#include <curses.h>WINDOW *newpad(int nlines, int ncols);WINDOW *subpad(WINDOW *orig, int nlines, int ncols,int begin_y, int begin_x);int prefresh(WINDOW *pad, int pminrow, int pmincol,int sminrow, int smincol, int smaxrow, int smaxcol);int pnoutrefresh(WINDOW *pad, int pminrow, int pmincol,int sminrow, int smincol, int smaxrow, int smaxcol);int pechochar(WINDOW *pad, chtype ch);int pecho_wchar(WINDOW *pad, const cchar_t *wch);
The newpad routine creates and returns a pointer to a new pad
data structure with the given number of lines, nlines, and
columns, ncols. A pad is like a window, except that it is not
restricted by the screen size, and is not necessarily associated
with a particular part of the screen. Pads can be used when a
large window is needed, and only a part of the window will be on
the screen at one time. Automatic refreshes of pads (e.g., from
scrolling or echoing of input) do not occur.
It is not legal to call wrefresh with a pad as an argument; the
routines prefresh or pnoutrefresh should be called instead. Note
that these routines require additional parameters to specify the
part of the pad to be displayed and the location on the screen to
be used for the display.
The subpad routine creates and returns a pointer to a subwindow
within a pad with the given number of lines, nlines, and columns,
ncols. Unlike subwin, which uses screen coordinates, the window
is at position (begin_x, begin_y) on the pad. The window is made
in the middle of the window orig, so that changes made to one
window affect both windows. During the use of this routine, it
will often be necessary to call touchwin or touchline on orig
before calling prefresh.
The prefresh and pnoutrefresh routines are analogous to wrefresh
and wnoutrefresh except that they relate to pads instead of
windows. The additional parameters are needed to indicate what
part of the pad and screen are involved.
• The pminrow and pmincol parameters specify the upper left-
hand corner of the rectangle to be displayed in the pad.
• The sminrow, smincol, smaxrow, and smaxcol parameters specify
the edges of the rectangle to be displayed on the screen.
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. Both rectangles must be
entirely contained within their respective structures. Negative
values of pminrow, pmincol, sminrow, or smincol are treated as if
they were zero.
The pechochar routine is functionally equivalent to a call to
addch followed by a call to refresh(3X), a call to waddch
followed by a call to wrefresh, or a call to waddch followed by a
call to prefresh. The knowledge that only a single character is
being output is taken into consideration and, for non-control
characters, a considerable performance gain might be seen by
using these routines instead of their equivalents. In the case
of pechochar, the last location of the pad on the screen is
reused for the arguments to prefresh.
The pecho_wchar function is the analogous wide-character form of
pechochar. It outputs one character to a pad and immediately
refreshes the pad. It does this by a call to wadd_wch followed
by a call to prefresh.
Routines that return an integer return ERR upon failure and OK
(SVr4 only specifies "an integer value other than ERR") upon
Routines that return pointers return NULL on error, and set errno
X/Open does not define any error conditions. In this
prefresh and pnoutrefresh
return an error if the window pointer is null, or if the
window is not really a pad or if the area to refresh
extends off-screen or if the minimum coordinates are
greater than the maximum.
returns an error if the window is not really a pad, and
the associated call to wechochar returns an error.
returns an error if the window is not really a pad, and
the associated call to wecho_wchar returns an error.
BSD curses has no pad feature.
SVr2 curses (1986) provided the newpad and related functions,
documenting them in a single line each. SVr3 (1987) provided
more extensive documentation.
The documentation does not explain the term pad. However, the
Apollo Aegis workstation operating system supported a graphical
• These graphical pads could be much larger than the computer's
• The read-only output from a command could be scrolled back to
inspect, and select text from the pad.
The two uses may be related.
The XSI Curses standard, Issue 4 describes these functions,
without significant change from the SVr3 documentation. It
describes no error conditions. The behavior of subpad if the
parent window is not a pad is undocumented, and is not checked by
the vendor Unix implementations:
• SVr4 curses sets a flag in the WINDOW structure in newpad
which tells if the window is a pad.
However, it uses this information only in waddch (to decide
if it should call wrefresh) and wscrl (to avoid scrolling a
pad), and does not check in wrefresh to ensure that the pad
is refreshed properly.
• Solaris X/Open Curses checks if a window is a pad in
wnoutrefresh, returning ERR in that case.
However, it only sets the flag for subwindows if the parent
window is a pad. Its newpad function does not set this
information. Consequently, the check will never fail.
It makes no comparable check in pnoutrefresh, though
interestingly enough, a comment in the source code states
that the lack of a check was an MKS extension.
• NetBSD 7 curses sets a flag in the WINDOW structure for
newpad and subpad, using this to help with the distinction
between wnoutrefresh and pnoutrefresh.
It does not check for the case where a subwindow is created
in a pad using subwin or derwin.
The dupwin function returns a regular window when duplicating
a pad. Likewise, getwin always returns a window, even if the
saved data was from a pad.
• sets a flag in the WINDOW structure for newpad and subpad,
• allows a subwin or derwin call to succeed having a pad parent
by forcing the subwindow to be a pad,
• checks in both wnoutrefresh and pnoutrefresh to ensure that
pads and windows are handled distinctly, and
• ensures that dupwin and getwin treat pads versus windows
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