+ PC, UP, BC, ospeed, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs -
+ direct curses interface to the terminfo capability database
-
-
DESCRIPTION
- These routines are included as a conversion aid for pro-
- grams that use the termcap library. Their parameters are
- the same and the routines are emulated using the terminfo
- database. Thus, they can only be used to query the capa-
- bilities of entries for which a terminfo entry has been
- compiled.
- The tgetent routine loads the entry for name. It returns
- 1 on success, 0 if there is no such entry, and -1 if the
- terminfo database could not be found. The emulation
- ignores the buffer pointer bp.
+
+ #include<curses.h>
+ #include<term.h>
- The tgetflag routine gets the boolean entry for id, or
- zero if it is not available.
+ externcharPC;
+ externchar*UP;
+ externchar*BC;
+ externshortospeed;
- The tgetnum routine gets the numeric entry for id, or -1
- if it is not available.
+ inttgetent(char*bp,constchar*name);
+ inttgetflag(char*id);
+ inttgetnum(char*id);
+ char*tgetstr(char*id,char**area);
+ char*tgoto(constchar*cap,intcol,introw);
+ inttputs(constchar*str,intaffcnt,int(*putc)(int));
- The tgetstr routine returns the string entry for id, or
- zero if it is not available. Use tputs to output the
- returned string. The return value will also be copied to
- the buffer pointed to by area, and the area value will be
- updated to point past the null ending this value.
- The tgoto routine instantiates the parameters into the
- given capability. The output from this routine is to be
- passed to tputs.
+
+ These routines are included as a conversion aid for programs that use
+ the termcap library. Their parameters are the same and the routines
+ are emulated using the terminfo database. Thus, they can only be used
+ to query the capabilities of entries for which a terminfo entry has
+ been compiled.
- The tputs routine is described on the curs_terminfo(3x)
- manual page. It can retrieve capabilities by either term-
- cap or terminfo name.
+
+ The tgetent routine loads the entry for name. It returns:
+ 1 on success,
-
-
RETURN VALUE
- Except where explicitly noted, routines that return an
- integer return ERR upon failure and OK (SVr4 only speci-
- fies "an integer value other than ERR") upon successful
- completion.
+ 0 if there is no such entry (or that it is a generic type, having
+ too little information for curses applications to run), and
- Routines that return pointers return NULL on error.
+ -1 if the terminfo database could not be found.
+ This differs from the termcap library in two ways:
-
-
BUGS
- If you call tgetstr to fetch ca or any other parameterized
- string, be aware that it will be returned in terminfo
- notation, not the older and not-quite-compatible termcap
- notation. This won't cause problems if all you do with it
- is call tgoto or tparm, which both expand terminfo-style.
+ o The emulation ignores the buffer pointer bp. The termcap li-
+ brary would store a copy of the terminal description in the area
+ referenced by this pointer. However, ncurses stores its termi-
+ nal descriptions in compiled binary form, which is not the same
+ thing.
- Because terminfo conventions for representing padding in
- string capabilities differ from termcap's, tputs("50");
- will put out a literal "50" rather than busy-waiting for
- 50 milliseconds. Cope with it.
+ o There is a difference in return codes. The termcap library does
+ not check if the terminal description is marked with the generic
+ capability, or if the terminal description has cursor-address-
+ ing.
-
-
PORTABILITY
- The XSI Curses standard, Issue 4 describes these func-
- tions. However, they are marked TO BE WITHDRAWN and may
- be removed in future versions.
+
+ The tgetflag routine gets the boolean entry for id, or zero if it is
+ not available.
- Neither the XSI Curses standard nor the SVr4 man pages
- documented the return values of tgetent correctly, though
- all three were in fact returned ever since SVr1.
+ The tgetnum routine gets the numeric entry for id, or -1 if it is not
+ available.
+ The tgetstr routine returns the string entry for id, or zero if it is
+ not available. Use tputs to output the returned string. The area pa-
+ rameter is used as follows:
-
-
SEE ALSO
- curses(3x), terminfo(5), putc(3S).
+ o It is assumed to be the address of a pointer to a buffer managed
+ by the calling application.
+
+ o However, ncurses checks to ensure that area is not NULL, and al-
+ so that the resulting buffer pointer is not NULL. If either
+ check fails, the area parameter is ignored.
+
+ o If the checks succeed, ncurses also copies the return value to
+ the buffer pointed to by area, and the area value will be updat-
+ ed to point past the null ending this value.
