.\"***************************************************************************
-.\" Copyright 2018-2020,2021 Thomas E. Dickey *
+.\" Copyright 2018-2022,2023 Thomas E. Dickey *
.\" Copyright 1998-2016,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_initscr.3x,v 1.36 2021/12/25 21:41:58 tom Exp $
-.TH curs_initscr 3X ""
+.\" $Id: curs_initscr.3x,v 1.54 2023/11/11 23:20:20 tom Exp $
+.TH curs_initscr 3X 2023-11-11 "ncurses 6.4" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el .ds `` ""
+.ie t .ds '' ''
+.el .ds '' ""
+.\}
+.
.de bP
.ie n .IP \(bu 4
.el .IP \(bu 2
..
-.ie \n(.g .ds `` \(lq
-.el .ds `` ``
-.ie \n(.g .ds '' \(rq
-.el .ds '' ''
-.na
-.hy 0
.SH NAME
-\fBinitscr\fP,
-\fBnewterm\fP,
-\fBendwin\fP,
-\fBisendwin\fP,
-\fBset_term\fP,
-\fBdelscreen\fP \- \fBcurses\fP screen initialization and manipulation routines
-.ad
-.hy
+\fB\%initscr\fP,
+\fB\%newterm\fP,
+\fB\%endwin\fP,
+\fB\%isendwin\fP,
+\fB\%set_term\fP,
+\fB\%delscreen\fP \-
+initialize, manipulate, or tear down \fIcurses\fR terminal interface
.SH SYNOPSIS
-\fB#include <curses.h>\fP
-.sp
-\fBWINDOW *initscr(void);\fP
-.br
-\fBint endwin(void);\fP
-.sp
-\fBbool isendwin(void);\fP
-.sp
-\fBSCREEN *newterm(const char *\fP\fItype\fP\fB, FILE *\fP\fIoutfd\fP\fB, FILE *\fP\fIinfd\fP\fB);\fP
-.br
-\fBSCREEN *set_term(SCREEN *\fP\fInew\fP\fB);\fP
-.br
-\fBvoid delscreen(SCREEN* \fP\fIsp\fP\fB);\fP
-.br
+.nf
+\fB#include <curses.h>
+.PP
+\fBWINDOW *initscr(void);
+\fBint endwin(void);
+.PP
+\fBbool isendwin(void);
+.PP
+\fBSCREEN *newterm(const char *\fItype\fP, FILE *\fIoutf\fP, FILE *\fIinf\fP);
+\fBSCREEN *set_term(SCREEN *\fInew\fP);
+\fBvoid delscreen(SCREEN* \fIsp\fP);
+.fi
.SH DESCRIPTION
.SS initscr
\fBinitscr\fP is normally the first \fBcurses\fP routine to call when
message to standard error and exits;
otherwise, a pointer is returned to \fBstdscr\fP.
.SS newterm
-.PP
A program that outputs to more than one terminal should use the \fBnewterm\fP
routine for each terminal instead of \fBinitscr\fP.
A program that needs to inspect capabilities,
so it can continue to run in a line-oriented mode if the
terminal cannot support a screen-oriented program, would also use
\fBnewterm\fP.
+.PP
The routine \fBnewterm\fP should be called once for each terminal.
It returns a variable of type \fBSCREEN *\fP which should be saved
as a reference to that terminal.
.bP
the \fItype\fP of the terminal to be used in place of \fB$TERM\fP,
.bP
-a file pointer for output to the terminal, and
+an output stream connected to the terminal, and
.bP
-another file pointer for input from the terminal
+an input stream connected to the terminal
.PP
If the \fItype\fP parameter is \fBNULL\fP, \fB$TERM\fP will be used.
-.SS endwin
.PP
+The file descriptor of the output stream is passed to \fBsetupterm\fP(3X),
+which returns a pointer to a \fBTERMINAL\fP structure.
+\fBnewterm\fP's return value holds a pointer to the \fBTERMINAL\fP structure.
+.SS endwin
The program must also call
\fBendwin\fP for each terminal being used before exiting from \fBcurses\fP.
If \fBnewterm\fP is called more than once for the same terminal, the first
Calling \fBrefresh\fP(3X) or \fBdoupdate\fP(3X) after a
temporary escape causes the program to resume visual mode.
.SS isendwin
-.PP
The \fBisendwin\fP routine returns \fBTRUE\fP if \fBendwin\fP has been
called without any subsequent calls to \fBwrefresh\fP,
and \fBFALSE\fP otherwise.
.SS set_term
-.PP
The \fBset_term\fP routine is used to switch between different terminals.
The screen reference \fInew\fP becomes the new current terminal.
The previous terminal is returned by the routine.
This is the only routine which manipulates \fBSCREEN\fP pointers;
all other routines affect only the current terminal.
.SS delscreen
-.PP
The \fBdelscreen\fP routine frees storage associated with the
\fBSCREEN\fP data structure.
The \fBendwin\fP routine does not do
X/Open defines no error conditions.
In this implementation
.bP
-\fBendwin\fP returns an error if the terminal was not initialized.
+\fBendwin\fP returns an error if
+.RS
+.bP
+the terminal was not initialized, or
+.bP
+\fBendwin\fP is called more than once without updating the screen, or
+.bP
+\fBreset_shell_mode\fP(3X) returns an error.
