From: deraadt Date: Wed, 16 Jul 2014 10:35:48 +0000 (+0000) Subject: lynx has left the tree, and let's be honest noone will find these html X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=a9872cbcbdcbc9b82e7dd1e7ee10bd167f87e7bd;p=openbsd lynx has left the tree, and let's be honest noone will find these html files in their installed system. this extended documentation experience is available better on the net using a browser installed with pkg_add. (also note that two of the subsystems involved in this issue are heading to the bit bucket sometime soon) --- diff --git a/etc/mtree/4.4BSD.dist b/etc/mtree/4.4BSD.dist index c5db6a0b3fa..0577837dde8 100644 --- a/etc/mtree/4.4BSD.dist +++ b/etc/mtree/4.4BSD.dist @@ -1,4 +1,4 @@ -# $OpenBSD: 4.4BSD.dist,v 1.256 2014/07/16 02:02:49 deraadt Exp $ +# $OpenBSD: 4.4BSD.dist,v 1.257 2014/07/16 10:35:48 deraadt Exp $ /set type=dir uname=root gname=wheel mode=0755 @@ -444,14 +444,6 @@ usr # ./usr/share/doc doc - html - bind - .. - curses - .. - milter - .. - .. .. # ./usr/share/games diff --git a/gnu/usr.sbin/sendmail/libmilter/Makefile b/gnu/usr.sbin/sendmail/libmilter/Makefile index e250c3ae4dd..3369abc589f 100644 --- a/gnu/usr.sbin/sendmail/libmilter/Makefile +++ b/gnu/usr.sbin/sendmail/libmilter/Makefile @@ -1,23 +1,9 @@ -# $OpenBSD: Makefile,v 1.12 2009/05/13 18:24:15 jakob Exp $ +# $OpenBSD: Makefile,v 1.13 2014/07/16 10:35:53 deraadt Exp $ .include LIB= milter HDRS= mfapi.h milter.h mfdef.h -DOCS= api.html design.html figure1.jpg figure2.jpg index.html \ - installation.html other.html overview.html sample.html \ - smfi_addheader.html smfi_addrcpt.html smfi_chgheader.html \ - smfi_delrcpt.html smfi_getpriv.html smfi_getsymval.html \ - smfi_insheader.html smfi_main.html smfi_opensocket.html \ - smfi_progress.html smfi_quarantine.html smfi_register.html \ - smfi_replacebody.html smfi_setbacklog.html \ - smfi_setconn.html smfi_setdbg.html smfi_setmlreply.html \ - smfi_setpriv.html smfi_setreply.html smfi_settimeout.html \ - smfi_stop.html xxfi_abort.html xxfi_body.html \ - xxfi_close.html xxfi_connect.html xxfi_envfrom.html \ - xxfi_envrcpt.html xxfi_eoh.html xxfi_eom.html \ - xxfi_header.html xxfi_helo.html -MDOCDIR= ${DESTDIR}${DOCDIR}/html/milter SRCS= main.c engine.c listener.c worker.c handler.c comm.c smfi.c \ signal.c sm_gethost.c monitor.c errstring.c strl.c CPPFLAGS+= -D_FFR_MILTER_ROOT_UNSAFE -ULDAPMAP -pthread \ @@ -40,12 +26,5 @@ beforeinstall: cmp -s ${.CURDIR}/README ${DESTDIR}${SHAREDIR}/sendmail/README.milter || \ ${INSTALL} ${INSTALL_COPY} -o ${BINOWN} -g ${BINGRP} -m 444 \ ${.CURDIR}/README ${DESTDIR}${SHAREDIR}/sendmail/README.milter - @echo "installing ${DOCS} -> ${MDOCDIR}" - @test -d ${MDOCDIR} || mkdir ${MDOCDIR} - @-for i in ${DOCS}; do \ - cmp -s ${.CURDIR}/docs/$$i ${MDOCDIR}/$$i || \ - ${INSTALL} ${INSTALL_COPY} -o ${DOCOWN} -g ${DOCGRP} \ - -m ${DOCMODE} ${.CURDIR}/docs/$$i ${MDOCDIR} ; \ - done .include diff --git a/lib/libcurses/Makefile b/lib/libcurses/Makefile index 7a2e4ce4275..aaa00dc9054 100644 --- a/lib/libcurses/Makefile +++ b/lib/libcurses/Makefile @@ -1,4 +1,4 @@ -# $OpenBSD: Makefile,v 1.63 2012/12/21 08:50:27 espie Exp $ +# $OpenBSD: Makefile,v 1.64 2014/07/16 10:35:53 deraadt Exp $ # Uncomment this to enable tracing in libcurses #CURSESTRACE=-DTRACE @@ -272,10 +272,6 @@ GENERATED= init_keytry.h codes.c comp_captab.c expanded.c fallback.c \ CLEANFILES+= ${GENERATED} term.5 terminfo.5 curses.3 \ curs_addch.3 curs_attr.3 curs_getch.3 curs_inch.3 curs_mouse.3 -.if make(install) -SUBDIR+= doc -.endif - all: ${GENERATED} beforedepend: ${GENERATED} diff --git a/lib/libcurses/doc/Makefile b/lib/libcurses/doc/Makefile deleted file mode 100644 index 5d22907f5c6..00000000000 --- a/lib/libcurses/doc/Makefile +++ /dev/null @@ -1,16 +0,0 @@ -# $OpenBSD: Makefile,v 1.2 1999/01/20 17:29:30 millert Exp $ - -FILES= hackguide.html ncurses-intro.html - -all: - @echo nothing to do - -install: - test -d ${DESTDIR}/usr/share/doc/html/curses || ${INSTALL} -d -m 755 \ - -o $(BINOWN) -g $(BINGRP) ${DESTDIR}/usr/share/doc/html/curses - for f in ${FILES}; do \ - ${INSTALL} ${INSTALL_COPY} -m 444 -o $(BINOWN) -g $(BINGRP) \ - ${.CURDIR}/$$f ${DESTDIR}/usr/share/doc/html/curses/$$f; \ - done - -.include diff --git a/lib/libcurses/doc/hackguide.html b/lib/libcurses/doc/hackguide.html deleted file mode 100644 index 938fa4c0969..00000000000 --- a/lib/libcurses/doc/hackguide.html +++ /dev/null @@ -1,914 +0,0 @@ - - - - -A Hacker's Guide to Ncurses Internals - - - - - - -

A Hacker's Guide to NCURSES

- -

Contents

- - -

Abstract

- -This document is a hacker's tour of the ncurses library and utilities. -It discusses design philosophy, implementation methods, and the -conventions used for coding and documentation. It is recommended -reading for anyone who is interested in porting, extending or improving the -package. - -

Objective of the Package

- -The objective of the ncurses package is to provide a free software API for -character-cell terminals and terminal emulators with the following -characteristics: - -
    -
  • Source-compatible with historical curses implementations (including - the original BSD curses and System V curses. -
  • Conformant with the XSI Curses standard issued as part of XPG4 by - X/Open. -
  • High-quality -- stable and reliable code, wide portability, good - packaging, superior documentation. -
  • Featureful -- should eliminate as much of the drudgery of C interface - programming as possible, freeing programmers to think at a higher - level of design. -
- -These objectives are in priority order. So, for example, source -compatibility with older version must trump featurefulness -- we cannot -add features if it means breaking the portion of the API corresponding -to historical curses versions. - -

Why System V Curses?

- -We used System V curses as a model, reverse-engineering their API, in -order to fulfill the first two objectives.

- -System V curses implementations can support BSD curses programs with -just a recompilation, so by capturing the System V API we also -capture BSD's.

- -More importantly for the future, the XSI Curses standard issued by X/Open -is explicitly and closely modeled on System V. So conformance with -System V took us most of the way to base-level XSI conformance. - -

How to Design Extensions

- -The third objective (standards conformance) requires that it be easy to -condition source code using ncurses so that the absence of nonstandard -extensions does not break the code.

- -Accordingly, we have a policy of associating with each nonstandard extension -a feature macro, so that ncurses client code can use this macro to condition -in or out the code that requires the ncurses extension.

- -For example, there is a macro NCURSES_MOUSE_VERSION which XSI Curses -does not define, but which is defined in the ncurses library header. -You can use this to condition the calls to the mouse API calls. - -

Portability and Configuration

- -Code written for ncurses may assume an ANSI-standard C compiler and -POSIX-compatible OS interface. It may also assume the presence of a -System-V-compatible select(2) call.

- -We encourage (but do not require) developers to make the code friendly -to less-capable UNIX environments wherever possible.

- -We encourage developers to support OS-specific optimizations and methods -not available under POSIX/ANSI, provided only that: - -

    -
  • All such code is properly conditioned so the build process does not - attempt to compile it under a plain ANSI/POSIX environment. -
  • Adding such implementation methods does not introduce incompatibilities - in the ncurses API between platforms. -
- -We use GNU autoconf(1) as a tool to deal with portability issues. -The right way to leverage an OS-specific feature is to modify the autoconf -specification files (configure.in and aclocal.m4) to set up a new feature -macro, which you then use to condition your code. - -

Documentation Conventions

- -There are three kinds of documentation associated with this package. Each -has a different preferred format: - -
    -
  • Package-internal files (README, INSTALL, TO-DO etc.) -
  • Manual pages. -
  • Everything else (i.e., narrative documentation). -
- -Our conventions are simple: -
    -
  1. Maintain package-internal files in plain text. - The expected viewer for them more(1) or an editor window; there's - no point in elaborate mark-up. - -
  2. Mark up manual pages in the man macros. These have to be viewable - through traditional man(1) programs. - -
  3. Write everything else in HTML. -
- -When in doubt, HTMLize a master and use lynx(1) to generate -plain ASCII (as we do for the announcement document).

- -The reason for choosing HTML is that it's (a) well-adapted for on-line -browsing through viewers that are everywhere; (b) more easily readable -as plain text than most other mark-ups, if you don't have a viewer; and (c) -carries enough information that you can generate a nice-looking printed -version from it. Also, of course, it make exporting things like the -announcement document to WWW pretty trivial. - -

How to Report Bugs

- -The reporting address for bugs is -bug-ncurses@gnu.org. -This is a majordomo list; to join, write -to bug-ncurses-request@gnu.org with a message containing the line: -
-             subscribe <name>@<host.domain>
-
- -The ncurses code is maintained by a small group of -volunteers. While we try our best to fix bugs promptly, we simply -don't have a lot of hours to spend on elementary hand-holding. We rely -on intelligent cooperation from our users. If you think you have -found a bug in ncurses, there are some steps you can take -before contacting us that will help get the bug fixed quickly.

- -In order to use our bug-fixing time efficiently, we put people who -show us they've taken these steps at the head of our queue. This -means that if you don't, you'll probably end up at the tail end and -have to wait a while. - -

    -
  1. Develop a recipe to reproduce the bug. -

    -Bugs we can reproduce are likely to be fixed very quickly, often -within days. The most effective single thing you can do to get a -quick fix is develop a way we can duplicate the bad behavior -- -ideally, by giving us source for a small, portable test program that -breaks the library. (Even better is a keystroke recipe using one of -the test programs provided with the distribution.) - -

  2. Try to reproduce the bug on a different terminal type.

    - -In our experience, most of the behaviors people report as library bugs -are actually due to subtle problems in terminal descriptions. This is -especially likely to be true if you're using a traditional -asynchronous terminal or PC-based terminal emulator, rather than xterm -or a UNIX console entry.

    - -It's therefore extremely helpful if you can tell us whether or not your -problem reproduces on other terminal types. Usually you'll have both -a console type and xterm available; please tell us whether or not your -bug reproduces on both.

    - -If you have xterm available, it is also good to collect xterm reports for -different window sizes. This is especially true if you normally use an -unusual xterm window size -- a surprising number of the bugs we've seen -are either triggered or masked by these. - -

  3. Generate and examine a trace file for the broken behavior.

    - -Recompile your program with the debugging versions of the libraries. -Insert a trace() call with the argument set to TRACE_UPDATE. -(See "Writing Programs with -NCURSES" for details on trace levels.) -Reproduce your bug, then look at the trace file to see what the library -was actually doing.

    - -Another frequent cause of apparent bugs is application coding errors -that cause the wrong things to be put on the virtual screen. Looking -at the virtual-screen dumps in the trace file will tell you immediately if -this is happening, and save you from the possible embarrassment of being -told that the bug is in your code and is your problem rather than ours.

    - -If the virtual-screen dumps look correct but the bug persists, it's -possible to crank up the trace level to give more and more information -about the library's update actions and the control sequences it issues -to perform them. The test directory of the distribution contains a -tool for digesting these logs to make them less tedious to wade -through.

    - -Often you'll find terminfo problems at this stage by noticing that the -escape sequences put out for various capabilities are wrong. If not, -you're likely to learn enough to be able to characterize any bug in -the screen-update logic quite exactly. - -

  4. Report details and symptoms, not just interpretations.

    - -If you do the preceding two steps, it is very likely that you'll discover -the nature of the problem yourself and be able to send us a fix. This -will create happy feelings all around and earn you good karma for the first -time you run into a bug you really can't characterize and fix yourself.

    - -If you're still stuck, at least you'll know what to tell us. Remember, we -need details. If you guess about what is safe to leave out, you are too -likely to be wrong.

    - -If your bug produces a bad update, include a trace file. Try to make -the trace at the least voluminous level that pins down the -bug. Logs that have been through tracemunch are OK, it doesn't throw -away any information (actually they're better than un-munched ones because -they're easier to read).

    - -If your bug produces a core-dump, please include a symbolic stack trace -generated by gdb(1) or your local equivalent.

    - -Tell us about every terminal on which you've reproduced the bug -- and -every terminal on which you can't. Ideally, sent us terminfo sources -for all of these (yours might differ from ours).

    - -Include your ncurses version and your OS/machine type, of course! You can -find your ncurses version in the curses.h file. -

- -If your problem smells like a logic error or in cursor movement or -scrolling or a bad capability, there are a couple of tiny test frames -for the library algorithms in the progs directory that may help you -isolate it. These are not part of the normal build, but do have their -own make productions.

- -The most important of these is mvcur, a test frame for the -cursor-movement optimization code. With this program, you can see -directly what control sequences will be emitted for any given cursor -movement or scroll/insert/delete operations. If you think you've got -a bad capability identified, you can disable it and test again. The -program is command-driven and has on-line help.

