diff options
| author | Theo de Raadt <deraadt@cvs.openbsd.org> | 2014-07-16 10:35:55 +0000 |
|---|---|---|
| committer | Theo de Raadt <deraadt@cvs.openbsd.org> | 2014-07-16 10:35:55 +0000 |
| commit | 3c6ca3672af23db42fb310780b8dc299f5e60597 (patch) | |
| tree | 29da41ee7abc7c219c0a341a8adf5ec6a334ebbe /lib/libcurses/doc/ncurses-intro.html | |
| parent | 63921c3353023c5ce3cbe958fa80269120237374 (diff) | |
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)
Diffstat (limited to 'lib/libcurses/doc/ncurses-intro.html')
| -rw-r--r-- | lib/libcurses/doc/ncurses-intro.html | 2722 |
1 files changed, 0 insertions, 2722 deletions
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 @@ -<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"> -<!-- - $Id: ncurses-intro.html,v 1.7 2010/01/12 23:22:06 nicm Exp $ - **************************************************************************** - * Copyright (c) 1998-2006,2007 Free Software Foundation, Inc. * - * * - * Permission is hereby granted, free of charge, to any person obtaining a * - * copy of this software and associated documentation files (the * - * "Software"), to deal in the Software without restriction, including * - * without limitation the rights to use, copy, modify, merge, publish, * - * distribute, distribute with modifications, sublicense, and/or sell * - * copies of the Software, and to permit persons to whom the Software is * - * furnished to do so, subject to the following conditions: * - * * - * The above copyright notice and this permission notice shall be included * - * in all copies or substantial portions of the Software. * - * * - * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * - * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * - * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * - * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * - * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * - * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * - * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * - * * - * Except as contained in this notice, the name(s) of the above copyright * - * holders shall not be used in advertising or otherwise to promote the * - * sale, use or other dealings in this Software without prior written * - * authorization. * - **************************************************************************** ---> -<HTML> -<HEAD> -<TITLE>Writing Programs with NCURSES</TITLE> -<link rev="made" href="mailto:bugs-ncurses@gnu.org"> -<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> -</HEAD> -<BODY> - -<H1>Writing Programs with NCURSES</H1> - -<BLOCKQUOTE> -by Eric S. Raymond and Zeyd M. Ben-Halim<BR> -updates since release 1.9.9e by Thomas Dickey -</BLOCKQUOTE> - -<H1>Contents</H1> -<UL> -<LI><A HREF="#introduction">Introduction</A> -<UL> -<LI><A HREF="#history">A Brief History of Curses</A> -<LI><A HREF="#scope">Scope of This Document</A> -<LI><A HREF="#terminology">Terminology</A> -</UL> -<LI><A HREF="#curses">The Curses Library</A> -<UL> -<LI><A HREF="#overview">An Overview of Curses</A> -<UL> -<LI><A HREF="#compiling">Compiling Programs using Curses</A> -<LI><A HREF="#updating">Updating the Screen</A> -<LI><A HREF="#stdscr">Standard Windows and Function Naming Conventions</A> -<LI><A HREF="#variables">Variables</A> -</UL> -<LI><A HREF="#using">Using the Library</A> -<UL> -<LI><A HREF="#starting">Starting up</A> -<LI><A HREF="#output">Output</A> -<LI><A HREF="#input">Input</A> -<LI><A HREF="#formschars">Using Forms Characters</A> -<LI><A HREF="#attributes">Character Attributes and Color</A> -<LI><A HREF="#mouse">Mouse Interfacing</A> -<LI><A HREF="#finishing">Finishing Up</A> -</UL> -<LI><A HREF="#functions">Function Descriptions</A> -<UL> -<LI><A HREF="#init">Initialization and Wrapup</A> -<LI><A HREF="#flush">Causing Output to the Terminal</A> -<LI><A HREF="#lowlevel">Low-Level Capability Access</A> -<LI><A HREF="#debugging">Debugging</A> -</UL> -<LI><A HREF="#hints">Hints, Tips, and Tricks</A> -<UL> -<LI><A HREF="#caution">Some Notes of Caution</A> -<LI><A HREF="#leaving">Temporarily Leaving ncurses Mode</A> -<LI><A HREF="#xterm">Using <CODE>ncurses</CODE> under <CODE>xterm</CODE></A> -<LI><A HREF="#screens">Handling Multiple Terminal Screens</A> -<LI><A HREF="#testing">Testing for Terminal Capabilities</A> -<LI><A HREF="#tuning">Tuning for Speed</A> -<LI><A HREF="#special">Special Features of <CODE>ncurses</CODE></A> -</UL> -<LI><A HREF="#compat">Compatibility with Older Versions</A> -<UL> -<LI><A HREF="#refbug">Refresh of Overlapping Windows</A> -<LI><A HREF="#backbug">Background Erase</A> -</UL> -<LI><A HREF="#xsifuncs">XSI Curses Conformance</A> -</UL> -<LI><A HREF="#panels">The Panels Library</A> -<UL> -<LI><A HREF="#pcompile">Compiling With the Panels Library</A> -<LI><A HREF="#poverview">Overview of Panels</A> -<LI><A HREF="#pstdscr">Panels, Input, and the Standard Screen</A> -<LI><A HREF="#hiding">Hiding Panels</A> -<LI><A HREF="#pmisc">Miscellaneous Other Facilities</A> -</UL> -<LI><A HREF="#menu">The Menu Library</A> -<UL> -<LI><A HREF="#mcompile">Compiling with the menu Library</A> -<LI><A HREF="#moverview">Overview of Menus</A> -<LI><A HREF="#mselect">Selecting items</A> -<LI><A HREF="#mdisplay">Menu Display</A> -<LI><A HREF="#mwindows">Menu Windows</A> -<LI><A HREF="#minput">Processing Menu Input</A> -<LI><A HREF="#mmisc">Miscellaneous Other Features</A> -</UL> -<LI><A HREF="#form">The Forms Library</A> -<UL> -<LI><A HREF="#fcompile">Compiling with the forms Library</A> -<LI><A HREF="#foverview">Overview of Forms</A> -<LI><A HREF="#fcreate">Creating and Freeing Fields and Forms</A> -<LI><A HREF="#fattributes">Fetching and Changing Field Attributes</A> -<UL> -<LI><A HREF="#fsizes">Fetching Size and Location Data</A> -<LI><A HREF="#flocation">Changing the Field Location</A> -<LI><A HREF="#fjust">The Justification Attribute</A> -<LI><A HREF="#fdispatts">Field Display Attributes</A> -<LI><A HREF="#foptions">Field Option Bits</A> -<LI><A HREF="#fstatus">Field Status</A> -<LI><A HREF="#fuser">Field User Pointer</A> -</UL> -<LI><A HREF="#fdynamic">Variable-Sized Fields</A> -<LI><A HREF="#fvalidation">Field Validation</A> -<UL> -<LI><A HREF="#ftype_alpha">TYPE_ALPHA</A> -<LI><A HREF="#ftype_alnum">TYPE_ALNUM</A> -<LI><A HREF="#ftype_enum">TYPE_ENUM</A> -<LI><A HREF="#ftype_integer">TYPE_INTEGER</A> -<LI><A HREF="#ftype_numeric">TYPE_NUMERIC</A> -<LI><A HREF="#ftype_regexp">TYPE_REGEXP</A> -</UL> -<LI><A HREF="#fbuffer">Direct Field Buffer Manipulation</A> -<LI><A HREF="#formattrs">Attributes of Forms</A> -<LI><A HREF="#fdisplay">Control of Form Display</A> -<LI><A HREF="#fdriver">Input Processing in the Forms Driver</A> -<UL> -<LI><A HREF="#fpage">Page Navigation Requests</A> -<LI><A HREF="#ffield">Inter-Field Navigation Requests</A> -<LI><A HREF="#fifield">Intra-Field Navigation Requests</A> -<LI><A HREF="#fscroll">Scrolling Requests</A> -<LI><A HREF="#fedit">Field Editing Requests</A> -<LI><A HREF="#forder">Order Requests</A> -<LI><A HREF="#fappcmds">Application Commands</A> -</UL> -<LI><A HREF="#fhooks">Field Change Hooks</A> -<LI><A HREF="#ffocus">Field Change Commands</A> -<LI><A HREF="#frmoptions">Form Options</A> -<LI><A HREF="#fcustom">Custom Validation Types</A> -<UL> -<LI><A HREF="#flinktypes">Union Types</A> -<LI><A HREF="#fnewtypes">New Field Types</A> -<LI><A HREF="#fcheckargs">Validation Function Arguments</A> -<LI><A HREF="#fcustorder">Order Functions For Custom Types</A> -<LI><A HREF="#fcustprobs">Avoiding Problems</A> -</UL> -</UL> -</UL> - -<HR> -<H1><A NAME="introduction">Introduction</A></H1> - -This document is an introduction to programming with <CODE>curses</CODE>. It is -not an exhaustive reference for the curses Application Programming Interface -(API); that role is filled by the <CODE>curses</CODE> manual pages. Rather, it -is intended to help C programmers ease into using the package. <P> - -This document is aimed at C applications programmers not yet specifically -familiar with ncurses. If you are already an experienced <CODE>curses</CODE> -programmer, you should nevertheless read the sections on -<A HREF="#mouse">Mouse Interfacing</A>, <A HREF="#debugging">Debugging</A>, -<A HREF="#compat">Compatibility with Older Versions</A>, -and <A HREF="#hints">Hints, Tips, and Tricks</A>. These will bring you up -to speed on the special features and quirks of the <CODE>ncurses</CODE> -implementation. If you are not so experienced, keep reading. <P> - -The <CODE>curses</CODE> 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. <CODE>Curses</CODE> uses terminfo, which -is a database format that can describe the capabilities of thousands of -different terminals. <P> - -The <CODE>curses</CODE> 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 <EM>xterm(1)</EM>; the <CODE>curses</CODE> -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 <CODE>curses</CODE> -will typically be a great deal simpler and less expensive than one using an -X toolkit. - -<H2><A NAME="history">A Brief History of Curses</A></H2> - -Historically, the first ancestor of <CODE>curses</CODE> was the routines written to -provide screen-handling for the game <CODE>rogue</CODE>; these used the -already-existing <CODE>termcap</CODE> database facility for describing terminal -capabilities. These routines were abstracted into a documented library and -first released with the early BSD UNIX versions. <P> - -System III UNIX from Bell Labs featured a rewritten and much-improved -<CODE>curses</CODE> 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, <CODE>curses</CODE> evolved to use more facilities and offer -more capabilities, going far beyond BSD curses in power and flexibility. - -<H2><A NAME="scope">Scope of This Document</A></H2> - -This document describes <CODE>ncurses</CODE>, a free implementation of -the System V <CODE>curses</CODE> API with some clearly marked extensions. -It includes the following System V curses features: -<UL> -<LI>Support for multiple screen highlights (BSD curses could only -handle one `standout' highlight, usually reverse-video). -<LI>Support for line- and box-drawing using forms characters. -<LI>Recognition of function keys on input. -<LI>Color support. -<LI>Support for pads (windows of larger than screen size on which the -screen or a subwindow defines a viewport). -</UL> - -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. <P> - -The <CODE>ncurses</CODE> 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. <P> - -The <CODE>ncurses</CODE> package was originated by Pavel Curtis. The original -maintainer of this package is -<A HREF="mailto:zmbenhal@netcom.com">Zeyd Ben-Halim</A> -<zmbenhal@netcom.com>. -<A HREF="mailto:esr@snark.thyrsus.com">Eric S. Raymond</A> -<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 -<A HREF="http://www.adahome.com">Ada95</A> binding. -Ongoing work is being done by -<A HREF="mailto:dickey@invisible-island.net">Thomas Dickey</A> (maintainer). -Contact the current maintainers at -<A HREF="mailto:bug-ncurses@gnu.org">bug-ncurses@gnu.org</A>. -<P> - -This document also describes the <A HREF="#panels">panels</A> 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). <P> - -Finally, this document describes in detail the <A HREF="#menu">menus</A> and <A -HREF="#form">forms</A> extension libraries, also cloned from System V, -which support easy construction and sequences of menus and fill-in -forms. - - -<H2><A NAME="terminology">Terminology</A></H2> - -In this document, the following terminology is used with reasonable -consistency: - -<DL> -<DT> window -<DD> -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. -<DT> screens -<DD> -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, <CODE>stdscr</CODE>, is automatically provided for the programmer. -<DT> terminal screen -<DD> -The package's idea of what the terminal display currently looks like, i.e., -what the user sees now. This is a special screen. -</DL> - -<H1><A NAME="curses">The Curses Library</A></H1> - -<H2><A NAME="overview">An Overview of Curses</A></H2> - -<H3><A NAME="compiling">Compiling Programs using Curses</A></H3> - -In order to use the library, it is necessary to have certain types and -variables defined. Therefore, the programmer must have a line: - -<PRE> - #include <curses.h> -</PRE> - -at the top of the program source. The screen package uses the Standard I/O -library, so <CODE><curses.h></CODE> includes -<CODE><stdio.h></CODE>. <CODE><curses.h></CODE> also includes -<CODE><termios.h></CODE>, <CODE><termio.h></CODE>, or -<CODE><sgtty.h></CODE> depending on your system. It is redundant (but -harmless) for the programmer to do these includes, too. In linking with -<CODE>curses</CODE> you need to have <CODE>-lncurses</CODE> in your LDFLAGS or on the -command line. There is no need for any other libraries. - -<H3><A NAME="updating">Updating the Screen</A></H3> - -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 <CODE>curscr</CODE>, for current screen) is a -screen image of what the terminal currently looks like. Another screen (called -<CODE>stdscr</CODE>, for standard screen) is provided by default to make changes -on. <P> - -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. <P> - -To make the section of physical screen corresponding to a window reflect the -contents of the window structure, the routine <CODE>refresh()</CODE> (or -<CODE>wrefresh()</CODE> if the window is not <CODE>stdscr</CODE>) is called. <P> - -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. - -<H3><A NAME="stdscr">Standard Windows and Function Naming Conventions</A></H3> - -As hinted above, the routines can use several windows, but two are -automatically given: <CODE>curscr</CODE>, which knows what the terminal looks like, -and <CODE>stdscr</CODE>, which is what the programmer wants the terminal to look -like next. The user should never actually access <CODE>curscr</CODE> directly. -Changes should be made to through the API, and then the routine -<CODE>refresh()</CODE> (or <CODE>wrefresh()</CODE>) called. <P> - -Many functions are defined to use <CODE>stdscr</CODE> as a default screen. For -example, to add a character to <CODE>stdscr</CODE>, one calls <CODE>addch()</CODE> with -the desired character as argument. To write to a different window. use the -routine <CODE>waddch()</CODE> (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. <P> - -In order to move the current (y, x) coordinates from one point to another, the -routines <CODE>move()</CODE> and <CODE>wmove()</CODE> 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 - -<PRE> - move(y, x); - addch(ch); -</PRE> - -can be replaced by - -<PRE> - mvaddch(y, x, ch); -</PRE> - -and - -<PRE> - wmove(win, y, x); - waddch(win, ch); -</PRE> - -can be replaced by - -<PRE> - mvwaddch(win, y, x, ch); -</PRE> - -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. - -<H3><A NAME="variables">Variables</A></H3> - -The <CODE>curses</CODE> library sets some variables describing the terminal -capabilities. - -<PRE> - type name description - ------------------------------------------------------------------ - int LINES number of lines on the terminal - int COLS number of columns on the terminal -</PRE> - -The <CODE>curses.h</CODE> also introduces some <CODE>#define</CODE> constants and types -of general usefulness: - -<DL> -<DT> <CODE>bool</CODE> -<DD> boolean type, actually a `char' (e.g., <CODE>bool doneit;</CODE>) -<DT> <CODE>TRUE</CODE> -<DD> boolean `true' flag (1). -<DT> <CODE>FALSE</CODE> -<DD> boolean `false' flag (0). -<DT> <CODE>ERR</CODE> -<DD> error flag returned by routines on a failure (-1). -<DT> <CODE>OK</CODE> -<DD> error flag returned by routines when things go right. -</DL> - -<H2><A NAME="using">Using the Library</A></H2> - -Now we describe how to actually use the screen package. In it, we assume all -updating, reading, etc. is applied to <CODE>stdscr</CODE>. These instructions will -work on any window, providing you change the function names and parameters as -mentioned above. <P> - -Here is a sample program to motivate the discussion: - -<PRE> -#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); -} -</PRE> - -<H3><A NAME="starting">Starting up</A></H3> - -In order to use the screen package, the routines must know about terminal -characteristics, and the space for <CODE>curscr</CODE> and <CODE>stdscr</CODE> must be -allocated. These function <CODE>initscr()</CODE> 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, <CODE>initscr()</CODE> will terminate -the program with an error message. <CODE>initscr()</CODE> 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 <CODE>curscr</CODE> or <CODE>stdscr</CODE> 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 <CODE>nl()</CODE> and <CODE>cbreak()</CODE> should be called -after <CODE>initscr()</CODE>. <P> - -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 -<CODE>scrollok()</CODE>. If you want the cursor to be left in place after -the last change, use <CODE>leaveok()</CODE>. If this isn't done, -<CODE>refresh()</CODE> will move the cursor to the window's current (y, x) -coordinates after updating it. <P> - -You can create new windows of your own using the functions <CODE>newwin()</CODE>, -<CODE>derwin()</CODE>, and <CODE>subwin()</CODE>. The routine <CODE>delwin()</CODE> will -allow you to get rid of old windows. All the options described above can be -applied to any window. - -<H3><A NAME="output">Output</A></H3> - -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 -<CODE>addch()</CODE> and <CODE>move()</CODE>. <CODE>addch()</CODE> adds a character at the -current (y, x) coordinates. <CODE>move()</CODE> changes the current (y, x) -coordinates to whatever you want them to be. It returns <CODE>ERR</CODE> if you -try to move off the window. As mentioned above, you can combine the two into -<CODE>mvaddch()</CODE> to do both things at once. <P> - -The other output functions, such as <CODE>addstr()</CODE> and <CODE>printw()</CODE>, -all call <CODE>addch()</CODE> to add characters to the window. <P> - -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 -<CODE>refresh()</CODE>. In order to optimize finding changes, <CODE>refresh()</CODE> -assumes that any part of the window not changed since the last -<CODE>refresh()</CODE> 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 <CODE>touchwin()</CODE> is provided -to make it look like the entire window has been changed, thus making -<CODE>refresh()</CODE> check the whole subsection of the terminal for changes. <P> - -If you call <CODE>wrefresh()</CODE> with <CODE>curscr</CODE> as its argument, it will -make the screen look like <CODE>curscr</CODE> thinks it looks like. This is useful -for implementing a command which would redraw the screen in case it get messed -up. - -<H3><A NAME="input">Input</A></H3> - -The complementary function to <CODE>addch()</CODE> is <CODE>getch()</CODE> which, if -echo is set, will call <CODE>addch()</CODE> 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 <CODE>getch()</CODE>; otherwise, -the program's output will be unpredictable. <P> - -When you need to accept line-oriented input in a window, the functions -<CODE>wgetstr()</CODE> and friends are available. There is even a <CODE>wscanw()</CODE> -function that can do <CODE>scanf()</CODE>(3)-style multi-field parsing on window -input. These pseudo-line-oriented functions turn on echoing while they -execute. <P> - -The example code above uses the call <CODE>keypad(stdscr, TRUE)</CODE> to enable -support for function-key mapping. With this feature, the <CODE>getch()</CODE> code -watches the input stream for character sequences that correspond to arrow and -function keys. These sequences are returned as pseudo-character values. The -<CODE>#define</CODE> values returned are listed in the <CODE>curses.h</CODE> The -mapping from sequences to <CODE>#define</CODE> values is determined by -<CODE>key_</CODE> capabilities in the terminal's terminfo entry. - -<H3><A NAME="formschars">Using Forms Characters</A></H3> - -The <CODE>addch()</CODE> function (and some others, including <CODE>box()</CODE> and -<CODE>border()</CODE>) can accept some pseudo-character arguments which are specially -defined by <CODE>ncurses</CODE>. These are <CODE>#define</CODE> values set up in -the <CODE>curses.h</CODE> header; see there for a complete list (look for -the prefix <CODE>ACS_</CODE>). <P> - -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, <CODE>curses.h</CODE> will map them to a -recognizable (though ugly) set of ASCII defaults. - -<H3><A NAME="attributes">Character Attributes and Color</A></H3> - -The <CODE>ncurses</CODE> package supports screen highlights including standout, -reverse-video, underline, and blink. It also supports color, which is treated -as another kind of highlight. <P> - -Highlights are encoded, internally, as high bits of the pseudo-character type -(<CODE>chtype</CODE>) that <CODE>curses.h</CODE> uses to represent the contents of a -screen cell. See the <CODE>curses.h</CODE> header file for a complete list of -highlight mask values (look for the prefix <CODE>A_</CODE>).