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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON |
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curs_pad(3X) curs_pad(3X)
newpad, subpad, prefresh, pnoutrefresh, pechochar, pecho_wchar -
create and display curses pads
#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);
newpad
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 par‐
ticular 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.
subpad
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 win‐
dow affect both windows. During the use of this routine, it will
often be necessary to call touchwin or touchline on orig before
calling prefresh.
prefresh, pnoutrefresh
The prefresh and pnoutrefresh routines are analogous to wrefresh
and wnoutrefresh except that they relate to pads instead of win‐
dows. 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 rec‐
tangles 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.
pechochar
The pechochar routine is functionally equivalent to a call to add‐
ch 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 pre‐
fresh. 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 rou‐
tines 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.
pecho_wchar
The pecho_wchar function is the analogous wide-character form of
pechochar. It outputs one character to a pad and immediately re‐
freshes 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 suc‐
cessful completion.
Routines that return pointers return NULL on error, and set errno
to ENOMEM.
X/Open does not define any error conditions. In this implementa‐
tion
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 ex‐
tends off-screen or if the minimum coordinates are greater
than the maximum.
pechochar
returns an error if the window is not really a pad, and
the associated call to wechochar returns an error.
pecho_wchar
returns an error if the window is not really a pad, and
the associated call to wecho_wchar returns an error.
Note that pechochar may be a macro.
BSD curses has no pad feature.
SVr2 curses (1986) provided the newpad and related functions, doc‐
umenting 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
pad feature:
• These graphical pads could be much larger than the computer's
display.
• 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, with‐
out 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 re‐
freshed properly.
• Solaris X/Open Curses checks if a window is a pad in wnoutre‐
fresh, 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 infor‐
mation. Consequently, the check will never fail.
It makes no comparable check in pnoutrefresh, though interest‐
ingly 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.
This implementation
• 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 con‐
sistently.
curses(3X), curs_refresh(3X), curs_touch(3X), curs_addch(3X).
This page is part of the ncurses (new curses) project. Informa‐
tion about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨https://github.com/mirror/ncurses.git⟩ on 2025-02-02. (At that
time, the date of the most recent commit that was found in the
repository was 2023-03-12.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
curs_pad(3X)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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