+
+ o The return value itself is an address in the terminal descrip-
+ tion which is loaded into memory.
+
+ Only the first two characters of the id parameter of tgetflag, tgetnum
+ and tgetstr are compared in lookups.
+
+ The tgoto routine expands the given capability using the parameters.
+ o Because the capability may have padding characters, the output of
+ tgoto should be passed to tputs rather than some other output func-
+ tion such as printf.
+ o While tgoto is assumed to be used for the two-parameter cursor po-
+ sitioning capability, termcap applications also use it for single-
+ parameter capabilities.
+ Doing this shows a quirk in tgoto: most hardware terminals use cur-
+ sor addressing with row first, but the original developers of the
+ termcap interface chose to put the column parameter first. The
+ tgoto function swaps the order of parameters. It does this also
+ for calls requiring only a single parameter. In that case, the
+ first parameter is merely a placeholder.
+ o Normally the ncurses library is compiled with terminfo support. In
+ that case, tgoto uses tparm(3x) (a more capable formatter).
+ The tputs routine is described on the curs_terminfo(3x) manual page.
+ It can retrieve capabilities by either termcap or terminfo name.
+
+ The variables PC, UP and BC are set by tgetent to the terminfo entry's
+ data for pad_char, cursor_up and backspace_if_not_bs, respectively. UP
+ is not used by ncurses. PC is used in the tdelay_output function. BC
+ is used in the tgoto emulation. The variable ospeed is set by ncurses
+ in a system-specific coding to reflect the terminal speed.
+
+ Except where explicitly noted, routines that return an integer return
+ ERR upon failure and OK (SVr4 only specifies "an integer value other
+ than ERR") upon successful completion.
+ Routines that return pointers return NULL on error.
+
+ If you call tgetstr to fetch ca or any other parameterized string, be
+ aware that it will be returned in terminfo notation, not the older and
+ not-quite-compatible termcap notation. This will not cause problems if
+ all you do with it is call tgoto or tparm, which both expand terminfo-
+ style strings as terminfo. (The tgoto function, if configured to sup-
+ port termcap, will check if the string is indeed terminfo-style by
+ looking for "%p" parameters or "$<..>" delays, and invoke a termcap-
+ style parser if the string does not appear to be terminfo).
+ Because terminfo conventions for representing padding in string capa-
+ bilities differ from termcap's, tputs("50"); will put out a literal
+ "50" rather than busy-waiting for 50 milliseconds. Cope with it.
+ Note that termcap has nothing analogous to terminfo's sgr string. One
+ consequence of this is that termcap applications assume me (terminfo
+ sgr0) does not reset the alternate character set. This implementation
+ checks for, and modifies the data shown to the termcap interface to ac-
+ commodate termcap's limitation in this respect.
+
+ The XSI Curses standard, Issue 4 describes these functions. However,
+ they are marked TO BE WITHDRAWN and may be removed in future versions.
+ Neither the XSI Curses standard nor the SVr4 man pages documented the
+ return values of tgetent correctly, though all three were in fact re-
+ turned ever since SVr1. In particular, an omission in the XSI Curses
+ documentation has been misinterpreted to mean that tgetent returns OK
+ or ERR. Because the purpose of these functions is to provide compati-
+ bility with the termcap library, that is a defect in XCurses, Issue 4,
+ Version 2 rather than in ncurses.
+ External variables are provided for support of certain termcap applica-
+ tions. However, termcap applications' use of those variables is poorly
+ documented, e.g., not distinguishing between input and output. In par-
+ ticular, some applications are reported to declare and/or modify os-
+ peed.
+ The comment that only the first two characters of the id parameter are
+ used escapes many application developers. The original BSD 4.2 termcap
+ library (and historical relics thereof) did not require a trailing null
+ NUL on the parameter name passed to tgetstr, tgetnum and tgetflag.
+ Some applications assume that the termcap interface does not require
+ the trailing NUL for the parameter name. Taking into account these is-
+ sues:
+ o As a special case, tgetflag matched against a single-character
+ identifier provided that was at the end of the terminal descrip-
+ tion. You should not rely upon this behavior in portable programs.
+ This implementation disallows matches against single-character ca-
+ pability names.
+ o This implementation disallows matches by the termcap interface
+ against extended capability names which are longer than two charac-
+ ters.
+