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The Mini Shell Extension Framework – Part III

, 18 Sep 2005
Discussion of a small C++ framework to create Windows shell extensions (IShellFolderImpl).
msf091.zip
include
columnprovider.rgs
contextmenu.rgs
contextmenu_sf.rgs
extension.rgs
extractimage_sf.rgs
infotip.rgs
infotip_sf.rgs
propertysheetext.rgs
propertysheetext_sf.rgs
shell32missing.def
shell32missing.lib
shellfolder.rgs
shellfolderwin98.rgs
vvvsample
Copy of sample1.vvv
menuicon.bmp
sample.def
sample.manifest
sample1.vvv
vvv.ico
vvvtest
sample.yyy
sample1.vvv
sample2.vvv
//
// (C) Copyright by Victor Derks <vba64@xs4all.nl>
//
// See README.TXT for the details of the software licence.
//
#pragma once


#include <atlctl.h> // for IDataObjectImpl
#include "macros.h"
#include "cfhandler.h"
#include "enumformatetc.h"
#include "formatetc.h"


namespace MSF
{

template<typename T>
class CClipboardDataObjectImpl : public ATL::IDataObjectImpl<T>
{
	class CExternalData;

	typedef std::vector<CCfHandler*>    CCfHandlers;
	typedef std::vector<CExternalData*> CExternalDatas;

public:

	CClipboardDataObjectImpl() throw()
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::CClipboardDataObjectImpl (instance=%p)\n"), this);
	}


	~CClipboardDataObjectImpl() throw()
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::~CClipboardDataObjectImpl (instance=%p)\n"), this);

		for_each(m_cfhandlers, CDeleteObject());
		for_each(m_externaldatas, CDeleteObject());
	}


	void RegisterCfHandler(std::auto_ptr<CCfHandler> qcfhandler)
	{
		ATLASSERT(FindCfHandler(qcfhandler->GetClipFormat()) == NULL && "Cannot register twice");
		m_cfhandlers.push_back(qcfhandler.get());
		qcfhandler.release();
	}


	STDMETHOD(EnumFormatEtc)(DWORD dwDirection, IEnumFORMATETC** ppenumFormatEtc)
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::EnumFormatEtc (dwDirection=%d)\n"), dwDirection);

		try
		{
			if (dwDirection != DATADIR_GET && dwDirection != DATADIR_SET)
				return E_INVALIDARG;

			std::vector<FORMATETC> formatetcs;
			GetRegisteredFormats(formatetcs, dwDirection);
			GetExternalFormats(formatetcs);

			SHCreateStdEnumFmtEtc(formatetcs, ppenumFormatEtc);
			return S_OK;
		}
		MSF_COM_CATCH_HANDLER()
	}


	STDMETHOD(QueryGetData)(FORMATETC* pformatetc)
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::QueryGetData, cfformat=%d (%s)\n"),
			pformatetc->cfFormat, GetClipboardFormatName(pformatetc->cfFormat).GetString());

		try
		{
			const CCfHandler* pcfhandler = FindCfHandler(pformatetc->cfFormat);
			if (pcfhandler != NULL)
			{
				if (pcfhandler->CanGetData())
				{
					return pcfhandler->Validate(*pformatetc);
				}
			}
			else
			{
				const CExternalData* pexternaldata = FindExternalData(pformatetc->cfFormat);
				if (pexternaldata != NULL)
				{
					return pexternaldata->Validate(*pformatetc);
				}
			}

			ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::QueryGetData (DV_E_FORMATETC)\n"));
			return DV_E_FORMATETC;
		}
		MSF_COM_CATCH_HANDLER()
	}


	STDMETHOD(GetData)(FORMATETC *pformatetc, STGMEDIUM *pstgmedium)
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::GetData cfformat=%d (%s)\n"), 
			pformatetc->cfFormat, GetClipboardFormatName(pformatetc->cfFormat).GetString());

		try
		{
			CCfHandler* pcfhandler = FindCfHandler(pformatetc->cfFormat);
			if (pcfhandler != NULL)
			{
				if (pcfhandler->CanGetData())
				{
					RaiseExceptionIfFailed(pcfhandler->Validate(*pformatetc));
					pcfhandler->GetData(*pformatetc, *pstgmedium);
					return S_OK;
				}
			}
			else
			{
				CExternalData* pexternaldata = FindExternalData(pformatetc->cfFormat);
				if (pexternaldata != NULL)
				{
					pexternaldata->Copy(*pstgmedium);
					return S_OK;
				}
			}

			ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::GetData (DV_E_FORMATETC)\n"));
			return DV_E_FORMATETC;
		}
		MSF_COM_CATCH_HANDLER()
	}


	STDMETHOD(SetData)(FORMATETC* pformatetc, STGMEDIUM* pstgmedium, BOOL fRelease)
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CClipboardDataObjectImpl::SetData cfformat=%d (%s), tymed=%d, fRelease=%d\n"),
			pformatetc->cfFormat, GetClipboardFormatName(pformatetc->cfFormat).GetString(), pformatetc->tymed, fRelease);

		try
		{
			if (pformatetc->ptd != NULL)
				return DV_E_DVTARGETDEVICE;

			if (pformatetc->tymed != pstgmedium->tymed)
				return DV_E_TYMED;

