how to use WinUI3 control in an Xaml page which is loaded by an unpackaged win32 app?

[oldoldman]

Hi Guys,
I have the following win32 code, which load an Xaml page (MainPage.xaml) into the content.

int WinMain(HINSTANCE,HINSTANCE,PSTR,int) {
  winrt::init_apartment(winrt::apartment_type::single_threaded);
  HWND mHWND;
  HWND xHWND;
  auto mWin = AppWindow::Create();
  mWin.Changed(
  [&](AppWindow const&,AppWindowChangedEventArgs const&args) {
    if (args.DidSizeChange()) {
      auto size = mWin.Size();
      SetWindowPos(xHWND, 0, 5, 5, size.Width-10, size.Height-10, SWP_SHOWWINDOW);
    }
  });
  mHWND = GetWindowFromWindowId(mWin.Id());
  DesktopWindowXamlSource xaml;
  auto native = xaml.as<IDesktopWindowXamlSourceNative>();
  winrt::check_hresult(native->AttachToWindow(mHWND));
  winrt::check_hresult(native->get_WindowHandle(&xHWND));
  SetFocus(xHWND);

  std::stringbuf buf;
  std::fstream("MainPage.xaml",std::ios_base::in) >> &buf;
  auto root = XamlReader::Load(winrt::to_hstring(buf.str()));
  auto fwk = root.as<FrameworkElement>();
  xaml.Content(fwk);
      
  mWin.Title(L"WIN32 & WINUI 3");
  auto bar = mWin.TitleBar();
  auto bgc = winrt::Windows::UI::Colors::DeepSkyBlue();
  bar.BackgroundColor(bgc);
  bar.ButtonBackgroundColor(bgc);
  bar.ExtendsContentIntoTitleBar(true);
  mWin.Resize({400,300});
  mWin.Show();
  
  auto qCtl = DispatcherQueueController::CreateOnCurrentThread();
  auto eQue = qCtl.DispatcherQueue();
  auto tokn = mWin.Destroying(
  [&](AppWindow const&,fnd::IInspectable const&) {
    eQue.EnqueueEventLoopExit();
  });
      
  eQue.RunEventLoop();
  qCtl.ShutdownQueue();
  mWin.Destroying(tokn);
}

It works fine if I just use widgets under Windows.UI.Xaml.Controls. But when I'm trying to add widget from WinUI3, it will fail. Here is my MainPage.xaml

<?xml version="1.0" encoding="UTF-8"?>
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:mux="using:Microsoft.UI.Xaml.Controls" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
mc:Ignorable="d">
   <Page.Resources>
      <ThemeShadow x:Name="SharedShadow" />
      <Color x:Key="AppAccentColor">#4C6CB3</Color>
   </Page.Resources>
   <NavigationView x:Name="nvSample" PaneDisplayMode="Auto">
      <NavigationView.MenuItems>
         <NavigationViewItem Icon="Play" Content="Menu Item1" Tag="SamplePage1" />
         <NavigationViewItem Icon="Save" Content="Menu Item2" Tag="SamplePage2" />
         <NavigationViewItem Icon="Refresh" Content="Menu Item3" Tag="SamplePage3" />
         <NavigationViewItem Icon="Download" Content="Menu Item4" Tag="SamplePage4" />
      </NavigationView.MenuItems>
      <mux:InfoBar IsOpen="True" Severity="Informational" Title="Title"
        Message="Essential app message for your users to be informed of, acknowledge, or take action on." />
   </NavigationView>
</Page>

the InfoBar will fail to add. I've linked against the MddBootstrapAutoInitializer.cpp, so, WindowsAppsRuntime should be bootstrapped correctly. Should I add some activatableClass entries in the SxS manifest? Many thanks!

[DarranRowe]

Since you don't show the namespace, I would have to assume from the information provided that you are trying to use Windows.UI.Xaml.Hosting.DesktopWindowXamlSource here. To put it simply, DesktopWindowXamlSource is unable to host WinUI 3 controls. As the documentation states, DesktopWindowXamlSource is able to host any control that derives from Windows.UI.Xaml.UIElement, and WinUI 3 controls do not derive from this.

[oldoldman]

Thank you. I got it. So, in the near future, there will be a Microsoft::UI::Xaml::Hosting::DesktopWindowXamlSource to host the widgets under Microsoft::UI::Xaml::Controls namespace?

[lhak]

The experimental releases of the app sdk contain an implementation of DesktopWindowXamlSource for WinUI 3.

[oldoldman]

thank you. I got it