- -If you think the vertical-scroll optimization is broken, or just want to -understand how it works better, build hashmap and read the -header comments of hardscroll.c and hashmap.c; then try -it out. You can also test the hardware-scrolling optimization separately -with hardscroll.

- -

A Tour of the Ncurses Library

- -

Library Overview

- -Most of the library is superstructure -- fairly trivial convenience -interfaces to a small set of basic functions and data structures used -to manipulate the virtual screen (in particular, none of this code -does any I/O except through calls to more fundamental modules -described below). The files -
- -lib_addch.c -lib_bkgd.c -lib_box.c -lib_chgat.c -lib_clear.c -lib_clearok.c -lib_clrbot.c -lib_clreol.c -lib_colorset.c -lib_data.c -lib_delch.c -lib_delwin.c -lib_echo.c -lib_erase.c -lib_gen.c -lib_getstr.c -lib_hline.c -lib_immedok.c -lib_inchstr.c -lib_insch.c -lib_insdel.c -lib_insstr.c -lib_instr.c -lib_isendwin.c -lib_keyname.c -lib_leaveok.c -lib_move.c -lib_mvwin.c -lib_overlay.c -lib_pad.c -lib_printw.c -lib_redrawln.c -lib_scanw.c -lib_screen.c -lib_scroll.c -lib_scrollok.c -lib_scrreg.c -lib_set_term.c -lib_slk.c -lib_slkatr_set.c -lib_slkatrof.c -lib_slkatron.c -lib_slkatrset.c -lib_slkattr.c -lib_slkclear.c -lib_slkcolor.c -lib_slkinit.c -lib_slklab.c -lib_slkrefr.c -lib_slkset.c -lib_slktouch.c -lib_touch.c -lib_unctrl.c -lib_vline.c -lib_wattroff.c -lib_wattron.c -lib_window.c - -
-are all in this category. They are very -unlikely to need change, barring bugs or some fundamental -reorganization in the underlying data structures.

- -These files are used only for debugging support: -

- -lib_trace.c -lib_traceatr.c -lib_tracebits.c -lib_tracechr.c -lib_tracedmp.c -lib_tracemse.c -trace_buf.c - -
-It is rather unlikely you will ever need to change these, unless -you want to introduce a new debug trace level for some reason.

- -There is another group of files that do direct I/O via tputs(), -computations on the terminal capabilities, or queries to the OS -environment, but nevertheless have only fairly low complexity. These -include: -

- -lib_acs.c -lib_beep.c -lib_color.c -lib_endwin.c -lib_initscr.c -lib_longname.c -lib_newterm.c -lib_options.c -lib_termcap.c -lib_ti.c -lib_tparm.c -lib_tputs.c -lib_vidattr.c -read_entry.c. - -
-They are likely to need revision only if -ncurses is being ported to an environment without an underlying -terminfo capability representation.

- -These files -have serious hooks into -the tty driver and signal facilities: -

- -lib_kernel.c -lib_baudrate.c -lib_raw.c -lib_tstp.c -lib_twait.c - -
-If you run into porting snafus -moving the package to another UNIX, the problem is likely to be in one -of these files. -The file lib_print.c uses sleep(2) and also -falls in this category.

- -Almost all of the real work is done in the files -

- -hardscroll.c -hashmap.c -lib_addch.c -lib_doupdate.c -lib_getch.c -lib_mouse.c -lib_mvcur.c -lib_refresh.c -lib_setup.c -lib_vidattr.c - -
-Most of the algorithmic complexity in the -library lives in these files. -If there is a real bug in ncurses itself, it's probably here. -We'll tour some of these files in detail -below (see The Engine Room).

- -Finally, there is a group of files that is actually most of the -terminfo compiler. The reason this code lives in the ncurses -library is to support fallback to /etc/termcap. These files include -

- -alloc_entry.c -captoinfo.c -comp_captab.c -comp_error.c -comp_hash.c -comp_parse.c -comp_scan.c -parse_entry.c -read_termcap.c -write_entry.c - -
-We'll discuss these in the compiler tour. - -

The Engine Room

- -

Keyboard Input

- -All ncurses input funnels through the function -wgetch(), defined in lib_getch.c. This function is -tricky; it has to poll for keyboard and mouse events and do a running -match of incoming input against the set of defined special keys.

- -The central data structure in this module is a FIFO queue, used to -match multiple-character input sequences against special-key -capabilities; also to implement pushback via ungetch().

- -The wgetch() code distinguishes between function key -sequences and the same sequences typed manually by doing a timed wait -after each input character that could lead a function key sequence. -If the entire sequence takes less than 1 second, it is assumed to have -been generated by a function key press.

- -Hackers bruised by previous encounters with variant select(2) -calls may find the code in lib_twait.c interesting. It deals -with the problem that some BSD selects don't return a reliable -time-left value. The function timed_wait() effectively -simulates a System V select. - -

Mouse Events

- -If the mouse interface is active, wgetch() polls for mouse -events each call, before it goes to the keyboard for input. It is -up to lib_mouse.c how the polling is accomplished; it may vary -for different devices.

- -Under xterm, however, mouse event notifications come in via the keyboard -input stream. They are recognized by having the kmous capability -as a prefix. This is kind of klugey, but trying to wire in recognition of -a mouse key prefix without going through the function-key machinery would -be just too painful, and this turns out to imply having the prefix somewhere -in the function-key capabilities at terminal-type initialization.

- -This kluge only works because kmous isn't actually used by any -historic terminal type or curses implementation we know of. Best -guess is it's a relic of some forgotten experiment in-house at Bell -Labs that didn't leave any traces in the publicly-distributed System V -terminfo files. If System V or XPG4 ever gets serious about using it -again, this kluge may have to change.

- -Here are some more details about mouse event handling:

- -The lib_mouse()code is logically split into a lower level that -accepts event reports in a device-dependent format and an upper level that -parses mouse gestures and filters events. The mediating data structure is a -circular queue of event structures.

- -Functionally, the lower level's job is to pick up primitive events and -put them on the circular queue. This can happen in one of two ways: -either (a) _nc_mouse_event() detects a series of incoming -mouse reports and queues them, or (b) code in lib_getch.c detects the -kmous prefix in the keyboard input stream and calls _nc_mouse_inline -to queue up a series of adjacent mouse reports.

- -In either case, _nc_mouse_parse() should be called after the -series is accepted to parse the digested mouse reports (low-level -events) into a gesture (a high-level or composite event). - -

Output and Screen Updating

- -With the single exception of character echoes during a wgetnstr() -call (which simulates cooked-mode line editing in an ncurses window), -the library normally does all its output at refresh time.

- -The main job is to go from the current state of the screen (as represented -in the curscr window structure) to the desired new state (as -represented in the newscr window structure), while doing as -little I/O as possible.

- -The brains of this operation are the modules hashmap.c, -hardscroll.c and lib_doupdate.c; the latter two use -lib_mvcur.c. Essentially, what happens looks like this:

- -The hashmap.c module tries to detect vertical motion -changes between the real and virtual screens. This information -is represented by the oldindex members in the newscr structure. -These are modified by vertical-motion and clear operations, and both are -re-initialized after each update. To this change-journalling -information, the hashmap code adds deductions made using a modified Heckel -algorithm on hash values generated from the line contents.

- -The hardscroll.c module computes an optimum set of scroll, -insertion, and deletion operations to make the indices match. It calls -_nc_mvcur_scrolln() in lib_mvcur.c to do those motions.

- -Then lib_doupdate.c goes to work. Its job is to do line-by-line -transformations of curscr lines to newscr lines. Its main -tool is the routine mvcur() in lib_mvcur.c. This routine -does cursor-movement optimization, attempting to get from given screen -location A to given location B in the fewest output characters possible.

- -If you want to work on screen optimizations, you should use the fact -that (in the trace-enabled version of the library) enabling the -TRACE_TIMES trace level causes a report to be emitted after -each screen update giving the elapsed time and a count of characters -emitted during the update. You can use this to tell when an update -optimization improves efficiency.

- -In the trace-enabled version of the library, it is also possible to disable -and re-enable various optimizations at runtime by tweaking the variable -_nc_optimize_enable. See the file include/curses.h.in -for mask values, near the end. - -

The Forms and Menu Libraries

- -The forms and menu libraries should work reliably in any environment you -can port ncurses to. The only portability issue anywhere in them is what -flavor of regular expressions the built-in form field type TYPE_REGEXP -will recognize.

- -The configuration code prefers the POSIX regex facility, modeled on -System V's, but will settle for BSD regexps if the former isn't available.

- -Historical note: the panels code was written primarily to assist in -porting u386mon 2.0 (comp.sources.misc v14i001-4) to systems lacking -panels support; u386mon 2.10 and beyond use it. This version has been -slightly cleaned up for ncurses. - -

A Tour of the Terminfo Compiler

- -The ncurses implementation of tic is rather complex -internally; it has to do a trying combination of missions. This starts -with the fact that, in addition to its normal duty of compiling -terminfo sources into loadable terminfo binaries, it has to be able to -handle termcap syntax and compile that too into terminfo entries.

- -The implementation therefore starts with a table-driven, dual-mode -lexical analyzer (in comp_scan.c). The lexer chooses its -mode (termcap or terminfo) based on the first `,' or `:' it finds in -each entry. The lexer does all the work of recognizing capability -names and values; the grammar above it is trivial, just "parse entries -till you run out of file". - -

Translation of Non-use Capabilities

- -Translation of most things besides use capabilities is pretty -straightforward. The lexical analyzer's tokenizer hands each capability -name to a hash function, which drives a table lookup. The table entry -yields an index which is used to look up the token type in another table, -and controls interpretation of the value.

- -One possibly interesting aspect of the implementation is the way the -compiler tables are initialized. All the tables are generated by various -awk/sed/sh scripts from a master table include/Caps; these -scripts actually write C initializers which are linked to the compiler. -Furthermore, the hash table is generated in the same way, so it doesn't -have to be generated at compiler startup time (another benefit of this -organization is that the hash table can be in shareable text space).

- -Thus, adding a new capability is usually pretty trivial, just a matter -of adding one line to the include/Caps file. We'll have more -to say about this in the section on Source-Form -Translation. - -

Use Capability Resolution

- -The background problem that makes tic tricky isn't the capability -translation itself, it's the resolution of use capabilities. Older -versions would not handle forward use references for this reason -(that is, a using terminal always had to follow its use target in the -source file). By doing this, they got away with a simple implementation -tactic; compile everything as it blows by, then resolve uses from compiled -entries.

- -This won't do for ncurses. The problem is that that the whole -compilation process has to be embeddable in the ncurses library -so that it can be called by the startup code to translate termcap -entries on the fly. The embedded version can't go promiscuously writing -everything it translates out to disk -- for one thing, it will typically -be running with non-root permissions.

- -So our tic is designed to parse an entire terminfo file into a -doubly-linked circular list of entry structures in-core, and then do -use resolution in-memory before writing everything out. This -design has other advantages: it makes forward and back use-references -equally easy (so we get the latter for free), and it makes checking for -name collisions before they're written out easy to do.

- -And this is exactly how the embedded version works. But the stand-alone -user-accessible version of tic partly reverts to the historical -strategy; it writes to disk (not keeping in core) any entry with no -use references.

- -This is strictly a core-economy kluge, implemented because the -terminfo master file is large enough that some core-poor systems swap -like crazy when you compile it all in memory...there have been reports of -this process taking three hours, rather than the twenty seconds -or less typical on the author's development box.

- -So. The executable tic passes the entry-parser a hook that -immediately writes out the referenced entry if it has no use -capabilities. The compiler main loop refrains from adding the entry -to the in-core list when this hook fires. If some other entry later -needs to reference an entry that got written immediately, that's OK; -the resolution code will fetch it off disk when it can't find it in -core.

- -Name collisions will still be detected, just not as cleanly. The -write_entry() code complains before overwriting an entry that -postdates the time of tic's first call to -write_entry(), Thus it will complain about overwriting -entries newly made during the tic run, but not about -overwriting ones that predate it. - -

Source-Form Translation

- -Another use of tic is to do source translation between various termcap -and terminfo formats. There are more variants out there than you might -think; the ones we know about are described in the captoinfo(1) -manual page.

- -The translation output code (dump_entry() in -ncurses/dump_entry.c) is shared with the infocmp(1) -utility. It takes the same internal representation used to generate -the binary form and dumps it to standard output in a specified -format.

- -The include/Caps file has a header comment describing ways you -can specify source translations for nonstandard capabilities just by -altering the master table. It's possible to set up capability aliasing -or tell the compiler to plain ignore a given capability without writing -any C code at all.

- -For circumstances where you need to do algorithmic translation, there -are functions in parse_entry.c called after the parse of each -entry that are specifically intended to encapsulate such -translations. This, for example, is where the AIX box1 capability -get translated to an acsc string. - -

Other Utilities

- -The infocmp utility is just a wrapper around the same -entry-dumping code used by tic for source translation. Perhaps -the one interesting aspect of the code is the use of a predicate -function passed in to dump_entry() to control which -capabilities are dumped. This is necessary in order to handle both -the ordinary De-compilation case and entry difference reporting.

- -The tput and clear utilities just do an entry load -followed by a tputs() of a selected capability. - -

Style Tips for Developers

- -See the TO-DO file in the top-level directory of the source distribution -for additions that would be particularly useful.

- -The prefix _nc_ should be used on library public functions that are -not part of the curses API in order to prevent pollution of the -application namespace. - -If you have to add to or modify the function prototypes in curses.h.in, -read ncurses/MKlib_gen.sh first so you can avoid breaking XSI conformance. - -Please join the ncurses mailing list. See the INSTALL file in the -top level of the distribution for details on the list.

- -Look for the string FIXME in source files to tag minor bugs -and potential problems that could use fixing.

- -Don't try to auto-detect OS features in the main body of the C code. -That's the job of the configuration system.

- -To hold down complexity, do make your code data-driven. Especially, -if you can drive logic from a table filtered out of -include/Caps, do it. If you find you need to augment the -data in that file in order to generate the proper table, that's still -preferable to ad-hoc code -- that's why the fifth field (flags) is -there.

- -Have fun! - -

Porting Hints

- -The following notes are intended to be a first step towards DOS and Macintosh -ports of the ncurses libraries.

