- The unctrl macro expands to a character string which is a
- printable representation of the character c. Control
- characters are displayed in the ^X notation. Printing
- characters are displayed as is.
-
- The keyname routine returns a character string correspond-
- ing to the key c.
-
- 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 use_env routine, if used, is called before initscr or
- newterm are called. When called with FALSE as an argu-
- ment, the values of lines and columns specified in the
- terminfo database will be used, even if environment vari-
- ables 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).
-
- 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
+ The unctrl routine returns a character string which is a
+ printable representation of the character c, ignoring at-
+ tributes. Control characters are displayed in the ^X no-
+ tation. Printing characters are displayed as is. The
+ corresponding wunctrl returns a printable representation
+ of a wide-character.
+
+ The keyname routine returns a character string correspond-
+ ing 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 no-
+ tation, or are displayed as themselves. In the lat-
+ ter case, the values may not be printable; this fol-
+ lows 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 cor-
+ responding to the wide-character value w. The two func-
+ tions do not return the same set of strings; the latter
+ returns null where the former would display a meta charac-
+ ter.
+
+ 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 argu-
+ ment, the values of lines and columns specified in the
+ terminfo database will be used, even if environment vari-
+ ables LINES and COLUMNS (used by default) are set, or if
+ curses is running in a window (in which case default be-
+ havior would be to use the window size if LINES and COL-
+ UMNS 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
+ 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.
- The flushinp routine throws away any typeahead that has
- been typed by the user and has not yet been read by the
+ 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.
+ Except for flushinp, routines that return an integer re-
+ turn ERR upon failure and OK (SVr4 specifies only "an in-
+ teger value other than ERR") upon successful completion.
- flushinp always returns OK.
+ Routines that return pointers return NULL on error.
- Routines that return pointers return NULL on error.
+ X/Open does not define any error conditions. In this im-
+ plementation
+
+ flushinp
+ returns an error if the terminal was not initial-
+ ized.
+
+ meta returns an error if the terminal was not initial-
+ ized.
+
+ putwin
+ returns an error if the associated fwrite calls
+ return an error.
PORTABILITY
The XSI Curses standard, Issue 4 describes these func-
- tions.
-
- The SVr4 documentation describes the action of filter only
+ tions. It states that unctrl and wunctrl will return a
+ null pointer if unsuccessful, but does not define any er-
+ ror conditions. This implementation checks for three cas-
+ es:
+
+ - 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).
-
-
-
-
NOTES
- Note that unctrl is a macro, which is defined in <unc-
- trl.h>.
+ 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 print-
+ able. This implementation uses 8 bits but does not modify
+ the string to reflect locale. The use_legacy_coding func-
+ tion 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 af-
+ ter curses is initialized. X/Open Curses does not docu-
+ ment the treatment of codes 128 to 159. When treating
+ them as ``meta'' keys (or if keyname is called before ini-
+ tializing 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 en-
+ try via the -x option of tic. This implementation auto-
+ matically 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 li-
+ brary.
+
+ 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 ex-
+ tensions be conditioned using NCURSES_VERSION.