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28 .\"
29 .\" $Id: curs_outopts.3x,v 1.28 2017/01/07 19:25:15 tom Exp $
30 .TH curs_outopts 3X ""
31 .na
32 .hy 0
33 .SH NAME
34 \fBclearok\fR,
35 \fBidlok\fR,
36 \fBidcok\fR,
37 \fBimmedok\fR,
38 \fBleaveok\fR,
39 \fBsetscrreg\fR,
40 \fBwsetscrreg\fR,
41 \fBscrollok\fR,
42 \fBnl\fR,
43 \fBnonl\fR \- \fBcurses\fR output options
44 .ad
45 .hy
46 .SH SYNOPSIS
47 \fB#include <curses.h>\fR
48 .sp
49 \fBint clearok(WINDOW *\fP\fIwin\fP\fB, bool \fP\fIbf\fP\fB);\fR
50 .br
51 \fBint idlok(WINDOW *\fP\fIwin\fP\fB, bool \fP\fIbf\fP\fB);\fR
52 .br
53 \fBvoid idcok(WINDOW *\fP\fIwin\fP\fB, bool \fP\fIbf\fP\fB);\fR
54 .br
55 \fBvoid immedok(WINDOW *\fP\fIwin\fP\fB, bool \fP\fIbf\fP\fB);\fR
56 .br
57 \fBint leaveok(WINDOW *\fP\fIwin\fP\fB, bool \fP\fIbf\fP\fB);\fR
58 .br
59 \fBint setscrreg(int \fP\fItop\fP\fB, int \fP\fIbot\fP\fB);\fR
60 .br
61 \fBint wsetscrreg(WINDOW *\fP\fIwin\fP\fB, int \fP\fItop\fP\fB, int \fP\fIbot\fP\fB);\fR
62 .br
63 \fBint scrollok(WINDOW *\fP\fIwin\fP\fB, bool \fP\fIbf\fP\fB);\fR
64 .br
65 \fBint nl(void);\fR
66 .br
67 \fBint nonl(void);\fR
68 .br
69 .SH DESCRIPTION
70 These routines set options that change the style of output within
71 \fBcurses\fR.
72 All options are initially \fBFALSE\fR, unless otherwise stated.
73 It is not necessary to turn these options off before calling \fBendwin\fR(3X).
74 .SS clearok
75 .PP
76 If \fBclearok\fR is called with \fBTRUE\fR as argument, the next
77 call to \fBwrefresh\fR with this window will clear the screen completely and
78 redraw the entire screen from scratch.
79 This is useful when the contents of the
80 screen are uncertain, or in some cases for a more pleasing visual effect.
81 If
82 the \fIwin\fR argument to \fBclearok\fR is the global variable \fBcurscr\fR,
83 the next call to \fBwrefresh\fR with any window causes the screen to be cleared
84 and repainted from scratch.
85 .SS idlok
86 .PP
87 If \fBidlok\fR is called with \fBTRUE\fR as second argument, \fBcurses\fR
88 considers using the hardware insert/delete line feature of terminals so
89 equipped.
90 Calling \fBidlok\fR with \fBFALSE\fR as second argument disables use
91 of line insertion and deletion.
92 This option should be enabled only if the
93 application needs insert/delete line, for example, for a screen editor.
94 It is
95 disabled by default because insert/delete line tends to be visually annoying
96 when used in applications where it is not really needed.
97 If insert/delete line
98 cannot be used, \fBcurses\fR redraws the changed portions of all lines.
99 .SS idcok
100 .PP
101 If \fBidcok\fR is called with \fBFALSE\fR as second argument, \fBcurses\fR
102 no longer considers using the hardware insert/delete character feature of
103 terminals so equipped.
104 Use of character insert/delete is enabled by default.
105 Calling \fBidcok\fR with \fBTRUE\fR as second argument re-enables use
106 of character insertion and deletion.
107 .SS immedok
108 .PP
109 If \fBimmedok\fR is called with \fBTRUE as argument\fR, any change
110 in the window image, such as the ones caused by \fBwaddch, wclrtobot, wscrl\fR,
111 etc., automatically cause a call to \fBwrefresh\fR.
112 However, it may
113 degrade performance considerably, due to repeated calls to \fBwrefresh\fR.
114 It is disabled by default.
115 .SS leaveok
116 .PP
117 Normally, the hardware cursor is left at the location of the window cursor
118 being refreshed.
119 The \fBleaveok\fR option allows the cursor to be left
120 wherever the update happens to leave it.
121 It is useful for applications where
122 the cursor is not used, since it reduces the need for cursor motions.
123 .SS setscrreg
124 .PP
125 The \fBsetscrreg\fR and \fBwsetscrreg\fR routines allow the application
126 programmer to set a software scrolling region in a window.