- -The following library modules are `pure curses'; they operate only on -the curses internal structures, do all output through other curses -calls (not including tputs() and putp()) and do not -call any other UNIX routines such as signal(2) or the stdio library. -Thus, they should not need to be modified for single-terminal -ports. - -

- -lib_addch.c -lib_addstr.c -lib_bkgd.c -lib_box.c -lib_clear.c -lib_clrbot.c -lib_clreol.c -lib_delch.c -lib_delwin.c -lib_erase.c -lib_inchstr.c -lib_insch.c -lib_insdel.c -lib_insstr.c -lib_keyname.c -lib_move.c -lib_mvwin.c -lib_newwin.c -lib_overlay.c -lib_pad.c -lib_printw.c -lib_refresh.c -lib_scanw.c -lib_scroll.c -lib_scrreg.c -lib_set_term.c -lib_touch.c -lib_tparm.c -lib_tputs.c -lib_unctrl.c -lib_window.c -panel.c - -
-

- -This module is pure curses, but calls outstr(): - -

- -lib_getstr.c - -
-

- -These modules are pure curses, except that they use tputs() -and putp(): - -

- -lib_beep.c -lib_color.c -lib_endwin.c -lib_options.c -lib_slk.c -lib_vidattr.c - -
-

- -This modules assist in POSIX emulation on non-POSIX systems: -

-
sigaction.c -
signal calls -
- -The following source files will not be needed for a -single-terminal-type port. - -
- -alloc_entry.c -captoinfo.c -clear.c -comp_captab.c -comp_error.c -comp_hash.c -comp_main.c -comp_parse.c -comp_scan.c -dump_entry.c -infocmp.c -parse_entry.c -read_entry.c -tput.c -write_entry.c - -
-

- -The following modules will use open()/read()/write()/close()/lseek() on files, -but no other OS calls. - -

-
lib_screen.c -
used to read/write screen dumps -
lib_trace.c -
used to write trace data to the logfile -
- -Modules that would have to be modified for a port start here:

- -The following modules are `pure curses' but contain assumptions inappropriate -for a memory-mapped port. - -

-
lib_longname.c
assumes there may be multiple terminals -
lib_acs.c
assumes acs_map as a double indirection -
lib_mvcur.c
assumes cursor moves have variable cost -
lib_termcap.c
assumes there may be multiple terminals -
lib_ti.c
assumes there may be multiple terminals -
- -The following modules use UNIX-specific calls: - -
-
lib_doupdate.c
input checking -
lib_getch.c
read() -
lib_initscr.c
getenv() -
lib_newterm.c -
lib_baudrate.c -
lib_kernel.c
various tty-manipulation and system calls -
lib_raw.c
various tty-manipulation calls -
lib_setup.c
various tty-manipulation calls -
lib_restart.c
various tty-manipulation calls -
lib_tstp.c
signal-manipulation calls -
lib_twait.c
gettimeofday(), select(). -
- -
-
Eric S. Raymond <esr@snark.thyrsus.com>
-(Note: This is not the bug address!) - - diff --git a/lib/libcurses/doc/ncurses-intro.html b/lib/libcurses/doc/ncurses-intro.html deleted file mode 100644 index d0ccb74e719..00000000000 --- a/lib/libcurses/doc/ncurses-intro.html +++ /dev/null @@ -1,2722 +0,0 @@ - - - - -Writing Programs with NCURSES - - - - - -

Writing Programs with NCURSES

- -
-by Eric S. Raymond and Zeyd M. Ben-Halim
-updates since release 1.9.9e by Thomas Dickey -
- -

Contents

- - -
-

Introduction

- -This document is an introduction to programming with curses. It is -not an exhaustive reference for the curses Application Programming Interface -(API); that role is filled by the curses manual pages. Rather, it -is intended to help C programmers ease into using the package.

- -This document is aimed at C applications programmers not yet specifically -familiar with ncurses. If you are already an experienced curses -programmer, you should nevertheless read the sections on -Mouse Interfacing, Debugging, -Compatibility with Older Versions, -and Hints, Tips, and Tricks. These will bring you up -to speed on the special features and quirks of the ncurses -implementation. If you are not so experienced, keep reading.

- -The curses package is a subroutine library for -terminal-independent screen-painting and input-event handling which -presents a high level screen model to the programmer, hiding differences -between terminal types and doing automatic optimization of output to change -one screen full of text into another. Curses uses terminfo, which -is a database format that can describe the capabilities of thousands of -different terminals.

- -The curses API may seem something of an archaism on UNIX desktops -increasingly dominated by X, Motif, and Tcl/Tk. Nevertheless, UNIX still -supports tty lines and X supports xterm(1); the curses -API has the advantage of (a) back-portability to character-cell terminals, -and (b) simplicity. For an application that does not require bit-mapped -graphics and multiple fonts, an interface implementation using curses -will typically be a great deal simpler and less expensive than one using an -X toolkit. - -

A Brief History of Curses

- -Historically, the first ancestor of curses was the routines written to -provide screen-handling for the game rogue; these used the -already-existing termcap database facility for describing terminal -capabilities. These routines were abstracted into a documented library and -first released with the early BSD UNIX versions.

- -System III UNIX from Bell Labs featured a rewritten and much-improved -curses library. It introduced the terminfo format. Terminfo is based -on Berkeley's termcap database, but contains a number of improvements and -extensions. Parameterized capabilities strings were introduced, making it -possible to describe multiple video attributes, and colors and to handle far -more unusual terminals than possible with termcap. In the later AT&T -System V releases, curses evolved to use more facilities and offer -more capabilities, going far beyond BSD curses in power and flexibility. - -

Scope of This Document

- -This document describes ncurses, a free implementation of -the System V curses API with some clearly marked extensions. -It includes the following System V curses features: -
    -
  • Support for multiple screen highlights (BSD curses could only -handle one `standout' highlight, usually reverse-video). -
  • Support for line- and box-drawing using forms characters. -
  • Recognition of function keys on input. -
  • Color support. -
  • Support for pads (windows of larger than screen size on which the -screen or a subwindow defines a viewport). -
- -Also, this package makes use of the insert and delete line and character -features of terminals so equipped, and determines how to optimally use these -features with no help from the programmer. It allows arbitrary combinations of -video attributes to be displayed, even on terminals that leave ``magic -cookies'' on the screen to mark changes in attributes.

- -The ncurses package can also capture and use event reports from a -mouse in some environments (notably, xterm under the X window system). This -document includes tips for using the mouse.

- -The ncurses package was originated by Pavel Curtis. The original -maintainer of this package is -Zeyd Ben-Halim -<zmbenhal@netcom.com>. -Eric S. Raymond -<esr@snark.thyrsus.com> -wrote many of the new features in versions after 1.8.1 -and wrote most of this introduction. -Jürgen Pfeifer -wrote all of the menu and forms code as well as the -Ada95 binding. -Ongoing work is being done by -Thomas Dickey (maintainer). -Contact the current maintainers at -bug-ncurses@gnu.org. -

- -This document also describes the panels extension library, -similarly modeled on the SVr4 panels facility. This library allows you to -associate backing store with each of a stack or deck of overlapping windows, -and provides operations for moving windows around in the stack that change -their visibility in the natural way (handling window overlaps).

- -Finally, this document describes in detail the menus and forms extension libraries, also cloned from System V, -which support easy construction and sequences of menus and fill-in -forms. - - -

Terminology

- -In this document, the following terminology is used with reasonable -consistency: - -
-
window -
-A data structure describing a sub-rectangle of the screen (possibly the -entire screen). You can write to a window as though it were a miniature -screen, scrolling independently of other windows on the physical screen. -
screens -
-A subset of windows which are as large as the terminal screen, i.e., they start -at the upper left hand corner and encompass the lower right hand corner. One -of these, stdscr, is automatically provided for the programmer. -
terminal screen -
-The package's idea of what the terminal display currently looks like, i.e., -what the user sees now. This is a special screen. -
- -

The Curses Library

- -

An Overview of Curses

- -

Compiling Programs using Curses

- -In order to use the library, it is necessary to have certain types and -variables defined. Therefore, the programmer must have a line: - -
-	  #include <curses.h>
-
- -at the top of the program source. The screen package uses the Standard I/O -library, so <curses.h> includes -<stdio.h>. <curses.h> also includes -<termios.h>, <termio.h>, or -<sgtty.h> depending on your system. It is redundant (but -harmless) for the programmer to do these includes, too. In linking with -curses you need to have -lncurses in your LDFLAGS or on the -command line. There is no need for any other libraries. - -

Updating the Screen

- -In order to update the screen optimally, it is necessary for the routines to -know what the screen currently looks like and what the programmer wants it to -look like next. For this purpose, a data type (structure) named WINDOW is -defined which describes a window image to the routines, including its starting -position on the screen (the (y, x) coordinates of the upper left hand corner) -and its size. One of these (called curscr, for current screen) is a -screen image of what the terminal currently looks like. Another screen (called -stdscr, for standard screen) is provided by default to make changes -on.

- -A window is a purely internal representation. It is used to build and store a -potential image of a portion of the terminal. It doesn't bear any necessary -relation to what is really on the terminal screen; it's more like a -scratchpad or write buffer.

- -To make the section of physical screen corresponding to a window reflect the -contents of the window structure, the routine refresh() (or -wrefresh() if the window is not stdscr) is called.

- -A given physical screen section may be within the scope of any number of -overlapping windows. Also, changes can be made to windows in any order, -without regard to motion efficiency. Then, at will, the programmer can -effectively say ``make it look like this,'' and let the package implementation -determine the most efficient way to repaint the screen. - -

Standard Windows and Function Naming Conventions

- -As hinted above, the routines can use several windows, but two are -automatically given: curscr, which knows what the terminal looks like, -and stdscr, which is what the programmer wants the terminal to look -like next. The user should never actually access curscr directly. -Changes should be made to through the API, and then the routine -refresh() (or wrefresh()) called.

- -Many functions are defined to use stdscr as a default screen. For -example, to add a character to stdscr, one calls addch() with -the desired character as argument. To write to a different window. use the -routine waddch() (for `w'indow-specific addch()) is provided. This -convention of prepending function names with a `w' when they are to be -applied to specific windows is consistent. The only routines which do not -follow it are those for which a window must always be specified.

- -In order to move the current (y, x) coordinates from one point to another, the -routines move() and wmove() are provided. However, it is -often desirable to first move and then perform some I/O operation. In order to -avoid clumsiness, most I/O routines can be preceded by the prefix 'mv' and -the desired (y, x) coordinates prepended to the arguments to the function. For -example, the calls - -

-	  move(y, x);
-	  addch(ch);
-
- -can be replaced by - -
-	  mvaddch(y, x, ch);
-
- -and - -
-	  wmove(win, y, x);
-	  waddch(win, ch);
-
- -can be replaced by - -
-	  mvwaddch(win, y, x, ch);
-
- -Note that the window description pointer (win) comes before the added (y, x) -coordinates. If a function requires a window pointer, it is always the first -parameter passed. - -

Variables

- -The curses library sets some variables describing the terminal -capabilities. - -
-      type   name      description
-      ------------------------------------------------------------------
-      int    LINES     number of lines on the terminal
-      int    COLS      number of columns on the terminal
-
- -The curses.h also introduces some #define constants and types -of general usefulness: - -
-
bool -
boolean type, actually a `char' (e.g., bool doneit;) -
TRUE -
boolean `true' flag (1). -
FALSE -
boolean `false' flag (0). -
ERR -
error flag returned by routines on a failure (-1). -
OK -
error flag returned by routines when things go right. -
- -

Using the Library

- -Now we describe how to actually use the screen package. In it, we assume all -updating, reading, etc. is applied to stdscr. These instructions will -work on any window, providing you change the function names and parameters as -mentioned above.

- -Here is a sample program to motivate the discussion: - -

-#include <curses.h>
-#include <signal.h>
-
-static void finish(int sig);
-
-int
-main(int argc, char *argv[])
-{
-    int num = 0;
-
-    /* initialize your non-curses data structures here */
-
-    (void) signal(SIGINT, finish);      /* arrange interrupts to terminate */
-
-    (void) initscr();      /* initialize the curses library */
-    keypad(stdscr, TRUE);  /* enable keyboard mapping */
-    (void) nonl();         /* tell curses not to do NL->CR/NL on output */
-    (void) cbreak();       /* take input chars one at a time, no wait for \n */
-    (void) echo();         /* echo input - in color */
-
-    if (has_colors())
-    {
-        start_color();
-
-        /*
-         * Simple color assignment, often all we need.  Color pair 0 cannot
-	 * be redefined.  This example uses the same value for the color
-	 * pair as for the foreground color, though of course that is not
-	 * necessary:
-         */
-        init_pair(1, COLOR_RED,     COLOR_BLACK);
-        init_pair(2, COLOR_GREEN,   COLOR_BLACK);
-        init_pair(3, COLOR_YELLOW,  COLOR_BLACK);
-        init_pair(4, COLOR_BLUE,    COLOR_BLACK);
-        init_pair(5, COLOR_CYAN,    COLOR_BLACK);
-        init_pair(6, COLOR_MAGENTA, COLOR_BLACK);
-        init_pair(7, COLOR_WHITE,   COLOR_BLACK);
-    }
-
-    for (;;)
-    {
-        int c = getch();     /* refresh, accept single keystroke of input */
-	attrset(COLOR_PAIR(num % 8));
-	num++;
-
-        /* process the command keystroke */
-    }
-
-    finish(0);               /* we're done */
-}
-
-static void finish(int sig)
-{
-    endwin();
-
-    /* do your non-curses wrapup here */
-
-    exit(0);
-}
-
- -

Starting up

- -In order to use the screen package, the routines must know about terminal -characteristics, and the space for curscr and stdscr must be -allocated. These function initscr() does both these things. Since it -must allocate space for the windows, it can overflow memory when attempting to -do so. On the rare occasions this happens, initscr() will terminate -the program with an error message. initscr() must always be called -before any of the routines which affect windows are used. If it is not, the -program will core dump as soon as either curscr or stdscr are -referenced. However, it is usually best to wait to call it until after you are -sure you will need it, like after checking for startup errors. Terminal status -changing routines like nl() and cbreak() should be called -after initscr().

- -Once the screen windows have been allocated, you can set them up for -your program. If you want to, say, allow a screen to scroll, use -scrollok(). If you want the cursor to be left in place after -the last change, use leaveok(). If this isn't done, -refresh() will move the cursor to the window's current (y, x) -coordinates after updating it.

- -You can create new windows of your own using the functions newwin(), -derwin(), and subwin(). The routine delwin() will -allow you to get rid of old windows. All the options described above can be -applied to any window. - -

Output

- -Now that we have set things up, we will want to actually update the terminal. -The basic functions used to change what will go on a window are -addch() and move(). addch() adds a character at the -current (y, x) coordinates. move() changes the current (y, x) -coordinates to whatever you want them to be. It returns ERR if you -try to move off the window. As mentioned above, you can combine the two into -mvaddch() to do both things at once.

