'\" t
.\"***************************************************************************
-.\" Copyright (c) 1998-2015,2017 Free Software Foundation, Inc. *
+.\" Copyright 2018-2019,2020 Thomas E. Dickey *
+.\" Copyright 1998-2015,2017 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_addch.3x,v 1.39 2017/04/17 00:14:02 tom Exp $
+.\" $Id: curs_addch.3x,v 1.55 2020/10/24 09:12:31 tom Exp $
.TH curs_addch 3X ""
+.ie \n(.g .ds `` \(lq
+.el .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el .ds '' ''
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.SH NAME
\fBaddch\fR,
.SH SYNOPSIS
\fB#include <curses.h>\fR
.PP
-\fBint addch(const chtype ch);\fR
+\fBint addch(const chtype \fP\fIch\fP\fB);\fR
.br
-\fBint waddch(WINDOW *win, const chtype ch);\fR
+\fBint waddch(WINDOW *\fP\fIwin\fP\fB, const chtype \fP\fIch\fP\fB);\fR
.br
-\fBint mvaddch(int y, int x, const chtype ch);\fR
+\fBint mvaddch(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB, const chtype \fP\fIch\fP\fB);\fR
.br
-\fBint mvwaddch(WINDOW *win, int y, int x, const chtype ch);\fR
+\fBint mvwaddch(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB, const chtype \fP\fIch\fP\fB);\fR
+.sp
+\fBint echochar(const chtype \fP\fIch\fP\fB);\fR
.br
-\fBint echochar(const chtype ch);\fR
-.br
-\fBint wechochar(WINDOW *win, const chtype ch);\fR
+\fBint wechochar(WINDOW *\fP\fIwin\fP\fB, const chtype \fP\fIch\fP\fB);\fR
.br
.SH DESCRIPTION
.SS Adding characters
The \fBaddch\fR, \fBwaddch\fR, \fBmvaddch\fR and \fBmvwaddch\fR routines put
the character \fIch\fR into the given window at its current window position,
-which is then advanced. They are analogous to \fBputchar\fR(3) in \fBstdio\fR(3).
+which is then advanced.
+They are analogous to \fBputchar\fR(3) in \fBstdio\fR(3).
If the advance is at the right margin:
.bP
The cursor automatically wraps to the beginning of the next line.
Tabs are considered to be at every eighth column.
The tab interval may be altered by setting the \fBTABSIZE\fR variable.
.PP
-If \fIch\fR is any other control character, it
-is drawn in \fB^\fR\fIX\fR notation. Calling \fBwinch\fR after adding a
-control character does not return the character itself, but instead returns
-the ^-representation of the control character.
+If \fIch\fR is any other nonprintable character,
+it is drawn in printable form,
+i.e., the \fB^\fR\fIX\fR notation used by \fBunctrl\fR(3X).
+Calling \fBwinch\fR after adding a
+nonprintable character does not return the character itself,
+but instead returns the printable representation of the character.
.PP
Video attributes can be combined with a character argument passed to
\fBaddch\fR or related functions by logical-ORing them into the character.
.PP
The \fBechochar\fR and \fBwechochar\fR routines are equivalent to a call to
\fBaddch\fR followed by a call to \fBrefresh\fR(3X), or a call to \fBwaddch\fR
-followed by a call to \fBwrefresh\fR. The knowledge that only a single
+followed by a call to \fBwrefresh\fR.
+The knowledge that only a single
character is being output is used and, for non-control characters, a
considerable performance gain may be seen by using these routines instead of
their equivalents.
.SS Line Graphics
The following variables may be used to add line drawing characters to the
-screen with routines of the \fBaddch\fR family. The default character listed
+screen with routines of the \fBaddch\fR family.
+The default character listed
below is used if the \fBacsc\fR capability does not define a terminal-specific
replacement for it,
or if the terminal and locale configuration requires Unicode but the
The names are taken from VT100 nomenclature.
.PP
.TS
-l l l
-_ _ _
-l l l.
