Provided by: ncurses-doc_5.9+20140118-1ubuntu1_all bug

NAME

       delay_output, filter, flushinp, getwin, key_name, keyname, nofilter, putwin, unctrl, use_env, use_tioctl,
       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);
       void use_tioctl(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  attributes.   Control  characters  are  displayed  in the ^X notation.  Printing characters are
       displayed as is.  The corresponding wunctrl returns a printable representation of a wide character.

       The keyname routine returns a character string corresponding to the key c:

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

          •   Control characters are displayed in the ^X notation.

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

          •   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.

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

          •   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 corresponding to the wide-character value  w.   The
       two  functions  do  not  return  the  same set of strings; the latter returns null where the former would
       display a meta character.

       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, should be called before  initscr  or  newterm  are  called  (because  those
       compute  the screen size).  It modifies the way ncurses treats environment variables when determining the
       screen size.

       •   Normally ncurses looks first at the terminal database for the screen size.

           If use_env was called with FALSE for parameter, it stops here unless If use_tioctl  was  also  called
           with TRUE for parameter.

       •   Then  it asks for the screen size via operating system calls.  If successful, it overrides the values
           from the terminal database.

       •   Finally (unless use_env was called with FALSE parameter),  ncurses  examines  the  LINES  or  COLUMNS
           environment  variables,  using  a value in those to override the results from the operating system or
           terminal database.

           Ncurses also updates the screen size in response to SIGWINCH,  unless  overridden  by  the  LINES  or
           COLUMNS environment variables,

       The  use_tioctl  routine,  if  used, should be called before initscr or newterm are called (because those
       compute the screen size).  After use_tioctl is called with TRUE as an argument, ncurses modifies the last
       step in its computation of screen size as follows:

       •   checks if the LINES and COLUMNS environment variables are set to a number greater than zero.

       •   for  each, ncurses updates the corresponding environment variable with the value that it has obtained
           via operating system call or from the terminal database.

       •   ncurses re-fetches the value of the environment  variables  so  that  it  is  still  the  environment
           variables which set the screen size.

       The use_env and use_tioctl routines combine as summarized here:

                            use_env   use_tioctl   Summary
                            ────────────────────────────────────────────────────────────────
                            TRUE      FALSE        This  is  the default behavior.  ncurses
                                                   uses  operating  system   calls   unless
                                                   overridden   by   $LINES   or   $COLUMNS
                                                   environment variables.
                            TRUE      TRUE         ncurses  updates  $LINES  and   $COLUMNS
                                                   based on operating system calls.
                            FALSE     TRUE         ncurses  ignores  $LINES  and  $COLUMNS,
                                                   uses operating system  calls  to  obtain
                                                   size.
                            FALSE     FALSE        ncurses  relies on the terminal database
                                                   to determine size.

       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 return ERR upon failure and OK (SVr4 specifies only
       "an integer 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 implementation

          flushinp
               returns an error if the terminal was not initialized.

          meta returns an error if the terminal was not initialized.

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

PORTABILITY

       The XSI Curses standard, Issue 4 describes these functions.  It  states  that  unctrl  and  wunctrl  will
       return  a  null  pointer  if unsuccessful, but does not define any error conditions.  This implementation
       checks for three cases:

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

          •   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 controls.

              X/Open  Curses  does  not  document whether unctrl can be called before initializing curses.  This
              implementation permits that, and returns the “~@”, etc., values in that case.

          •   parameter values outside the 0 to 255 range.  unctrl 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  printable.
       This  implementation uses 8 bits but does not modify the string to reflect locale.  The use_legacy_coding
       function 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 after curses is initialized.  X/Open Curses does  not  document  the  treatment  of
       codes  128  to  159.   When  treating  them  as  “meta” keys (or if keyname is called before initializing
       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  entry via the -x option of tic.  This implementation automatically 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 library.

       The  nofilter and use_tioctl routines are specific to ncurses.  They were not supported on Version 7, BSD
       or System V implementations.  It is  recommended  that  any  code  depending  on  ncurses  extensions  be
       conditioned using NCURSES_VERSION.

SEE ALSO

       legacy_coding(3NCURSES),   ncurses(3NCURSES),  initscr(3NCURSES),  kernel(3NCURSES),  scr_dump(3NCURSES),
       curses_variables(3NCURSES), legacy_coding(3NCURSES).

                                                                                                  util(3NCURSES)