- 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 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.
-
- 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
- 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.
-
- The flushinp routine throws away any typeahead that has
- been typed by the user and has not yet been read by the
- program.
+
- 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.
+
+ The unctrl routine returns a character string which is a printable
+ representation of the character 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 Printing characters are displayed as is.
+
+ 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 latter case, the values may not be printable;
+ this follows the X/Open specification.
+
+ The corresponding wunctrl returns a printable representation of a
+ complex character c.
+
+ In both unctrl and wunctrl the attributes and color associated with the
+ character parameter are ignored.
+
+
+
+ The keyname routine returns a character string corresponding to the key
+ c. Key codes are different from character codes.
+
+ o Key codes below 256 are characters. They are displayed using
+ unctrl.
+
+ o Values above 256 may be the codes for function keys. The function
+ key name is displayed.
+
+ o Otherwise (if there is no corresponding name and the key is not a
+ character) 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 multibyte character string
+ corresponding to the wide-character value w. The two functions
+ (keyname and key_name) do not return the same set of strings:
+
+ okeyname returns null where key_name would display a meta character.
+
+ okey_name does not return the name of a function key.
+
+
+
+ The filter routine, if used, must be called before initscr or newterm
+ are called. Calling filter causes these changes in initialization:
+
+ oLINES is set to 1;
+
+ o the capabilities clear, cud1, cud, cup, cuu1, cuu, vpa are
+ disabled;
+
+ o the capability ed is disabled if bce is set;
+
+ o 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, 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.
+
+ o Normally ncurses looks first at the terminal database for the
+ screen size.
- flushinp always returns OK.
+ If use_env was called with FALSE for parameter, it stops here
+ unless 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 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,
+
+
+
+ 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:
+
+ o checks if the LINES and COLUMNS environment variables are set to a
+ number greater than zero.
+
+ o for each, ncurses updates the corresponding environment 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 variables so that
+ it is still the environment variables which set the screen size.
+
+ The use_env and use_tioctl routines combine as follows.
+
+ use_envuse_tioctlSummary
+ -----------------------------------------------------------------
+ TRUEFALSE This is the default behavior. ncurses
+ uses operating system calls unless
+ overridden by LINES or COLUMNS
+ environment variables; default.
+ TRUETRUEncurses updates LINES and COLUMNS based
+ on operating system calls.
+ FALSETRUEncurses ignores LINES and COLUMNS, using
+ operating system calls to obtain 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 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:
+
+ o 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.
+
+ 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.
+ Employ this function judiciously when terminal output uses padding,
+ because ncurses transmits null characters (consuming CPU and I/O
+ resources) instead of sleeping and requesting resumption from the
+ operating system. Padding is used unless:
+
+ o the terminal description has npc (no_pad_char) capability, or
+
+ o the environment variable NCURSES_NO_PADDING is set.
+
+ If padding is not in use, ncurses uses napms to perform the delay. If
+ the value of ms exceeds 30,000 (thirty seconds), it is capped at that
+ 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
-
-
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.
+ flushinp
+ returns an error if the terminal was not initialized.
- 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).
+ putwin
+ returns an error if the associated fwrite calls return an
+ error.
-
+ 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 limitation to 30 seconds and the use of napms differ from other
+ implementations.
+
+ o SVr4 curses does not delay if no padding character is available.
+
+ o NetBSD curses uses napms when no padding character is available,
+ but does not take timing into account when using the padding
+ character.
+
+ Neither limits the delay.
+
+
+
+ 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(3x) function controls
+ whether this data is loaded when the terminal description is read by
+ the library.
+
+
+
+ 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) incorporated 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 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.
+
+ 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:
+ 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(3x) 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.
+ 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 printable.
+ This implementation uses 8 bits but does not modify the string to
+ reflect locale. The use_legacy_coding(3x) function 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(3x) and meta(3x) 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.
+ X/Open Curses documents unctrl as declared in <unctrl.h>, which ncurses
+ does. However, ncurses' <curses.h> includes <unctrl.h>, matching the
+ behavior of SVr4 curses. Other implementations may not do that.
+
+
+ If ncurses is configured to provide the sp-functions extension, the
+ state of use_env and use_tioctl may be updated before creating each
+ screen rather than once only (curs_sp_funcs(3x)). This feature of
+ use_env is not provided by other implementations of curses.
+
+
+