GdiPlus载入PNG图片，内存泄漏解决办法

最近开发项目需要使用GdiPlus+PNG图片的方式，实现窗口半透明效果。在网上DOWN了一些SAMPLE后，发现载入PNG图片后，直接delete掉Gdiplus::Image::FromStream返回的指针不能正确释放内存空间，在CODEPROJECT上找到了解决办法。

使用如下代码，管理载入的PNG图片，简单delete对象指针即可正确释放内存。

using namespace Gdiplus;

class CGdiPlusPng
{
public:
	Gdiplus::Image* m_pImage;

public:
	CGdiPlusPng()
	{
		m_pImage = NULL;
	}

	CGdiPlusPng(LPCWSTR pFile)
	{
		m_pImage = NULL;
		Load(pFile);
	}

	virtual ~CGdiPlusPng()
	{
		Empty();
	}

	void Empty()
	{
		delete m_pImage;
		m_pImage = NULL;
	}

	bool Load(LPCWSTR pFile)
	{
		Empty();
		m_pImage = Gdiplus::Bitmap::FromFile(pFile);
		return m_pImage->GetLastStatus() == Gdiplus::Ok;
	}

	operator Gdiplus::Image * () const
	{
		return m_pImage;
	}

	Gdiplus::Image *GetPngImage() const
	{
		return m_pImage;
	}
};

class CGdiPlusPngResource : public CGdiPlusPng
{
protected:
	HGLOBAL m_hBuffer;

public:
	CGdiPlusPngResource()
	{
		m_hBuffer = NULL;
	}

	CGdiPlusPngResource(LPCTSTR pName, LPCTSTR pType = RT_RCDATA, HMODULE hInst = NULL)
	{
		m_hBuffer = NULL;
		Load(pName, pType, hInst);
	}
	
	CGdiPlusPngResource(UINT id, LPCTSTR pType = RT_RCDATA, HMODULE hInst = NULL)
	{
		m_hBuffer = NULL;
		Load(id, pType, hInst);
	}
	CGdiPlusPngResource(UINT id, UINT type, HMODULE hInst = NULL)
	{
		m_hBuffer = NULL;
		Load(id, type, hInst);
	}
	
	virtual ~CGdiPlusPngResource()
	{
		Empty();
	}

	void Empty();

	bool Load(LPCTSTR pName, LPCTSTR pType = RT_RCDATA, HMODULE hInst = NULL);

	bool Load(UINT id, LPCTSTR pType = RT_RCDATA, HMODULE hInst = NULL)
	{
		return Load(MAKEINTRESOURCE(id), pType, hInst);
	}

	bool Load(UINT id, UINT type, HMODULE hInst = NULL)
	{
		return Load(MAKEINTRESOURCE(id), MAKEINTRESOURCE(type), hInst);
	}
};

inline void CGdiPlusPngResource::Empty()
{
	CGdiPlusPng::Empty();
	if (m_hBuffer)
	{
		::GlobalUnlock(m_hBuffer);
		::GlobalFree(m_hBuffer);
		m_hBuffer = NULL;
	} 
}

inline bool CGdiPlusPngResource::Load(LPCTSTR pName, LPCTSTR pType, HMODULE hInst)
{
	Empty();

	HRSRC hResource = ::FindResource(hInst, pName, pType);
	if(hResource == NULL)
	{
		return false;
	}
	
	DWORD imageSize = ::SizeofResource(hInst, hResource);
	if(imageSize == 0)
	{
		return false;
	}

	const void* pResourceData = ::LockResource(::LoadResource(hInst, hResource));
	if(pResourceData == NULL)
	{
		return false;
	}

	m_hBuffer  = ::GlobalAlloc(GMEM_MOVEABLE, imageSize);
	if(m_hBuffer != NULL)
	{
		void* pBuffer = ::GlobalLock(m_hBuffer);
		if(pBuffer != NULL)
		{
			CopyMemory(pBuffer, pResourceData, imageSize);

			IStream* pStream = NULL;
			if(::CreateStreamOnHGlobal(m_hBuffer, FALSE, &pStream) == S_OK)
			{
				m_pImage = Gdiplus::Image::FromStream(pStream);
				pStream->Release();
				if(m_pImage != NULL)
				{ 
					if(m_pImage->GetLastStatus() == Gdiplus::Ok)
					{
						return true;
					}

					delete m_pImage;
					m_pImage = NULL;
				}
			}
			::GlobalUnlock(m_hBuffer);
		}
		::GlobalFree(m_hBuffer);
		m_hBuffer = NULL;
	}
	return false;
}