Writing Win32 Apps with C++ only classes

//GdiWrp.h
#pragma once
//wrapper classes for GDI handles


namespace GE_{ namespace NGDI{

	template<class W>
	struct SHdcSave_base:
		public NWrp::HndBase<HDC, W>
	{
	protected:
		int _savedDC;
	public:
		void OnAddRef(NWrp::XRefCount_base* pRC)
		{  _savedDC = SaveDC(Value()); }

		void OnRelease(NWrp::XRefCount_base* pRC)
		{	RestoreDC(Value(), _savedDC); }
	};
	
  
	class SHdcSave:
		public SHdcSave_base<SHdcSave>
	{
	public:
		SHdcSave(HDC hdc) { Attach(hdc); }
	};

	class SHdcPaint:
		public SHdcSave_base<SHdcPaint>
	{
	protected:
		PAINTSTRUCT _ps;
		HWND _hWnd;

		friend TWrpBase;
		
        void Create(HDC& h)
		{
			BeginPaint(_hWnd, &_ps);
			h = _ps.hdc;
		}

		void Destroy(HDC& h)
		{
			EndPaint(_hWnd, &_ps);
		}

	public:
		SHdcPaint(HWND hWnd)
		{	_hWnd = hWnd;  New(); }

		const PAINTSTRUCT& PaintStruct() const { return _ps; }

	};

	class SHdcClient:
		public SHdcSave_base<SHdcClient>
	{
	protected:
		HWND _hWnd;

		friend TWrpBase;

		void Create(HDC& h)
		{	h = GetDC(_hWnd);	}

		void Destroy(HDC& h)
		{	ReleaseDC(_hWnd, h); }

	public:
		SHdcClient(HWND hWnd)
		{	_hWnd = hWnd; New(); }
	};


	class SHdcWnd:
		public SHdcSave_base<SHdcClient>
	{
	protected:
		HWND _hWnd;

		friend TWrpBase;

		void Create(HDC& h)
		{	h = GetWindowDC(_hWnd);	}

		void Destroy(HDC& h)
		{	ReleaseDC(_hWnd, h); }

	public:
		SHdcWnd(HWND hWnd)
		{	_hWnd = hWnd; New(); }
	};

	
	class SHdcMem:
		public SHdcSave_base<SHdcMem>
	{
	protected:
		HBITMAP _hBmp;
		SIZE _size; //null size means _hBmp not created here
		
		friend TWrpBase;
		
		void Create(HDC& h)
		{
			HDC hScreen = GetWindowDC(GetDesktopWindow());
			h = CreateCompatibleDC(hScreen);
			if(!_hBmp && _size.cx && _size.cy)
				_hBmp = CreateCompatibleBitmap(hScreen, _size.cx, _size.cy);
			ReleaseDC(GetDesktopWindow(), hScreen);
		}

		void Destroy(HDC& h)
		{
			DeleteDC(h);
			if(_size.cx && _size.cy && _hBmp)
				DeleteObject(_hBmp);
		}

	public:

		SHdcMem(const SIZE& sz)
		{
			_size = sz;
			_hBmp = NULL;
			New();
			SelectObject(*this, _hBmp);
		}

        SHdcMem(HBITMAP bmp)
		{
			_size.cx = _size.cy = 0;
			_hBmp = bmp;
			New();
			SelectObject(*this, _hBmp);
		}
	};

	
	template<class H>
	class SGdiObj:
		public NWrp::HndBase<H, SGdiObj>
	{
	protected:
		friend TWrpBase;
		void Destroy(H& h)
		{	DeleteObject((HGDIOBJ)h);	}
	};

	typedef NWrp::Wrp<SGdiObj<HPEN> > TPen;
	typedef NWrp::Wrp<SGdiObj<HBRUSH> > TBrush;
	typedef NWrp::Wrp<SGdiObj<HFONT> > TFont;
	typedef NWrp::Wrp<SGdiObj<HRGN> > TRgn;

}}