- 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
+ 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.
+ INITIALIZATION
+ The tgetent routine loads the entry for name. It returns:
+
+ 1 on success,
+
+ 0 if there is no such entry (or that it is a generic
+ type, having too little information for curses ap-
+ plications to run), and
+
+ -1 if the terminfo database could not be found.
+
+ This differs from the termcap library in two ways:
- The tgetflag routine gets the boolean entry for id, or
- zero if it is not available.
+ o The emulation ignores the buffer pointer bp. The
+ termcap library would store a copy of the terminal
+ description in the area referenced by this pointer.
+ However, ncurses stores its terminal descriptions
+ in compiled binary form, which is not the same
+ thing.
- The tgetnum routine gets the numeric entry for id, or -1
+ 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-addressing.
+
+ CAPABILITYVALUES
+ The tgetflag routine gets the boolean entry for id, or ze-
+ ro if it is not available.
+
+ 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 return value will also be copied to
- the buffer pointed to by area, and the area value will be
+ The tgetstr routine returns the string entry for id, or
+ zero if it is not available. Use tputs to output the re-
+ turned 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.
+ Only the first two characters of the id parameter of tget-
+ flag, tgetnum and tgetstr are compared in lookups.
+
+ FORMATTINGCAPABILITIES
+ The tgoto routine instantiates the parameters into the
+ given capability. The output from this routine is to be
+ passed to tputs.
- The tputs routine is described on the curs_terminfo(3x)
+ The tputs routine is described on the curs_terminfo(3x)
manual page. It can retrieve capabilities by either term-
cap or terminfo name.
+ GLOBALVARIABLES
+ The variables PC, UP and BC are set by tgetent to the ter-
+ minfo 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 ter-
+ minal speed.
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.
+ Except where explicitly noted, routines that return an in-
+ teger return ERR upon failure and OK (SVr4 only specifies
+ "an integer value other than ERR") upon successful comple-
+ tion.
- Routines that return pointers return NULL on error.
+ Routines that return pointers return NULL on error.
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.
-
- 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
+ If you call tgetstr to fetch ca or any other parameterized
+ string, be aware that it will be returned in terminfo no-
+ tation, not the older and not-quite-compatible termcap no-
+ tation. 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 con-
+ figured to support 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 capabilities 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 applica-
+ tions assume me (terminfo sgr0) does not reset the alter-
+ nate character set. This implementation checks for, and
+ modifies the data shown to the termcap interface to accom-
+ modate termcap's limitation in this respect.
+
PORTABILITY
@@ -88,42 +182,50 @@
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 returned ever since SVr1.
+ documented the return values of tgetent correctly, though
+ all three were in fact returned ever since SVr1. In par-
+ ticular, 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
+ compatibility 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 applications. However, termcap applications' use
+ of those variables is poorly documented, e.g., not distin-
+ guishing between input and output. In particular, some
+ applications are reported to declare and/or modify ospeed.
+
+ 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. Tak-
+ ing into account these issues:
+
+ o As a special case, tgetflag matched against a single-
+ character identifier provided that was at the end of
+ the terminal description. You should not rely upon
+ this behavior in portable programs. This implementa-
+ tion disallows matches against single-character capa-
+ bility names.
+
+ o This implementation disallows matches by the termcap
+ interface against extended capability names which are
+ longer than two characters.