- -The other output functions, such as addstr() and printw(), -all call addch() to add characters to the window.

- -After you have put on the window what you want there, when you want the portion -of the terminal covered by the window to be made to look like it, you must call -refresh(). In order to optimize finding changes, refresh() -assumes that any part of the window not changed since the last -refresh() of that window has not been changed on the terminal, i.e., -that you have not refreshed a portion of the terminal with an overlapping -window. If this is not the case, the routine touchwin() is provided -to make it look like the entire window has been changed, thus making -refresh() check the whole subsection of the terminal for changes.

- -If you call wrefresh() with curscr as its argument, it will -make the screen look like curscr thinks it looks like. This is useful -for implementing a command which would redraw the screen in case it get messed -up. - -

Input

- -The complementary function to addch() is getch() which, if -echo is set, will call addch() to echo the character. Since the -screen package needs to know what is on the terminal at all times, if -characters are to be echoed, the tty must be in raw or cbreak mode. Since -initially the terminal has echoing enabled and is in ordinary ``cooked'' mode, -one or the other has to changed before calling getch(); otherwise, -the program's output will be unpredictable.

- -When you need to accept line-oriented input in a window, the functions -wgetstr() and friends are available. There is even a wscanw() -function that can do scanf()(3)-style multi-field parsing on window -input. These pseudo-line-oriented functions turn on echoing while they -execute.

- -The example code above uses the call keypad(stdscr, TRUE) to enable -support for function-key mapping. With this feature, the getch() code -watches the input stream for character sequences that correspond to arrow and -function keys. These sequences are returned as pseudo-character values. The -#define values returned are listed in the curses.h The -mapping from sequences to #define values is determined by -key_ capabilities in the terminal's terminfo entry. - -

Using Forms Characters

- -The addch() function (and some others, including box() and -border()) can accept some pseudo-character arguments which are specially -defined by ncurses. These are #define values set up in -the curses.h header; see there for a complete list (look for -the prefix ACS_).

- -The most useful of the ACS defines are the forms-drawing characters. You can -use these to draw boxes and simple graphs on the screen. If the terminal -does not have such characters, curses.h will map them to a -recognizable (though ugly) set of ASCII defaults. - -

Character Attributes and Color

- -The ncurses package supports screen highlights including standout, -reverse-video, underline, and blink. It also supports color, which is treated -as another kind of highlight.

- -Highlights are encoded, internally, as high bits of the pseudo-character type -(chtype) that curses.h uses to represent the contents of a -screen cell. See the curses.h header file for a complete list of -highlight mask values (look for the prefix A_).

- -There are two ways to make highlights. One is to logical-or the value of the -highlights you want into the character argument of an addch() call, -or any other output call that takes a chtype argument.

- -The other is to set the current-highlight value. This is logical-or'ed with -any highlight you specify the first way. You do this with the functions -attron(), attroff(), and attrset(); see the manual -pages for details. - -Color is a special kind of highlight. The package actually thinks in terms -of color pairs, combinations of foreground and background colors. The sample -code above sets up eight color pairs, all of the guaranteed-available colors -on black. Note that each color pair is, in effect, given the name of its -foreground color. Any other range of eight non-conflicting values could -have been used as the first arguments of the init_pair() values.

- -Once you've done an init_pair() that creates color-pair N, you can -use COLOR_PAIR(N) as a highlight that invokes that particular -color combination. Note that COLOR_PAIR(N), for constant N, -is itself a compile-time constant and can be used in initializers. - -

Mouse Interfacing

- -The ncurses library also provides a mouse interface. - -
-NOTE: this facility is specific to ncurses, it is not part of either -the XSI Curses standard, nor of System V Release 4, nor BSD curses. -System V Release 4 curses contains code with similar interface definitions, -however it is not documented. Other than by disassembling the library, we -have no way to determine exactly how that mouse code works. -Thus, we recommend that you wrap mouse-related code in an #ifdef using the -feature macro NCURSES_MOUSE_VERSION so it will not be compiled and linked -on non-ncurses systems. -
- -Presently, mouse event reporting works in the following environments: -
    -
  • xterm and similar programs such as rxvt. -
  • Linux console, when configured with gpm(1), Alessandro -Rubini's mouse server. -
  • FreeBSD sysmouse (console) -
  • OS/2 EMX -
-

-The mouse interface is very simple. To activate it, you use the function -mousemask(), passing it as first argument a bit-mask that specifies -what kinds of events you want your program to be able to see. It will -return the bit-mask of events that actually become visible, which may differ -from the argument if the mouse device is not capable of reporting some of -the event types you specify.

- -Once the mouse is active, your application's command loop should watch -for a return value of KEY_MOUSE from wgetch(). When -you see this, a mouse event report has been queued. To pick it off -the queue, use the function getmouse() (you must do this before -the next wgetch(), otherwise another mouse event might come -in and make the first one inaccessible).

- -Each call to getmouse() fills a structure (the address of which you'll -pass it) with mouse event data. The event data includes zero-origin, -screen-relative character-cell coordinates of the mouse pointer. It also -includes an event mask. Bits in this mask will be set, corresponding -to the event type being reported.

- -The mouse structure contains two additional fields which may be -significant in the future as ncurses interfaces to new kinds of -pointing device. In addition to x and y coordinates, there is a slot -for a z coordinate; this might be useful with touch-screens that can -return a pressure or duration parameter. There is also a device ID -field, which could be used to distinguish between multiple pointing -devices.

- -The class of visible events may be changed at any time via mousemask(). -Events that can be reported include presses, releases, single-, double- and -triple-clicks (you can set the maximum button-down time for clicks). If -you don't make clicks visible, they will be reported as press-release -pairs. In some environments, the event mask may include bits reporting -the state of shift, alt, and ctrl keys on the keyboard during the event.

- -A function to check whether a mouse event fell within a given window is -also supplied. You can use this to see whether a given window should -consider a mouse event relevant to it.

- -Because mouse event reporting will not be available in all -environments, it would be unwise to build ncurses -applications that require the use of a mouse. Rather, you should -use the mouse as a shortcut for point-and-shoot commands your application -would normally accept from the keyboard. Two of the test games in the -ncurses distribution (bs and knight) contain -code that illustrates how this can be done.

- -See the manual page curs_mouse(3X) for full details of the -mouse-interface functions. - -

Finishing Up

- -In order to clean up after the ncurses routines, the routine -endwin() is provided. It restores tty modes to what they were when -initscr() was first called, and moves the cursor down to the -lower-left corner. Thus, anytime after the call to initscr, endwin() -should be called before exiting. - -

Function Descriptions

- -We describe the detailed behavior of some important curses functions here, as a -supplement to the manual page descriptions. - -

Initialization and Wrapup

- -
-
initscr() -
The first function called should almost always be initscr(). -This will determine the terminal type and -initialize curses data structures. initscr() also arranges that -the first call to refresh() will clear the screen. If an error -occurs a message is written to standard error and the program -exits. Otherwise it returns a pointer to stdscr. A few functions may be -called before initscr (slk_init(), filter(), -ripoffline(), use_env(), and, if you are using multiple -terminals, newterm().) -
endwin() -
Your program should always call endwin() before exiting or -shelling out of the program. This function will restore tty modes, -move the cursor to the lower left corner of the screen, reset the -terminal into the proper non-visual mode. Calling refresh() -or doupdate() after a temporary escape from the program will -restore the ncurses screen from before the escape. -
newterm(type, ofp, ifp) -
A program which outputs to more than one terminal should use -newterm() instead of initscr(). newterm() should -be called once for each terminal. It returns a variable of type -SCREEN * which should be saved as a reference to that -terminal. -(NOTE: a SCREEN variable is not a screen in the sense we -are describing in this introduction, but a collection of -parameters used to assist in optimizing the display.) -The arguments are the type of the terminal (a string) and -FILE pointers for the output and input of the terminal. If -type is NULL then the environment variable $TERM is used. -endwin() should called once at wrapup time for each terminal -opened using this function. -
set_term(new) -
This function is used to switch to a different terminal previously -opened by newterm(). The screen reference for the new terminal -is passed as the parameter. The previous terminal is returned by the -function. All other calls affect only the current terminal. -
delscreen(sp) -
The inverse of newterm(); deallocates the data structures -associated with a given SCREEN reference. -
- -

Causing Output to the Terminal

- -
-
refresh() and wrefresh(win) -
These functions must be called to actually get any output on -the terminal, as other routines merely manipulate data -structures. wrefresh() copies the named window to the physical -terminal screen, taking into account what is already -there in order to do optimizations. refresh() does a -refresh of stdscr. Unless leaveok() has been -enabled, the physical cursor of the terminal is left at the -location of the window's cursor. -
doupdate() and wnoutrefresh(win) -
These two functions allow multiple updates with more efficiency -than wrefresh. To use them, it is important to understand how curses -works. In addition to all the window structures, curses keeps two -data structures representing the terminal screen: a physical screen, -describing what is actually on the screen, and a virtual screen, -describing what the programmer wants to have on the screen. wrefresh -works by first copying the named window to the virtual screen -(wnoutrefresh()), and then calling the routine to update the -screen (doupdate()). If the programmer wishes to output -several windows at once, a series of calls to wrefresh will result -in alternating calls to wnoutrefresh() and doupdate(), -causing several bursts of output to the screen. By calling -wnoutrefresh() for each window, it is then possible to call -doupdate() once, resulting in only one burst of output, with -fewer total characters transmitted (this also avoids a visually annoying -flicker at each update). -
- -

Low-Level Capability Access

- -
-
setupterm(term, filenum, errret) -
This routine is called to initialize a terminal's description, without setting -up the curses screen structures or changing the tty-driver mode bits. -term is the character string representing the name of the terminal -being used. filenum is the UNIX file descriptor of the terminal to -be used for output. errret is a pointer to an integer, in which a -success or failure indication is returned. The values returned can be 1 (all -is well), 0 (no such terminal), or -1 (some problem locating the terminfo -database).

- -The value of term can be given as NULL, which will cause the value of -TERM in the environment to be used. The errret pointer can -also be given as NULL, meaning no error code is wanted. If errret is -defaulted, and something goes wrong, setupterm() will print an -appropriate error message and exit, rather than returning. Thus, a simple -program can call setupterm(0, 1, 0) and not worry about initialization -errors.

- -After the call to setupterm(), the global variable cur_term is -set to point to the current structure of terminal capabilities. By calling -setupterm() for each terminal, and saving and restoring -cur_term, it is possible for a program to use two or more terminals at -once. Setupterm() also stores the names section of the terminal -description in the global character array ttytype[]. Subsequent calls -to setupterm() will overwrite this array, so you'll have to save it -yourself if need be. -

- -

Debugging

- - -
-NOTE: These functions are not part of the standard curses API! -
- -
-
trace() -
-This function can be used to explicitly set a trace level. If the -trace level is nonzero, execution of your program will generate a file -called `trace' in the current working directory containing a report on -the library's actions. Higher trace levels enable more detailed (and -verbose) reporting -- see comments attached to TRACE_ defines -in the curses.h file for details. (It is also possible to set -a trace level by assigning a trace level value to the environment variable -NCURSES_TRACE). -
_tracef() -
-This function can be used to output your own debugging information. It is only -available only if you link with -lncurses_g. It can be used the same way as -printf(), only it outputs a newline after the end of arguments. -The output goes to a file called trace in the current directory. -
- -Trace logs can be difficult to interpret due to the sheer volume of -data dumped in them. There is a script called tracemunch -included with the ncurses distribution that can alleviate -this problem somewhat; it compacts long sequences of similar operations into -more succinct single-line pseudo-operations. These pseudo-ops can be -distinguished by the fact that they are named in capital letters. - -

Hints, Tips, and Tricks

- -The ncurses manual pages are a complete reference for this library. -In the remainder of this document, we discuss various useful methods that -may not be obvious from the manual page descriptions. - -

Some Notes of Caution

- -If you find yourself thinking you need to use noraw() or -nocbreak(), think again and move carefully. It's probably -better design to use getstr() or one of its relatives to -simulate cooked mode. The noraw() and nocbreak() -functions try to restore cooked mode, but they may end up clobbering -some control bits set before you started your application. Also, they -have always been poorly documented, and are likely to hurt your -application's usability with other curses libraries.

- -Bear in mind that refresh() is a synonym for wrefresh(stdscr). -Don't try to mix use of stdscr with use of windows declared -by newwin(); a refresh() call will blow them off the -screen. The right way to handle this is to use subwin(), or -not touch stdscr at all and tile your screen with declared -windows which you then wnoutrefresh() somewhere in your program -event loop, with a single doupdate() call to trigger actual -repainting.

- -You are much less likely to run into problems if you design your screen -layouts to use tiled rather than overlapping windows. Historically, -curses support for overlapping windows has been weak, fragile, and poorly -documented. The ncurses library is not yet an exception to this -rule.

- -There is a panels library included in the ncurses -distribution that does a pretty good job of strengthening the -overlapping-windows facilities.

- -Try to avoid using the global variables LINES and COLS. Use -getmaxyx() on the stdscr context instead. Reason: -your code may be ported to run in an environment with window resizes, -in which case several screens could be open with different sizes. - -

Temporarily Leaving NCURSES Mode

- -Sometimes you will want to write a program that spends most of its time in -screen mode, but occasionally returns to ordinary `cooked' mode. A common -reason for this is to support shell-out. This behavior is simple to arrange -in ncurses.

- -To leave ncurses mode, call endwin() as you would if you -were intending to terminate the program. This will take the screen back to -cooked mode; you can do your shell-out. When you want to return to -ncurses mode, simply call refresh() or doupdate(). -This will repaint the screen.

- -There is a boolean function, isendwin(), which code can use to -test whether ncurses screen mode is active. It returns TRUE -in the interval between an endwin() call and the following -refresh(), FALSE otherwise.

- -Here is some sample code for shellout: - -

-    addstr("Shelling out...");
-    def_prog_mode();           /* save current tty modes */
-    endwin();                  /* restore original tty modes */
-    system("sh");              /* run shell */
-    addstr("returned.\n");     /* prepare return message */
-    refresh();                 /* restore save modes, repaint screen */
-
- -

Using NCURSES under XTERM

- -A resize operation in X sends SIGWINCH to the application running -under xterm. - -The easiest way to handle SIGWINCH -is to do an endwin, -followed by an refresh and a screen repaint you code -yourself. -The refresh will pick up the new screen size from the -xterm's environment.

