Implementing Exif Features

BITMAPHANDLE LeadBitmap;   /* Bitmap handle for the image */ 
void TestFunction(HWND hWnd, L_TCHAR *szFilename ) 
{ 
   L_CHAR  * pCommentToGet; /* Comment string that we will get */ 
   HGLOBAL hCommentToGet;        /* Handle for memory management */ 
   L_INT CommentLength;          /* Length of the string */ 
   L_UCHAR CommentToSet[80]; /* Comment string that we will set */ 
   L_CHAR  * pCommentToSet = CommentToSet; 
   L_UCHAR szUserComment[80]; /* User comment that we will add */ 
   L_CHAR  * pUserComment = szUserComment; 
   L_UINT32  * pDistance;       /* Pointer for the Exif RATIONAL */ 
   L_UINT32 Numerator, Denominator; /* Components of the Exif RATIONAL */ 
   float fDistance; /* Result of the distance calculation */ 
   L_TCHAR szMessage[256]; /* MessageBox string */ 
   L_TCHAR szBuf[80]; 
   L_INT i; /* Loop counter */ 
   /* Load the bitmap */ 
   L_LoadBitmap (szFilename, &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL); 
   /* Load the current comments from the file */ 
   for(i = 0 ; i < CMNT_LAST ; i++ ) 
   { 
      /* Clear the comment */ 
      L_SetComment(i, NULL, 0); 
      /* Use the return value to get the length of a comment in the file */ 
      CommentLength = L_ReadFileComment(szFilename, i, NULL, 0, NULL); 
      if (CommentLength > 0) 
      { 
         /* Allocate and lock a zero-filled buffer for the comment */ 
         hCommentToGet = GlobalAlloc(GHND, CommentLength); 
         pCommentToGet = (L_UCHAR  *)GlobalLock( hCommentToGet ); 
         /* Get the comment from the file */ 
         L_ReadFileComment(szFilename, i, pCommentToGet, CommentLength, NULL); 
         /* Set the comment to be saved */ 
         L_SetComment(i, pCommentToGet, CommentLength); 
         /* Unlock and free memory */ 
         GlobalUnlock( hCommentToGet ); 
         GlobalFree(hCommentToGet); 
      } 
   } 
   /* Reverse the image */ 
   L_ReverseBitmap(&LeadBitmap); 
   /* Create the CMNT_USERCOMMENT comment as a byte array */ 
   L_SetComment(CMNT_USERCOMMENT, NULL, 0); 
   pUserComment = "The image has been reversed."; 
   pCommentToSet[0] = 'A'; 
   pCommentToSet[1] = 'S'; 
   pCommentToSet[2] = 'C'; 
   pCommentToSet[3] = 'I'; 
   pCommentToSet[4] = 'I'; 
   pCommentToSet[5] = '\0'; 
   pCommentToSet[6] = '\0'; 
   pCommentToSet[7] = '\0'; 
   for( i = 0; pUserComment[i] != '\0'; i++) 
   { 
      pCommentToSet[i+8] = pUserComment[i]; 
   } 
   pCommentToSet[i+8] = '\0'; 
   /* Set the CMNT_USERCOMMENT comment  */ 
   L_SetComment(CMNT_USERCOMMENT, pCommentToSet, strlen(pUserComment) + 9); 
   /* Save the image as an Exif file */ 
   L_SaveBitmap(szFilename, &LeadBitmap, FILE_EXIF, 24, 0, NULL); 
   /* Initialize the message string */ 
   szMessage[0] = '\0'; 
   /* Use the return value to get the length of the CMNT_SUBJECTDISTANCE comment */ 
   /* This shows how to translate the Exif RATIONAL data type */ 
   CommentLength = L_ReadFileComment(szFilename, CMNT_SUBJECTDISTANCE, NULL, 0, NULL); 
   if (CommentLength > 0) 
   { 
      /* Allocate and lock a zero-filled buffer for the comment */ 
      hCommentToGet = GlobalAlloc(GPTR, CommentLength); 
      pCommentToGet = (L_UCHAR  *)GlobalLock( hCommentToGet ); 
      /* Get the actual comment from the file */ 
      L_ReadFileComment(szFilename, CMNT_SUBJECTDISTANCE, pCommentToGet, CommentLength, NULL); 
      pDistance = (L_UINT32  *)pCommentToGet; 
      Numerator = pDistance[0]; 
      Denominator = pDistance[1]; 
      fDistance = (float)Numerator / (float)Denominator; 
      wsprintf (szMessage, TEXT("Subject distance: %.6f\n"),fDistance ); 
      /* Unlock and free memory */ 
      GlobalUnlock( hCommentToGet ); 
      GlobalFree(hCommentToGet); 
   } 
   /* Use the return value to get the length of the CMNT_USERCOMMENT comment */ 
   CommentLength = L_ReadFileComment(szFilename, CMNT_USERCOMMENT, NULL, 0, NULL); 
   if (CommentLength > 0) 
   { 
      /* Allocate and lock a zero-filled buffer for the comment */ 
      hCommentToGet = GlobalAlloc(GPTR, CommentLength); 
      pCommentToGet = (L_UCHAR  *)GlobalLock( hCommentToGet ); 
      /* Get the actual comment from the file */ 
      L_ReadFileComment(szFilename, CMNT_USERCOMMENT, pCommentToGet, CommentLength, NULL); 
      /* If the prefix is ASCII, move the pointer and update the message string */ 
      if (strcmp(pCommentToGet,"ASCII")== 0) 
      { 
         pCommentToGet = pCommentToGet + 8; 
      } 
      wsprintf (szBuf, TEXT("%hs"), pCommentToGet); 
      lstrcat(szMessage, szBuf); 
      /* Unlock and free memory */ 
      GlobalUnlock( hCommentToGet ); 
      GlobalFree(hCommentToGet); 
   } 
   /* Show the two comments */ 
   MessageBox (NULL, szMessage, TEXT("Notice"), MB_OK); 
   /* Clear the comments */ 
   for(i = 0 ; i < CMNT_LAST ; i++ ) 
   L_SetComment(i, NULL, 0); 
   /* Force a repaint */ 
   SendMessage (hWnd, WM_QUERYNEWPALETTE, 0, 0L); 
   return; 
}