FreeImageIO

#ifdef __cplusplus
#define FI_STRUCT(x)	struct x
#else
#define FI_STRUCT(x)	typedef struct x x; struct x
#endif

FI_STRUCT(FreeImageIO) {
    FI_ReadProc  read_proc;     //! pointer to the function used to read data
    FI_WriteProc write_proc;    //! pointer to the function used to write data
    FI_SeekProc  seek_proc;     //! pointer to the function used to seek
    FI_TellProc  tell_proc;     //! pointer to the function used to aquire the current position
};