- -That is the standard way, of course (it even works with some vendor's curses -implementations). -Its drawback is that it clears the screen to reinitialize the display, and does -not resize subwindows which must be shrunk. -Ncurses provides an extension which works better, the -resizeterm function. That function ensures that all windows -are limited to the new screen dimensions, and pads stdscr -with blanks if the screen is larger.

- -The ncurses library provides a SIGWINCH signal handler, -which pushes a KEY_RESIZE via the wgetch() calls. -When ncurses returns that code, -it calls resizeterm -to update the size of the standard screen's window, repainting that -(filling with blanks or truncating as needed). -It also resizes other windows, -but its effect may be less satisfactory because it cannot -know how you want the screen re-painted. -You will usually have to write special-purpose code to handle -KEY_RESIZE yourself. - -

Handling Multiple Terminal Screens

- -The initscr() function actually calls a function named -newterm() to do most of its work. If you are writing a program that -opens multiple terminals, use newterm() directly.

- -For each call, you will have to specify a terminal type and a pair of file -pointers; each call will return a screen reference, and stdscr will be -set to the last one allocated. You will switch between screens with the -set_term call. Note that you will also have to call -def_shell_mode and def_prog_mode on each tty yourself. - -

Testing for Terminal Capabilities

- -Sometimes you may want to write programs that test for the presence of various -capabilities before deciding whether to go into ncurses mode. An easy -way to do this is to call setupterm(), then use the functions -tigetflag(), tigetnum(), and tigetstr() to do your -testing.

- -A particularly useful case of this often comes up when you want to -test whether a given terminal type should be treated as `smart' -(cursor-addressable) or `stupid'. The right way to test this is to see -if the return value of tigetstr("cup") is non-NULL. Alternatively, -you can include the term.h file and test the value of the -macro cursor_address. - -

Tuning for Speed

- -Use the addchstr() family of functions for fast -screen-painting of text when you know the text doesn't contain any -control characters. Try to make attribute changes infrequent on your -screens. Don't use the immedok() option! - -

Special Features of NCURSES

- -The wresize() function allows you to resize a window in place. -The associated resizeterm() function simplifies the construction -of SIGWINCH handlers, for resizing all windows.

- -The define_key() function allows you -to define at runtime function-key control sequences which are not in the -terminal description. -The keyok() function allows you to temporarily -enable or disable interpretation of any function-key control sequence.

- -The use_default_colors() function allows you to construct -applications which can use the terminal's default foreground and -background colors as an additional "default" color. -Several terminal emulators support this feature, which is based on ISO 6429.

- -Ncurses supports up 16 colors, unlike SVr4 curses which defines only 8. -While most terminals which provide color allow only 8 colors, about -a quarter (including XFree86 xterm) support 16 colors. - -

Compatibility with Older Versions

- -Despite our best efforts, there are some differences between ncurses -and the (undocumented!) behavior of older curses implementations. These arise -from ambiguities or omissions in the documentation of the API. - -

Refresh of Overlapping Windows

- -If you define two windows A and B that overlap, and then alternately scribble -on and refresh them, the changes made to the overlapping region under historic -curses versions were often not documented precisely.

- -To understand why this is a problem, remember that screen updates are -calculated between two representations of the entire display. The -documentation says that when you refresh a window, it is first copied to the -virtual screen, and then changes are calculated to update the physical screen -(and applied to the terminal). But "copied to" is not very specific, and -subtle differences in how copying works can produce different behaviors in the -case where two overlapping windows are each being refreshed at unpredictable -intervals.

- -What happens to the overlapping region depends on what wnoutrefresh() -does with its argument -- what portions of the argument window it copies to the -virtual screen. Some implementations do "change copy", copying down only -locations in the window that have changed (or been marked changed with -wtouchln() and friends). Some implementations do "entire copy", -copying all window locations to the virtual screen whether or not -they have changed.

- -The ncurses library itself has not always been consistent on this -score. Due to a bug, versions 1.8.7 to 1.9.8a did entire copy. Versions -1.8.6 and older, and versions 1.9.9 and newer, do change copy.

- -For most commercial curses implementations, it is not documented and not known -for sure (at least not to the ncurses maintainers) whether they do -change copy or entire copy. We know that System V release 3 curses has logic -in it that looks like an attempt to do change copy, but the surrounding logic -and data representations are sufficiently complex, and our knowledge -sufficiently indirect, that it's hard to know whether this is reliable. - -It is not clear what the SVr4 documentation and XSI standard intend. The XSI -Curses standard barely mentions wnoutrefresh(); the SVr4 documents seem to be -describing entire-copy, but it is possible with some effort and straining to -read them the other way.

- -It might therefore be unwise to rely on either behavior in programs that might -have to be linked with other curses implementations. Instead, you can do an -explicit touchwin() before the wnoutrefresh() call to -guarantee an entire-contents copy anywhere.

- -The really clean way to handle this is to use the panels library. If, -when you want a screen update, you do update_panels(), it will -do all the necessary wnoutrefresh() calls for whatever panel -stacking order you have defined. Then you can do one doupdate() -and there will be a single burst of physical I/O that will do -all your updates. - -

Background Erase

- -If you have been using a very old versions of ncurses (1.8.7 or -older) you may be surprised by the behavior of the erase functions. In older -versions, erased areas of a window were filled with a blank modified by the -window's current attribute (as set by wattrset(), wattron(), -wattroff() and friends).

- -In newer versions, this is not so. Instead, the attribute of erased blanks -is normal unless and until it is modified by the functions bkgdset() -or wbkgdset().

- -This change in behavior conforms ncurses to System V Release 4 and -the XSI Curses standard. - -

XSI Curses Conformance

- -The ncurses library is intended to be base-level conformant with the -XSI Curses standard from X/Open. Many extended-level features (in fact, almost -all features not directly concerned with wide characters and -internationalization) are also supported.

- -One effect of XSI conformance is the change in behavior described under -"Background Erase -- Compatibility with Old Versions".

- -Also, ncurses meets the XSI requirement that every macro -entry point have a corresponding function which may be linked (and -will be prototype-checked) if the macro definition is disabled with -#undef. - -

The Panels Library

- -The ncurses library by itself provides good support for screen -displays in which the windows are tiled (non-overlapping). In the more -general case that windows may overlap, you have to use a series of -wnoutrefresh() calls followed by a doupdate(), and be -careful about the order you do the window refreshes in. It has to be -bottom-upwards, otherwise parts of windows that should be obscured will -show through.

- -When your interface design is such that windows may dive deeper into the -visibility stack or pop to the top at runtime, the resulting book-keeping -can be tedious and difficult to get right. Hence the panels library.

- -The panel library first appeared in AT&T System V. The -version documented here is the panel code distributed -with ncurses. - -

Compiling With the Panels Library

- -Your panels-using modules must import the panels library declarations with - -
-	  #include <panel.h>
-
- -and must be linked explicitly with the panels library using an --lpanel argument. Note that they must also link the -ncurses library with -lncurses. Many linkers -are two-pass and will accept either order, but it is still good practice -to put -lpanel first and -lncurses second. - -

Overview of Panels

- -A panel object is a window that is implicitly treated as part of a -deck including all other panel objects. The deck has an implicit -bottom-to-top visibility order. The panels library includes an update -function (analogous to refresh()) that displays all panels in the -deck in the proper order to resolve overlaps. The standard window, -stdscr, is considered below all panels.

- -Details on the panels functions are available in the man pages. We'll just -hit the highlights here.

- -You create a panel from a window by calling new_panel() on a -window pointer. It then becomes the top of the deck. The panel's window -is available as the value of panel_window() called with the -panel pointer as argument.

- -You can delete a panel (removing it from the deck) with del_panel. -This will not deallocate the associated window; you have to do that yourself. - -You can replace a panel's window with a different window by calling -replace_window. The new window may be of different size; -the panel code will re-compute all overlaps. This operation doesn't -change the panel's position in the deck.

- -To move a panel's window, use move_panel(). The -mvwin() function on the panel's window isn't sufficient because it -doesn't update the panels library's representation of where the windows are. -This operation leaves the panel's depth, contents, and size unchanged.

- -Two functions (top_panel(), bottom_panel()) are -provided for rearranging the deck. The first pops its argument window to the -top of the deck; the second sends it to the bottom. Either operation leaves -the panel's screen location, contents, and size unchanged.

- -The function update_panels() does all the -wnoutrefresh() calls needed to prepare for -doupdate() (which you must call yourself, afterwards).

- -Typically, you will want to call update_panels() and -doupdate() just before accepting command input, once in each cycle -of interaction with the user. If you call update_panels() after -each and every panel write, you'll generate a lot of unnecessary refresh -activity and screen flicker. - -

Panels, Input, and the Standard Screen

- -You shouldn't mix wnoutrefresh() or wrefresh() -operations with panels code; this will work only if the argument window -is either in the top panel or unobscured by any other panels.

- -The stsdcr window is a special case. It is considered below all -panels. Because changes to panels may obscure parts of stdscr, -though, you should call update_panels() before -doupdate() even when you only change stdscr.

- -Note that wgetch automatically calls wrefresh. -Therefore, before requesting input from a panel window, you need to be sure -that the panel is totally unobscured.

- -There is presently no way to display changes to one obscured panel without -repainting all panels. - -

Hiding Panels

- -It's possible to remove a panel from the deck temporarily; use -hide_panel for this. Use show_panel() to render it -visible again. The predicate function panel_hidden -tests whether or not a panel is hidden.

- -The panel_update code ignores hidden panels. You cannot do -top_panel() or bottom_panel on a hidden panel(). -Other panels operations are applicable. - -

Miscellaneous Other Facilities

- -It's possible to navigate the deck using the functions -panel_above() and panel_below. Handed a panel -pointer, they return the panel above or below that panel. Handed -NULL, they return the bottom-most or top-most panel.

- -Every panel has an associated user pointer, not used by the panel code, to -which you can attach application data. See the man page documentation -of set_panel_userptr() and panel_userptr for -details. - -

The Menu Library

- -A menu is a screen display that assists the user to choose some subset -of a given set of items. The menu library is a curses -extension that supports easy programming of menu hierarchies with a -uniform but flexible interface.

- -The menu library first appeared in AT&T System V. The -version documented here is the menu code distributed -with ncurses. - -

Compiling With the menu Library

- -Your menu-using modules must import the menu library declarations with - -
-	  #include <menu.h>
-
- -and must be linked explicitly with the menus library using an --lmenu argument. Note that they must also link the -ncurses library with -lncurses. Many linkers -are two-pass and will accept either order, but it is still good practice -to put -lmenu first and -lncurses second. - -

Overview of Menus

- -The menus created by this library consist of collections of -items including a name string part and a description string -part. To make menus, you create groups of these items and connect -them with menu frame objects.

- -The menu can then by posted, that is written to an -associated window. Actually, each menu has two associated windows; a -containing window in which the programmer can scribble titles or -borders, and a subwindow in which the menu items proper are displayed. -If this subwindow is too small to display all the items, it will be a -scrollable viewport on the collection of items.

- -A menu may also be unposted (that is, undisplayed), and finally -freed to make the storage associated with it and its items available for -re-use.

- -The general flow of control of a menu program looks like this: - -

    -
  1. Initialize curses. -
  2. Create the menu items, using new_item(). -
  3. Create the menu using new_menu(). -
  4. Post the menu using post_menu(). -
  5. Refresh the screen. -
  6. Process user requests via an input loop. -
  7. Unpost the menu using unpost_menu(). -
  8. Free the menu, using free_menu(). -
  9. Free the items using free_item(). -
  10. Terminate curses. -
- -

Selecting items

- -Menus may be multi-valued or (the default) single-valued (see the manual -page menu_opts(3x) to see how to change the default). -Both types always have a current item.

- -From a single-valued menu you can read the selected value simply by looking -at the current item. From a multi-valued menu, you get the selected set -by looping through the items applying the item_value() -predicate function. Your menu-processing code can use the function -set_item_value() to flag the items in the select set.

- -Menu items can be made unselectable using set_item_opts() -or item_opts_off() with the O_SELECTABLE -argument. This is the only option so far defined for menus, but it -is good practice to code as though other option bits might be on. - -

Menu Display

- -The menu library calculates a minimum display size for your window, based -on the following variables: - -
    -
  • The number and maximum length of the menu items -
  • Whether the O_ROWMAJOR option is enabled -
  • Whether display of descriptions is enabled -
  • Whatever menu format may have been set by the programmer -
  • The length of the menu mark string used for highlighting selected items -
- -The function set_menu_format() allows you to set the -maximum size of the viewport or menu page that will be used -to display menu items. You can retrieve any format associated with a -menu with menu_format(). The default format is rows=16, -columns=1.

- -The actual menu page may be smaller than the format size. This depends -on the item number and size and whether O_ROWMAJOR is on. This option -(on by default) causes menu items to be displayed in a `raster-scan' -pattern, so that if more than one item will fit horizontally the first -couple of items are side-by-side in the top row. The alternative is -column-major display, which tries to put the first several items in -the first column.

- -As mentioned above, a menu format not large enough to allow all items to fit -on-screen will result in a menu display that is vertically scrollable.

-You can scroll it with requests to the menu driver, which will be described -in the section on menu input handling.

- -Each menu has a mark string used to visually tag selected items; -see the menu_mark(3x) manual page for details. The mark -string length also influences the menu page size.

- -The function scale_menu() returns the minimum display size -that the menu code computes from all these factors. - -There are other menu display attributes including a select attribute, -an attribute for selectable items, an attribute for unselectable items, -and a pad character used to separate item name text from description -text. These have reasonable defaults which the library allows you to -change (see the menu_attribs(3x) manual page. - -

Menu Windows

- -Each menu has, as mentioned previously, a pair of associated windows. -Both these windows are painted when the menu is posted and erased when -the menu is unposted.

- -The outer or frame window is not otherwise touched by the menu -routines. It exists so the programmer can associate a title, a -border, or perhaps help text with the menu and have it properly -refreshed or erased at post/unpost time. The inner window or -subwindow is where the current menu page is displayed.

- -By default, both windows are stdscr. You can set them with the -functions in menu_win(3x).

