curs_util



curs_util(3)              OpenBSD Programmer's Manual             curs_util(3)


NAME

       delay_output, filter, flushinp, getwin, key_name, keyname, nofilter,
       putwin, unctrl, use_env, wunctrl - miscellaneous curses utility
       routines


SYNOPSIS

       #include <curses.h>

       char *unctrl(chtype c);
       wchar_t *wunctrl(cchar_t *c);
       char *keyname(int c);
       char *key_name(wchar_t w);
       void filter(void);
       void nofilter(void);
       void use_env(bool f);
       int putwin(WINDOW *win, FILE *filep);
       WINDOW *getwin(FILE *filep);
       int delay_output(int ms);
       int flushinp(void);


DESCRIPTION

       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 corresponding 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 notation, or are displayed as
             themselves.  In the latter case, the values may not be printable;
             this follows 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 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 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 argument, the values of lines and
       columns specified in the terminfo database will be used, even if
       environment variables 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).  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 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 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.

       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.

          meta returns an error if the terminal was not initialized.

          putwin
               returns an error if the associated fwrite calls return an
               error.


PORTABILITY

       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:

              -    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).

       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 function 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 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 function controls
       whether this data is loaded when the terminal description is read by
       the library.

       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 extensions be conditioned using
       NCURSES_VERSION.


SEE ALSO

       legacy_coding(3), curses(3), curs_initscr(3), curs_kernel(3),
       curs_scr_dump(3), legacy_coding(3).

                                                                  curs_util(3)

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