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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 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.
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 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.
prefresh, pnoutrefresh
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.
pechochar
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.
pecho_wchar
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 successful
completion.
Routines that return pointers return NULL on error, and set errno to
ENOMEM.
X/Open does not define any error conditions. In this implementation
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.
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,
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 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, 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.
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
consistently.
curses(3X), curs_refresh(3X), curs_touch(3X), curs_addch(3X).
This page is part of the ncurses (new curses) project. Information
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
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2018-01-30.) 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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