241 lines
9.8 KiB
Groff
241 lines
9.8 KiB
Groff
.\" $OpenBSD: curs_pad.3,v 1.10 2023/10/17 09:52:08 nicm Exp $
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.\"
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.\"***************************************************************************
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.\" Copyright 2018-2022,2023 Thomas E. Dickey *
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.\" Copyright 1998-2015,2017 Free Software Foundation, Inc. *
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.\" *
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.\" Permission is hereby granted, free of charge, to any person obtaining a *
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.\" copy of this software and associated documentation files (the *
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.\" "Software"), to deal in the Software without restriction, including *
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.\" without limitation the rights to use, copy, modify, merge, publish, *
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.\" distribute, distribute with modifications, sublicense, and/or sell *
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.\" copies of the Software, and to permit persons to whom the Software is *
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.\" furnished to do so, subject to the following conditions: *
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.\" *
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.\" The above copyright notice and this permission notice shall be included *
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.\" in all copies or substantial portions of the Software. *
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.\" *
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
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.\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
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.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
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.\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
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.\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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.\" *
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.\" Except as contained in this notice, the name(s) of the above copyright *
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.\" holders shall not be used in advertising or otherwise to promote the *
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.\" sale, use or other dealings in this Software without prior written *
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.\" authorization. *
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.\"***************************************************************************
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.\"
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.\" $Id: curs_pad.3,v 1.10 2023/10/17 09:52:08 nicm Exp $
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.de bP
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.ie n .IP \(bu 4
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.el .IP \(bu 2
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..
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.TH curs_pad 3 2023-07-01 "ncurses 6.4" "Library calls"
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.na
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.hy 0
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.SH NAME
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\fBnewpad\fP,
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\fBsubpad\fP,
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\fBprefresh\fP,
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\fBpnoutrefresh\fP,
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\fBpechochar\fP,
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\fBpecho_wchar\fP \- create and display \fBcurses\fP pads
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.ad
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.hy
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.SH SYNOPSIS
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\fB#include <curses.h>\fP
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.sp
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\fBWINDOW *newpad(int \fInlines\fB, int \fIncols\fB);\fR
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.br
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\fBWINDOW *subpad(WINDOW *\fIorig\fB, int \fInlines\fB, int \fIncols\fB,\fR
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\fBint \fIbegin_y\fB, int \fIbegin_x\fB);\fR
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.br
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\fBint prefresh(WINDOW *\fIpad\fB, int \fIpminrow\fB, int \fIpmincol\fB,\fR
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\fBint \fIsminrow\fB, int \fIsmincol\fB, int \fIsmaxrow\fB, int \fIsmaxcol\fB);\fR
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.br
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\fBint pnoutrefresh(WINDOW *\fIpad\fB, int \fIpminrow\fB, int \fIpmincol\fB,\fR
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\fBint \fIsminrow\fB, int \fIsmincol\fB, int \fIsmaxrow\fB, int \fIsmaxcol\fB);\fR
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.br
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\fBint pechochar(WINDOW *\fIpad\fB, chtype \fIch\fB);\fR
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.br
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\fBint pecho_wchar(WINDOW *\fIpad\fB, const cchar_t *\fIwch\fB);\fR
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.SH DESCRIPTION
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.SS newpad
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The \fBnewpad\fP routine creates and returns a pointer to a new pad data
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structure with the given number of lines, \fInlines\fP, and columns,
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\fIncols\fP.
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A pad is like a window, except that it is not restricted by the
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screen size, and is not necessarily associated with a particular part of the
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screen.
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Pads can be used when a large window is needed, and only a part of the
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window will be on the screen at one time.
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Automatic refreshes of pads
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(e.g., from scrolling or echoing of input) do not occur.
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.PP
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It is not
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legal to call \fBwrefresh\fP with a \fIpad\fP as an argument; the routines
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\fBprefresh\fP or \fBpnoutrefresh\fP should be called instead.
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Note that these
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routines require additional parameters to specify the part of the pad to be
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displayed and the location on the screen to be used for the display.
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.SS subpad
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The \fBsubpad\fP routine creates and returns a pointer to a subwindow within a
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pad with the given number of lines, \fInlines\fP, and columns, \fIncols\fP.
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Unlike \fBsubwin\fP, which uses screen coordinates, the window is at position
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(\fIbegin\fR_\fIx\fB,\fR \fIbegin\fR_\fIy\fR) on the pad.
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The window is
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made in the middle of the window \fIorig\fP, so that changes made to one window
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affect both windows.
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During the use of this routine, it will often be
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necessary to call \fBtouchwin\fP or \fBtouchline\fP on \fIorig\fP before
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calling \fBprefresh\fP.
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.SS prefresh, pnoutrefresh
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The \fBprefresh\fP and \fBpnoutrefresh\fP routines are analogous to
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\fBwrefresh\fP and \fBwnoutrefresh\fP except that they relate to pads instead
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of windows.
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The additional parameters are needed to indicate what part of the
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pad and screen are involved.
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.bP
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The \fIpminrow\fP and \fIpmincol\fP parameters specify the upper
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left-hand corner of the rectangle to be displayed in the pad.
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.bP
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The \fIsminrow\fP,
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\fIsmincol\fP, \fIsmaxrow\fP, and \fIsmaxcol\fP
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parameters specify the edges of the
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rectangle to be displayed on the screen.