- -When you call post_menu(), you write the menu to its -subwindow. When you call unpost_menu(), you erase the -subwindow, However, neither of these actually modifies the screen. To -do that, call wrefresh() or some equivalent. - -

Processing Menu Input

- -The main loop of your menu-processing code should call -menu_driver() repeatedly. The first argument of this routine -is a menu pointer; the second is a menu command code. You should write an -input-fetching routine that maps input characters to menu command codes, and -pass its output to menu_driver(). The menu command codes are -fully documented in menu_driver(3x).

- -The simplest group of command codes is REQ_NEXT_ITEM, -REQ_PREV_ITEM, REQ_FIRST_ITEM, -REQ_LAST_ITEM, REQ_UP_ITEM, -REQ_DOWN_ITEM, REQ_LEFT_ITEM, -REQ_RIGHT_ITEM. These change the currently selected -item. These requests may cause scrolling of the menu page if it only -partially displayed.

- -There are explicit requests for scrolling which also change the -current item (because the select location does not change, but the -item there does). These are REQ_SCR_DLINE, -REQ_SCR_ULINE, REQ_SCR_DPAGE, and -REQ_SCR_UPAGE.

- -The REQ_TOGGLE_ITEM selects or deselects the current item. -It is for use in multi-valued menus; if you use it with O_ONEVALUE -on, you'll get an error return (E_REQUEST_DENIED).

- -Each menu has an associated pattern buffer. The -menu_driver() logic tries to accumulate printable ASCII -characters passed in in that buffer; when it matches a prefix of an -item name, that item (or the next matching item) is selected. If -appending a character yields no new match, that character is deleted -from the pattern buffer, and menu_driver() returns -E_NO_MATCH.

- -Some requests change the pattern buffer directly: -REQ_CLEAR_PATTERN, REQ_BACK_PATTERN, -REQ_NEXT_MATCH, REQ_PREV_MATCH. The latter -two are useful when pattern buffer input matches more than one item -in a multi-valued menu.

- -Each successful scroll or item navigation request clears the pattern -buffer. It is also possible to set the pattern buffer explicitly -with set_menu_pattern().

- -Finally, menu driver requests above the constant MAX_COMMAND -are considered application-specific commands. The menu_driver() -code ignores them and returns E_UNKNOWN_COMMAND. - -

Miscellaneous Other Features

- -Various menu options can affect the processing and visual appearance -and input processing of menus. See menu_opts(3x) for -details.

- -It is possible to change the current item from application code; this -is useful if you want to write your own navigation requests. It is -also possible to explicitly set the top row of the menu display. See -mitem_current(3x). - -If your application needs to change the menu subwindow cursor for -any reason, pos_menu_cursor() will restore it to the -correct location for continuing menu driver processing.

- -It is possible to set hooks to be called at menu initialization and -wrapup time, and whenever the selected item changes. See -menu_hook(3x).

- -Each item, and each menu, has an associated user pointer on which you -can hang application data. See mitem_userptr(3x) and -menu_userptr(3x). - -

The Forms Library

- -The form library is a curses extension that supports easy -programming of on-screen forms for data entry and program control.

- -The form library first appeared in AT&T System V. The -version documented here is the form code distributed -with ncurses. - -

Compiling With the form Library

- -Your form-using modules must import the form library declarations with - -
-	  #include <form.h>
-
- -and must be linked explicitly with the forms library using an --lform argument. Note that they must also link the -ncurses library with -lncurses. Many linkers -are two-pass and will accept either order, but it is still good practice -to put -lform first and -lncurses second. - -

Overview of Forms

- -A form is a collection of fields; each field may be either a label -(explanatory text) or a data-entry location. Long forms may be -segmented into pages; each entry to a new page clears the screen.

-To make forms, you create groups of fields and connect them with form -frame objects; the form library makes this relatively simple.

- -Once defined, a form can be posted, that is written to an -associated window. Actually, each form has two associated windows; a -containing window in which the programmer can scribble titles or -borders, and a subwindow in which the form fields proper are displayed.

- -As the form user fills out the posted form, navigation and editing -keys support movement between fields, editing keys support modifying -field, and plain text adds to or changes data in a current field. The -form library allows you (the forms designer) to bind each navigation -and editing key to any keystroke accepted by curses - -Fields may have validation conditions on them, so that they check input -data for type and value. The form library supplies a rich set of -pre-defined field types, and makes it relatively easy to define new ones.

- -Once its transaction is completed (or aborted), a form may be -unposted (that is, undisplayed), and finally freed to make -the storage associated with it and its items available for re-use.

- -The general flow of control of a form program looks like this: - -

    -
  1. Initialize curses. -
  2. Create the form fields, using new_field(). -
  3. Create the form using new_form(). -
  4. Post the form using post_form(). -
  5. Refresh the screen. -
  6. Process user requests via an input loop. -
  7. Unpost the form using unpost_form(). -
  8. Free the form, using free_form(). -
  9. Free the fields using free_field(). -
  10. Terminate curses. -
- -Note that this looks much like a menu program; the form library handles -tasks which are in many ways similar, and its interface was obviously -designed to resemble that of the menu library -wherever possible.

- -In forms programs, however, the `process user requests' is somewhat more -complicated than for menus. Besides menu-like navigation operations, -the menu driver loop has to support field editing and data validation. - -

Creating and Freeing Fields and Forms

- -The basic function for creating fields is new_field(): - -
-FIELD *new_field(int height, int width,   /* new field size */
-                 int top, int left,       /* upper left corner */
-                 int offscreen,           /* number of offscreen rows */
-                 int nbuf);               /* number of working buffers */
-
- -Menu items always occupy a single row, but forms fields may have -multiple rows. So new_field() requires you to specify a -width and height (the first two arguments, which mist both be greater -than zero).

- -You must also specify the location of the field's upper left corner on -the screen (the third and fourth arguments, which must be zero or -greater). Note that these coordinates are relative to the form -subwindow, which will coincide with stdscr by default but -need not be stdscr if you've done an explicit -set_form_win() call.

- -The fifth argument allows you to specify a number of off-screen rows. If -this is zero, the entire field will always be displayed. If it is -nonzero, the form will be scrollable, with only one screen-full (initially -the top part) displayed at any given time. If you make a field dynamic -and grow it so it will no longer fit on the screen, the form will become -scrollable even if the offscreen argument was initially zero.

- -The forms library allocates one working buffer per field; the size of -each buffer is ((height + offscreen)*width + 1, one character -for each position in the field plus a NUL terminator. The sixth -argument is the number of additional data buffers to allocate for the -field; your application can use them for its own purposes. - -

-FIELD *dup_field(FIELD *field,            /* field to copy */
-                 int top, int left);      /* location of new copy */
-
- -The function dup_field() duplicates an existing field at a -new location. Size and buffering information are copied; some -attribute flags and status bits are not (see the -form_field_new(3X) for details). - -
-FIELD *link_field(FIELD *field,           /* field to copy */
-                  int top, int left);     /* location of new copy */
-
- -The function link_field() also duplicates an existing field -at a new location. The difference from dup_field() is that -it arranges for the new field's buffer to be shared with the old one.

- -Besides the obvious use in making a field editable from two different -form pages, linked fields give you a way to hack in dynamic labels. If -you declare several fields linked to an original, and then make them -inactive, changes from the original will still be propagated to the -linked fields.

- -As with duplicated fields, linked fields have attribute bits separate -from the original.

- -As you might guess, all these field-allocations return NULL if -the field allocation is not possible due to an out-of-memory error or -out-of-bounds arguments.

- -To connect fields to a form, use - -

-FORM *new_form(FIELD **fields);
-
- -This function expects to see a NULL-terminated array of field pointers. -Said fields are connected to a newly-allocated form object; its address -is returned (or else NULL if the allocation fails).

- -Note that new_field() does not copy the pointer array -into private storage; if you modify the contents of the pointer array -during forms processing, all manner of bizarre things might happen. Also -note that any given field may only be connected to one form.

- -The functions free_field() and free_form are available -to free field and form objects. It is an error to attempt to free a field -connected to a form, but not vice-versa; thus, you will generally free -your form objects first. - -

Fetching and Changing Field Attributes

- -Each form field has a number of location and size attributes -associated with it. There are other field attributes used to control -display and editing of the field. Some (for example, the O_STATIC bit) -involve sufficient complications to be covered in sections of their own -later on. We cover the functions used to get and set several basic -attributes here.

- -When a field is created, the attributes not specified by the -new_field function are copied from an invisible system -default field. In attribute-setting and -fetching functions, the -argument NULL is taken to mean this field. Changes to it persist -as defaults until your forms application terminates. - -

Fetching Size and Location Data

- -You can retrieve field sizes and locations through: - -
-int field_info(FIELD *field,              /* field from which to fetch */
-               int *height, *int width,   /* field size */
-               int *top, int *left,       /* upper left corner */
-               int *offscreen,            /* number of offscreen rows */
-               int *nbuf);                /* number of working buffers */
-
- -This function is a sort of inverse of new_field(); instead of -setting size and location attributes of a new field, it fetches them -from an existing one. - -

Changing the Field Location

- -It is possible to move a field's location on the screen: - -
-int move_field(FIELD *field,              /* field to alter */
-               int top, int left);        /* new upper-left corner */
-
- -You can, of course. query the current location through field_info(). - -

The Justification Attribute

- -One-line fields may be unjustified, justified right, justified left, -or centered. Here is how you manipulate this attribute: - -
-int set_field_just(FIELD *field,          /* field to alter */
-                   int justmode);         /* mode to set */
-
-int field_just(FIELD *field);             /* fetch mode of field */
-
- -The mode values accepted and returned by this functions are -preprocessor macros NO_JUSTIFICATION, JUSTIFY_RIGHT, -JUSTIFY_LEFT, or JUSTIFY_CENTER. - -

Field Display Attributes

- -For each field, you can set a foreground attribute for entered -characters, a background attribute for the entire field, and a pad -character for the unfilled portion of the field. You can also -control pagination of the form.

- -This group of four field attributes controls the visual appearance -of the field on the screen, without affecting in any way the data -in the field buffer. - -

-int set_field_fore(FIELD *field,          /* field to alter */
-                   chtype attr);          /* attribute to set */
-
-chtype field_fore(FIELD *field);          /* field to query */
-
-int set_field_back(FIELD *field,          /* field to alter */
-                   chtype attr);          /* attribute to set */
-
-chtype field_back(FIELD *field);          /* field to query */
-
-int set_field_pad(FIELD *field,           /* field to alter */
-                 int pad);                /* pad character to set */
-
-chtype field_pad(FIELD *field);
-
-int set_new_page(FIELD *field,            /* field to alter */
-                 int flag);               /* TRUE to force new page */
-
-chtype new_page(FIELD *field);            /* field to query */
-
- -The attributes set and returned by the first four functions are normal -curses(3x) display attribute values (A_STANDOUT, -A_BOLD, A_REVERSE etc). - -The page bit of a field controls whether it is displayed at the start of -a new form screen. - -

Field Option Bits

- -There is also a large collection of field option bits you can set to control -various aspects of forms processing. You can manipulate them with these -functions: - -
-int set_field_opts(FIELD *field,          /* field to alter */
-                   int attr);             /* attribute to set */
-
-int field_opts_on(FIELD *field,           /* field to alter */
-                  int attr);              /* attributes to turn on */
-
-int field_opts_off(FIELD *field,          /* field to alter */
-                   int attr);             /* attributes to turn off */
-
-int field_opts(FIELD *field);             /* field to query */
-
- -By default, all options are on. Here are the available option bits: -
-
O_VISIBLE -
Controls whether the field is visible on the screen. Can be used -during form processing to hide or pop up fields depending on the value -of parent fields. -
O_ACTIVE -
Controls whether the field is active during forms processing (i.e. -visited by form navigation keys). Can be used to make labels or derived -fields with buffer values alterable by the forms application, not the user. -
O_PUBLIC -
Controls whether data is displayed during field entry. If this option is -turned off on a field, the library will accept and edit data in that field, -but it will not be displayed and the visible field cursor will not move. -You can turn off the O_PUBLIC bit to define password fields. -
O_EDIT -
Controls whether the field's data can be modified. When this option is -off, all editing requests except REQ_PREV_CHOICE and -REQ_NEXT_CHOICE will fail. Such read-only fields may be useful for -help messages. -
O_WRAP -
Controls word-wrapping in multi-line fields. Normally, when any -character of a (blank-separated) word reaches the end of the current line, the -entire word is wrapped to the next line (assuming there is one). When this -option is off, the word will be split across the line break. -
O_BLANK -
Controls field blanking. When this option is on, entering a character at -the first field position erases the entire field (except for the just-entered -character). -
O_AUTOSKIP -
Controls automatic skip to next field when this one fills. Normally, -when the forms user tries to type more data into a field than will fit, -the editing location jumps to next field. When this option is off, the -user's cursor will hang at the end of the field. This option is ignored -in dynamic fields that have not reached their size limit. -
O_NULLOK -
Controls whether validation is applied to -blank fields. Normally, it is not; the user can leave a field blank -without invoking the usual validation check on exit. If this option is -off on a field, exit from it will invoke a validation check. -
O_PASSOK -
Controls whether validation occurs on every exit, or only after -the field is modified. Normally the latter is true. Setting O_PASSOK -may be useful if your field's validation function may change during -forms processing. -
O_STATIC -
Controls whether the field is fixed to its initial dimensions. If you -turn this off, the field becomes dynamic and will -stretch to fit entered data. -
- -A field's options cannot be changed while the field is currently selected. -However, options may be changed on posted fields that are not current.

- -The option values are bit-masks and can be composed with logical-or in -the obvious way. - -

Field Status

- -Every field has a status flag, which is set to FALSE when the field is -created and TRUE when the value in field buffer 0 changes. This flag can -be queried and set directly: - -
-int set_field_status(FIELD *field,      /* field to alter */
-                   int status);         /* mode to set */
-
-int field_status(FIELD *field);         /* fetch mode of field */
-
- -Setting this flag under program control can be useful if you use the same -form repeatedly, looking for modified fields each time.

- -Calling field_status() on a field not currently selected -for input will return a correct value. Calling field_status() on a -field that is currently selected for input may not necessarily give a -correct field status value, because entered data isn't necessarily copied to -buffer zero before the exit validation check. - -To guarantee that the returned status value reflects reality, call -field_status() either (1) in the field's exit validation check -routine, (2) from the field's or form's initialization or termination -hooks, or (3) just after a REQ_VALIDATION request has been -processed by the forms driver. - -

Field User Pointer

- -Each field structure contains one character pointer slot that is not used -by the forms library. It is intended to be used by applications to store -private per-field data. You can manipulate it with: - -
-int set_field_userptr(FIELD *field,       /* field to alter */
-                   char *userptr);        /* mode to set */
-
-char *field_userptr(FIELD *field);        /* fetch mode of field */
-
- -(Properly, this user pointer field ought to have (void *) type. -The (char *) type is retained for System V compatibility.)

