The GDI+

Environment: [VC6 SP4, NT4 SP3, W2k, Win 9x]

I have found that the Microsft GDI+ can do many cool things for you. Previously you had to find code or write your own code to do the same things. One of these things is the ability to load or save the following types of images:

  • BMP
  • DIB
  • RLE
  • GIF
  • JPEG
  • EMF
  • TIFF
  • PNG

These can be loaded with just a few lines of code like this:

#include <Gdiplus.h>
using namespace Gdiplus;
#pragma comment(lib, "gdiplus.lib")

Image Im(L"c:\\fig.jpg", FALSE);
CLSID GifCodec;
GetCodecClsid(L"image/gif", &GifCodec);
Im.Save(L"c:\\fig.gif", &GifCodec, NULL);

Here is the code to GetCodecClsid

int GetCodecClsid(const WCHAR* format, CLSID* pClsid)
{
  UINT num = 0;  // number of image encoders
  UINT size = 0; // size of the image encoder array in bytes

  ImageCodecInfo* pImageCodecInfo = NULL;

  GetImageEncodersSize(&num, &size);
  if(size == 0)
    return -1; // Failure

  pImageCodecInfo = (ImageCodecInfo*)(malloc(size));
  if(pImageCodecInfo == NULL)
    return -1; // Failure
    
  GetImageEncoders(num, size, pImageCodecInfo);

  for(UINT j = 0; j < num; ++j)
  {
     if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 )
     {
       *pClsid = pImageCodecInfo[j].Clsid;
       return j; // Success
     }
  } // for

  return -1; // Failure
} // GetCodecClsid

All help about GDI+ can be found at: http://msdn.microsoft.com/library/default.asp

Downloads

Here is the library, headers and the dll to build the samples gdiplus.zip (900K):