwndSource(*sourceParams);
    BatchSelectionDialogGlobals::gHwndSource->AddHook(gcnew HwndSourceHook(ChildHwndSourceHook));

    // Save a reference to the new frame
    BatchSelectionDialogGlobals::BatchSelectionFrame = gcnew ProteinSimple::ParticleDetection::Console::BatchSelection();

    // Establish an event handler for the buttons
    BatchSelectionDialogGlobals::BatchSelectionFrame->EnableExecuteButton += gcnew ProteinSimple::ParticleDetection::Console::BatchSelection::GeneralHandler(&BatchSelectionDialog::EnableExecuteButton);
    BatchSelectionDialogGlobals::BatchSelectionFrame->DisableExecuteButton += gcnew ProteinSimple::ParticleDetection::Console::BatchSelection::GeneralHandler(&BatchSelectionDialog::DisableExecuteButton);

    // Finalize the visual parts and return the handle
    BatchSelectionDialogGlobals::gHwndSource->RootVisual = BatchSelectionDialogGlobals::BatchSelectionFrame;
    return (HWND) BatchSelectionDialogGlobals::gHwndSource->Handle.ToPointer();

This is certainly a strange one. I have some of my users that have never seen it, while others it happens many times a day.

It feels like a bug in MFC in how it displays the WPF control. However, I have searched on-line and have never heard anybody describe this problem. The code is not throwing any exceptions, so I am not sure what the problem could be.

I am stumped and would appreciate any insight into the problem.

Upvotes: 0

Views: 677

Answers (1)

Ajay
Ajay

Reputation: 18431

WPF doesn't draw the stuff as windows-controls as MFC or WinForms do draw - you can check it using Spy++. That's why its not possible/easy to mix WPF and MFC.

Upvotes: 0

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