<P> - -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 <CODE>addch()</CODE> call, -or any other output call that takes a <CODE>chtype</CODE> argument. <P> - -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 -<CODE>attron()</CODE>, <CODE>attroff()</CODE>, and <CODE>attrset()</CODE>; 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 <CODE>init_pair()</CODE> values. <P> - -Once you've done an <CODE>init_pair()</CODE> that creates color-pair N, you can -use <CODE>COLOR_PAIR(N)</CODE> as a highlight that invokes that particular -color combination. Note that <CODE>COLOR_PAIR(N)</CODE>, for constant N, -is itself a compile-time constant and can be used in initializers. - -<H3><A NAME="mouse">Mouse Interfacing</A></H3> - -The <CODE>ncurses</CODE> library also provides a mouse interface. -<!-- The 'note' tag is not portable enough --> -<blockquote> -<strong>NOTE:</strong> this facility is specific to <CODE>ncurses</CODE>, 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. -</blockquote> - -Presently, mouse event reporting works in the following environments: -<ul> -<li>xterm and similar programs such as rxvt. -<li>Linux console, when configured with <CODE>gpm</CODE>(1), Alessandro -Rubini's mouse server. -<li>FreeBSD sysmouse (console) -<li>OS/2 EMX -</ul> -<P> -The mouse interface is very simple. To activate it, you use the function -<CODE>mousemask()</CODE>, 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. <P> - -Once the mouse is active, your application's command loop should watch -for a return value of <CODE>KEY_MOUSE</CODE> from <CODE>wgetch()</CODE>. When -you see this, a mouse event report has been queued. To pick it off -the queue, use the function <CODE>getmouse()</CODE> (you must do this before -the next <CODE>wgetch()</CODE>, otherwise another mouse event might come -in and make the first one inaccessible). <P> - -Each call to <CODE>getmouse()</CODE> 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. <P> - -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. <P> - -The class of visible events may be changed at any time via <CODE>mousemask()</CODE>. -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. <P> - -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. <P> - -Because mouse event reporting will not be available in all -environments, it would be unwise to build <CODE>ncurses</CODE> -applications that <EM>require</EM> 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 -<CODE>ncurses</CODE> distribution (<CODE>bs</CODE> and <CODE>knight</CODE>) contain -code that illustrates how this can be done. <P> - -See the manual page <CODE>curs_mouse(3X)</CODE> for full details of the -mouse-interface functions. - -<H3><A NAME="finishing">Finishing Up</A></H3> - -In order to clean up after the <CODE>ncurses</CODE> routines, the routine -<CODE>endwin()</CODE> is provided. It restores tty modes to what they were when -<CODE>initscr()</CODE> was first called, and moves the cursor down to the -lower-left corner. Thus, anytime after the call to initscr, <CODE>endwin()</CODE> -should be called before exiting. - -<H2><A NAME="functions">Function Descriptions</A></H2> - -We describe the detailed behavior of some important curses functions here, as a -supplement to the manual page descriptions. - -<H3><A NAME="init">Initialization and Wrapup</A></H3> - -<DL> -<DT> <CODE>initscr()</CODE> -<DD> The first function called should almost always be <CODE>initscr()</CODE>. -This will determine the terminal type and -initialize curses data structures. <CODE>initscr()</CODE> also arranges that -the first call to <CODE>refresh()</CODE> 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 (<CODE>slk_init()</CODE>, <CODE>filter()</CODE>, -<CODE>ripoffline()</CODE>, <CODE>use_env()</CODE>, and, if you are using multiple -terminals, <CODE>newterm()</CODE>.) -<DT> <CODE>endwin()</CODE> -<DD> Your program should always call <CODE>endwin()</CODE> 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 <CODE>refresh()</CODE> -or <CODE>doupdate()</CODE> after a temporary escape from the program will -restore the ncurses screen from before the escape. -<DT> <CODE>newterm(type, ofp, ifp)</CODE> -<DD> A program which outputs to more than one terminal should use -<CODE>newterm()</CODE> instead of <CODE>initscr()</CODE>. <CODE>newterm()</CODE> should -be called once for each terminal. It returns a variable of type -<CODE>SCREEN *</CODE> which should be saved as a reference to that -terminal. -(NOTE: a SCREEN variable is not a <em>screen</em> 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 -<CODE>FILE</CODE> pointers for the output and input of the terminal. If -type is NULL then the environment variable <CODE>$TERM</CODE> is used. -<CODE>endwin()</CODE> should called once at wrapup time for each terminal -opened using this function. -<DT> <CODE>set_term(new)</CODE> -<DD> This function is used to switch to a different terminal previously -opened by <CODE>newterm()</CODE>. 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. -<DT> <CODE>delscreen(sp)</CODE> -<DD> The inverse of <CODE>newterm()</CODE>; deallocates the data structures -associated with a given <CODE>SCREEN</CODE> reference. -</DL> - -<H3><A NAME="flush">Causing Output to the Terminal</A></H3> - -<DL> -<DT> <CODE>refresh()</CODE> and <CODE>wrefresh(win)</CODE> -<DD> These functions must be called to actually get any output on -the terminal, as other routines merely manipulate data -structures. <CODE>wrefresh()</CODE> copies the named window to the physical -terminal screen, taking into account what is already -there in order to do optimizations. <CODE>refresh()</CODE> does a -refresh of <CODE>stdscr</CODE>. Unless <CODE>leaveok()</CODE> has been -enabled, the physical cursor of the terminal is left at the -location of the window's cursor. -<DT> <CODE>doupdate()</CODE> and <CODE>wnoutrefresh(win)</CODE> -<DD> 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 -(<CODE>wnoutrefresh()</CODE>), and then calling the routine to update the -screen (<CODE>doupdate()</CODE>). If the programmer wishes to output -several windows at once, a series of calls to <CODE>wrefresh</CODE> will result -in alternating calls to <CODE>wnoutrefresh()</CODE> and <CODE>doupdate()</CODE>, -causing several bursts of output to the screen. By calling -<CODE>wnoutrefresh()</CODE> for each window, it is then possible to call -<CODE>doupdate()</CODE> once, resulting in only one burst of output, with -fewer total characters transmitted (this also avoids a visually annoying -flicker at each update). -</DL> - -<H3><A NAME="lowlevel">Low-Level Capability Access</A></H3> - -<DL> -<DT> <CODE>setupterm(term, filenum, errret)</CODE> -<DD> This routine is called to initialize a terminal's description, without setting -up the curses screen structures or changing the tty-driver mode bits. -<CODE>term</CODE> is the character string representing the name of the terminal -being used. <CODE>filenum</CODE> is the UNIX file descriptor of the terminal to -be used for output. <CODE>errret</CODE> 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). <P> - -The value of <CODE>term</CODE> can be given as NULL, which will cause the value of -<CODE>TERM</CODE> in the environment to be used. The <CODE>errret</CODE> pointer can -also be given as NULL, meaning no error code is wanted. If <CODE>errret</CODE> is -defaulted, and something goes wrong, <CODE>setupterm()</CODE> 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. <P> - -After the call to <CODE>setupterm()</CODE>, the global variable <CODE>cur_term</CODE> is -set to point to the current structure of terminal capabilities. By calling -<CODE>setupterm()</CODE> for each terminal, and saving and restoring -<CODE>cur_term</CODE>, it is possible for a program to use two or more terminals at -once. <CODE>Setupterm()</CODE> also stores the names section of the terminal -description in the global character array <CODE>ttytype[]</CODE>. Subsequent calls -to <CODE>setupterm()</CODE> will overwrite this array, so you'll have to save it -yourself if need be. -</DL> - -<H3><A NAME="debugging">Debugging</A></H3> - -<!-- The 'note' tag is not portable enough --> -<blockquote> -<strong>NOTE:</strong> These functions are not part of the standard curses API! -</blockquote> - -<DL> -<DT> <CODE>trace()</CODE> -<DD> -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 <CODE>TRACE_</CODE> defines -in the <CODE>curses.h</CODE> file for details. (It is also possible to set -a trace level by assigning a trace level value to the environment variable -<CODE>NCURSES_TRACE</CODE>). -<DT> <CODE>_tracef()</CODE> -<DD> -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 -<CODE>printf()</CODE>, only it outputs a newline after the end of arguments. -The output goes to a file called <CODE>trace</CODE> in the current directory. -</DL> - -Trace logs can be difficult to interpret due to the sheer volume of -data dumped in them. There is a script called <STRONG>tracemunch</STRONG> -included with the <CODE>ncurses</CODE> 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. - -<H2><A NAME="hints">Hints, Tips, and Tricks</A></H2> - -The <CODE>ncurses</CODE> 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. - -<H3><A NAME="caution">Some Notes of Caution</A></H3> - -If you find yourself thinking you need to use <CODE>noraw()</CODE> or -<CODE>nocbreak()</CODE>, think again and move carefully. It's probably -better design to use <CODE>getstr()</CODE> or one of its relatives to -simulate cooked mode. The <CODE>noraw()</CODE> and <CODE>nocbreak()</CODE> -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. <P> - -Bear in mind that <CODE>refresh()</CODE> is a synonym for <CODE>wrefresh(stdscr)</CODE>. -Don't try to mix use of <CODE>stdscr</CODE> with use of windows declared -by <CODE>newwin()</CODE>; a <CODE>refresh()</CODE> call will blow them off the -screen. The right way to handle this is to use <CODE>subwin()</CODE>, or -not touch <CODE>stdscr</CODE> at all and tile your screen with declared -windows which you then <CODE>wnoutrefresh()</CODE> somewhere in your program -event loop, with a single <CODE>doupdate()</CODE> call to trigger actual -repainting. <P> - -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 <CODE>ncurses</CODE> library is not yet an exception to this -rule. <P> - -There is a panels library included in the <CODE>ncurses</CODE> -distribution that does a pretty good job of strengthening the -overlapping-windows facilities. <P> - -Try to avoid using the global variables LINES and COLS. Use -<CODE>getmaxyx()</CODE> on the <CODE>stdscr</CODE> 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. - -<H3><A NAME="leaving">Temporarily Leaving NCURSES Mode</A></H3> - -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 <CODE>ncurses</CODE>. <P> - -To leave <CODE>ncurses</CODE> mode, call <CODE>endwin()</CODE> 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 -<CODE>ncurses</CODE> mode, simply call <CODE>refresh()</CODE> or <CODE>doupdate()</CODE>. -This will repaint the screen. <P> - -There is a boolean function, <CODE>isendwin()</CODE>, which code can use to -test whether <CODE>ncurses</CODE> screen mode is active. It returns <CODE>TRUE</CODE> -in the interval between an <CODE>endwin()</CODE> call and the following -<CODE>refresh()</CODE>, <CODE>FALSE</CODE> otherwise. <P> - -Here is some sample code for shellout: - -<PRE> - 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 */ -</PRE> - -<H3><A NAME="xterm">Using NCURSES under XTERM</A></H3> - -A resize operation in X sends <CODE>SIGWINCH</CODE> to the application running -under xterm. - -The easiest way to handle <CODE>SIGWINCH</CODE> -is to do an <CODE>endwin</CODE>, -followed by an <CODE>refresh</CODE> and a screen repaint you code -yourself. -The <CODE>refresh</CODE> will pick up the new screen size from the -xterm's environment. <P> - -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. -<CODE>Ncurses</CODE> provides an extension which works better, the -<CODE>resizeterm</CODE> function. That function ensures that all windows -are limited to the new screen dimensions, and pads <CODE>stdscr</CODE> -with blanks if the screen is larger. <P> - -The <CODE>ncurses</CODE> library provides a SIGWINCH signal handler, -which pushes a <CODE>KEY_RESIZE</CODE> via the wgetch() calls. -When <CODE>ncurses</CODE> returns that code, -it calls <code>resizeterm</CODE> -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 -<CODE>KEY_RESIZE</CODE> yourself. - -<H3><A NAME="screens">Handling Multiple Terminal Screens</A></H3> - -The <CODE>initscr()</CODE> function actually calls a function named -<CODE>newterm()</CODE> to do most of its work. If you are writing a program that -opens multiple terminals, use <CODE>newterm()</CODE> directly. <P> - -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 <CODE>stdscr</CODE> will be -set to the last one allocated. You will switch between screens with the -<CODE>set_term</CODE> call. Note that you will also have to call -<CODE>def_shell_mode</CODE> and <CODE>def_prog_mode</CODE> on each tty yourself. - -<H3><A NAME="testing">Testing for Terminal Capabilities</A></H3> - -Sometimes you may want to write programs that test for the presence of various -capabilities before deciding whether to go into <CODE>ncurses</CODE> mode. An easy -way to do this is to call <CODE>setupterm()</CODE>, then use the functions -<CODE>tigetflag()</CODE>, <CODE>tigetnum()</CODE>, and <CODE>tigetstr()</CODE> to do your -testing. <P> - -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 <CODE>tigetstr("cup")</CODE> is non-NULL. Alternatively, -you can include the <CODE>term.h</CODE> file and test the value of the -macro <CODE>cursor_address</CODE>. - -<H3><A NAME="tuning">Tuning for Speed</A></H3> - -Use the <CODE>addchstr()</CODE> 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 <CODE>immedok()</CODE> option! - -<H3><A NAME="special">Special Features of NCURSES</A></H3> - -The <CODE>wresize()</CODE> function allows you to resize a window in place. -The associated <CODE>resizeterm()</CODE> function simplifies the construction -of <a HREF="#xterm">SIGWINCH</a> handlers, for resizing all windows. <P> - -The <CODE>define_key()</CODE> function allows you -to define at runtime function-key control sequences which are not in the -terminal description. -The <CODE>keyok()</CODE> function allows you to temporarily -enable or disable interpretation of any function-key control sequence. <P> - -The <CODE>use_default_colors()</CODE> 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. <P> - -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. - -<H2><A NAME="compat">Compatibility with Older Versions</A></H2> - -Despite our best efforts, there are some differences between <CODE>ncurses</CODE> -and the (undocumented!) behavior of older curses implementations. These arise -from ambiguities or omissions in the documentation of the API. - -<H3><A NAME="refbug">Refresh of Overlapping Windows</A></H3> - -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 -<CODE>curses</CODE> versions were often not documented precisely. <P> - -To understand why this is a problem, remember that screen updates are -calculated between two representations of the <EM>entire</EM> 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. <P> - -What happens to the overlapping region depends on what <CODE>wnoutrefresh()</CODE> -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 -<CODE>wtouchln()</CODE> and friends). Some implementations do "entire copy", -copying <EM>all</EM> window locations to the virtual screen whether or not -they have changed. <P> - -The <CODE>ncurses</CODE> 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. <P> - -For most commercial curses implementations, it is not documented and not known -for sure (at least not to the <CODE>ncurses</CODE> 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. <P> - -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 <CODE>touchwin()</CODE> before the <CODE>wnoutrefresh()</CODE> call to -guarantee an entire-contents copy anywhere. <P> - -The really clean way to handle this is to use the panels library. If, -when you want a screen update, you do <CODE>update_panels()</CODE>, it will -do all the necessary <CODE>wnoutrefresh()</CODE> calls for whatever panel -stacking order you have defined. Then you can do one <CODE>doupdate()</CODE> -and there will be a <EM>single</EM> burst of physical I/O that will do -all your updates. - -<H3><A NAME="backbug">Background Erase</A></H3> - -If you have been using a very old versions of <CODE>ncurses</CODE> (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 <STRONG>wattrset()</STRONG>, <STRONG>wattron()</STRONG>, -<STRONG>wattroff()</STRONG> and friends). <P> - -In newer versions, this is not so. Instead, the attribute of erased blanks -is normal unless and until it is modified by the functions <CODE>bkgdset()</CODE> -or <CODE>wbkgdset()</CODE>. <P> - -This change in behavior conforms <CODE>ncurses</CODE> to System V Release 4 and -the XSI Curses standard. - -<H2><A NAME="xsifuncs">XSI Curses Conformance</A></H2> - -The <CODE>ncurses</CODE> 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. <P> - -One effect of XSI conformance is the change in behavior described under -<A HREF="#backbug">"Background Erase -- Compatibility with Old Versions"</A>. <P> - -Also, <CODE>ncurses</CODE> 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 -<CODE>#undef</CODE>. - -<H1><A NAME="panels">The Panels Library</A></H1> - -The <CODE>ncurses</CODE> 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 -<CODE>wnoutrefresh()</CODE> calls followed by a <CODE>doupdate()</CODE>, 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. <P> - -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. <P> - -The <CODE>panel</CODE> library first appeared in AT&T System V. The -version documented here is the <CODE>panel</CODE> code distributed -with <CODE>ncurses</CODE>. - -<H2><A NAME="pcompile">Compiling With the Panels Library</A></H2> - -Your panels-using modules must import the panels library declarations with - -<PRE> - #include <panel.h> -</PRE> - -and must be linked explicitly with the panels library using an -<CODE>-lpanel</CODE> argument. Note that they must also link the -<CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers -are two-pass and will accept either order, but it is still good practice -to put <CODE>-lpanel</CODE> first and <CODE>-lncurses</CODE> second. - -<H2><A NAME="poverview">Overview of Panels</A></H2> - -A panel object is a window that is implicitly treated as part of a -<DFN>deck</DFN> including all other panel objects. The deck has an implicit -bottom-to-top visibility order. The panels library includes an update -function (analogous to <CODE>refresh()</CODE>) that displays all panels in the -deck in the proper order to resolve overlaps. The standard window, -<CODE>stdscr</CODE>, is considered below all panels. <P> - -Details on the panels functions are available in the man pages. We'll just -hit the highlights here. <P> - -You create a panel from a window by calling <CODE>new_panel()</CODE> on a -window pointer. It then becomes the top of the deck. The panel's window -is available as the value of <CODE>panel_window()</CODE> called with the -panel pointer as argument.<P> - -You can delete a panel (removing it from the deck) with <CODE>del_panel</CODE>. -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 -<CODE>replace_window</CODE>. 