.\"***************************************************************************
-.\" Copyright (c) 1998-2015,2017 Free Software Foundation, Inc. *
+.\" Copyright 2018,2020 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_pad.3x,v 1.19 2017/01/07 19:25:15 tom Exp $
+.\" $Id: curs_pad.3x,v 1.26 2020/02/02 23:34:34 tom Exp $
+.de bP
+.ie n .IP \(bu 4
+.el .IP \(bu 2
+..
.TH curs_pad 3X ""
.na
.hy 0
window will be on the screen at one time.
Automatic refreshes of pads
(e.g., from scrolling or echoing of input) do not occur.
+.PP
It is not
legal to call \fBwrefresh\fR with a \fIpad\fR as an argument; the routines
\fBprefresh\fR or \fBpnoutrefresh\fR should be called instead.
of windows.
The additional parameters are needed to indicate what part of the
pad and screen are involved.
+.bP
The \fIpminrow\fR and \fIpmincol\fR parameters specify the upper
left-hand corner of the rectangle to be displayed in the pad.
+.bP
The \fIsminrow\fR,
\fIsmincol\fR, \fIsmaxrow\fR, and \fIsmaxcol\fR
parameters specify the edges of the
rectangle to be displayed on the screen.
+.PP
The lower right-hand corner of the
rectangle to be displayed in the pad is calculated from the screen coordinates,
since the rectangles must be the same size.
.SS pechochar
.PP
The \fBpechochar\fR routine is functionally equivalent to a call to \fBaddch\fR
-followed by a call to \fBrefresh\fR(3X), a call to \fBwaddch\fR followed by a call
+followed by a call to \fBrefresh\fR(3X),
+a call to \fBwaddch\fR followed by a call
to \fBwrefresh\fR, or a call to \fBwaddch\fR followed by a call to
\fBprefresh\fR.
The knowledge that only a single character is being output is
.SH NOTES
Note that \fBpechochar\fR may be a macro.
.SH PORTABILITY
-The XSI Curses standard, Issue 4 describes these functions.
+BSD curses has no \fIpad\fP feature.
+.PP
+SVr2 curses (1986) provided the \fBnewpad\fP and related functions,
+documenting them in a single line each.
+SVr3 (1987) provided more extensive documentation.
+.PP
+The documentation does not explain the term \fIpad\fP.
+However, the Apollo \fIAegis\fP workstation operating system
+supported a graphical \fIpad\fP feature:
+.bP
+These graphical pads could be much larger than the computer's display.
+.bP
+The read-only output from a command could be scrolled back to inspect,
+and select text from the pad.
+.PP
+The two uses may be related.
+.PP
+The XSI Curses standard, Issue 4 describes these functions,
+without significant change from the SVr3 documentation.
+It describes no error conditions.
+The behavior of \fBsubpad\fP if the parent window is not
+a pad is undocumented,
+and is not checked by the vendor Unix implementations:
+.bP
+SVr4 curses sets a flag in the \fBWINDOW\fP structure in \fBnewpad\fP
+which tells if the window is a \fIpad\fP.
+.IP
+However, it uses this information only in
+\fBwaddch\fP (to decide if it should call \fBwrefresh\fP) and
+\fBwscrl\fP (to avoid scrolling a pad),
+and does not check in \fBwrefresh\fP to ensure that the pad
+is refreshed properly.
+.bP
+Solaris X/Open Curses checks if a window is a pad in \fBwnoutrefresh\fP,
+returning \fBERR\fP in that case.
+.IP
+However, it only sets the flag for subwindows if the parent window is a pad.
+Its \fBnewpad\fP function does not set this information.
+Consequently, the check will never fail.
+.IP
+It makes no comparable check in \fBpnoutrefresh\fP,
+though interestingly enough, a comment in the source code
+states that the lack of a check was an MKS extension.
+.bP
+NetBSD 7 curses
+sets a flag in the \fBWINDOW\fP structure for \fBnewpad\fP and \fBsubpad\fP,
+using this to help with the distinction between \fBwnoutrefresh\fP
+and \fBpnoutrefresh\fP.
+.IP
+It does not check for the case where a subwindow is created in
+a pad using \fBsubwin\fP or \fBderwin\fP.
+.IP
+The \fBdupwin\fP function returns a regular window when duplicating a pad.
+Likewise, \fBgetwin\fP always returns a window, even if the saved
+data was from a pad.
+.PP
+This implementation
+.bP
+sets a flag in the \fBWINDOW\fP structure for \fBnewpad\fP and \fBsubpad\fP,
+.bP
+allows a \fBsubwin\fP or \fBderwin\fP call to succeed having a pad parent by
+forcing the subwindow to be a pad,
+.bP
+checks in both \fBwnoutrefresh\fP and \fBpnoutrefresh\fP to ensure
+that pads and windows are handled distinctly, and
+.bP
+ensures that \fBdupwin\fP and \fBgetwin\fP treat
+pads versus windows consistently.
.SH SEE ALSO
-\fBcurses\fR(3X), \fBcurs_refresh\fR(3X), \fBcurs_touch\fR(3X), \fBcurs_addch\fR(3X).
+\fBcurses\fR(3X),
+\fBcurs_refresh\fR(3X),
+\fBcurs_touch\fR(3X),
+\fBcurs_addch\fR(3X).
projects / ncurses.git / blobdiff