C++ BMP转JPG

#include <atlimage.h>
unsigned long BMP2JPEG(const char* pUnZipData, unsigned long ulUnZipDataLen, std::string& jpgData)
{
    
    
	unsigned long ulBufferLen = 0;
	HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, ulUnZipDataLen);
	void* pData = GlobalLock(hGlobal);
	memcpy(pData, pUnZipData, ulUnZipDataLen);
	GlobalUnlock(hGlobal);
	IStream* pStream = NULL;
	if (CreateStreamOnHGlobal(hGlobal, TRUE, &pStream) == S_OK)
	{
    
    
		CImage image;
		if (SUCCEEDED(image.Load(pStream)))
		{
    
    
			IStream* pOutStream = NULL;
			if (CreateStreamOnHGlobal(NULL, TRUE, &pOutStream) == S_OK)
			{
    
    
				image.Save(pOutStream, Gdiplus::ImageFormatJPEG);
				HGLOBAL hOutGlobal = NULL;
				GetHGlobalFromStream(pOutStream, &hOutGlobal);
				LPBYTE pBits = (LPBYTE)GlobalLock(hOutGlobal);
				ulBufferLen = (DWORD)GlobalSize(pBits);
				char *pBuffer = new char[ulBufferLen];
				memcpy(pBuffer, pBits, ulBufferLen);
				jpgData = std::string(pBuffer, ulBufferLen);
				delete pBuffer;
				pBuffer = nullptr;
				GlobalUnlock(hOutGlobal);
				pOutStream->Release();
			}
		}
		pStream->Release();
	}
	GlobalFree(hGlobal);
	return ulBufferLen;
}