Shows Windows' "Modern Share" UI in a standard desktop Win32 app.

Windows.ModernShare.cpp

#include <Windows.h>
#include <ShObjIdl_core.h>
#include <windows.applicationmodel.datatransfer.h> // for the IIDs (ABI namespace)
#include <winrt/windows.applicationmodel.datatransfer.h>
#include <winrt/windows.foundation.collections.h>
#include <winrt/windows.storage.h>

// compile at least with ISO C++20 Standard (/std:c++20)

using namespace winrt;
using namespace winrt::Windows::ApplicationModel::DataTransfer;
using namespace winrt::Windows::Foundation;
using namespace winrt::Windows::Storage;

IAsyncAction OnDataRequested(DataTransferManager const& sender, DataRequestedEventArgs const& args)
{
	auto referral = args.Request().GetDeferral(); // see https://learn.microsoft.com/en-us/uwp/api/windows.applicationmodel.datatransfer.datarequest.getdeferral?view=winrt-22621#remarks
	auto data = args.Request().Data();

	// get a storage item
	auto file = co_await StorageFile::GetFileFromPathAsync(L"d:\\temp\\zzz.txt");

	// build a collection with it and assign to data
	auto items{ single_threaded_vector<IStorageItem>() };
	items.Append(file);
	data.SetStorageItems(items.GetView());

	// set title & description
	data.Properties().Title(file.Name());
	data.Properties().Description(L"This item will be shared.");

	referral.Complete(); // commit
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch (msg)
	{
	case WM_LBUTTONDOWN:
	{
		// get a IDataTransferManagerInterop reference so we can work with an HWND
		// as we're a regular Win32 desktop app
		auto dtmi = get_activation_factory<DataTransferManager, IDataTransferManagerInterop>();

		// DataTransferManager Class "Programmatically initiates an exchange of content with other apps."
		// https://learn.microsoft.com/en-us/uwp/api/windows.applicationmodel.datatransfer.datatransfermanager
		DataTransferManager dtm{ nullptr };
		check_hresult(dtmi->GetForWindow(hwnd, __uuidof(ABI::Windows::ApplicationModel::DataTransfer::IDataTransferManager), put_abi(dtm)));

		// hook on event (when dtm asks us for data)
		dtm.DataRequested(OnDataRequested);

		// show the UI
		check_hresult(dtmi->ShowShareUIForWindow(hwnd));
	}
	break;

	case WM_CREATE:
		SetWindowText(hwnd, L"Click somewhere");
		break;

	case WM_DESTROY:
		PostQuitMessage(0);
		break;

	default:
		return DefWindowProc(hwnd, msg, wParam, lParam);
	}
	return 0;
}

int APIENTRY wWinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE, _In_ LPWSTR, _In_ int nCmdShow)
{
	WNDCLASSEXW wc = {};
	wc.cbSize = sizeof(WNDCLASSEX);
	wc.style = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc = WndProc;
	wc.hInstance = hInstance;
	wc.lpszClassName = L"MyClass";
	RegisterClassExW(&wc);

	auto hwnd = CreateWindowW(L"MyClass", L"Test", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 500, 700, nullptr, nullptr, hInstance, nullptr);
	ShowWindow(hwnd, nCmdShow);
	UpdateWindow(hwnd);

	MSG msg;
	while (GetMessage(&msg, nullptr, 0, 0))
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return 0;
}

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