- -It is valid to set the user pointer of the default field (with a -set_field_userptr() call passed a NULL field pointer.) -When a new field is created, the default-field user pointer is copied -to initialize the new field's user pointer. - -

Variable-Sized Fields

- -Normally, a field is fixed at the size specified for it at creation -time. If, however, you turn off its O_STATIC bit, it becomes -dynamic and will automatically resize itself to accommodate -data as it is entered. If the field has extra buffers associated with it, -they will grow right along with the main input buffer.

- -A one-line dynamic field will have a fixed height (1) but variable -width, scrolling horizontally to display data within the field area as -originally dimensioned and located. A multi-line dynamic field will -have a fixed width, but variable height (number of rows), scrolling -vertically to display data within the field area as originally -dimensioned and located.

- -Normally, a dynamic field is allowed to grow without limit. But it is -possible to set an upper limit on the size of a dynamic field. You do -it with this function: - -

-int set_max_field(FIELD *field,     /* field to alter (may not be NULL) */
-                   int max_size);   /* upper limit on field size */
-
- -If the field is one-line, max_size is taken to be a column size -limit; if it is multi-line, it is taken to be a line size limit. To disable -any limit, use an argument of zero. The growth limit can be changed whether -or not the O_STATIC bit is on, but has no effect until it is.

- -The following properties of a field change when it becomes dynamic: - -

    -
  • If there is no growth limit, there is no final position of the field; -therefore O_AUTOSKIP and O_NL_OVERLOAD are ignored. -
  • Field justification will be ignored (though whatever justification is -set up will be retained internally and can be queried). -
  • The dup_field() and link_field() calls copy -dynamic-buffer sizes. If the O_STATIC option is set on one of a -collection of links, buffer resizing will occur only when the field is -edited through that link. -
  • The call field_info() will retrieve the original static size of -the field; use dynamic_field_info() to get the actual dynamic size. -
- -

Field Validation

- -By default, a field will accept any data that will fit in its input buffer. -However, it is possible to attach a validation type to a field. If you do -this, any attempt to leave the field while it contains data that doesn't -match the validation type will fail. Some validation types also have a -character-validity check for each time a character is entered in the field.

- -A field's validation check (if any) is not called when -set_field_buffer() modifies the input buffer, nor when that buffer -is changed through a linked field.

- -The form library provides a rich set of pre-defined validation -types, and gives you the capability to define custom ones of your own. You -can examine and change field validation attributes with the following -functions: - -

-int set_field_type(FIELD *field,          /* field to alter */
-                   FIELDTYPE *ftype,      /* type to associate */
-                   ...);                  /* additional arguments*/
-
-FIELDTYPE *field_type(FIELD *field);      /* field to query */
-
- -The validation type of a field is considered an attribute of the field. As -with other field attributes, Also, doing set_field_type() with a -NULL field default will change the system default for validation of -newly-created fields.

- -Here are the pre-defined validation types: - -

TYPE_ALPHA

- -This field type accepts alphabetic data; no blanks, no digits, no special -characters (this is checked at character-entry time). It is set up with: - -
-int set_field_type(FIELD *field,          /* field to alter */
-                   TYPE_ALPHA,            /* type to associate */
-                   int width);            /* maximum width of field */
-
- -The width argument sets a minimum width of data. Typically -you'll want to set this to the field width; if it's greater than the -field width, the validation check will always fail. A minimum width -of zero makes field completion optional. - -

TYPE_ALNUM

- -This field type accepts alphabetic data and digits; no blanks, no special -characters (this is checked at character-entry time). It is set up with: - -
-int set_field_type(FIELD *field,          /* field to alter */
-                   TYPE_ALNUM,            /* type to associate */
-                   int width);            /* maximum width of field */
-
- -The width argument sets a minimum width of data. As with -TYPE_ALPHA, typically you'll want to set this to the field width; if it's -greater than the field width, the validation check will always fail. A -minimum width of zero makes field completion optional. - -

TYPE_ENUM

- -This type allows you to restrict a field's values to be among a specified -set of string values (for example, the two-letter postal codes for U.S. -states). It is set up with: - -
-int set_field_type(FIELD *field,          /* field to alter */
-                   TYPE_ENUM,             /* type to associate */
-                   char **valuelist;      /* list of possible values */
-                   int checkcase;         /* case-sensitive? */
-                   int checkunique);      /* must specify uniquely? */
-
- -The valuelist parameter must point at a NULL-terminated list of -valid strings. The checkcase argument, if true, makes comparison -with the string case-sensitive.

- -When the user exits a TYPE_ENUM field, the validation procedure tries to -complete the data in the buffer to a valid entry. If a complete choice string -has been entered, it is of course valid. But it is also possible to enter a -prefix of a valid string and have it completed for you.

- -By default, if you enter such a prefix and it matches more than one value -in the string list, the prefix will be completed to the first matching -value. But the checkunique argument, if true, requires prefix -matches to be unique in order to be valid.

- -The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests -can be particularly useful with these fields. - -

TYPE_INTEGER

- -This field type accepts an integer. It is set up as follows: - -
-int set_field_type(FIELD *field,          /* field to alter */
-                   TYPE_INTEGER,          /* type to associate */
-                   int padding,           /* # places to zero-pad to */
-                   int vmin, int vmax);   /* valid range */
-
- -Valid characters consist of an optional leading minus and digits. -The range check is performed on exit. If the range maximum is less -than or equal to the minimum, the range is ignored.

- -If the value passes its range check, it is padded with as many leading -zero digits as necessary to meet the padding argument.

- -A TYPE_INTEGER value buffer can conveniently be interpreted -with the C library function atoi(3). - -

TYPE_NUMERIC

- -This field type accepts a decimal number. It is set up as follows: - -
-int set_field_type(FIELD *field,              /* field to alter */
-                   TYPE_NUMERIC,              /* type to associate */
-                   int padding,               /* # places of precision */
-                   double vmin, double vmax); /* valid range */
-
- -Valid characters consist of an optional leading minus and digits. possibly -including a decimal point. If your system supports locale's, the decimal point -character used must be the one defined by your locale. The range check is -performed on exit. If the range maximum is less than or equal to the minimum, -the range is ignored.

- -If the value passes its range check, it is padded with as many trailing -zero digits as necessary to meet the padding argument.

- -A TYPE_NUMERIC value buffer can conveniently be interpreted -with the C library function atof(3). - -

TYPE_REGEXP

- -This field type accepts data matching a regular expression. It is set up -as follows: - -
-int set_field_type(FIELD *field,          /* field to alter */
-                   TYPE_REGEXP,           /* type to associate */
-                   char *regexp);         /* expression to match */
-
- -The syntax for regular expressions is that of regcomp(3). -The check for regular-expression match is performed on exit. - -

Direct Field Buffer Manipulation

- -The chief attribute of a field is its buffer contents. When a form has -been completed, your application usually needs to know the state of each -field buffer. You can find this out with: - -
-char *field_buffer(FIELD *field,          /* field to query */
-                   int bufindex);         /* number of buffer to query */
-
- -Normally, the state of the zero-numbered buffer for each field is set by -the user's editing actions on that field. It's sometimes useful to be able -to set the value of the zero-numbered (or some other) buffer from your -application: - -
-int set_field_buffer(FIELD *field,        /* field to alter */
-                   int bufindex,          /* number of buffer to alter */
-                   char *value);          /* string value to set */
-
- -If the field is not large enough and cannot be resized to a sufficiently -large size to contain the specified value, the value will be truncated -to fit.

- -Calling field_buffer() with a null field pointer will raise an -error. Calling field_buffer() on a field not currently selected -for input will return a correct value. Calling field_buffer() on a -field that is currently selected for input may not necessarily give a -correct field buffer value, because entered data isn't necessarily copied to -buffer zero before the exit validation check. - -To guarantee that the returned buffer value reflects on-screen reality, -call field_buffer() either (1) in the field's exit validation -check routine, (2) from the field's or form's initialization or termination -hooks, or (3) just after a REQ_VALIDATION request has been processed -by the forms driver. - -

Attributes of Forms

- -As with field attributes, form attributes inherit a default from a -system default form structure. These defaults can be queried or set by -of these functions using a form-pointer argument of NULL.

- -The principal attribute of a form is its field list. You can query -and change this list with: - -

-int set_form_fields(FORM *form,           /* form to alter */
-                    FIELD **fields);      /* fields to connect */
-
-char *form_fields(FORM *form);            /* fetch fields of form */
-
-int field_count(FORM *form);              /* count connect fields */
-
- -The second argument of set_form_fields() may be a -NULL-terminated field pointer array like the one required by -new_form(). In that case, the old fields of the form are -disconnected but not freed (and eligible to be connected to other -forms), then the new fields are connected.

- -It may also be null, in which case the old fields are disconnected -(and not freed) but no new ones are connected.

- -The field_count() function simply counts the number of fields -connected to a given from. It returns -1 if the form-pointer argument -is NULL. - -

Control of Form Display

- -In the overview section, you saw that to display a form you normally -start by defining its size (and fields), posting it, and refreshing -the screen. There is an hidden step before posting, which is the -association of the form with a frame window (actually, a pair of -windows) within which it will be displayed. By default, the forms -library associates every form with the full-screen window -stdscr.

- -By making this step explicit, you can associate a form with a declared -frame window on your screen display. This can be useful if you want to -adapt the form display to different screen sizes, dynamically tile -forms on the screen, or use a form as part of an interface layout -managed by panels.

- -The two windows associated with each form have the same functions as -their analogues in the menu library. Both these -windows are painted when the form is posted and erased when the form -is unposted.

- -The outer or frame window is not otherwise touched by the form -routines. It exists so the programmer can associate a title, a -border, or perhaps help text with the form and have it properly -refreshed or erased at post/unpost time. The inner window or subwindow -is where the current form page is actually displayed.

- -In order to declare your own frame window for a form, you'll need to -know the size of the form's bounding rectangle. You can get this -information with: - -

-int scale_form(FORM *form,                /* form to query */
-               int *rows,                 /* form rows */
-               int *cols);                /* form cols */
-
- -The form dimensions are passed back in the locations pointed to by -the arguments. Once you have this information, you can use it to -declare of windows, then use one of these functions: - -
-int set_form_win(FORM *form,              /* form to alter */
-                 WINDOW *win);            /* frame window to connect */
-
-WINDOW *form_win(FORM *form);             /* fetch frame window of form */
-
-int set_form_sub(FORM *form,              /* form to alter */
-                 WINDOW *win);            /* form subwindow to connect */
-
-WINDOW *form_sub(FORM *form);             /* fetch form subwindow of form */
-
- -Note that curses operations, including refresh(), on the form, -should be done on the frame window, not the form subwindow.

- -It is possible to check from your application whether all of a -scrollable field is actually displayed within the menu subwindow. Use -these functions: - -

-int data_ahead(FORM *form);               /* form to be queried */
-
-int data_behind(FORM *form);              /* form to be queried */
-
- -The function data_ahead() returns TRUE if (a) the current -field is one-line and has undisplayed data off to the right, (b) the current -field is multi-line and there is data off-screen below it.

- -The function data_behind() returns TRUE if the first (upper -left hand) character position is off-screen (not being displayed).

- -Finally, there is a function to restore the form window's cursor to the -value expected by the forms driver: - -

-int pos_form_cursor(FORM *)               /* form to be queried */
-
- -If your application changes the form window cursor, call this function before -handing control back to the forms driver in order to re-synchronize it. - -

Input Processing in the Forms Driver

- -The function form_driver() handles virtualized input requests -for form navigation, editing, and validation requests, just as -menu_driver does for menus (see the section on menu input handling). - -
-int form_driver(FORM *form,               /* form to pass input to */
-                int request);             /* form request code */
-
- -Your input virtualization function needs to take input and then convert it -to either an alphanumeric character (which is treated as data to be -entered in the currently-selected field), or a forms processing request.

- -The forms driver provides hooks (through input-validation and -field-termination functions) with which your application code can check -that the input taken by the driver matched what was expected. - -

Page Navigation Requests

- -These requests cause page-level moves through the form, -triggering display of a new form screen. - -
-
REQ_NEXT_PAGE -
Move to the next form page. -
REQ_PREV_PAGE -
Move to the previous form page. -
REQ_FIRST_PAGE -
Move to the first form page. -
REQ_LAST_PAGE -
Move to the last form page. -
- -These requests treat the list as cyclic; that is, REQ_NEXT_PAGE -from the last page goes to the first, and REQ_PREV_PAGE from -the first page goes to the last. - -

Inter-Field Navigation Requests

- -These requests handle navigation between fields on the same page. - -
-
REQ_NEXT_FIELD -
Move to next field. -
REQ_PREV_FIELD -
Move to previous field. -
REQ_FIRST_FIELD -
Move to the first field. -
REQ_LAST_FIELD -
Move to the last field. -
REQ_SNEXT_FIELD -
Move to sorted next field. -
REQ_SPREV_FIELD -
Move to sorted previous field. -
REQ_SFIRST_FIELD -
Move to the sorted first field. -
REQ_SLAST_FIELD -
Move to the sorted last field. -
REQ_LEFT_FIELD -
Move left to field. -
REQ_RIGHT_FIELD -
Move right to field. -
REQ_UP_FIELD -
Move up to field. -
REQ_DOWN_FIELD -
Move down to field. -
- -These requests treat the list of fields on a page as cyclic; that is, -REQ_NEXT_FIELD from the last field goes to the first, and -REQ_PREV_FIELD from the first field goes to the last. The -order of the fields for these (and the REQ_FIRST_FIELD and -REQ_LAST_FIELD requests) is simply the order of the field -pointers in the form array (as set up by new_form() or -set_form_fields()

- -It is also possible to traverse the fields as if they had been sorted in -screen-position order, so the sequence goes left-to-right and top-to-bottom. -To do this, use the second group of four sorted-movement requests.

- -Finally, it is possible to move between fields using visual directions up, -down, right, and left. To accomplish this, use the third group of four -requests. Note, however, that the position of a form for purposes of these -requests is its upper-left corner.

