Ubuntu Manpage: delay_output, filter, flushinp, getwin, key_name, keyname, nofilter, putwin, unctrl,

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

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.

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

PORTABILITY

SEE ALSO