gdiplus图片格式转换

还没来得及kan ,先转了再说

vc6.0必须装gdiplus库文件和头文件

Given an input stream of some type of image, the followingfunction converts that image into another type of image given thedestination format. The destination format should be a propermime-type such as "image/jpeg", "image/png".

Gdiplus::Status imageToImage(
  IStream *pStreamIn, IStream *pStreamOut, BSTRwszOutputMimeType)
{
    namespace G= Gdiplus;
    G::Statusstatus = G::Ok;
    G::ImageimageSrc(pStreamIn);
    status =imageSrc.GetLastStatus();
    if (G::Ok !=status) {
     return status;
    }
    UINTnumEncoders = 0;
    UINTsizeEncodersInBytes = 0;
    status =G::GetImageEncodersSize(&numEncoders,&sizeEncodersInBytes);
    if (status!= G::Ok) {
     return status;
    }
   G::ImageCodecInfo *pImageCodecInfo =
        (G::ImageCodecInfo *) malloc(sizeEncodersInBytes);
    status =G::GetImageEncoders(
         numEncoders, sizeEncodersInBytes, pImageCodecInfo);
    if (status!= G::Ok) {
     return status;
    }
    CLSIDclsidOut;
    status =G::UnknownImageFormat;
    for (UINT j= 0; j < numEncoders; j ++) {
     if (0 == wcscmp(pImageCodecInfo[j].MimeType, wszOutputMimeType)){
       clsidOut = pImageCodecInfo[j].Clsid;
       status = G::Ok;
       break;
     }   
    }
   free(pImageCodecInfo);
    if (status!= G::Ok) {
     return status;
    }
    returnimageSrc.Save(pStreamOut, &clsidOut);
  }

It can be used like so:

extern IStream *pSomeImg; // source image format is notimportant
extern IStream *pMyJpeg;
if (Gdiplus::Ok == imageToImage(pSomeImg, pMyJpeg, L"image/jpeg")){
// pMyJpeg holds the converted jpeg.
}

If there is a need to put/retrieve data into/from IStream inbyte-array format (such as char*), it can by done by usingCreateStreamOnHGlobal, GlobalAlloc, GlobalLock Win32 API functions.See this tip for more details
Note: List of supported formats: BMP, ICON, GIF, JPEG, Exif, PNG,TIFF, WMF, and EMF.

摘自:http://blog.sina.com.cn/s/blog_ad0672d601017qpn.html