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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 rep‐
       resentation of the character c, ignoring attributes.   Control  charac‐
       ters  are  displayed  in the ^X notation.  Printing characters are dis‐
       played as is.  The corresponding wunctrl returns a printable  represen‐
       tation 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  pa‐
	     rameter),	shown  in  the M-X notation, or are displayed as them‐
	     selves.  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 re‐
	     turns 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, is called before initscr or newterm are
       called.	When called with FALSE as an argument, the values of lines and
       columns	specified in the terminfo database will be used, even if envi‐
       ronment variables LINES and COLUMNS (used by default) are  set,	or  if
       curses  is running in a window (in which case default behavior 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	speci‐
       fied, 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  er‐
	       ror.

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 param‐
		   eter,  unctrl  returns the parameter, i.e., a one-character
		   string with the parameter as the first  character.	Other‐
		   wise, 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 re‐
		   turns 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  conven‐
       tions.  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	 capa‐
       bilities	 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 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 extensions be conditioned using  NCURSES_VER‐
       SION.

SEE ALSO
       legacy_coding(3X),   curses(3X),	  curs_initscr(3X),   curs_kernel(3X),
       curs_scr_dump(3X), legacy_coding(3X).

								 curs_util(3X)
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