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
+ 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 notation.
+
+ 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(3x) has
+ been called with a TRUE parameter), shown in the M-X
+ notation, or are displayed as themselves. In the lat-
+ ter case, the values may not be printable; this fol-
+ lows 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 al-
+ so lists an "UNKNOWN KEY" return value, which some im-
+ plementations 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
+ 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 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.
- 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.
+ 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.
+
+ oncurses 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
+ (or pad) win into the file to which filep points. This
+ information can be later retrieved using the getwin func-
+ tion.
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.
+ new window. There are a few caveats:
+
+ o the data written is a copy of the WINDOW structure,
+ and its associated character cells. The format dif-
+ fers between the wide-character (ncursesw) and non-
+ wide (ncurses) libraries. You can transfer data be-
+ tween the two, however.
+
+ o the retrieved window is always created as a top-level
+ window (or pad), rather than a subwindow.
+
+ o 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.
- 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
+
+
+ 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
+
+
+ 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.
-
- flushinp always returns OK.
+
+ 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.
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.
+
+ 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
- error conditions.
+
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 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.
+
+
+
+ The putwin and getwin functions have several issues with
+ portability:
+
+ o 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) incorpo-
+ rated into SVr4. Oddly, there are no such functions
+ in the 4.3BSD curses sources.
+
+ o Most implementations simply dump the binary WINDOW
+ structure to the file. These include SVr4 curses,
+ NetBSD and PDCurses, as well as older ncurses ver-
+ sions. 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. Howev-
+ er, reading from a file written using mixed schemes
+ may not be successful.
+
+
+
+ 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 con-
+ trol 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 implementa-
+ tion permits that, and returns the "~@", etc., values
+ in that case.
+
+ o 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 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(3x) 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 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.
+
+
+
+ If ncurses is configured to provide the sp-functions ex-
+ tension, the state of use_env and use_tioctl may be updat-
+ ed before creating each screen rather than once only
+ (curs_sp_funcs(3x)). This feature of use_env is not pro-
+ vided by other implementation of curses.
+
+
+