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
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, 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 environment 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 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 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_VERSION.
SEE ALSO¶
legacy_coding(3NCURSES),
ncurses(3NCURSES),
initscr(3NCURSES),
kernel(3NCURSES),
scr_dump(3NCURSES),
curses_variables(3NCURSES),
legacy_coding(3NCURSES).