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. <P> - -To move a panel's window, use <CODE>move_panel()</CODE>. The -<CODE>mvwin()</CODE> 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. <P> - -Two functions (<CODE>top_panel()</CODE>, <CODE>bottom_panel()</CODE>) 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. <P> - -The function <CODE>update_panels()</CODE> does all the -<CODE>wnoutrefresh()</CODE> calls needed to prepare for -<CODE>doupdate()</CODE> (which you must call yourself, afterwards). <P> - -Typically, you will want to call <CODE>update_panels()</CODE> and -<CODE>doupdate()</CODE> just before accepting command input, once in each cycle -of interaction with the user. If you call <CODE>update_panels()</CODE> after -each and every panel write, you'll generate a lot of unnecessary refresh -activity and screen flicker. - -<H2><A NAME="pstdscr">Panels, Input, and the Standard Screen</A></H2> - -You shouldn't mix <CODE>wnoutrefresh()</CODE> or <CODE>wrefresh()</CODE> -operations with panels code; this will work only if the argument window -is either in the top panel or unobscured by any other panels. <P> - -The <CODE>stsdcr</CODE> window is a special case. It is considered below all -panels. Because changes to panels may obscure parts of <CODE>stdscr</CODE>, -though, you should call <CODE>update_panels()</CODE> before -<CODE>doupdate()</CODE> even when you only change <CODE>stdscr</CODE>. <P> - -Note that <CODE>wgetch</CODE> automatically calls <CODE>wrefresh</CODE>. -Therefore, before requesting input from a panel window, you need to be sure -that the panel is totally unobscured. <P> - -There is presently no way to display changes to one obscured panel without -repainting all panels. - -<H2><A NAME="hiding">Hiding Panels</A></H2> - -It's possible to remove a panel from the deck temporarily; use -<CODE>hide_panel</CODE> for this. Use <CODE>show_panel()</CODE> to render it -visible again. The predicate function <CODE>panel_hidden</CODE> -tests whether or not a panel is hidden. <P> - -The <CODE>panel_update</CODE> code ignores hidden panels. You cannot do -<CODE>top_panel()</CODE> or <CODE>bottom_panel</CODE> on a hidden panel(). -Other panels operations are applicable. - -<H2><A NAME="pmisc">Miscellaneous Other Facilities</A></H2> - -It's possible to navigate the deck using the functions -<CODE>panel_above()</CODE> and <CODE>panel_below</CODE>. Handed a panel -pointer, they return the panel above or below that panel. Handed -<CODE>NULL</CODE>, they return the bottom-most or top-most panel. <P> - -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 <CODE>set_panel_userptr()</CODE> and <CODE>panel_userptr</CODE> for -details. - -<H1><A NAME="menu">The Menu Library</A></H1> - -A menu is a screen display that assists the user to choose some subset -of a given set of items. The <CODE>menu</CODE> library is a curses -extension that supports easy programming of menu hierarchies with a -uniform but flexible interface. <P> - -The <CODE>menu</CODE> library first appeared in AT&T System V. The -version documented here is the <CODE>menu</CODE> code distributed -with <CODE>ncurses</CODE>. - -<H2><A NAME="mcompile">Compiling With the menu Library</A></H2> - -Your menu-using modules must import the menu library declarations with - -<PRE> - #include <menu.h> -</PRE> - -and must be linked explicitly with the menus library using an -<CODE>-lmenu</CODE> argument. Note that they must also link the -<CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers -are two-pass and will accept either order, but it is still good practice -to put <CODE>-lmenu</CODE> first and <CODE>-lncurses</CODE> second. - -<H2><A NAME="moverview">Overview of Menus</A></H2> - -The menus created by this library consist of collections of -<DFN>items</DFN> 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. <P> - -The menu can then by <DFN>posted</DFN>, 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. <P> - -A menu may also be <DFN>unposted</DFN> (that is, undisplayed), and finally -freed to make the storage associated with it and its items available for -re-use. <P> - -The general flow of control of a menu program looks like this: - -<OL> -<LI>Initialize <CODE>curses</CODE>. -<LI>Create the menu items, using <CODE>new_item()</CODE>. -<LI>Create the menu using <CODE>new_menu()</CODE>. -<LI>Post the menu using <CODE>post_menu()</CODE>. -<LI>Refresh the screen. -<LI>Process user requests via an input loop. -<LI>Unpost the menu using <CODE>unpost_menu()</CODE>. -<LI>Free the menu, using <CODE>free_menu()</CODE>. -<LI>Free the items using <CODE>free_item()</CODE>. -<LI>Terminate <CODE>curses</CODE>. -</OL> - -<H2><A NAME="mselect">Selecting items</A></H2> - -Menus may be multi-valued or (the default) single-valued (see the manual -page <CODE>menu_opts(3x)</CODE> to see how to change the default). -Both types always have a <DFN>current item</DFN>. <P> - -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 <CODE>item_value()</CODE> -predicate function. Your menu-processing code can use the function -<CODE>set_item_value()</CODE> to flag the items in the select set. <P> - -Menu items can be made unselectable using <CODE>set_item_opts()</CODE> -or <CODE>item_opts_off()</CODE> with the <CODE>O_SELECTABLE</CODE> -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. - -<H2><A NAME="mdisplay">Menu Display</A></H2> - -The menu library calculates a minimum display size for your window, based -on the following variables: - -<UL> -<LI>The number and maximum length of the menu items -<LI>Whether the O_ROWMAJOR option is enabled -<LI>Whether display of descriptions is enabled -<LI>Whatever menu format may have been set by the programmer -<LI>The length of the menu mark string used for highlighting selected items -</UL> - -The function <CODE>set_menu_format()</CODE> allows you to set the -maximum size of the viewport or <DFN>menu page</DFN> that will be used -to display menu items. You can retrieve any format associated with a -menu with <CODE>menu_format()</CODE>. The default format is rows=16, -columns=1. <P> - -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. <P> - -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. <P> -You can scroll it with requests to the menu driver, which will be described -in the section on <A HREF="#minput">menu input handling</A>. <P> - -Each menu has a <DFN>mark string</DFN> used to visually tag selected items; -see the <CODE>menu_mark(3x)</CODE> manual page for details. The mark -string length also influences the menu page size. <P> - -The function <CODE>scale_menu()</CODE> 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 <CODE>menu_attribs(3x)</CODE> manual page. - -<H2><A NAME="mwindows">Menu Windows</A></H2> - -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. <P> - -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 -<DFN>subwindow</DFN> is where the current menu page is displayed. <P> - -By default, both windows are <CODE>stdscr</CODE>. You can set them with the -functions in <CODE>menu_win(3x)</CODE>. <P> - -When you call <CODE>post_menu()</CODE>, you write the menu to its -subwindow. When you call <CODE>unpost_menu()</CODE>, you erase the -subwindow, However, neither of these actually modifies the screen. To -do that, call <CODE>wrefresh()</CODE> or some equivalent. - -<H2><A NAME="minput">Processing Menu Input</A></H2> - -The main loop of your menu-processing code should call -<CODE>menu_driver()</CODE> 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 <CODE>menu_driver()</CODE>. The menu command codes are -fully documented in <CODE>menu_driver(3x)</CODE>. <P> - -The simplest group of command codes is <CODE>REQ_NEXT_ITEM</CODE>, -<CODE>REQ_PREV_ITEM</CODE>, <CODE>REQ_FIRST_ITEM</CODE>, -<CODE>REQ_LAST_ITEM</CODE>, <CODE>REQ_UP_ITEM</CODE>, -<CODE>REQ_DOWN_ITEM</CODE>, <CODE>REQ_LEFT_ITEM</CODE>, -<CODE>REQ_RIGHT_ITEM</CODE>. These change the currently selected -item. These requests may cause scrolling of the menu page if it only -partially displayed. <P> - -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 <CODE>REQ_SCR_DLINE</CODE>, -<CODE>REQ_SCR_ULINE</CODE>, <CODE>REQ_SCR_DPAGE</CODE>, and -<CODE>REQ_SCR_UPAGE</CODE>. <P> - -The <CODE>REQ_TOGGLE_ITEM</CODE> selects or deselects the current item. -It is for use in multi-valued menus; if you use it with <CODE>O_ONEVALUE</CODE> -on, you'll get an error return (<CODE>E_REQUEST_DENIED</CODE>). <P> - -Each menu has an associated pattern buffer. The -<CODE>menu_driver()</CODE> 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 <CODE>menu_driver()</CODE> returns -<CODE>E_NO_MATCH</CODE>. <P> - -Some requests change the pattern buffer directly: -<CODE>REQ_CLEAR_PATTERN</CODE>, <CODE>REQ_BACK_PATTERN</CODE>, -<CODE>REQ_NEXT_MATCH</CODE>, <CODE>REQ_PREV_MATCH</CODE>. The latter -two are useful when pattern buffer input matches more than one item -in a multi-valued menu. <P> - -Each successful scroll or item navigation request clears the pattern -buffer. It is also possible to set the pattern buffer explicitly -with <CODE>set_menu_pattern()</CODE>. <P> - -Finally, menu driver requests above the constant <CODE>MAX_COMMAND</CODE> -are considered application-specific commands. The <CODE>menu_driver()</CODE> -code ignores them and returns <CODE>E_UNKNOWN_COMMAND</CODE>. - -<H2><A NAME="mmisc">Miscellaneous Other Features</A></H2> - -Various menu options can affect the processing and visual appearance -and input processing of menus. See <CODE>menu_opts(3x) for -details.</CODE> <P> - -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 -<CODE>mitem_current(3x)</CODE>. - -If your application needs to change the menu subwindow cursor for -any reason, <CODE>pos_menu_cursor()</CODE> will restore it to the -correct location for continuing menu driver processing. <P> - -It is possible to set hooks to be called at menu initialization and -wrapup time, and whenever the selected item changes. See -<CODE>menu_hook(3x)</CODE>. <P> - -Each item, and each menu, has an associated user pointer on which you -can hang application data. See <CODE>mitem_userptr(3x)</CODE> and -<CODE>menu_userptr(3x)</CODE>. - -<H1><A NAME="form">The Forms Library</A></H1> - -The <CODE>form</CODE> library is a curses extension that supports easy -programming of on-screen forms for data entry and program control. <P> - -The <CODE>form</CODE> library first appeared in AT&T System V. The -version documented here is the <CODE>form</CODE> code distributed -with <CODE>ncurses</CODE>. - -<H2><A NAME="fcompile">Compiling With the form Library</A></H2> - -Your form-using modules must import the form library declarations with - -<PRE> - #include <form.h> -</PRE> - -and must be linked explicitly with the forms library using an -<CODE>-lform</CODE> argument. Note that they must also link the -<CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers -are two-pass and will accept either order, but it is still good practice -to put <CODE>-lform</CODE> first and <CODE>-lncurses</CODE> second. - -<H2><A NAME="foverview">Overview of Forms</A></H2> - -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. <P> -To make forms, you create groups of fields and connect them with form -frame objects; the form library makes this relatively simple. <P> - -Once defined, a form can be <DFN>posted</DFN>, 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. <P> - -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 <CODE>curses</CODE> - -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. <P> - -Once its transaction is completed (or aborted), a form may be -<DFN>unposted</DFN> (that is, undisplayed), and finally freed to make -the storage associated with it and its items available for re-use. <P> - -The general flow of control of a form program looks like this: - -<OL> -<LI>Initialize <CODE>curses</CODE>. -<LI>Create the form fields, using <CODE>new_field()</CODE>. -<LI>Create the form using <CODE>new_form()</CODE>. -<LI>Post the form using <CODE>post_form()</CODE>. -<LI>Refresh the screen. -<LI>Process user requests via an input loop. -<LI>Unpost the form using <CODE>unpost_form()</CODE>. -<LI>Free the form, using <CODE>free_form()</CODE>. -<LI>Free the fields using <CODE>free_field()</CODE>. -<LI>Terminate <CODE>curses</CODE>. -</OL> - -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 <A HREF="#menu">menu library</A> -wherever possible. <P> - -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. - -<H2><A NAME="fcreate">Creating and Freeing Fields and Forms</A></H2> - -The basic function for creating fields is <CODE>new_field()</CODE>: - -<PRE> -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 */ -</PRE> - -Menu items always occupy a single row, but forms fields may have -multiple rows. So <CODE>new_field()</CODE> requires you to specify a -width and height (the first two arguments, which mist both be greater -than zero). <P> - -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 <CODE>stdscr</CODE> by default but -need not be <CODE>stdscr</CODE> if you've done an explicit -<CODE>set_form_win()</CODE> call. <P> - -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 <CODE>offscreen</CODE> argument was initially zero. <P> - -The forms library allocates one working buffer per field; the size of -each buffer is <CODE>((height + offscreen)*width + 1</CODE>, 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. - -<PRE> -FIELD *dup_field(FIELD *field, /* field to copy */ - int top, int left); /* location of new copy */ -</PRE> - -The function <CODE>dup_field()</CODE> duplicates an existing field at a -new location. Size and buffering information are copied; some -attribute flags and status bits are not (see the -<CODE>form_field_new(3X)</CODE> for details). - -<PRE> -FIELD *link_field(FIELD *field, /* field to copy */ - int top, int left); /* location of new copy */ -</PRE> - -The function <CODE>link_field()</CODE> also duplicates an existing field -at a new location. The difference from <CODE>dup_field()</CODE> is that -it arranges for the new field's buffer to be shared with the old one. <P> - -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. <P> - -As with duplicated fields, linked fields have attribute bits separate -from the original. <P> - -As you might guess, all these field-allocations return <CODE>NULL</CODE> if -the field allocation is not possible due to an out-of-memory error or -out-of-bounds arguments. <P> - -To connect fields to a form, use - -<PRE> -FORM *new_form(FIELD **fields); -</PRE> - -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). <P> - -Note that <CODE>new_field()</CODE> does <EM>not</EM> 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. <P> - -The functions <CODE>free_field()</CODE> and <CODE>free_form</CODE> 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. - -<H2><A NAME="fattributes">Fetching and Changing Field Attributes</A></H2> - -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 <CODE>O_STATIC</CODE> 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. <P> - -When a field is created, the attributes not specified by the -<CODE>new_field</CODE> 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. - -<H3><A NAME="fsizes">Fetching Size and Location Data</A></H3> - -You can retrieve field sizes and locations through: - -<PRE> -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 */ -</PRE> - -This function is a sort of inverse of <CODE>new_field()</CODE>; instead of -setting size and location attributes of a new field, it fetches them -from an existing one. - -<H3><A NAME="flocation">Changing the Field Location</A></H3> - -It is possible to move a field's location on the screen: - -<PRE> -int move_field(FIELD *field, /* field to alter */ - int top, int left); /* new upper-left corner */ -</PRE> - -You can, of course. query the current location through <CODE>field_info()</CODE>. - -<H3><A NAME="fjust">The Justification Attribute</A></H3> - -One-line fields may be unjustified, justified right, justified left, -or centered. Here is how you manipulate this attribute: - -<PRE> -int set_field_just(FIELD *field, /* field to alter */ - int justmode); /* mode to set */ - -int field_just(FIELD *field); /* fetch mode of field */ -</PRE> - -The mode values accepted and returned by this functions are -preprocessor macros <CODE>NO_JUSTIFICATION</CODE>, <CODE>JUSTIFY_RIGHT</CODE>, -<CODE>JUSTIFY_LEFT</CODE>, or <CODE>JUSTIFY_CENTER</CODE>. - -<H3><A NAME="fdispatts">Field Display Attributes</A></H3> - -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. <P> - -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. - -<PRE> -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 */ -</PRE> - -The attributes set and returned by the first four functions are normal -<CODE>curses(3x)</CODE> display attribute values (<CODE>A_STANDOUT</CODE>, -<CODE>A_BOLD</CODE>, <CODE>A_REVERSE</CODE> etc). - -The page bit of a field controls whether it is displayed at the start of -a new form screen. - -<H3><A NAME="foptions">Field Option Bits</A></H3> - -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: - -<PRE> -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 */ -</PRE> - -By default, all options are on. Here are the available option bits: -<DL> -<DT> O_VISIBLE -<DD> 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. -<DT> O_ACTIVE -<DD> 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. -<DT> O_PUBLIC -<DD> 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. -<DT> O_EDIT -<DD> Controls whether the field's data can be modified. When this option is -off, all editing requests except <CODE>REQ_PREV_CHOICE</CODE> and -<CODE>REQ_NEXT_CHOICE</CODE> will fail. Such read-only fields may be useful for -help messages. -<DT> O_WRAP -<DD> 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. -<DT> O_BLANK -<DD> 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). -<DT> O_AUTOSKIP -<DD> 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. -<DT> O_NULLOK -<DD> Controls whether <A HREF="#fvalidation">validation</A> 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. -<DT> O_PASSOK -<DD> 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. -<DT> O_STATIC -<DD> Controls whether the field is fixed to its initial dimensions. If you -turn this off, the field becomes <A HREF="#fdynamic">dynamic</A> and will -stretch to fit entered data. -</DL> - -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. <P> - -The option values are bit-masks and can be composed with logical-or in -the obvious way. - -<H2><A NAME="fstatus">Field Status</A></H2> - -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: - -<PRE> -int set_field_status(FIELD *field, /* field to alter */ - int status); /* mode to set */ - -int field_status(FIELD *field); /* fetch mode of field */ -</PRE> - -Setting this flag under program control can be useful if you use the same -form repeatedly, looking for modified fields each time. <P> - -Calling <CODE>field_status()</CODE> on a field not currently selected -for input will return a correct value. Calling <CODE>field_status()</CODE> 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 -<CODE>field_status()</CODE> 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 <CODE>REQ_VALIDATION</CODE> request has been -processed by the forms driver. - -<H2><A NAME="fuser">Field User Pointer</A></H2> - -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: - -<PRE> -int set_field_userptr(FIELD *field, /* field to alter */ - char *userptr); /* mode to set */ - -char *field_userptr(FIELD *field); /* fetch mode of field */ -</PRE> - -(Properly, this user pointer field ought to have <CODE>(void *)</CODE> type. -The <CODE>(char *)</CODE> type is retained for System V compatibility.) <P> - -It is valid to set the user pointer of the default field (with a -<CODE>set_field_userptr()</CODE> 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. - -<H2><A NAME="fdynamic">Variable-Sized Fields</A></H2> - -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 -<DFN>dynamic</DFN> 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. <P> - -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. <P> - -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: - -<PRE> -int set_max_field(FIELD *field, /* field to alter (may not be NULL) */ - int max_size); /* upper limit on field size */ -</PRE> - -If the field is one-line, <CODE>max_size</CODE> 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. <P> - -The following properties of a field change when it becomes dynamic: - -<UL> -<LI>If there is no growth limit, there is no final position of the field; -therefore <CODE>O_AUTOSKIP</CODE> and <CODE>O_NL_OVERLOAD</CODE> are ignored. -<LI>Field justification will be ignored (though whatever justification is -set up will be retained internally and can be queried). -<LI>The <CODE>dup_field()</CODE> and <CODE>link_field()</CODE> calls copy -dynamic-buffer sizes. If the <CODE>O_STATIC</CODE> option is set on one of a -collection of links, buffer resizing will occur only when the field is -edited through that link. -<LI>The call <CODE>field_info()</CODE> will retrieve the original static size of -the field; use <CODE>dynamic_field_info()</CODE> to get the actual dynamic size. -</UL> - -<H2><A NAME="fvalidation">Field Validation</A></H2> - -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. <P> - -A field's validation check (if any) is not called when -<CODE>set_field_buffer()</CODE> modifies the input buffer, nor when that buffer -is changed through a linked field. <P> - -The <CODE>form</CODE> 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: - -<PRE> -int set_field_type(FIELD *field, /* field to alter */ - FIELDTYPE *ftype, /* type to associate */ - ...); /* additional arguments*/ - -FIELDTYPE *field_type(FIELD *field); /* field to query */ -</PRE> - -The validation type of a field is considered an attribute of the field. As -with other field attributes, Also, doing <CODE>set_field_type()</CODE> with a -<CODE>NULL</CODE> field default will change the system default for validation of -newly-created fields. <P> - -Here are the pre-defined validation types: - -<H3><A NAME="ftype_alpha">TYPE_ALPHA</A></H3> - -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: - -<PRE> -int set_field_type(FIELD *field, /* field to alter */ - TYPE_ALPHA, /* type to associate */ - int width); /* maximum width of field */ -</PRE> - -The <CODE>width</CODE> 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. - -<H3><A NAME="ftype_alnum">TYPE_ALNUM</A></H3> - -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: - -<PRE> -int set_field_type(FIELD *field, /* field to alter */ - TYPE_ALNUM, /* type to associate */ - int width); /* maximum width of field */ -</PRE> - -The <CODE>width</CODE> 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. - -<H3><A NAME="ftype_enum">TYPE_ENUM</A></H3> - -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: - -<PRE> -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? */ -</PRE> - -The <CODE>valuelist</CODE> parameter must point at a NULL-terminated list of -valid strings. The <CODE>checkcase</CODE> argument, if true, makes comparison -with the string case-sensitive. <P> - -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. <P> - -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 <CODE>checkunique</CODE> argument, if true, requires prefix -matches to be unique in order to be valid. <P> - -The <CODE>REQ_NEXT_CHOICE</CODE> and <CODE>REQ_PREV_CHOICE</CODE> input requests -can be particularly useful with these fields. - -<H3><A NAME="ftype_integer">TYPE_INTEGER</A></H3> - -This field type accepts an integer. It is set up as follows: - -<PRE> -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 */ -</PRE> - -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. <P> - -If the value passes its range check, it is padded with as many leading -zero digits as necessary to meet the padding argument. <P> - -A <CODE>TYPE_INTEGER</CODE> value buffer can conveniently be interpreted -with the C library function <CODE>atoi(3)</CODE>. - -<H3><A NAME="ftype_numeric">TYPE_NUMERIC</A></H3> - -This field type accepts a decimal number. It is set up as follows: - -<PRE> -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 */ -</PRE> - -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. <P> - -If the value passes its range check, it is padded with as many trailing -zero digits as necessary to meet the padding argument. <P> - -A <CODE>TYPE_NUMERIC</CODE> value buffer can conveniently be interpreted -with the C library function <CODE>atof(3)</CODE>. - -<H3><A NAME="ftype_regexp">TYPE_REGEXP</A></H3> - -This field type accepts data matching a regular expression. It is set up -as follows: - -<PRE> -int set_field_type(FIELD *field, /* field to alter */ - TYPE_REGEXP, /* type to associate */ - char *regexp); /* expression to match */ -</PRE> - -The syntax for regular expressions is that of <CODE>regcomp(3)</CODE>. -The check for regular-expression match is performed on exit. - -<H2><A NAME="fbuffer">Direct Field Buffer Manipulation</A></H2> - -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: - -<PRE> -char *field_buffer(FIELD *field, /* field to query */ - int bufindex); /* number of buffer to query */ -</PRE> - -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: - -<PRE> -int set_field_buffer(FIELD *field, /* field to alter */ - int bufindex, /* number of buffer to alter */ - char *value); /* string value to set */ -</PRE> - -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. <P> - -Calling <CODE>field_buffer()</CODE> with a null field pointer will raise an -error. Calling <CODE>field_buffer()</CODE> on a field not currently selected -for input will return a correct value. Calling <CODE>field_buffer()</CODE> 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 <CODE>field_buffer()</CODE> 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 <CODE>REQ_VALIDATION</CODE> request has been processed -by the forms driver. - -<H2><A NAME="formattrs">Attributes of Forms</A></H2> - -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 <CODE>NULL</CODE>. <P> - -The principal attribute of a form is its field list. You can query -and change this list with: - -<PRE> -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 */ -</PRE> - -The second argument of <CODE>set_form_fields()</CODE> may be a -NULL-terminated field pointer array like the one required by -<CODE>new_form()</CODE>. 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. <P> - -It may also be null, in which case the old fields are disconnected -(and not freed) but no new ones are connected. <P> - -The <CODE>field_count()</CODE> function simply counts the number of fields -connected to a given from. It returns -1 if the form-pointer argument -is NULL. - -<H2><A NAME="fdisplay">Control of Form Display</A></H2> - -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 -<CODE>stdscr</CODE>. <P> - -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 <A HREF="#panels">panels</A>. <P> - -The two windows associated with each form have the same functions as -their analogues in the <A HREF="#menu">menu library</A>. Both these -windows are painted when the form is posted and erased when the form -is unposted. <P> - -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. <P> - -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: - -<PRE> -int scale_form(FORM *form, /* form to query */ - int *rows, /* form rows */ - int *cols); /* form cols */ -</PRE> - -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: - -<PRE> -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 */ -</PRE> - -Note that curses operations, including <CODE>refresh()</CODE>, on the form, -should be done on the frame window, not the form subwindow. <P> - -It is possible to check from your application whether all of a -scrollable field is actually displayed within the menu subwindow. Use -these functions: - -<PRE> -int data_ahead(FORM *form); /* form to be queried */ - -int data_behind(FORM *form); /* form to be queried */ -</PRE> - -The function <CODE>data_ahead()</CODE> 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. <P> - -The function <CODE>data_behind()</CODE> returns TRUE if the first (upper -left hand) character position is off-screen (not being displayed). <P> - -Finally, there is a function to restore the form window's cursor to the -value expected by the forms driver: - -<PRE> -int pos_form_cursor(FORM *) /* form to be queried */ -</PRE> - -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. - -<H2><A NAME="fdriver">Input Processing in the Forms Driver</A></H2> - -The function <CODE>form_driver()</CODE> handles virtualized input requests -for form navigation, editing, and validation requests, just as -<CODE>menu_driver</CODE> does for menus (see the section on <A -HREF="#minput">menu input handling</A>). - -<PRE> -int form_driver(FORM *form, /* form to pass input to */ - int request); /* form request code */ -</PRE> - -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. <P> - -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. - -<H3><A NAME="fpage">Page Navigation Requests</A></H3> - -These requests cause page-level moves through the form, -triggering display of a new form screen. - -<DL> -<DT> <CODE>REQ_NEXT_PAGE</CODE> -<DD> Move to the next form page. -<DT> <CODE>REQ_PREV_PAGE</CODE> -<DD> Move to the previous form page. -<DT> <CODE>REQ_FIRST_PAGE</CODE> -<DD> Move to the first form page. -<DT> <CODE>REQ_LAST_PAGE</CODE> -<DD> Move to the last form page. -</DL> - -These requests treat the list as cyclic; that is, <CODE>REQ_NEXT_PAGE</CODE> -from the last page goes to the first, and <CODE>REQ_PREV_PAGE</CODE> from -the first page goes to the last. - -<H3><A NAME="ffield">Inter-Field Navigation Requests</A></H3> - -These requests handle navigation between fields on the same page. - -<DL> -<DT> <CODE>REQ_NEXT_FIELD</CODE> -<DD> Move to next field. -<DT> <CODE>REQ_PREV_FIELD</CODE> -<DD> Move to previous field. -<DT> <CODE>REQ_FIRST_FIELD</CODE> -<DD> Move to the first field. -<DT> <CODE>REQ_LAST_FIELD</CODE> -<DD> Move to the last field. -<DT> <CODE>REQ_SNEXT_FIELD</CODE> -<DD> Move to sorted next field. -<DT> <CODE>REQ_SPREV_FIELD</CODE> -<DD> Move to sorted previous field. -<DT> <CODE>REQ_SFIRST_FIELD</CODE> -<DD> Move to the sorted first field. -<DT> <CODE>REQ_SLAST_FIELD</CODE> -<DD> Move to the sorted last field. -<DT> <CODE>REQ_LEFT_FIELD</CODE> -<DD> Move left to field. -<DT> <CODE>REQ_RIGHT_FIELD</CODE> -<DD> Move right to field. -<DT> <CODE>REQ_UP_FIELD</CODE> -<DD> Move up to field. -<DT> <CODE>REQ_DOWN_FIELD</CODE> -<DD> Move down to field. -</DL> - -These requests treat the list of fields on a page as cyclic; that is, -<CODE>REQ_NEXT_FIELD</CODE> from the last field goes to the first, and -<CODE>REQ_PREV_FIELD</CODE> from the first field goes to the last. The -order of the fields for these (and the <CODE>REQ_FIRST_FIELD</CODE> and -<CODE>REQ_LAST_FIELD</CODE> requests) is simply the order of the field -pointers in the form array (as set up by <CODE>new_form()</CODE> or -<CODE>set_form_fields()</CODE> <P> - -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. <P> - -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. <P> - -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 <CODE>REQ_MOVE_RIGHT</CODE> from A will -go to B only if A, B, and C <EM>all</EM> share the same first line; -otherwise it will skip over B to C. - -<H3><A NAME="fifield">Intra-Field Navigation Requests</A></H3> - -These requests drive movement of the edit cursor within the currently -selected field. - -<DL> -<DT> <CODE>REQ_NEXT_CHAR</CODE> -<DD> Move to next character. -<DT> <CODE>REQ_PREV_CHAR</CODE> -<DD> Move to previous character. -<DT> <CODE>REQ_NEXT_LINE</CODE> -<DD> Move to next line. -<DT> <CODE>REQ_PREV_LINE</CODE> -<DD> Move to previous line. -<DT> <CODE>REQ_NEXT_WORD</CODE> -<DD> Move to next word. -<DT> <CODE>REQ_PREV_WORD</CODE> -<DD> Move to previous word. -<DT> <CODE>REQ_BEG_FIELD</CODE> -<DD> Move to beginning of field. -<DT> <CODE>REQ_END_FIELD</CODE> -<DD> Move to end of field. -<DT> <CODE>REQ_BEG_LINE</CODE> -<DD> Move to beginning of line. -<DT> <CODE>REQ_END_LINE</CODE> -<DD> Move to end of line. -<DT> <CODE>REQ_LEFT_CHAR</CODE> -<DD> Move left in field. -<DT> <CODE>REQ_RIGHT_CHAR</CODE> -<DD> Move right in field. -<DT> <CODE>REQ_UP_CHAR</CODE> -<DD> Move up in field. -<DT> <CODE>REQ_DOWN_CHAR</CODE> -<DD> Move down in field. -</DL> - -Each <EM>word</EM> 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. - -<H3><A NAME="fscroll">Scrolling Requests</A></H3> - -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: - -<DL> -<DT> <CODE>REQ_SCR_FLINE</CODE> -<DD> Scroll vertically forward a line. -<DT> <CODE>REQ_SCR_BLINE</CODE> -<DD> Scroll vertically backward a line. -<DT> <CODE>REQ_SCR_FPAGE</CODE> -<DD> Scroll vertically forward a page. -<DT> <CODE>REQ_SCR_BPAGE</CODE> -<DD> Scroll vertically backward a page. -<DT> <CODE>REQ_SCR_FHPAGE</CODE> -<DD> Scroll vertically forward half a page. -<DT> <CODE>REQ_SCR_BHPAGE</CODE> -<DD> Scroll vertically backward half a page. -<DT> <CODE>REQ_SCR_FCHAR</CODE> -<DD> Scroll