-\fIName\fR \fIDefault\fR \fIDescription\fR
-ACS_BLOCK # solid square block
-ACS_BOARD # board of squares
-ACS_BTEE + bottom tee
-ACS_BULLET o bullet
-ACS_CKBOARD : checker board (stipple)
-ACS_DARROW v arrow pointing down
-ACS_DEGREE ' degree symbol
-ACS_DIAMOND + diamond
-ACS_GEQUAL > greater-than-or-equal-to
-ACS_HLINE \- horizontal line
-ACS_LANTERN # lantern symbol
-ACS_LARROW < arrow pointing left
-ACS_LEQUAL < less-than-or-equal-to
-ACS_LLCORNER + lower left-hand corner
-ACS_LRCORNER + lower right-hand corner
-ACS_LTEE + left tee
-ACS_NEQUAL ! not-equal
-ACS_PI * greek pi
-ACS_PLMINUS # plus/minus
-ACS_PLUS + plus
-ACS_RARROW > arrow pointing right
-ACS_RTEE + right tee
-ACS_S1 \- scan line 1
-ACS_S3 \- scan line 3
-ACS_S7 \- scan line 7
-ACS_S9 \&_ scan line 9
-ACS_STERLING f pound-sterling symbol
-ACS_TTEE + top tee
-ACS_UARROW ^ arrow pointing up
-ACS_ULCORNER + upper left-hand corner
-ACS_URCORNER + upper right-hand corner
-ACS_VLINE | vertical line
+l l l l
+l l l l
+_ _ _ _
+l l l l.
+\fBACS\fR \fBACS\fR \fBacsc\fP \fBGlyph\fR
+\fBName\fR \fBDefault\fR \fBchar\fP \fBName\fR
+ACS_BLOCK # 0 solid square block
+ACS_BOARD # h board of squares
+ACS_BTEE + v bottom tee
+ACS_BULLET o ~ bullet
+ACS_CKBOARD : a checker board (stipple)
+ACS_DARROW v . arrow pointing down
+ACS_DEGREE ' f degree symbol
+ACS_DIAMOND + ` diamond
+ACS_GEQUAL > > greater-than-or-equal-to
+ACS_HLINE \- q horizontal line
+ACS_LANTERN # i lantern symbol
+ACS_LARROW < , arrow pointing left
+ACS_LEQUAL < y less-than-or-equal-to
+ACS_LLCORNER + m lower left-hand corner
+ACS_LRCORNER + j lower right-hand corner
+ACS_LTEE + t left tee
+ACS_NEQUAL ! | not-equal
+ACS_PI * { greek pi
+ACS_PLMINUS # g plus/minus
+ACS_PLUS + n plus
+ACS_RARROW > + arrow pointing right
+ACS_RTEE + u right tee
+ACS_S1 \- o scan line 1
+ACS_S3 \- p scan line 3
+ACS_S7 \- r scan line 7
+ACS_S9 \&_ s scan line 9
+ACS_STERLING f } pound-sterling symbol
+ACS_TTEE + w top tee
+ACS_UARROW ^ \- arrow pointing up
+ACS_ULCORNER + l upper left-hand corner
+ACS_URCORNER + k upper right-hand corner
+ACS_VLINE | x vertical line
.TE
.SH RETURN VALUE
All routines return the integer \fBERR\fR upon failure and \fBOK\fR on success
-(the SVr4 manuals specify only "an integer value other than \fBERR\fR") upon
-successful completion, unless otherwise noted in the preceding routine
-descriptions.
+(the SVr4 manuals specify only
+\*(``an integer value other than \fBERR\fR\*('') upon successful completion,
+unless otherwise noted in the preceding routine descriptions.
.PP
-Functions with a "mv" prefix first perform a cursor movement using
+Functions with a \*(``mv\*('' prefix first perform a cursor movement using
\fBwmove\fP, and return an error if the position is outside the window,
or if the window pointer is null.
+.PP
+If it is not possible to add a complete character,
+an error is returned:
+.bP
+If \fBscrollok\fR is not enabled,
+writing a character at the lower right margin succeeds.
+However, an error is returned because
+it is not possible to wrap to a new line
+.bP
+If an error is detected when converting a multibyte character to a sequence
+of bytes,
+or if it is not possible to add all of the resulting bytes in the window,
+an error is returned.
.SH NOTES
Note that \fBaddch\fR, \fBmvaddch\fR, \fBmvwaddch\fR, and
\fBechochar\fR may be macros.
.SH PORTABILITY
All these functions are described in the XSI Curses standard, Issue 4.
The defaults specified for forms-drawing characters apply in the POSIX locale.
+.SS ACS Symbols
.LP
X/Open Curses states that the \fIACS_\fP definitions are \fBchar\fP constants.
