Using XAML Islands in a Win32 Project, using the most basic example from MS-Learn, WindowsXamlManager::InitializeForCurrentThread() throws a fatal exception.

Question

The following code from an MS-Learn page about XAML-Islands, crashes at the call to:

WindowsXamlManager winxamlmanager = WindowsXamlManager::InitializeForCurrentThread();

I have added the following two NuGet packages to the App:

Microsoft.Toolkit.Win32.UI.SDK (6.1.2)

Microsoft.Windows.CppWinRT (2.0.240405.15)

Also, added an app.manifest.xml file, as per the instructions in the example code.

Link to page of the example:

https://learn.microsoft.com/en-us/windows/apps/desktop/modernize/host-standard-control-with-xaml-islands-cpp

I am new to this; any insight would be much appreciated.

// Code

// WindowsProject3.cpp : Defines the entry point for the application.

//

#include "framework.h"

#include "WindowsProject3.h"

#include <string.h>

#include <winrt/Windows.Foundation.Collections.h>

#include <winrt/Windows.system.h>

#include <winrt/windows.ui.xaml.hosting.h>

#include <windows.ui.xaml.hosting.desktopwindowxamlsource.h>

#include <winrt/windows.ui.xaml.controls.h>

#include <winrt/Windows.ui.xaml.media.h>

#ifdef GetCurrentTime

#undef GetCurrentTime

#endif

using namespace winrt;

using namespace Windows::UI;

using namespace Windows::UI::Composition;

using namespace Windows::UI::Xaml::Hosting;

using namespace Windows::Foundation::Numerics;

LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM);

HWND _hWnd;

HWND _childhWnd;

HINSTANCE _hInstance;

int CALLBACK WinMain(In HINSTANCE hInstance, In_opt HINSTANCE hPrevInstance, In LPSTR lpCmdLine, In int nCmdShow)

{

// The call to winrt::init_apartment initializes COM; by default, in a multithreaded apartment.

winrt::init_apartment(apartment_type::single_threaded);



_hInstance = hInstance;

// The main window class name.

const wchar_t szWindowClass[] = L"Win32DesktopApp";

WNDCLASSEX windowClass = { };

windowClass.cbSize = sizeof(WNDCLASSEX);

windowClass.lpfnWndProc = WindowProc;

windowClass.hInstance = hInstance;

windowClass.lpszClassName = szWindowClass;

windowClass.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);

windowClass.hIconSm = LoadIcon(windowClass.hInstance, IDI_APPLICATION);

if (RegisterClassEx(&windowClass) == NULL)

{

    MessageBox(NULL, L"Windows registration failed!", L"Error", NULL);

    return 0;

}

_hWnd = CreateWindow(

    szWindowClass,

    L"Windows c++ Win32 Desktop App",

    WS_OVERLAPPEDWINDOW | WS_VISIBLE,

    CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,

    NULL,

    NULL,

    hInstance,

    NULL

);

if (_hWnd == NULL)

{

    MessageBox(NULL, L"Call to CreateWindow failed!", L"Error", NULL);

    return 0;

}

// Begin XAML Island section.

// The call to winrt::init_apartment initializes COM; by default, in a multithreaded apartment.

//winrt::init_apartment(apartment_type::single_threaded);

// Initialize the XAML framework's core window for the current thread.

WindowsXamlManager winxamlmanager = WindowsXamlManager::InitializeForCurrentThread();

// This DesktopWindowXamlSource is the object that enables a non-UWP desktop application 

// to host WinRT XAML controls in any UI element that is associated with a window handle (HWND).

DesktopWindowXamlSource desktopSource;

// Get handle to the core window.

auto interop = desktopSource.as<IDesktopWindowXamlSourceNative>();

// Parent the DesktopWindowXamlSource object to the current window.

check_hresult(interop->AttachToWindow(_hWnd));

// This HWND will be the window handler for the XAML Island: A child window that contains XAML.  

HWND hWndXamlIsland = nullptr;

// Get the new child window's HWND. 

interop->get_WindowHandle(&hWndXamlIsland);

// Update the XAML Island window size because initially it is 0,0.

SetWindowPos(hWndXamlIsland, 0, 200, 100, 800, 200, SWP_SHOWWINDOW);

// Create the XAML content.

Windows::UI::Xaml::Controls::StackPanel xamlContainer;

xamlContainer.Background(Windows::UI::Xaml::Media::SolidColorBrush{ Windows::UI::Colors::LightGray() });

Windows::UI::Xaml::Controls::TextBlock tb;

tb.Text(L"Hello World from Xaml Islands!");

tb.VerticalAlignment(Windows::UI::Xaml::VerticalAlignment::Center);

tb.HorizontalAlignment(Windows::UI::Xaml::HorizontalAlignment::Center);

tb.FontSize(48);

xamlContainer.Children().Append(tb);

xamlContainer.UpdateLayout();

desktopSource.Content(xamlContainer);

// End XAML Island section.

ShowWindow(_hWnd, nCmdShow);

UpdateWindow(_hWnd);

//Message loop:

MSG msg = { };

while (GetMessage(&msg, NULL, 0, 0))

{

    TranslateMessage(&msg);

    DispatchMessage(&msg);

}

return 0;

}

Answer 1

You may have renamed app.manifest.xml to app.manifest but there is probably one more change to make. Open the property page for app.manifest

If it looks like this -

You need to change the Item Type to Manifest Tool as shown here -

Then do a complete rebuild.

Answer 2

The fix, thanks to RLWA32, was to change the app.manifest file's property "Item Type" from "Xml" to "Manifest Tool".