127 The \fItop\fR and
128 \fIbot\fR parameters
129 are the line numbers of the top and bottom margin of the scrolling
130 region.
131 (Line 0 is the top line of the window.) If this option and
132 \fBscrollok\fR are enabled, an attempt to move off the bottom margin line
133 causes all lines in the scrolling region to scroll one line in the direction
134 of the first line.
135 Only the text of the window is scrolled.
136 (Note that this
137 has nothing to do with the use of a physical scrolling region capability in the
138 terminal, like that in the VT100.
139 If \fBidlok\fR is enabled and the terminal
140 has either a scrolling region or insert/delete line capability, they will
141 probably be used by the output routines.)
142 .SS scrollok
143 .PP
144 The \fBscrollok\fR option controls what happens when the cursor of a window is
145 moved off the edge of the window or scrolling region, either as a result of a
146 newline action on the bottom line, or typing the last character of the last
147 line.
148 If disabled, (\fIbf\fR is \fBFALSE\fR), the cursor is left on the bottom
149 line.
150 If enabled, (\fIbf\fR is \fBTRUE\fR), the window is scrolled up one line
151 (Note that to get the physical scrolling effect on the terminal, it is
152 also necessary to call \fBidlok\fR).
153 .SS nl, nonl
154 .PP
155 The \fBnl\fR and \fBnonl\fR routines control whether the underlying display
156 device translates the return key into newline on input, and whether it
157 translates newline into return and line-feed on output (in either case, the
158 call \fBaddch('\\n')\fR does the equivalent of return and line feed on the
159 virtual screen).
160 Initially, these translations do occur.
161 If you disable them
162 using \fBnonl\fR, \fBcurses\fR will be able to make better use of the line-feed
163 capability, resulting in faster cursor motion.
164 Also, \fBcurses\fR will then be
165 able to detect the return key.
166 .SH RETURN VALUE
167 The functions \fBsetscrreg\fR and \fBwsetscrreg\fR return \fBOK\fR upon success
168 and \fBERR\fR upon failure.
169 All other routines that return an integer always
170 return \fBOK\fR.
171 .PP
172 X/Open Curses does not define any error conditions.
173 .PP
174 In this implementation, those functions that have a window pointer
175 will return an error if the window pointer is null.
176 .RS
177 .TP 5
178 .B wclrtoeol
179 returns an error
180 if the cursor position is about to wrap.
181 .TP 5
182 .B wsetscrreg
183 returns an error if the scrolling region limits extend outside the window.
184 .RE
185 .PP
186 X/Open does not define any error conditions.
187 This implementation returns an error
188 if the window pointer is null.
189 .SH PORTABILITY
190 These functions are described in the XSI Curses standard, Issue 4.
191 .PP
192 The XSI Curses standard is ambiguous on the question of whether \fBraw\fR
193 should disable the CRLF translations controlled by \fBnl\fR and \fBnonl\fR.
194 BSD curses did turn off these translations; AT&T curses (at least as late as
195 SVr1) did not.
196 We choose to do so, on the theory that a programmer requesting
197 raw input wants a clean (ideally 8-bit clean) connection that the operating
198 system will not alter.
199 .PP
200 Some historic curses implementations had, as an undocumented feature, the
201 ability to do the equivalent of \fBclearok(..., 1)\fR by saying
202 \fBtouchwin(stdscr)\fR or \fBclear(stdscr)\fR.
203 This will not work under
204 ncurses.
205 .PP
206 Earlier System V curses implementations specified that with \fBscrollok\fR
207 enabled, any window modification triggering a scroll also forced a physical
208 refresh.
209 XSI Curses does not require this, and \fBncurses\fR avoids doing
210 it to perform better vertical-motion optimization at \fBwrefresh\fR
211 time.
212 .PP
213 The XSI Curses standard does not mention that the cursor should be
214 made invisible as a side-effect of \fBleaveok\fR.
215 SVr4 curses documentation does this, but the code does not.
216 Use \fBcurs_set\fR to make the cursor invisible.
217 .SH NOTES
218 Note that \fBclearok\fR, \fBleaveok\fR, \fBscrollok\fR, \fBidcok\fR, \fBnl\fR,
219 \fBnonl\fR and \fBsetscrreg\fR may be macros.
220 .PP
221 The \fBimmedok\fR routine is useful for windows that are used as terminal
222 emulators.
223 .SH SEE ALSO
224 .na
225 \fBcurses\fR(3X),
226 \fBcurs_addch\fR(3X),
227 \fBcurs_clear\fR(3X),
228 \fBcurs_initscr\fR(3X),
229 \fBcurs_scroll\fR(3X),
230 \fBcurs_refresh\fR(3X),
231 \fBcurs_variables\fR(3X).