Set MTA Thread on WinUI3

Question

Hi,
In winform, we have:

[MTAThread]  
 static void Main()  
 {  
      Application.Run(new Main());  
 }  

How can we set [MTAThread] in winUI3?

Thanks.

Answer 1

You can write your own wWinMain by defining DISABLE_XAML_GENERATED_MAIN.

int __stdcall wWinMain(HINSTANCE, HINSTANCE, PWSTR, int)  
{  
    {  
        void (WINAPI *pfnXamlCheckProcessRequirements)();  
        auto module = ::LoadLibrary(L"Microsoft.ui.xaml.dll");  
        if (module)  
        {  
            pfnXamlCheckProcessRequirements = reinterpret_cast<decltype(pfnXamlCheckProcessRequirements)>(GetProcAddress(module, "XamlCheckProcessRequirements"));  
            if (pfnXamlCheckProcessRequirements)  
            {  
                (*pfnXamlCheckProcessRequirements)();  
            }  
  
            ::FreeLibrary(module);  
        }  
    }  
  
    //instead of winrt::init_apartment(winrt::apartment_type::single_threaded);  
    winrt::init_apartment(winrt::apartment_type::multi_threaded);  
    ::winrt::Microsoft::UI::Xaml::Application::Start(  
        [](auto&&)  
        {  
            ::winrt::make<::winrt::Packaged::implementation::App>();  
        });  
  
    return 0;  
}  

Answer 2

It seems WinUI3 is implemented by MTA. You can see Application Class is applicable for Both ThreadingModel.
Besides you can Indicate the threading model of a Windows Runtime class using ThreadingAttribute Or You can dispatch any thread using the Windows::System::Threading APIs, or use CoreWindow::CoreDispatcher from ASTA thread.

Answer 3

@Xiaopo Yang - MSFT

I see that entry point of WinUI is auto generated

How can I adjust it ton MTA?

Answer 4

@Xiaopo Yang - MSFT yeah, I see your solution. However, with winUI 3, I see that it has some different

• We double click our Project and add define as attached picture

• Then, we can override entry point - Main function into App.xaml..cs file. In this case, I use same with generated source code and update to MTAThreadAttribute
  

Thank your support !