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.PP
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The lower right-hand corner of the
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rectangle to be displayed in the pad is calculated from the screen coordinates,
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since the rectangles must be the same size.
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Both rectangles must be entirely
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contained within their respective structures.
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Negative values of
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\fIpminrow\fP, \fIpmincol\fP, \fIsminrow\fP, or \fIsmincol\fP are treated as if
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they were zero.
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.SS pechochar
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The \fBpechochar\fP routine is functionally equivalent to a call to \fBaddch\fP
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followed by a call to \fBrefresh\fP(3),
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a call to \fBwaddch\fP followed by a call
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to \fBwrefresh\fP, or a call to \fBwaddch\fP followed by a call to
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\fBprefresh\fP.
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The knowledge that only a single character is being output is
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taken into consideration and, for non-control characters, a considerable
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performance gain might be seen by using these routines instead of their
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equivalents.
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In the case of \fBpechochar\fP, the last location of the pad on
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the screen is reused for the arguments to \fBprefresh\fP.
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.SS pecho_wchar
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The \fBpecho_wchar\fP function is the analogous wide-character
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form of \fBpechochar\fP.
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It outputs one character to a pad and immediately refreshes the pad.
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It does this by a call to \fBwadd_wch\fP followed by a call to \fBprefresh\fP.
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.SH RETURN VALUE
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Routines that return an integer return \fBERR\fP upon failure and \fBOK\fP
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(SVr4 only specifies "an integer value other than \fBERR\fP") upon successful
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completion.
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.PP
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Routines that return pointers return \fBNULL\fP on error, and set \fBerrno\fP
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to \fBENOMEM\fP.
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.PP
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X/Open does not define any error conditions.
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In this implementation
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.RS 3
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.TP 5
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\fBprefresh\fP and \fBpnoutrefresh\fP
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return an error
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if the window pointer is null, or
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if the window is not really a pad or
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if the area to refresh extends off-screen or
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if the minimum coordinates are greater than the maximum.
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.TP 5
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\fBpechochar\fP
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returns an error
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if the window is not really a pad, and the associated call
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to \fBwechochar\fP returns an error.
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.TP 5
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\fBpecho_wchar\fP
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returns an error
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if the window is not really a pad, and the associated call
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to \fBwecho_wchar\fP returns an error.
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.RE
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.SH NOTES
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Note that \fBpechochar\fP may be a macro.
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.SH PORTABILITY
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BSD curses has no \fIpad\fP feature.
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.PP
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SVr2 curses (1986) provided the \fBnewpad\fP and related functions,
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documenting them in a single line each.
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SVr3 (1987) provided more extensive documentation.
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.PP
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The documentation does not explain the term \fIpad\fP.
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However, the Apollo \fIAegis\fP workstation operating system
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supported a graphical \fIpad\fP feature:
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.bP
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These graphical pads could be much larger than the computer's display.
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.bP
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The read-only output from a command could be scrolled back to inspect,
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and select text from the pad.
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.PP
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The two uses may be related.
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.PP
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The XSI Curses standard, Issue 4 describes these functions,
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without significant change from the SVr3 documentation.
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It describes no error conditions.
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The behavior of \fBsubpad\fP if the parent window is not
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a pad is undocumented,
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and is not checked by the vendor Unix implementations:
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.bP
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SVr4 curses sets a flag in the \fBWINDOW\fP structure in \fBnewpad\fP
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which tells if the window is a \fIpad\fP.
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.IP
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However, it uses this information only in
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\fBwaddch\fP (to decide if it should call \fBwrefresh\fP) and
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\fBwscrl\fP (to avoid scrolling a pad),
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and does not check in \fBwrefresh\fP to ensure that the pad
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is refreshed properly.
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.bP
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Solaris X/Open Curses checks if a window is a pad in \fBwnoutrefresh\fP,
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returning \fBERR\fP in that case.
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.IP
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However, it only sets the flag for subwindows if the parent window is a pad.
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Its \fBnewpad\fP function does not set this information.
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Consequently, the check will never fail.
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.IP
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It makes no comparable check in \fBpnoutrefresh\fP,
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though interestingly enough, a comment in the source code
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states that the lack of a check was an MKS extension.
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.bP
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NetBSD 7 curses
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sets a flag in the \fBWINDOW\fP structure for \fBnewpad\fP and \fBsubpad\fP,
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using this to help with the distinction between \fBwnoutrefresh\fP
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and \fBpnoutrefresh\fP.
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.IP
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It does not check for the case where a subwindow is created in
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a pad using \fBsubwin\fP or \fBderwin\fP.
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.IP
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The \fBdupwin\fP function returns a regular window when duplicating a pad.
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Likewise, \fBgetwin\fP always returns a window, even if the saved
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data was from a pad.
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.PP
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This implementation
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.bP
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sets a flag in the \fBWINDOW\fP structure for \fBnewpad\fP and \fBsubpad\fP,
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.bP
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allows a \fBsubwin\fP or \fBderwin\fP call to succeed having a pad parent by
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forcing the subwindow to be a pad,
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.bP
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checks in both \fBwnoutrefresh\fP and \fBpnoutrefresh\fP to ensure
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that pads and windows are handled distinctly, and
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.bP
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ensures that \fBdupwin\fP and \fBgetwin\fP treat
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pads versus windows consistently.
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.SH SEE ALSO
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\fBcurses\fP(3),
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\fBcurs_refresh\fP(3),
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\fBcurs_touch\fP(3),
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\fBcurs_addch\fP(3).
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