How do I open a new Window in WinUI3 with WinRT/C++?

Question

How do I open a new window in WinRT / WinUI3? I want to click a button and open up another floating window on top of the current / main window.

I have tried code from several samples with zero luck:

• https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/windowing/windowing-overview
  • I can't import <winrt/Microsoft.UI.Windowing.h> (the dll does not load)
• https://github.com/microsoft/Windows-universal-samples/blob/main/Samples/AppWindow/cppwinrt/Scenario3_Size.h
  • This uses the old Windows:: namespace (not appropriate)
• https://github.com/microsoft/WinUI-3-Demos/tree/master/src/ContosoAirlinePOS
  • Does not navigate to a new window (BoardingPassWindow is actually a Page, not a Window)
• Frame.Navigate(xaml_typename<NewWindowClass>())
  • does not work / exception thrown

•   winrt::Microsoft::UI::Xaml::Controls::Frame rootFrame{ nullptr };
    auto content = Window::Current().Content();
    if (content)
    {
        rootFrame = content.try_as<winrt::Microsoft::UI::Xaml::Controls::Frame>();
    }
  

• above snippet^
  • Window::Current().Content(); throws an exception when called
• appWindow = Microsoft::UI::Xaml::Window(this, {}); appWindow.Activate()
  • throws exception

The majority of the C++ WinUI3 documentation still only has C# code samples in it and is largely useless to me for that reason. I just want to open a new window and nothing else.

Answer 1

You must upgrade to Project Reunion 1.0.0 EXPERIMENTAL or higher to use <winrt/Microsoft.UI.Windowing.h>. You can then create an AppWindow as follows:

auto appwind = winrt::Microsoft::UI::Windowing::AppWindow::Create();
appwind.Title(L"New Window Title");
appwind.Show();

This does NOT work in project reunion 0.8.2 or 0.8.3 stable releases.

Answer 2

You can use Windows App SDK Samples and for example modify this method: void DemoPage::TitleBtn_Click

like this:

void DemoPage::TitleBtn_Click(winrt::Windows::Foundation::IInspectable const& sender, winrt::Microsoft::UI::Xaml::RoutedEventArgs const& e)
{
    auto window = Window();
    auto tb = TextBlock();
    tb.Text(L"Hello");
    window.Content(tb);
    window.Activate();
}

Which looks exactly like the C# sample here: Create a new Window

var window = new Window();
window.Content = new TextBlock() { Text = "Hello" };
window.Activate();