horizontally forward a character. -<DT> <CODE>REQ_SCR_BCHAR</CODE> -<DD> Scroll horizontally backward a character. -<DT> <CODE>REQ_SCR_HFLINE</CODE> -<DD> Scroll horizontally one field width forward. -<DT> <CODE>REQ_SCR_HBLINE</CODE> -<DD> Scroll horizontally one field width backward. -<DT> <CODE>REQ_SCR_HFHALF</CODE> -<DD> Scroll horizontally one half field width forward. -<DT> <CODE>REQ_SCR_HBHALF</CODE> -<DD> Scroll horizontally one half field width backward. -</DL> - -For scrolling purposes, a <EM>page</EM> of a field is the height -of its visible part. - -<H3><A NAME="fedit">Editing Requests</A></H3> - -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. <P> - -The following requests support editing the field and changing the edit -mode: - -<DL> -<DT> <CODE>REQ_INS_MODE</CODE> -<DD> Set insertion mode. -<DT> <CODE>REQ_OVL_MODE</CODE> -<DD> Set overlay mode. -<DT> <CODE>REQ_NEW_LINE</CODE> -<DD> New line request (see below for explanation). -<DT> <CODE>REQ_INS_CHAR</CODE> -<DD> Insert space at character location. -<DT> <CODE>REQ_INS_LINE</CODE> -<DD> Insert blank line at character location. -<DT> <CODE>REQ_DEL_CHAR</CODE> -<DD> Delete character at cursor. -<DT> <CODE>REQ_DEL_PREV</CODE> -<DD> Delete previous word at cursor. -<DT> <CODE>REQ_DEL_LINE</CODE> -<DD> Delete line at cursor. -<DT> <CODE>REQ_DEL_WORD</CODE> -<DD> Delete word at cursor. -<DT> <CODE>REQ_CLR_EOL</CODE> -<DD> Clear to end of line. -<DT> <CODE>REQ_CLR_EOF</CODE> -<DD> Clear to end of field. -<DT> <CODE>REQ_CLEAR_FIELD</CODE> -<DD> Clear entire field. -</DL> - -The behavior of the <CODE>REQ_NEW_LINE</CODE> and <CODE>REQ_DEL_PREV</CODE> 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. <P> - -First, we consider <CODE>REQ_NEW_LINE</CODE>: <P> - -The normal behavior of <CODE>REQ_NEW_LINE</CODE> 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). <P> - -The normal behavior of <CODE>REQ_NEW_LINE</CODE> 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. <P> - -However, <CODE>REQ_NEW_LINE</CODE> at the beginning of a field, or on the -last line of a field, instead does a <CODE>REQ_NEXT_FIELD</CODE>. -<CODE>O_NL_OVERLOAD</CODE> option is off, this special action is -disabled. <P> - -Now, let us consider <CODE>REQ_DEL_PREV</CODE>: <P> - -The normal behavior of <CODE>REQ_DEL_PREV</CODE> 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). <P> - -However, <CODE>REQ_DEL_PREV</CODE> at the beginning of a field is instead -treated as a <CODE>REQ_PREV_FIELD</CODE>. <P> If the -<CODE>O_BS_OVERLOAD</CODE> option is off, this special action is -disabled and the forms driver just returns <CODE>E_REQUEST_DENIED</CODE>. <P> - -See <A HREF="#frmoptions">Form Options</A> for discussion of how to set -and clear the overload options. - -<H3><A NAME="forder">Order Requests</A></H3> - -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: - -<DL> -<DT> <CODE>REQ_NEXT_CHOICE</CODE> -<DD> Place the successor value of the current value in the buffer. -<DT> <CODE>REQ_PREV_CHOICE</CODE> -<DD> Place the predecessor value of the current value in the buffer. -</DL> - -Of the built-in field types, only <CODE>TYPE_ENUM</CODE> has built-in successor -and predecessor functions. When you define a field type of your own -(see <A HREF="#fcustom">Custom Validation Types</A>), you can associate -our own ordering functions. - -<H3><A NAME="fappcmds">Application Commands</A></H3> - -Form requests are represented as integers above the <CODE>curses</CODE> value -greater than <CODE>KEY_MAX</CODE> and less than or equal to the constant -<CODE>MAX_COMMAND</CODE>. If your input-virtualization routine returns a -value above <CODE>MAX_COMMAND</CODE>, the forms driver will ignore it. - -<H2><A NAME="fhooks">Field Change Hooks</A></H2> - -It is possible to set function hooks to be executed whenever the -current field or form changes. Here are the functions that support this: - -<PRE> -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 */ -</PRE> - -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. - -<DL> -<DT> form_init -<DD> This hook is called when the form is posted; also, just after -each page change operation. -<DT> field_init -<DD> This hook is called when the form is posted; also, just after -each field change -<DT> field_term -<DD> 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. -<DT> form_term -<DD> This hook is called when the form is unposted; also, just before -each page change operation. -</DL> - -Calls to these hooks may be triggered -<OL> -<LI>When user editing requests are processed by the forms driver -<LI>When the current page is changed by <CODE>set_current_field()</CODE> call -<LI>When the current field is changed by a <CODE>set_form_page()</CODE> call -</OL> - -See <A NAME="ffocus">Field Change Commands</A> for discussion of the latter -two cases. <P> - -You can set a default hook for all fields by passing one of the set functions -a NULL first argument. <P> - -You can disable any of these hooks by (re)setting them to NULL, the default -value. - -<H2><A HREF="#ffocus">Field Change Commands</A></H2> - -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: - -<PRE> -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 */ -</PRE> - -The function <CODE>field_index()</CODE> returns the index of the given field -in the given form's field array (the array passed to <CODE>new_form()</CODE> or -<CODE>set_form_fields()</CODE>). <P> - -The initial current field of a form is the first active field on the -first page. The function <CODE>set_form_fields()</CODE> resets this.<P> - -It is also possible to move around by pages. - -<PRE> -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 */ -</PRE> - -The initial page of a newly-created form is 0. The function -<CODE>set_form_fields()</CODE> resets this. - -<H2><A NAME="frmoptions">Form Options</A></H2> - -Like fields, forms may have control option bits. They can be changed -or queried with these functions: - -<PRE> -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 */ -</PRE> - -By default, all options are on. Here are the available option bits: - -<DL> -<DT> O_NL_OVERLOAD -<DD> Enable overloading of <CODE>REQ_NEW_LINE</CODE> as described in <A -href="#fedit">Editing Requests</A>. 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 -<CODE>REQ_NEXT_FIELD</CODE> never arise. -<DT> O_BS_OVERLOAD -<DD> Enable overloading of <CODE>REQ_DEL_PREV</CODE> as described in -<A href="#fedit">Editing Requests</A>. -</DL> - -The option values are bit-masks and can be composed with logical-or in -the obvious way. - -<H2><A NAME="fcustom">Custom Validation Types</A></H2> - -The <CODE>form</CODE> library gives you the capability to define custom -validation types of your own. Further, the optional additional arguments -of <CODE>set_field_type</CODE> 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. - -<H3><A NAME="flinktypes">Union Types</A></H3> - -The simplest way to create a custom data type is to compose it from two -preexisting ones: - -<PRE> -FIELD *link_fieldtype(FIELDTYPE *type1, - FIELDTYPE *type2); -</PRE> - -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 <CODE>set_field_type()</CODE> call later requires arguments, the new -composite type expects all arguments for the first type, than all arguments -for the second. Order functions (see <A HREF="#forder">Order Requests</A>) -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. - -<H3><A NAME="fnewtypes">New Field Types</A></H3> - -To create a field type from scratch, you need to specify one or both of the -following things: - -<UL> -<LI>A character-validation function, to check each character as it is entered. -<LI>A field-validation function to be applied on exit from the field. -</UL> - -Here's how you do that: -<PRE> -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 */ -</PRE> - -At least one of the arguments of <CODE>new_fieldtype()</CODE> 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. <P> - -The function <CODE>free_fieldtype()</CODE> deallocates the argument -fieldtype, freeing all storage associated with it. <P> - -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. <P> - -A character validator gets the character passed in as a first argument. -It too should return TRUE if the character is valid, FALSE otherwise. - -<H3><A NAME="fcheckargs">Validation Function Arguments</A></H3> - -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 <EM>pile</EM>) built from any of the -field-type-specific arguments passed to <CODE>set_field_type()</CODE>. If -no such arguments are defined for the field type, this pile pointer -argument will be NULL. <P> - -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 <CODE>set_field_type()</CODE> argument, and -a pointer to the pile will be passed to the validation functions. <P> - -Here is how you make the association: - -<PRE> -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 */ -</PRE> - -Here is how the storage-management hooks are used: - -<DL> -<DT> <CODE>make_str</CODE> -<DD> This function is called by <CODE>set_field_type()</CODE>. It gets one -argument, a <CODE>va_list</CODE> of the type-specific arguments passed to -<CODE>set_field_type()</CODE>. It is expected to return a pile pointer to a data -structure that encapsulates those arguments. -<DT> <CODE>copy_str</CODE> -<DD> 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. -<DT> <CODE>free_str</CODE> -<DD> 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. -</DL> - -The <CODE>make_str</CODE> and <CODE>copy_str</CODE> 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. - -<H3><A NAME="fcustorder">Order Functions For Custom Types</A></H3> - -Some custom field types are simply ordered in the same well-defined way -that <CODE>TYPE_ENUM</CODE> is. For such types, it is possible to define -successor and predecessor functions to support the <CODE>REQ_NEXT_CHOICE</CODE> -and <CODE>REQ_PREV_CHOICE</CODE> requests. Here's how: - -<PRE> -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 */ -</PRE> - -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 <CODE>field_buffer()</CODE> to read the -current value, and <CODE>set_field_buffer()</CODE> 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. - -<H3><A NAME="fcustprobs">Avoiding Problems</A></H3> - -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. <P> - -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 <CODE>ncurses</CODE> library has been specifically exempted from -the package copyright to support this. <P> - -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. -</BODY> -</HTML> |