+.RE
.bP
\fBnewterm\fP
returns an error if it cannot allocate the data structures for the screen,
.bP
This implementation allows using \fBinitscr\fP after \fBendwin\fP.
.PP
-Old versions of curses, e.g., BSD 4.4, may have returned a null pointer
+Old versions of curses, e.g., BSD 4.4, would return a null pointer
from \fBinitscr\fP when an error is detected, rather than exiting.
It is safe but redundant to check the return value of \fBinitscr\fP
in XSI Curses.
-.SS Unset TERM Variable
.PP
+Calling \fBendwin\fP does not dispose of the memory allocated in \fBinitscr\fP
+or \fBnewterm\fP.
+Deleting a \fBSCREEN\fP provides a way to do this:
+.bP
+X/Open Curses does not say what happens to \fBWINDOW\fPs when \fBdelscreen\fP
+\*(``frees storage associated with the \fBSCREEN\fP\*(''
+nor does the SVr4 documentation help,
+adding that it should be called after \fBendwin\fP if a \fBSCREEN\fP
+is no longer needed.
+.bP
+However, \fBWINDOW\fPs are implicitly associated with a \fBSCREEN\fP.
+so that it is reasonable to expect \fBdelscreen\fP to deal with these.
+.bP
+SVr4 curses deletes the standard \fBWINDOW\fP structures
+\fBstdscr\fP and \fBcurscr\fP as well as a work area \fBnewscr\fP.
+SVr4 curses ignores other windows.
+.bP
+Since version 4.0 (1996), ncurses has maintained a list of all windows
+for each screen,
+using that information to delete those windows when \fBdelscreen\fP is called.
+.bP
+NetBSD copied this feature of ncurses in 2001.
+PDCurses follows the SVr4 model,
+deleting only the standard \fBWINDOW\fP structures.
+.SS High-level versus low-level
+Different implementations may disagree regarding the level of some functions.
+For example, \fBSCREEN\fP (returned by \fBnewterm\fP) and
+\fBTERMINAL\fP (returned by \fBsetupterm\fP(3X)) hold file descriptors for
+the output stream.
+If an application switches screens using \fBset_term\fR,
+or switches terminals using \fBset_curterm\fP(3X),
+applications which use the output file descriptor can have different
+behavior depending on which structure holds the corresponding descriptor.
+.PP
+For example
+.bP
+NetBSD's \fBbaudrate\fP(3X) function uses the descriptor in \fBTERMINAL\fP.
+\fBncurses\fP and SVr4 use the descriptor in \fBSCREEN\fP.
+.bP
+NetBSD and \fBncurses\fP use the descriptor
+in \fBTERMINAL\fP
+for terminal I/O modes,
+e.g.,
+\fBdef_shell_mode\fP(3X),
+\fBdef_prog_mode\fP(3X).
+SVr4 curses uses the descriptor in \fBSCREEN\fP.
+.SS Unset TERM Variable
If the TERM variable is missing or empty, \fBinitscr\fP uses the
value \*(``unknown\*('',
which normally corresponds to a terminal entry with the \fIgeneric\fP
(\fIgn\fP) capability.
-Generic entries are detected by \fBsetupterm\fP
-(see curs_terminfo(3X)) and cannot be used for full-screen operation.
+Generic entries are detected by \fBsetupterm\fP(3X)
+and cannot be used for full-screen operation.
Other implementations may handle a missing/empty TERM variable differently.
.SS Signal Handlers
-.PP
-Quoting from X/Open Curses, section 3.1.1:
+Quoting from X/Open Curses Issue 7, section 3.1.1:
.RS 5
.PP
-\fICurses implementations may provide for special handling of the \fBSIGINT\fP,
-\fBSIGQUIT\fP and \fBSIGTSTP\fP signals
-if their disposition is \fBSIG_DFL\fP at the time
-\fBinitscr\fP is called \fP...
+Curses implementations may provide for special handling of the
+\%SIGINT,
+\%SIGQUIT,
+and \%SIGTSTP signals if their disposition is \%SIG_DFL at the time
+.I \%initscr
+is called.\|.\|.
.PP
-\fIAny special handling for these signals may remain in effect for the
+Any special handling for these signals may remain in effect for the
life of the process or until the process changes the disposition of
-the signal.\fP
+the signal.
.PP
-\fINone of the Curses functions are required to be safe
-with respect to signals \fP...
+None of the Curses functions are required to be safe
+with respect to signals.\|.\|.
.RE
.PP
This implementation establishes signal handlers during initialization,
standard screen \fBstdscr\fP,
and update other data such as \fBLINES\fP and \fBCOLS\fP.
.SH SEE ALSO
-\fBcurses\fP(3X),
-\fBcurs_kernel\fP(3X),
-\fBcurs_refresh\fP(3X),
-\fBcurs_slk\fP(3X),
-\fBcurs_terminfo\fP(3X),
-\fBcurs_util\fP(3X),
-\fBcurs_variables\fP(3X).
+\fB\%curses\fP(3X),
+\fB\%curs_kernel\fP(3X),
+\fB\%curs_refresh\fP(3X),
+\fB\%curs_slk\fP(3X),
+\fB\%curs_terminfo\fP(3X),
+\fB\%curs_util\fP(3X),
+\fB\%curs_variables\fP(3X)
projects / ncurses.git / blobdiff