			CCfHandler* pcfhandler = FindCfHandler(pformatetc->cfFormat);
			if (pcfhandler != NULL)
			{
				if (pcfhandler->CanSetData())
				{
					RaiseExceptionIfFailed(pcfhandler->Validate(*pformatetc));
					pcfhandler->SetData(*pformatetc, *pstgmedium, fRelease > 0);
					return S_OK;
				}

				return E_FAIL;
			}

			if (!fRelease || pstgmedium->pUnkForRelease != NULL)
				return E_INVALIDARG; // external data can only be set, if we can take ownership.

			if (pstgmedium->tymed != TYMED_HGLOBAL &&
			    pstgmedium->tymed != TYMED_ISTREAM &&
			    pstgmedium->tymed != TYMED_ISTORAGE)
			    return DV_E_TYMED; // only support for HGLOBAL and TYMED_ISTREAM.

			CExternalData* pexternaldata = FindExternalData(pformatetc->cfFormat);
			if (pexternaldata == NULL)
			{
				AddExternalData(*pformatetc, *pstgmedium);
			}
			else
			{
				pexternaldata->Update(*pformatetc, *pstgmedium);
			}

			return S_OK;
		}
		MSF_COM_CATCH_HANDLER()
	}


	// Required by ATL base class.
	LPDATAADVISEHOLDER m_spDataAdviseHolder;

private:

	class CExternalData
	{
	public:
		CExternalData(const FORMATETC& formatetc, const STGMEDIUM& stgmedium) throw() :
			_formatetc(formatetc),
			_stgmedium(stgmedium)
		{
		}


		CLIPFORMAT GetClipFormat() const throw()
		{
			return _formatetc.cfFormat;
		}


		const FORMATETC& GetFormatetc() const throw()
		{
			return _formatetc;
		}


		HRESULT Validate(const FORMATETC& formatetc) const throw()
		{
			if (formatetc.dwAspect != DVASPECT_CONTENT)
				return DV_E_DVASPECT;

			if (formatetc.tymed != _formatetc.tymed)
				return DV_E_TYMED;

			if (formatetc.lindex != -1)
				return DV_E_LINDEX;

			return S_OK;
		}


		void Update(const FORMATETC& formatetc, STGMEDIUM& stgmedium)
		{
			_formatetc = formatetc;
			_stgmedium = stgmedium;
		}


		void Copy(STGMEDIUM& stgmedium)
		{
			_stgmedium.CopyTo(stgmedium);
		}

	private:

		// Member variables.
		CFormatEtc _formatetc;
		CStgMedium _stgmedium;
	};


	CCfHandler* FindCfHandler(CLIPFORMAT clipformat) const throw()
	{
		for (CCfHandlers::const_iterator it = m_cfhandlers.begin(); it != m_cfhandlers.end(); ++it)
		{
			if ((*it)->GetClipFormat() == clipformat)
			{
				return *it;
			}
		}

		return NULL;
	}


	CExternalData* FindExternalData(CLIPFORMAT clipformat) const throw()
	{
		for (CExternalDatas::const_iterator it = m_externaldatas.begin(); it != m_externaldatas.end(); ++it)
		{
			if ((*it)->GetClipFormat() == clipformat)
			{
				return *it;
			}
		}

		return NULL;
	}


	void AddExternalData(const FORMATETC& formatetc, const STGMEDIUM& stgmedium)
	{
		ATLASSERT(FindExternalData(formatetc.cfFormat) == NULL && "External format already set");

		std::auto_ptr<CExternalData> qexternaldata(new CExternalData(formatetc, stgmedium));
		m_externaldatas.push_back(qexternaldata.get());
		qexternaldata.release();
	}


	void GetRegisteredFormats(std::vector<FORMATETC>& formatetcs, DWORD dwDirection) const
	{
		for (CCfHandlers::const_iterator it = m_cfhandlers.begin(); it != m_cfhandlers.end(); ++it)
		{
			if (dwDirection == DATADIR_GET)
			{
				if ((*it)->CanGetData())
				{
					formatetcs.push_back(CFormatEtc((*it)->GetClipFormat()));
				}
			}
			else
			{
				if ((*it)->CanSetData())
				{
					formatetcs.push_back(CFormatEtc((*it)->GetClipFormat()));
				}
			}
		}
	}


	void GetExternalFormats(std::vector<FORMATETC>& formatetcs) const
	{
		for (CExternalDatas::const_iterator it = m_externaldatas.begin(); it != m_externaldatas.end(); ++it)
		{
			formatetcs.push_back((*it)->GetFormatetc());
		}
	}


	// Member variables.
	CCfHandlers    m_cfhandlers;
	CExternalDatas m_externaldatas;
};

}

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About the Author

Victor Derks
Software Developer (Senior) Schneider Electric
Netherlands Netherlands
Victor lives in Nijmegen, the oldest city in The Netherlands.
He studied Applied Physics in Delft and now works for GE Healthcare.

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