- 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
- 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.
- flushinp always returns OK.
+
+ The unctrl routine returns a character string which is a printable rep-
+ resentation of the character c, ignoring attributes. Control charac-
+ ters are displayed in the ^X notation. Printing characters are dis-
+ played as is. The corresponding wunctrl returns a printable represen-
+ tation of a wide character.
-
-
PORTABILITY
- The XSI Curses standard, Issue 4 describes these func-
- tions.
+
+ The keyname routine returns a character string corresponding to the key
+ c:
- 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).
+ o Printable characters are displayed as themselves, e.g., a one-char-
+ acter string containing the key.
+ o Control characters are displayed in the ^X notation.
-
-
NOTES
- Note that unctrl is a macro, which is defined in <unc-
- trl.h>.
+ 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 param-
+ eter), 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" re-
+ turn 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.
+
+
+
+ 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 dis-
+ abled;
+
+ 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 modi-
+ fies the way ncurses treats environment 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 un-
+ less 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 ter-
+ minal database.
+
+ Ncurses also updates the screen size in response to SIGWINCH, un-
+ less 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 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 re-
+ trieved 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 associ-
+ ated character cells. The format differs between the wide-charac-
+ ter (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.
+ This routine should not be used extensively because padding characters
+ are used rather than a CPU pause. If no padding character is speci-
+ fied, this uses napms to perform the delay.
+
+
+
+ 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.
+ putwin
+ returns an error if the associated fwrite calls return an er-
+ ror.
+
+ 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 capa-
+ bilities 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 condi-
+ tioned using NCURSES_VERSION.
+
+ The putwin and getwin functions have several issues with portability:
+ o The files written and read by these functions use an implementa-
+ tion-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 has been called with a 2 parameter, unctrl re-
+ turns the parameter, i.e., a one-character string with the parame-
+ ter 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 conven-
+ tions. 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(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 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.
+
+ 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 implementation of curses.
+
+
+