For the wide-character implementation (see \fBcurs_add_wch\fP),
there are analogous \fIWACS_\fP definitions which are \fBcchar_t\fP constants.
+Some implementations are problematic:
+.bP
+Some implementations define the ACS symbols to a constant
+(such as Solaris), while others define those to entries in an array.
+.IP
+This implementation uses an array \fBacs_map\fP, as done in SVr4 curses.
+NetBSD also uses an array, actually named \fB_acs_char\fP, with a \fB#define\fP
+for compatibility.
+.bP
+HPUX curses equates some of the \fIACS_\fP symbols
+to the analogous \fIWACS_\fP symbols as if the \fIACS_\fP symbols were
+wide characters.
+The misdefined symbols are the arrows
+and other symbols which are not used for line-drawing.
+.bP
+X/Open Curses (issues 2 through 7) has a typographical error
+for the ACS_LANTERN symbol, equating its \*(``VT100+ Character\*(''
+to \fBI\fP (capital I), while the header files for SVr4 curses
+and the various implementations use \fBi\fP (lowercase).
+.IP
+None of the terminal descriptions on Unix platforms use uppercase-I,
+except for Solaris (i.e., \fIscreen\fP's terminal description,
+apparently based on the X/Open documentation around 1995).
+On the other hand, the terminal description \fIgs6300\fP
+(AT&T PC6300 with EMOTS Terminal Emulator) uses lowercase-i.
.LP
Some ACS symbols
(ACS_S3,
ACS_NEQUAL,
ACS_STERLING)
were not documented in
-any publicly released System V. However, many publicly available terminfos
+any publicly released System V.
+However, many publicly available terminfos
include \fBacsc\fR strings in which their key characters (pryz{|}) are
embedded, and a second-hand list of their character descriptions has come
-to light. The ACS-prefixed names for them were invented for \fBncurses\fR(3X).
+to light.
+The ACS-prefixed names for them were invented for \fBncurses\fR(3X).
.LP
The \fIdisplayed\fP values for the \fIACS_\fP and \fIWACS_\fP constants
depend on
In certain cases, the terminal is unable to display line-drawing characters
except by using UTF-8 (see the discussion of \fBNCURSES_NO_UTF8_ACS\fP in
ncurses(3X)).
+.SS Character Set
+X/Open Curses assumes that the parameter passed to \fBwaddch\fP contains
+a single character.
+As discussed in \fBcurs_attr\fP(3X), that character may have been
+more than eight bits in an SVr3 or SVr4 implementation,
+but in the X/Open Curses model, the details are not given.
+The important distinction between SVr4 curses and X/Open Curses is
+that the non-character information (attributes and color) was
+separated from the character information which is packed in a \fBchtype\fP
+to pass to \fBwaddch\fP.
+.PP
+In this implementation, \fBchtype\fP holds an eight-bit character.
+But ncurses allows multibyte characters to be passed in a succession
+of calls to \fBwaddch\fP.
+The other implementations do not do this;
+a call to \fBwaddch\fP passes exactly one character
+which may be rendered as one or more cells on the screen
+depending on whether it is printable.
+.PP
+Depending on the locale settings,
+ncurses will inspect the byte passed in each call to \fBwaddch\fP,
+and check if the latest call will continue a multibyte sequence.
+When a character is \fIcomplete\fP,
+ncurses displays the character and moves to the next position in the screen.
+.PP
+If the calling application interrupts the succession of bytes in
+a multibyte character by moving the current location (e.g., using \fBwmove\fP),
+ncurses discards the partially built character,
+starting over again.
+.PP
+For portability to other implementations,
+do not rely upon this behavior:
+.bP
+check if a character can be represented as a single byte in the current locale
+before attempting call \fBwaddch\fP, and
+.bP
+call \fBwadd_wch\fP for characters which cannot be handled by \fBwaddch\fP.
+.SS TABSIZE
.LP
-The \fBTABSIZE\fR variable is implemented in some versions of curses,
-but is not part of X/Open curses.
+The \fBTABSIZE\fR variable is implemented in SVr4 and other versions of curses,
+but is not part of X/Open curses
+(see \fBcurs_variables\fR(3X) for more details).
.LP
If \fIch\fR is a carriage return,
the cursor is moved to the beginning of the current row of the window.
projects / ncurses.git / blobdiff