.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_inch.3x,v 1.51 2024/04/20 21:20:07 tom Exp $
-.TH curs_inch 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.\" $Id: curs_inch.3x,v 1.52 2024/05/11 20:39:53 tom Exp $
+.TH curs_inch 3X 2024-05-11 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
.ie \n(.g \{\
.ds `` \(lq
.ds '' \(rq
.PP
\fBchtype inch(void);
\fBchtype winch(WINDOW *\fIwin\fP);
-.PP
\fBchtype mvinch(int \fIy\fP, int \fIx\fP);
\fBchtype mvwinch(WINDOW *\fIwin\fP, int \fIy\fP, int \fIx\fP);
.fi
.SH DESCRIPTION
-These routines return the character, of type \fBchtype\fP, at the current
-position in the named window.
-If any attributes are set for that position,
-their values are OR'ed into the value returned.
-Constants defined in
-\fB<curses.h>\fP can be used with the \fB&\fP (logical AND) operator to
-extract the character or attributes alone.
-.
-.SS Attributes
-The following bit masks may be AND-ed with characters returned by \fBwinch\fP.
-.PP
-.TS
-Lb Lb
-Lb Lx.
-Name Description
-_
-A_CHARTEXT Extract character
-A_ATTRIBUTES Extract attributes
-A_COLOR Extract color pair information
-.TE
+.B \%winch
+returns the
+.I curses
+character,
+including rendering attributes and color pair identifier,
+at the cursor position in the window
+.IR win "."
+Subsection \*(``Video Attributes\*('' of \fB\%attron\fP(3X) explains
+how to extract these data from a
+.IR chtype "."
+\fB\%ncurses\fP(3X) describes the variants of this function.
.SH RETURN VALUE
Functions prefixed with \*(``mv\*('' first perform cursor movement and
fail if the position
.IR x )
is outside the window boundaries.
.PP
-The \fBwinch\fP function does not return an error if the window contains
-characters larger than 8-bits (255).
-Only the low-order 8 bits of the character are used by \fBwinch\fP.
+These functions do not return an error if the window comprises cells of
+.I curses
+complex characters
+(that is,
+they contain characters with codes wider than eight bits,
+or greater than 255 as an unsigned decimal integer).
+They instead extract only the low-order eight bits of character data
+in the cell.
.SH NOTES
-Note that all of these routines may be macros.
+.BR \%inch ,
+.BR \%mvinch ,
+and
+.B \%mvwinch
+may be implemented as macros.
.SH PORTABILITY
-These functions are described in X/Open Curses, Issue 4.
+X/Open Curses,
+Issue 4 describes these functions.
+It specifies no error conditions for them.
+.SH HISTORY
+.B \%winch
+was implemented in the original 4BSD
+.I curses
+library
+(November 1980).
+It returned only the character code
+(as an integer)
+with the \*(``standout\*(`` attribute bit
+(the only one it supported)
+cleared.
+Because 7-bit ASCII was the only character encoding supported,
+4BSD's
+.B \%winch
+returned a
+.I char
+type.
+.\" Through macros, it directly accessed a `char` structure member.
.PP
-Very old systems (before standardization) provide a different function
-with the same name:
-.bP
-The \fBwinch\fP function was part of the original BSD curses library,
-which stored a 7-bit character combined with the \fIstandout\fP attribute.
-.IP
-In BSD curses, \fBwinch\fP returned only the character (as an integer)
-with the \fIstandout\fP attribute removed.
-.bP
-System V curses added support for several video attributes which
-could be combined with characters in the window.
-.IP
-Reflecting this improvement, the function was altered to return the
-character combined with all video attributes in a \fBchtype\fP value.
+System\ V
+.I curses
+(1983) permitted several rendering attributes to be combined with a
+character in a window.
+Reflecting this improvement,
+.B \%winch
+.\" XXX: possibly returned a `short` in SVr1 through SVr3 --GBR
+returned an
+.I int
+in SVr3.2 (1988)
+and switched to
+.I chtype
+in SVr4 (1989).
.PP
-X/Open Curses does not specify
-the size and layout of attributes, color and character values in
-\fBchtype\fP; it is implementation-dependent.
-This implementation uses 8 bits for character values.
-An application using more bits, e.g., a Unicode value,
-should use the wide-character equivalents to these functions.
+X/Open Curses does not specify the sizes of the character code or
+color pair identifier,
+nor the quantity of rendering attribute bits,
+in
+.IR chtype ";"
+these are implementation-dependent.
+.I \%ncurses
+uses eight bits for the character code.
+An application requiring a wider character type,
+for instance to handle Unicode,
+should use the wide-character counterparts of these functions.
.SH SEE ALSO
\fB\%curs_in_wch\fP(3X) describes comparable functions of the
.I \%ncurses
projects / ncurses.git / blobdiff