- -For example, suppose you have a multi-line field B, and two -single-line fields A and C on the same line with B, with A to the left -of B and C to the right of B. A REQ_MOVE_RIGHT from A will -go to B only if A, B, and C all share the same first line; -otherwise it will skip over B to C. - -

Intra-Field Navigation Requests

- -These requests drive movement of the edit cursor within the currently -selected field. - -
-
REQ_NEXT_CHAR -
Move to next character. -
REQ_PREV_CHAR -
Move to previous character. -
REQ_NEXT_LINE -
Move to next line. -
REQ_PREV_LINE -
Move to previous line. -
REQ_NEXT_WORD -
Move to next word. -
REQ_PREV_WORD -
Move to previous word. -
REQ_BEG_FIELD -
Move to beginning of field. -
REQ_END_FIELD -
Move to end of field. -
REQ_BEG_LINE -
Move to beginning of line. -
REQ_END_LINE -
Move to end of line. -
REQ_LEFT_CHAR -
Move left in field. -
REQ_RIGHT_CHAR -
Move right in field. -
REQ_UP_CHAR -
Move up in field. -
REQ_DOWN_CHAR -
Move down in field. -
- -Each word is separated from the previous and next characters -by whitespace. The commands to move to beginning and end of line or field -look for the first or last non-pad character in their ranges. - -

Scrolling Requests

- -Fields that are dynamic and have grown and fields explicitly created -with offscreen rows are scrollable. One-line fields scroll horizontally; -multi-line fields scroll vertically. Most scrolling is triggered by -editing and intra-field movement (the library scrolls the field to keep the -cursor visible). It is possible to explicitly request scrolling with the -following requests: - -
-
REQ_SCR_FLINE -
Scroll vertically forward a line. -
REQ_SCR_BLINE -
Scroll vertically backward a line. -
REQ_SCR_FPAGE -
Scroll vertically forward a page. -
REQ_SCR_BPAGE -
Scroll vertically backward a page. -
REQ_SCR_FHPAGE -
Scroll vertically forward half a page. -
REQ_SCR_BHPAGE -
Scroll vertically backward half a page. -
REQ_SCR_FCHAR -
Scroll horizontally forward a character. -
REQ_SCR_BCHAR -
Scroll horizontally backward a character. -
REQ_SCR_HFLINE -
Scroll horizontally one field width forward. -
REQ_SCR_HBLINE -
Scroll horizontally one field width backward. -
REQ_SCR_HFHALF -
Scroll horizontally one half field width forward. -
REQ_SCR_HBHALF -
Scroll horizontally one half field width backward. -
- -For scrolling purposes, a page of a field is the height -of its visible part. - -

Editing Requests

- -When you pass the forms driver an ASCII character, it is treated as a -request to add the character to the field's data buffer. Whether this -is an insertion or a replacement depends on the field's edit mode -(insertion is the default.

- -The following requests support editing the field and changing the edit -mode: - -

-
REQ_INS_MODE -
Set insertion mode. -
REQ_OVL_MODE -
Set overlay mode. -
REQ_NEW_LINE -
New line request (see below for explanation). -
REQ_INS_CHAR -
Insert space at character location. -
REQ_INS_LINE -
Insert blank line at character location. -
REQ_DEL_CHAR -
Delete character at cursor. -
REQ_DEL_PREV -
Delete previous word at cursor. -
REQ_DEL_LINE -
Delete line at cursor. -
REQ_DEL_WORD -
Delete word at cursor. -
REQ_CLR_EOL -
Clear to end of line. -
REQ_CLR_EOF -
Clear to end of field. -
REQ_CLEAR_FIELD -
Clear entire field. -
- -The behavior of the REQ_NEW_LINE and REQ_DEL_PREV requests -is complicated and partly controlled by a pair of forms options. -The special cases are triggered when the cursor is at the beginning of -a field, or on the last line of the field.

- -First, we consider REQ_NEW_LINE:

- -The normal behavior of REQ_NEW_LINE in insert mode is to break the -current line at the position of the edit cursor, inserting the portion of -the current line after the cursor as a new line following the current -and moving the cursor to the beginning of that new line (you may think -of this as inserting a newline in the field buffer).

- -The normal behavior of REQ_NEW_LINE in overlay mode is to clear the -current line from the position of the edit cursor to end of line. -The cursor is then moved to the beginning of the next line.

- -However, REQ_NEW_LINE at the beginning of a field, or on the -last line of a field, instead does a REQ_NEXT_FIELD. -O_NL_OVERLOAD option is off, this special action is -disabled.

- -Now, let us consider REQ_DEL_PREV:

- -The normal behavior of REQ_DEL_PREV is to delete the previous -character. If insert mode is on, and the cursor is at the start of a -line, and the text on that line will fit on the previous one, it -instead appends the contents of the current line to the previous one -and deletes the current line (you may think of this as deleting a -newline from the field buffer).

- -However, REQ_DEL_PREV at the beginning of a field is instead -treated as a REQ_PREV_FIELD.

If the -O_BS_OVERLOAD option is off, this special action is -disabled and the forms driver just returns E_REQUEST_DENIED.

- -See Form Options for discussion of how to set -and clear the overload options. - -

Order Requests

- -If the type of your field is ordered, and has associated functions -for getting the next and previous values of the type from a given value, -there are requests that can fetch that value into the field buffer: - -
-
REQ_NEXT_CHOICE -
Place the successor value of the current value in the buffer. -
REQ_PREV_CHOICE -
Place the predecessor value of the current value in the buffer. -
- -Of the built-in field types, only TYPE_ENUM has built-in successor -and predecessor functions. When you define a field type of your own -(see Custom Validation Types), you can associate -our own ordering functions. - -

Application Commands

- -Form requests are represented as integers above the curses value -greater than KEY_MAX and less than or equal to the constant -MAX_COMMAND. If your input-virtualization routine returns a -value above MAX_COMMAND, the forms driver will ignore it. - -

Field Change Hooks

- -It is possible to set function hooks to be executed whenever the -current field or form changes. Here are the functions that support this: - -
-typedef void	(*HOOK)();       /* pointer to function returning void */
-
-int set_form_init(FORM *form,    /* form to alter */
-                  HOOK hook);    /* initialization hook */
-
-HOOK form_init(FORM *form);      /* form to query */
-
-int set_form_term(FORM *form,    /* form to alter */
-                  HOOK hook);    /* termination hook */
-
-HOOK form_term(FORM *form);      /* form to query */
-
-int set_field_init(FORM *form,   /* form to alter */
-                  HOOK hook);    /* initialization hook */
-
-HOOK field_init(FORM *form);     /* form to query */
-
-int set_field_term(FORM *form,   /* form to alter */
-                  HOOK hook);    /* termination hook */
-
-HOOK field_term(FORM *form);     /* form to query */
-
- -These functions allow you to either set or query four different hooks. -In each of the set functions, the second argument should be the -address of a hook function. These functions differ only in the timing -of the hook call. - -
-
form_init -
This hook is called when the form is posted; also, just after -each page change operation. -
field_init -
This hook is called when the form is posted; also, just after -each field change -
field_term -
This hook is called just after field validation; that is, just before -the field is altered. It is also called when the form is unposted. -
form_term -
This hook is called when the form is unposted; also, just before -each page change operation. -
- -Calls to these hooks may be triggered -
    -
  1. When user editing requests are processed by the forms driver -
  2. When the current page is changed by set_current_field() call -
  3. When the current field is changed by a set_form_page() call -
- -See Field Change Commands for discussion of the latter -two cases.

- -You can set a default hook for all fields by passing one of the set functions -a NULL first argument.

- -You can disable any of these hooks by (re)setting them to NULL, the default -value. - -

Field Change Commands

- -Normally, navigation through the form will be driven by the user's -input requests. But sometimes it is useful to be able to move the -focus for editing and viewing under control of your application, or -ask which field it currently is in. The following functions help you -accomplish this: - -
-int set_current_field(FORM *form,         /* form to alter */
-                      FIELD *field);      /* field to shift to */
-
-FIELD *current_field(FORM *form);         /* form to query */
-
-int field_index(FORM *form,               /* form to query */
-                FIELD *field);            /* field to get index of */
-
- -The function field_index() returns the index of the given field -in the given form's field array (the array passed to new_form() or -set_form_fields()).

- -The initial current field of a form is the first active field on the -first page. The function set_form_fields() resets this.

- -It is also possible to move around by pages. - -

-int set_form_page(FORM *form,             /* form to alter */
-                  int page);              /* page to go to (0-origin) */
-
-int form_page(FORM *form);                /* return form's current page */
-
- -The initial page of a newly-created form is 0. The function -set_form_fields() resets this. - -

Form Options

- -Like fields, forms may have control option bits. They can be changed -or queried with these functions: - -
-int set_form_opts(FORM *form,             /* form to alter */
-                  int attr);              /* attribute to set */
-
-int form_opts_on(FORM *form,              /* form to alter */
-                 int attr);               /* attributes to turn on */
-
-int form_opts_off(FORM *form,             /* form to alter */
-                  int attr);              /* attributes to turn off */
-
-int form_opts(FORM *form);                /* form to query */
-
- -By default, all options are on. Here are the available option bits: - -
-
O_NL_OVERLOAD -
Enable overloading of REQ_NEW_LINE as described in Editing Requests. The value of this option is -ignored on dynamic fields that have not reached their size limit; -these have no last line, so the circumstances for triggering a -REQ_NEXT_FIELD never arise. -
O_BS_OVERLOAD -
Enable overloading of REQ_DEL_PREV as described in -Editing Requests. -
- -The option values are bit-masks and can be composed with logical-or in -the obvious way. - -

Custom Validation Types

- -The form library gives you the capability to define custom -validation types of your own. Further, the optional additional arguments -of set_field_type effectively allow you to parameterize validation -types. Most of the complications in the validation-type interface have to -do with the handling of the additional arguments within custom validation -functions. - -

Union Types

- -The simplest way to create a custom data type is to compose it from two -preexisting ones: - -
-FIELD *link_fieldtype(FIELDTYPE *type1,
-                      FIELDTYPE *type2);
-
- -This function creates a field type that will accept any of the values -legal for either of its argument field types (which may be either -predefined or programmer-defined). - -If a set_field_type() call later requires arguments, the new -composite type expects all arguments for the first type, than all arguments -for the second. Order functions (see Order Requests) -associated with the component types will work on the composite; what it does -is check the validation function for the first type, then for the second, to -figure what type the buffer contents should be treated as. - -

New Field Types

- -To create a field type from scratch, you need to specify one or both of the -following things: - -
    -
  • A character-validation function, to check each character as it is entered. -
  • A field-validation function to be applied on exit from the field. -
- -Here's how you do that: -
-typedef int	(*HOOK)();       /* pointer to function returning int */
-
-FIELDTYPE *new_fieldtype(HOOK f_validate, /* field validator */
-                         HOOK c_validate) /* character validator */
-
-
-int free_fieldtype(FIELDTYPE *ftype);     /* type to free */
-
- -At least one of the arguments of new_fieldtype() must be -non-NULL. The forms driver will automatically call the new type's -validation functions at appropriate points in processing a field of -the new type.

- -The function free_fieldtype() deallocates the argument -fieldtype, freeing all storage associated with it.

- -Normally, a field validator is called when the user attempts to -leave the field. Its first argument is a field pointer, from which it -can get to field buffer 0 and test it. If the function returns TRUE, -the operation succeeds; if it returns FALSE, the edit cursor stays in -the field.

- -A character validator gets the character passed in as a first argument. -It too should return TRUE if the character is valid, FALSE otherwise. - -

Validation Function Arguments

- -Your field- and character- validation functions will be passed a -second argument as well. This second argument is the address of a -structure (which we'll call a pile) built from any of the -field-type-specific arguments passed to set_field_type(). If -no such arguments are defined for the field type, this pile pointer -argument will be NULL.

- -In order to arrange for such arguments to be passed to your validation -functions, you must associate a small set of storage-management functions -with the type. The forms driver will use these to synthesize a pile -from the trailing arguments of each set_field_type() argument, and -a pointer to the pile will be passed to the validation functions.

- -Here is how you make the association: - -

-typedef char	*(*PTRHOOK)();    /* pointer to function returning (char *) */
-typedef void	(*VOIDHOOK)();    /* pointer to function returning void */
-
-int set_fieldtype_arg(FIELDTYPE *type,    /* type to alter */
-                      PTRHOOK make_str,   /* make structure from args */
-                      PTRHOOK copy_str,   /* make copy of structure */
-                      VOIDHOOK free_str); /* free structure storage */
-
- -Here is how the storage-management hooks are used: - -
-
make_str -
This function is called by set_field_type(). It gets one -argument, a va_list of the type-specific arguments passed to -set_field_type(). It is expected to return a pile pointer to a data -structure that encapsulates those arguments. -
copy_str -
This function is called by form library functions that allocate new -field instances. It is expected to take a pile pointer, copy the pile -to allocated storage, and return the address of the pile copy. -
free_str -
This function is called by field- and type-deallocation routines in the -library. It takes a pile pointer argument, and is expected to free the -storage of that pile. -
- -The make_str and copy_str functions may return NULL to -signal allocation failure. The library routines will that call them will -return error indication when this happens. Thus, your validation functions -should never see a NULL file pointer and need not check specially for it. - -

Order Functions For Custom Types

- -Some custom field types are simply ordered in the same well-defined way -that TYPE_ENUM is. For such types, it is possible to define -successor and predecessor functions to support the REQ_NEXT_CHOICE -and REQ_PREV_CHOICE requests. Here's how: - -
-typedef int	(*INTHOOK)();     /* pointer to function returning int */
-
-int set_fieldtype_arg(FIELDTYPE *type,    /* type to alter */
-                      INTHOOK succ,       /* get successor value */
-                      INTHOOK pred);      /* get predecessor value */
-
- -The successor and predecessor arguments will each be passed two arguments; -a field pointer, and a pile pointer (as for the validation functions). They -are expected to use the function field_buffer() to read the -current value, and set_field_buffer() on buffer 0 to set the next -or previous value. Either hook may return TRUE to indicate success (a -legal next or previous value was set) or FALSE to indicate failure. - -

Avoiding Problems

- -The interface for defining custom types is complicated and tricky. -Rather than attempting to create a custom type entirely from scratch, -you should start by studying the library source code for whichever of -the pre-defined types seems to be closest to what you want.

- -Use that code as a model, and evolve it towards what you really want. -You will avoid many problems and annoyances that way. The code -in the ncurses library has been specifically exempted from -the package copyright to support this.

- -If your custom type defines order functions, have do something intuitive -with a blank field. A useful convention is to make the successor of a -blank field the types minimum value, and its predecessor the maximum. - -