CFSTR_FILEDESCRIPTORで実在しないファイルをエクスプローラへドラッグ&ドロップする実験（SHCreateMemStream使用）

FileDescriptorTest-MemStream.cpp

#define UNICODE
#define _UNICODE

#define _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES 1
#define _CRT_SECURE_CPP_OVERLOAD_SECURE_NAMES 1

#define WINVER 0x0600
#define _WIN32_WINNT 0x0600

#define _ATL_NO_AUTOMATIC_NAMESPACE
#define _WTL_NO_AUTOMATIC_NAMESPACE

#define NOMINMAX

#include <string.h>
#include <algorithm>

#include <Windows.h>
#include <shlobj.h>

#include <atlbase.h>
#include <atlcom.h>
#include <atlctl.h>
#include <atltypes.h>
#include <atlwin.h>

#pragma warning(disable: 4996)
#include <atlapp.h>
#include <atlctrls.h>
#include <atlcrack.h>

#pragma comment(linker, "\"/manifestdependency:type='Win32' "\
	"name='Microsoft.Windows.Common-Controls' version='6.0.0.0' "\
	"processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")

class Module : public ATL::CAtlExeModuleT<Module> {};
Module module;

static const auto CF_FILEDESCRIPTOR = static_cast<CLIPFORMAT>(::RegisterClipboardFormat(CFSTR_FILEDESCRIPTOR));
static const auto CF_FILECONTENTS = static_cast<CLIPFORMAT>(::RegisterClipboardFormat(CFSTR_FILECONTENTS));

template<typename T>
ATL::CComPtr<T> CreateComObject()
{
	ATL::CComObject<T>* obj = nullptr;
	auto hr = ATL::CComObject<T>::CreateInstance(&obj);
	ATLENSURE_SUCCEEDED(hr);
	return ATL::CComPtr<T>(obj);
}

class ATL_NO_VTABLE DataObject
	: public ATL::CComObjectRootEx<ATL::CComSingleThreadModel>
	, public ATL::IDataObjectImpl<DataObject>
{
	BEGIN_COM_MAP(DataObject)
		COM_INTERFACE_ENTRY(IDataObject)
	END_COM_MAP()

public:
	DataObject();

	HRESULT IDataObject_GetData(
		_In_ FORMATETC* pformatetcIn,
		_Out_ STGMEDIUM* pmedium)
	{
		if (pformatetcIn == nullptr)
			return E_INVALIDARG;
		if (pmedium == nullptr)
			return E_POINTER;
		if (pformatetcIn->dwAspect != DVASPECT_CONTENT)
			return DV_E_DVASPECT;
		if (pformatetcIn->cfFormat == CF_FILEDESCRIPTOR)
		{
			if (auto hGlobal = GlobalAlloc(GHND, sizeof m_fileGroupDescriptor))
			{
				if (auto p = GlobalLock(hGlobal))
				{
					memcpy(p, &m_fileGroupDescriptor, sizeof m_fileGroupDescriptor);
					GlobalUnlock(hGlobal);
					pmedium->tymed = TYMED_HGLOBAL;
					pmedium->hGlobal = hGlobal;
					pmedium->pUnkForRelease = nullptr;
					return S_OK;
				}
			}
			return E_OUTOFMEMORY;
		}
		else if (pformatetcIn->cfFormat == CF_FILECONTENTS)
		{
			static const BYTE content[] = { 'A', 'B', 'C' };
			pmedium->tymed = TYMED_ISTREAM;
			pmedium->pstm = SHCreateMemStream(content, sizeof content);
			pmedium->pUnkForRelease = nullptr;
			return S_OK;
		}
		return DV_E_TYMED;
	}

	STDMETHOD(EnumFormatEtc)(
		_In_ DWORD dwDirection,
		__RPC__deref_out_opt IEnumFORMATETC** ppenumFormatEtc) override;

	FILEGROUPDESCRIPTOR m_fileGroupDescriptor = {};

	ATL::CComPtr<IDataAdviseHolder> m_spDataAdviseHolder;

private:
	static const FORMATETC s_formatetc[];
};

const FORMATETC DataObject::s_formatetc[] =
{
	{ CF_FILEDESCRIPTOR, nullptr, DVASPECT_CONTENT, -1, TYMED_HGLOBAL },
	{ CF_FILECONTENTS, nullptr, DVASPECT_CONTENT, -1, TYMED_ISTREAM },
};

DataObject::DataObject()
{
	m_fileGroupDescriptor.cItems = 1;
	m_fileGroupDescriptor.fgd[0].dwFlags = static_cast<DWORD>(FD_PROGRESSUI | FD_UNICODE);
	wcscpy_s(m_fileGroupDescriptor.fgd[0].cFileName, L"test.txt");
}

STDMETHODIMP DataObject::EnumFormatEtc(
	_In_ DWORD dwDirection,
	__RPC__deref_out_opt IEnumFORMATETC** ppenumFormatEtc)
{
	switch (dwDirection)
	{
	case DATADIR_GET:
		return CreateFormatEnumerator(
			ARRAYSIZE(s_formatetc),
			const_cast<FORMATETC*>(s_formatetc),
			ppenumFormatEtc);
	case DATADIR_SET:
		return E_NOTIMPL;
	default:
		return E_INVALIDARG;
	}
}

class ATL_NO_VTABLE TestWindow
	: public ATL::CWindowImpl<TestWindow>
	, public ATL::CComObjectRootEx<ATL::CComSingleThreadModel>
	, public IDropSource
{
public:
	DECLARE_WND_CLASS(TEXT("Test Window Class"));

	STDMETHOD(QueryContinueDrag)(
		_In_ BOOL fEscapePressed,
		_In_ DWORD grfKeyState) override
	{
		if (fEscapePressed)
		{
			return DRAGDROP_S_CANCEL;
		}
		if ((grfKeyState & MK_LBUTTON) == 0)
		{
			return DRAGDROP_S_DROP;
		}
		return S_OK;
	}

	STDMETHOD(GiveFeedback)(
		_In_ DWORD dwEffect) override
	{
		return DRAGDROP_S_USEDEFAULTCURSORS;
	}

	BEGIN_COM_MAP(TestWindow)
		COM_INTERFACE_ENTRY(IDropSource)
	END_COM_MAP()

private:
	BEGIN_MSG_MAP(TestWindow)
		MSG_WM_LBUTTONDOWN(OnLButtonDown)
		MSG_WM_DESTROY(OnDestroy)
	END_MSG_MAP()

	void OnLButtonDown(UINT nFlags, POINT point)
	{
		DWORD effect;
		auto dataObject = CreateComObject<DataObject>();
		DoDragDrop(dataObject, this, DROPEFFECT_COPY, &effect);
	}

	void OnDestroy()
	{
		PostQuitMessage(0);
	}
};

int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int cmdShow)
{
	OleInitialize(nullptr);
	InitCommonControls();

	ATL::CComObjectGlobal<TestWindow> wnd;
	if (!wnd.Create(nullptr, ATL::CWindow::rcDefault,
		TEXT("Hello, world"), WS_OVERLAPPEDWINDOW))
	{
		return -1;
	}

	wnd.ShowWindow(cmdShow);
	wnd.UpdateWindow();

	WTL::CMessageLoop msgLoop;
	auto ret = msgLoop.Run();
	CoDisconnectObject(&wnd, 0);
	OleUninitialize();
	return ret;
}