1curs_pad(3X) curs_pad(3X)
2
6 newpad, subpad, prefresh, pnoutrefresh, pechochar, pecho_wchar - create
7 and display curses pads
8
10 #include <curses.h>
11 WINDOW *newpad(int nlines, int ncols);
13 WINDOW *subpad(WINDOW *orig, int nlines, int ncols,
14 int begin_y, int begin_x);
15 int prefresh(WINDOW *pad, int pminrow, int pmincol,
16 int sminrow, int smincol, int smaxrow, int smaxcol);
17 int pnoutrefresh(WINDOW *pad, int pminrow, int pmincol,
18 int sminrow, int smincol, int smaxrow, int smaxcol);
19 int pechochar(WINDOW *pad, chtype ch);
20 int pecho_wchar(WINDOW *pad, const cchar_t *wch);
21
23 newpad
24 The newpad routine creates and returns a pointer to a new pad data
25 structure with the given number of lines, nlines, and columns, ncols.
26 A pad is like a window, except that it is not restricted by the screen
27 size, and is not necessarily associated with a particular part of the
28 screen. Pads can be used when a large window is needed, and only a
29 part of the window will be on the screen at one time. Automatic re‐
30 freshes of pads (e.g., from scrolling or echoing of input) do not oc‐
31 cur.
32 It is not legal to call wrefresh with a pad as an argument; the rou‐
34 tines prefresh or pnoutrefresh should be called instead. Note that
35 these routines require additional parameters to specify the part of the
36 pad to be displayed and the location on the screen to be used for the
37 display.
38 subpad
40 The subpad routine creates and returns a pointer to a subwindow within
41 a pad with the given number of lines, nlines, and columns, ncols. Un‐
42 like subwin, which uses screen coordinates, the window is at position
43 (begin_x, begin_y) on the pad. The window is made in the middle of the
44 window orig, so that changes made to one window affect both windows.
45 During the use of this routine, it will often be necessary to call
46 touchwin or touchline on orig before calling prefresh.
47 prefresh, pnoutrefresh
49 The prefresh and pnoutrefresh routines are analogous to wrefresh and
50 wnoutrefresh except that they relate to pads instead of windows. The
51 additional parameters are needed to indicate what part of the pad and
52 screen are involved.
53 • The pminrow and pmincol parameters specify the upper left-hand cor‐
55 ner of the rectangle to be displayed in the pad.
56 • The sminrow, smincol, smaxrow, and smaxcol parameters specify the
58 edges of the rectangle to be displayed on the screen.
59 The lower right-hand corner of the rectangle to be displayed in the pad
61 is calculated from the screen coordinates, since the rectangles must be
62 the same size. Both rectangles must be entirely contained within their
63 respective structures. Negative values of pminrow, pmincol, sminrow,
64 or smincol are treated as if they were zero.
65 pechochar
67 The pechochar routine is functionally equivalent to a call to addch
68 followed by a call to refresh(3X), a call to waddch followed by a call
69 to wrefresh, or a call to waddch followed by a call to prefresh. The
70 knowledge that only a single character is being output is taken into
71 consideration and, for non-control characters, a considerable perfor‐
72 mance gain might be seen by using these routines instead of their
73 equivalents. In the case of pechochar, the last location of the pad on
74 the screen is reused for the arguments to prefresh.
75 pecho_wchar
77 The pecho_wchar function is the analogous wide-character form of pe‐
78 chochar. It outputs one character to a pad and immediately refreshes
79 the pad. It does this by a call to wadd_wch followed by a call to pre‐
80 fresh.
81
83 Routines that return an integer return ERR upon failure and OK (SVr4
84 only specifies "an integer value other than ERR") upon successful com‐
85 pletion.
86 Routines that return pointers return NULL on error, and set errno to
88 ENOMEM.
89 X/Open does not define any error conditions. In this implementation
91 prefresh and pnoutrefresh
93 return an error if the window pointer is null, or if the window
94 is not really a pad or if the area to refresh extends off-
95 screen or if the minimum coordinates are greater than the maxi‐
96 mum.
97 pechochar
99 returns an error if the window is not really a pad, and the as‐
100 sociated call to wechochar returns an error.
101 pecho_wchar
103 returns an error if the window is not really a pad, and the as‐
104 sociated call to wecho_wchar returns an error.
105
107 Note that pechochar may be a macro.
108
110 BSD curses has no pad feature.
111 SVr2 curses (1986) provided the newpad and related functions, document‐
113 ing them in a single line each. SVr3 (1987) provided more extensive
114 documentation.
115 The documentation does not explain the term pad. However, the Apollo
117 Aegis workstation operating system supported a graphical pad feature:
118 • These graphical pads could be much larger than the computer's dis‐
120 play.
121 • The read-only output from a command could be scrolled back to in‐
123 spect, and select text from the pad.
124 The two uses may be related.
126 The XSI Curses standard, Issue 4 describes these functions, without
128 significant change from the SVr3 documentation. It describes no error
129 conditions. The behavior of subpad if the parent window is not a pad
130 is undocumented, and is not checked by the vendor Unix implementations:
131 • SVr4 curses sets a flag in the WINDOW structure in newpad which
133 tells if the window is a pad.
134 However, it uses this information only in waddch (to decide if it
136 should call wrefresh) and wscrl (to avoid scrolling a pad), and
137 does not check in wrefresh to ensure that the pad is refreshed
138 properly.
139 • Solaris X/Open Curses checks if a window is a pad in wnoutrefresh,
141 returning ERR in that case.
142 However, it only sets the flag for subwindows if the parent window
144 is a pad. Its newpad function does not set this information. Con‐
145 sequently, the check will never fail.
146 It makes no comparable check in pnoutrefresh, though interestingly
148 enough, a comment in the source code states that the lack of a
149 check was an MKS extension.
150 • NetBSD 7 curses sets a flag in the WINDOW structure for newpad and
152 subpad, using this to help with the distinction between wnoutre‐
153 fresh and pnoutrefresh.
154 It does not check for the case where a subwindow is created in a
156 pad using subwin or derwin.
157 The dupwin function returns a regular window when duplicating a
159 pad. Likewise, getwin always returns a window, even if the saved
160 data was from a pad.
161 This implementation
163 • sets a flag in the WINDOW structure for newpad and subpad,
165 • allows a subwin or derwin call to succeed having a pad parent by
167 forcing the subwindow to be a pad,
168 • checks in both wnoutrefresh and pnoutrefresh to ensure that pads
170 and windows are handled distinctly, and
171 • ensures that dupwin and getwin treat pads versus windows consis‐
173 tently.
174
176 curses(3X), curs_refresh(3X), curs_touch(3X), curs_addch(3X).
177 curs_pad(3X)