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.
+ of a wide character.
The keyname routine returns a character string correspond-
- ing to the key c. Control characters are displayed in the
- ^X notation. Values above 128 are either meta characters,
- shown in the M-X notation, or the names of function keys,
- or 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.
+ ing to the key c:
+
+ o Printable characters are displayed as themselves,
+ e.g., a one-character string containing the key.
+
+ o Control characters are displayed in the ^X nota-
+ tion.
+
+ o DEL (character 127) is displayed as ^?.
+
+ o 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.
+
+ o Values above 256 may be the names of the names of
+ function keys.
+
+ o 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
@@ -93,16 +119,72 @@
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 be-
- havior 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 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 environ-
+ ment variables when determining the screen size.
+
+ o 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.
+
+ o Then it asks for the screen size via operating system
+ calls. If successful, it overrides the values from
+ the terminal database.
+
+ o Finally (unless use_env was called with FALSE parame-
+ ter), ncurses examines the LINES or COLUMNS environ-
+ ment variables, using a value in those to override the
+ results from the operating system or terminal data-
+ base.
+
+ 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 computa-
+ tion of screen size as follows:
+
+ o checks if the LINES and COLUMNS environment variables
+ are set to a number greater than zero.
+
+ o for each, ncurses updates the corresponding environ-
+ ment variable with the value that it has obtained via
+ operating system call or from the terminal database.
+
+ o ncurses re-fetches the value of the environment vari-
+ ables 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_envuse_tioctlSummary
+ ----------------------------------------------------------------
+ TRUE FALSE This is the default behavior. ncurses
+ uses operating system calls unless over-
+ ridden 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, us-
+ es 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
@@ -125,7 +207,7 @@
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.
@@ -135,21 +217,43 @@
X/Open does not define any error conditions. In this im-
plementation
- flushinp
- returns an error if the terminal was not ini-
- tialized.
+ 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.
+ putwin
+ returns an error if the associated fwrite calls
+ return an error.
-
PORTABILITY
- The XSI Curses standard, Issue 4 describes these func-
- tions. It states that unctrl and wunctrl will return a
- null pointer if unsuccessful, but does not define any er-
- ror conditions.
+
+ The XSI Curses standard, Issue 4 describes these func-
+ 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:
+
+ o the parameter is a 7-bit US-ASCII code. This is
+ the case that X/Open Curses documented.
+
+ o 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 imple-
+ mentation permits that, and returns the "~@", etc.,
+ values in that case.
+
+ o parameter values outside the 0 to 255 range. unc-
+ trl returns a null pointer.
The SVr4 documentation describes the action of filter only
in the vaguest terms. The description here is adapted
@@ -159,29 +263,62 @@
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 typically show both sets of control char-
- acters with `^', and may strip the parameter to 7 bits.
- This implementation uses 8 bits but does not modify the
- string to reflect locale.
-
- 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.
+ 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 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 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 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.