# curs_util 3x

    curs_util(3x)                                             curs_util(3x)

## NAME

           delay_output, filter, flushinp, getwin, key_name, keyname,
           nofilter, putwin, unctrl, use_env, wunctrl - miscellaneous
           curses utility routines

## SYNOPSIS

           #include <curses.h>

           char *unctrl(chtype c);
           wchar_t *wunctrl(cchar_t *c);
           char *keyname(int c);
           char *key_name(wchar_t w);
           void filter(void);
           void nofilter(void);
           void use_env(bool f);
           int putwin(WINDOW *win, FILE *filep);
           WINDOW *getwin(FILE *filep);
           int delay_output(int ms);
           int flushinp(void);

## DESCRIPTION

           The  unctrl  routine returns a character string which is a
           printable representation of the character c, ignoring  at-
           tributes.   Control characters are displayed in the ^X no-
           tation.  Printing characters are  displayed  as  is.   The
           corresponding  wunctrl  returns a printable representation
           of a wide character.

           The keyname routine returns a character string correspond-
           ing to the key c:

              o   Printable  characters  are displayed as themselves,
                  e.g., a one-character string containing the key.

              o   Control characters are displayed in  the  ^X  nota-
                  tion.

              o   DEL (character 127) is displayed as ^?.

              o   Values above 128 are either meta characters (if the
                  screen has not been initialized,  or  if  meta  has
                  been  called  with  a TRUE parameter), shown in the
                  M-X notation, or are displayed as  themselves.   In
                  the  latter  case, the values may not be printable;
                  this follows the X/Open specification.

              o   Values above 256 may be the names of the  names  of
                  function keys.

              o   Otherwise  (if  there is no corresponding name) the
                  function returns null, to denote an error.   X/Open
                  also  lists  an  "UNKNOWN  KEY" return value, which
                  some implementations return rather than null.

           The corresponding key_name returns a character string cor-
           responding  to  the wide-character value w.  The two func-
           tions do not return the same set of  strings;  the  latter
           returns null where the former would display a meta charac-
           ter.

           The filter routine, if used, must be called before initscr
           or  newterm  are called.  The effect is that, during those
           calls, LINES is set to 1;  the  capabilities  clear,  cup,
           cud,  cud1,  cuu1,  cuu,  vpa  are  disabled; and the home
           string is set to the value of cr.

           The nofilter routine cancels the  effect  of  a  preceding
           filter  call.   That  allows  the  caller  to initialize a
           screen on a different device, using a different  value  of
           $TERM.   The  limitation arises because the filter routine
           modifies the in-memory copy of the terminal information.

           The use_env routine, if used, is called before initscr  or
           newterm  are  called.   When called with FALSE as an argu-
           ment, the values of lines and  columns  specified  in  the
           terminfo  database will be used, even if environment vari-
           ables LINES and COLUMNS (used by default) are set,  or  if
           curses  is  running in a window (in which case default be-
           havior would be to  use  the  window  size  if  LINES  and
           COLUMNS  are not set).  Note that setting LINES or COLUMNS
           overrides the corresponding size  which  may  be  obtained
           from the operating system.

           The  putwin routine writes all data associated with window
           win into the file to which filep points.  This information
           can be later retrieved using the getwin function.

           The getwin routine reads window related data stored in the
           file by putwin.  The routine then creates and  initializes
           a new window using that data.  It returns a pointer to the
           new window.

           The delay_output routine inserts an ms  millisecond  pause
           in  output.   This  routine should not be used extensively
           because padding characters are  used  rather  than  a  CPU
           pause.   If  no  padding character is specified, this uses
           napms to perform the delay.

           The flushinp routine throws away any  typeahead  that  has
           been  typed  by  the user and has not yet been read by the
           program.

## RETURN VALUE

           Except for flushinp, routines that return an  integer  re-
           turn  ERR upon failure and OK (SVr4 specifies only "an in-
           teger value other than ERR") upon successful completion.

           Routines that return pointers return NULL on error.

           X/Open does not define any error conditions.  In this  im-
           plementation

              flushinp
                   returns  an error if the terminal was not initial-
                   ized.

              meta returns an error if the terminal was not  initial-
                   ized.

              putwin
                   returns  an  error  if the associated fwrite calls
                   return an error.

## PORTABILITY

           The XSI Curses standard, Issue  4  describes  these  func-
           tions.   It  states  that unctrl and wunctrl will return a
           null pointer if unsuccessful, but does not define any  er-
           ror conditions.  This implementation checks for three cas-
           es:

              o   the parameter is a 7-bit US-ASCII  code.   This  is
                  the case that X/Open Curses documented.

              o   the  parameter  is in the range 128-159, i.e., a C1
                  control code.  If use_legacy_coding has been called
                  with  a  2 parameter, unctrl returns the parameter,
                  i.e., a one-character string with the parameter  as
                  the first character.  Otherwise, it returns ``~@'',
                  ``~A'', etc., analogous to ``^@'', ``^A'', C0  con-
                  trols.

                  X/Open  Curses does not document whether unctrl can
                  be called before initializing curses.  This  imple-
                  mentation  permits  that,  and  returns the ``~@'',
                  etc., values in that case.

              o   parameter values outside the 0 to 255 range.   unc-
                  trl returns a null pointer.

           The SVr4 documentation describes the action of filter only
           in the vaguest terms.  The  description  here  is  adapted
           from  the  XSI Curses standard (which erroneously fails to
           describe the disabling of cuu).

           The strings returned by unctrl in this implementation  are
           determined  at  compile time, showing C1 controls from the
           upper-128 codes with a `~' prefix rather than `^'.   Other
           implementations  have different conventions.  For example,
           they may show both sets of control  characters  with  `^',
           and  strip the parameter to 7 bits.  Or they may ignore C1
           controls and treat all of the upper-128  codes  as  print-
           able.  This implementation uses 8 bits but does not modify
           the string to reflect locale.  The use_legacy_coding func-
           tion allows the caller to change the output of unctrl.

           Likewise,  the  meta  function allows the caller to change
           the output of keyname, i.e., it determines whether to  use
           the  `M-' prefix for ``meta'' keys (codes in the range 128
           to 255).  Both use_legacy_coding and meta succeed only af-
           ter  curses  is initialized.  X/Open Curses does not docu-
           ment the treatment of codes 128  to  159.   When  treating
           them as ``meta'' keys (or if keyname is called before ini-
           tializing curses),  this  implementation  returns  strings
           ``M-^@'', ``M-^A'', etc.

           The  keyname function may return the names of user-defined
           string capabilities which are defined in the terminfo  en-
           try  via  the -x option of tic.  This implementation auto-
           matically assigns at  run-time  keycodes  to  user-defined
           strings  which  begin  with  "k".   The  keycodes start at
           KEY_MAX, but are not guaranteed to be the same  value  for
           different  runs because user-defined codes are merged from
           all terminal descriptions which  have  been  loaded.   The
           use_extended_names  function controls whether this data is
           loaded when the terminal description is read  by  the  li-
           brary.

           The  nofilter  routine is specific to ncurses.  It was not
           supported on Version 7, BSD or System  V  implementations.
           It  is  recommended that any code depending on ncurses ex-
           tensions be conditioned using NCURSES_VERSION.

## SEE ALSO

           legacy_coding(3x), curses(3x), curs_initscr(3x), curs_ker-
           nel(3x),   curs_scr_dump(3x),   curs_variables(3x),  lega-
           cy_coding(3x).

                                                              curs_util(3x)