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Going from a JPG/GIF/BMP File to a HBITMAP File Using Plain API

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This code has probably been superseded by MFC or OWL or whatever classes, which can load any image file. However, you will most probably do it with plain API, and converting a JPG file using Intel's library can be very painful.

Here is a simple function that loads a JPG/GIF/BMP file into memory and returns a HBITMAP. The function uses IPicture, an OLE interface. #include <olectl.h> and <ole2.h> are also needed.

// Function LoadAnImage: accepts a file name and returns a HBITMAP.
// On error, it returns 0.
HBITMAP LoadAnImage(char* FileName)
   {
   // Use IPicture stuff to use JPG / GIF files
   IPicture* p;
   IStream* s;
   IPersistStream* ps;
   HGLOBAL hG;
   void* pp;
   FILE* fp;


   // Read file in memory
   fp = fopen(FileName,"rb");
   if (!fp)
   return NULL;

   fseek(fp,0,SEEK_END);
   int fs = ftell(fp);
   fseek(fp,0,SEEK_SET);
   hG = GlobalAlloc(GPTR,fs);
   if (!hG)
      {
      fclose(fp);
      return NULL;
      }
   pp = (void*)hG;
   fread(pp,1,fs,fp);
   fclose(fp);

   // Create an IStream so IPicture can 
   // CreateStreamOnHGlobal(hG,false,&s);
   if (!s)
      {
      GlobalFree(hG);
      return NULL;
      }

   OleLoadPicture(s,0,false,IID_IPicture,(void**)&p);

   if (!p)
      {
      s->Release();
      GlobalFree(hG);
      return NULL;
      }
   s->Release();
   GlobalFree(hG);

   HBITMAP hB = 0;
   p->get_Handle((unsigned int*)&hB);

   // Copy the image. Necessary, because upon p's release,
   // the handle is destroyed.
   HBITMAP hBB = (HBITMAP)CopyImage(hB,IMAGE_BITMAP,0,0,
                                    LR_COPYRETURNORG);

   p->Release();
   return hBB;
   }


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