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

Provided by: ncurses-doc_6.0+20160213-1ubuntu1_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

unctrl
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.

keyname/key_name
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.

filter/nofilter
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.

use_env
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,

use_tioctl
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.

putwin/getwin
The putwin routine writes all data associated with window (or pad) 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. There are a few caveats:

• the data written is a copy of the WINDOW structure, and its associated character
cells. The format differs between the wide-character (ncursesw) and non-wide
(ncurses) libraries. You can transfer data between the two, however.

• the retrieved window is always created as a top-level window (or pad), rather than a
subwindow.

• the window's character cells contain the color pair value, but not the actual color
numbers. If cells in the retrieved window use color pairs which have not been created
in the application using init_pair, they will not be colored when the window is
refreshed.

delay_output
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.

flushinp
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

   filter
       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).

   keyname
       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.

   nofilter/use_tioctl
       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.

   putwin/getwin
       The putwin and getwin functions have several issues with portability:

       •   The files written and read by these functions use an  implementation-specific  format.
           Although the format is an obvious target for standardization, it has been overlooked.

           Interestingly  enough,  according  to  the  copyright  dates  in  Solaris  source, the
           functions (along with scr_init, etc.) originated with the  University  of  California,
           Berkeley  (in 1982) and were later (in 1988) incorporated into SVr4.  Oddly, there are
           no such functions in the 4.3BSD curses sources.

       •   Most implementations simply dump the binary  WINDOW  structure  to  the  file.   These
           include  SVr4  curses,  NetBSD  and PDCurses, as well as older ncurses versions.  This
           implementation (as well as the X/Open variant of  Solaris  curses,  dated  1995)  uses
           textual dumps.

           The  implementations  which  use  binary  dumps  use  block-I/O  (the fwrite and fread
           functions).  Those that use textual dumps use buffered-I/O.  A  few  applications  may
           happen to write extra data in the file using these functions.  Doing that can run into
           problems mixing block- and buffered-I/O.  This implementation reduces the  problem  on
           writes  by  flushing  the  output.   However,  reading from a file written using mixed
           schemes may not be successful.

   unctrl/wunctrl
       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 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.

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

PORTABILITY

SEE ALSO