curs_util
Section: Miscellaneous Library Functions (3X)
Updated:
Index
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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:
| T} | |
|
|
|
|
| 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.
SEE ALSO
legacy_coding(3X),
curses(3X),
curs_initscr(3X),
curs_kernel(3X),
curs_scr_dump(3X),
curs_variables(3X),
legacy_coding(3X).
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- unctrl
-
- keyname/key_name
-
- filter/nofilter
-
- use_env
-
- use_tioctl
-
- putwin/getwin
-
- delay_output
-
- flushinp
-
- RETURN VALUE
-
- PORTABILITY
-
- filter
-
- keyname
-
- nofilter/use_tioctl
-
- putwin/getwin
-
- unctrl/wunctrl
-
- SEE ALSO
-
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