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curs_util(3)                                                    curs_util(3)




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(3)

ncurses 5.7 - Generated Tue Nov 4 06:01:41 CST 2008