The Mini Shell Extension Framework – Part III

//
// (C) Copyright by Victor Derks <vba64@xs4all.nl>
//
// See README.TXT for the details of the software licence.
//
#pragma once


#include "macros.h"


namespace MSF
{

template <typename TItem>
class ATL_NO_VTABLE CExtractIcon :
	public CComObjectRootEx<CComSingleThreadModel>,
	public IExtractIcon
{
public:

	class CIcon
	{
	public:
		explicit CIcon(HICON hicon = NULL) :
			m_hicon(hicon)
		{
		}


		~CIcon() throw()
		{
			dispose();
		}


		HICON operator=(HICON hicon) throw()
		{
			dispose();
			m_hicon = hicon;
			return m_hicon;
		}


		void release() throw()
		{
			m_hicon = NULL;
		}


		HICON get() const throw()
		{
			return m_hicon;
		}

	private:

		void dispose() throw()
		{
			if (m_hicon != NULL)
			{
				ATLVERIFY(DestroyIcon(m_hicon));
				m_hicon = NULL;
			}
		}

		HICON m_hicon;
	};


	static CComPtr<IExtractIcon> CreateInstance(const TItem& item)
	{
		CComObject<CExtractIcon<TItem> >* pinstance;
		RaiseExceptionIfFailed(CComObject<CExtractIcon<TItem> >::CreateInstance(&pinstance));

		CComPtr<IExtractIcon> extracticon(pinstance);

		pinstance->Initialize(item);

		return extracticon;
	}


	static HICON GetIcon(HIMAGELIST himl, int i, UINT flags = 0)
	{
		HICON hicon = ImageList_GetIcon(himl, i, flags);
		RaiseExceptionIf(hicon == NULL);
		return hicon;
	}


	DECLARE_NOT_AGGREGATABLE(CExtractIcon)

	BEGIN_COM_MAP(CExtractIcon)
		COM_INTERFACE_ENTRY(IExtractIcon)
	END_COM_MAP()


	void Initialize(const TItem& item)
	{
		m_nIconIndex = -1;
		m_item = item;
	}


	STDMETHOD(GetIconLocation)(UINT uFlags, LPTSTR /*szIconFile*/, UINT /*cchMax*/, int* /*piIndex*/, UINT* pwFlags)
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CExtractIcon::GetIconLocation, instance=%p, uFlags=%x\n"), this, uFlags);

		try
		{
			m_nIconIndex = m_item.GetIconOf(uFlags);

			*pwFlags = GIL_NOTFILENAME;
			return S_OK;
		}
		MSF_COM_CATCH_HANDLER()
	}


	STDMETHOD(Extract)(LPCTSTR /*pszFile*/, UINT /*nIconIndex*/, HICON* phiconLarge, HICON* phiconSmall, UINT nIconSize)
	{
		ATLTRACE2(atlTraceCOM, 0, _T("CExtractIcon::Extract, instance=%p, pl=%p, ps=%p\n"), this, phiconLarge, phiconSmall);

		try
		{
			if (m_nIconIndex == -1)
				return E_INVALIDARG; // GetIconLocation not called.

			HIMAGELIST himLarge;
			HIMAGELIST himSmall;
			RaiseExceptionIf(!Shell_GetImageLists(&himLarge, &himSmall));

			CIcon iconLarge;
			if (phiconLarge != NULL)
			{
				if (LOWORD(nIconSize) != 32)
					return E_INVALIDARG;

				iconLarge = GetIcon(himLarge, m_nIconIndex);
				*phiconLarge = iconLarge.get();
			}

			if (phiconSmall != NULL)
			{
				if (HIWORD(nIconSize) != 16)
					return E_INVALIDARG;

				*phiconSmall = GetIcon(himSmall, m_nIconIndex);
			}

			iconLarge.release();

			return S_OK;
		}
		MSF_COM_CATCH_HANDLER()
	}

private:

	// Member variables.
	int   m_nIconIndex;
	UINT  m_uFlags;
	TItem m_item;
};

} // namespace MSF