之前写了一篇《》，通过CImage实现了在内存中Jpeg转Bmp。

既然Jpeg能转Bmp，那CImage也支持Bmp转Jpeg，与上一篇文章依赖CImage的Load函数相反，Bmp转Jpeg通过Save函数实现：

使用的也是IStream接口的函数重载，具体可以参考MSDN：http://msdn.microsoft.com/zh-cn/library/d06f3fhw.aspx

下面贴出使用CImage在内存中Bmp转换Jpeg的代码：

unsigned long BMP2JPEG(char* pUnZipData,unsigned long ulUnZipDataLen,char** pBuffer){	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);				*pBuffer = new char[ulBufferLen];				memcpy(*pBuffer, pBits, ulBufferLen);								GlobalUnlock(hOutGlobal);				pOutStream->Release();			}		}   		pStream->Release();       	}   	GlobalFree(hGlobal);  	return ulBufferLen;}

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记录，为更好的自己！