| 1 | .\"***************************************************************************
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| 2 | .\" Copyright (c) 1998-2007,2010 Free Software Foundation, Inc. *
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| 3 | .\" *
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| 4 | .\" Permission is hereby granted, free of charge, to any person obtaining a *
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| 5 | .\" copy of this software and associated documentation files (the *
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| 6 | .\" "Software"), to deal in the Software without restriction, including *
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| 7 | .\" without limitation the rights to use, copy, modify, merge, publish, *
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| 8 | .\" distribute, distribute with modifications, sublicense, and/or sell *
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| 9 | .\" copies of the Software, and to permit persons to whom the Software is *
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| 10 | .\" furnished to do so, subject to the following conditions: *
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| 11 | .\" *
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| 12 | .\" The above copyright notice and this permission notice shall be included *
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| 13 | .\" in all copies or substantial portions of the Software. *
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| 14 | .\" *
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| 15 | .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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| 16 | .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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| 17 | .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
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| 18 | .\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
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| 19 | .\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
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| 20 | .\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
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| 21 | .\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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| 22 | .\" *
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| 23 | .\" Except as contained in this notice, the name(s) of the above copyright *
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| 24 | .\" holders shall not be used in advertising or otherwise to promote the *
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| 25 | .\" sale, use or other dealings in this Software without prior written *
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| 26 | .\" authorization. *
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| 27 | .\"***************************************************************************
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| 28 | .\"
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| 29 | .\" $Id: curs_clear.3x,v 1.14 2010/12/04 18:36:44 tom Exp $
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| 30 | .TH curs_clear 3X ""
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| 31 | .na
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| 32 | .hy 0
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| 33 | .SH NAME
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| 34 | \fBerase\fR,
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| 35 | \fBwerase\fR,
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| 36 | \fBclear\fR,
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| 37 | \fBwclear\fR,
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| 38 | \fBclrtobot\fR,
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| 39 | \fBwclrtobot\fR,
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| 40 | \fBclrtoeol\fR,
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| 41 | \fBwclrtoeol\fR \- clear all or part of a \fBcurses\fR window
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| 42 | .ad
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| 43 | .hy
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| 44 | .SH SYNOPSIS
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| 45 | \fB# include <curses.h>\fR
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| 46 | .sp
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| 47 | \fBint erase(void);\fR
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| 48 | .br
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| 49 | \fBint werase(WINDOW *win);\fR
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| 50 | .br
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| 51 | \fBint clear(void);\fR
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| 52 | .br
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| 53 | \fBint wclear(WINDOW *win);\fR
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| 54 | .br
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| 55 | \fBint clrtobot(void);\fR
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| 56 | .br
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| 57 | \fBint wclrtobot(WINDOW *win);\fR
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| 58 | .br
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| 59 | \fBint clrtoeol(void);\fR
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| 60 | .br
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| 61 | \fBint wclrtoeol(WINDOW *win);\fR
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| 62 | .br
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| 63 | .SH DESCRIPTION
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| 64 | The \fBerase\fR and \fBwerase\fR routines copy blanks to every
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| 65 | position in the window, clearing the screen.
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| 66 | .PP
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| 67 | The \fBclear\fR and \fBwclear\fR routines are like \fBerase\fR and
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| 68 | \fBwerase\fR, but they also call \fBclearok\fR, so that the screen is
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| 69 | cleared completely on the next call to \fBwrefresh\fR for that window
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| 70 | and repainted from scratch.
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| 71 | .PP
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| 72 | The \fBclrtobot\fR and \fBwclrtobot\fR routines erase from the cursor to the
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| 73 | end of screen. That is, they erase all lines below the cursor in the window.
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| 74 | Also, the current line to the right of the cursor, inclusive, is erased.
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| 75 | .PP
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| 76 | The \fBclrtoeol\fR and \fBwclrtoeol\fR routines erase the current line
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| 77 | to the right of the cursor, inclusive, to the end of the current line.
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| 78 | .PP
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| 79 | Blanks created by erasure have the current background rendition (as set
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| 80 | by \fBwbkgdset\fR) merged into them.
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| 81 | .SH RETURN VALUE
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| 82 | All routines return the integer \fBOK\fR on success and \fBERR\fP on failure.
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| 83 | The SVr4.0 manual says "or a
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| 84 | non-negative integer if \fBimmedok\fR is set", but this appears to be an error.
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| 85 | .PP
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| 86 | X/Open defines no error conditions.
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| 87 | In this implementation,
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| 88 | functions using a window pointer parameter return an error if it is null.
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| 89 | .SH NOTES
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| 90 | Note that \fBerase\fR, \fBwerase\fR, \fBclear\fR, \fBwclear\fR,
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| 91 | \fBclrtobot\fR, and \fBclrtoeol\fR may be macros.
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| 92 | .SH PORTABILITY
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| 93 | These functions are described in the XSI Curses standard, Issue 4. The
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| 94 | standard specifies that they return \fBERR\fR on failure, but specifies no
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| 95 | error conditions.
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| 96 | .PP
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| 97 | Some historic curses implementations had, as an undocumented feature, the
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| 98 | ability to do the equivalent of \fBclearok(..., 1)\fR by saying
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| 99 | \fBtouchwin(stdscr)\fR or \fBclear(stdscr)\fR. This will not work under
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| 100 | ncurses.
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| 101 | .PP
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| 102 | This implementation, and others such as Solaris,
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| 103 | sets the current position to 0,0 after erasing
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| 104 | via \fBwerase()\fP and \fBwclear()\fP.
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| 105 | That fact is not documented in other implementations,
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| 106 | and may not be true of implementations
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| 107 | which were not derived from SVr4 source.
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| 108 | .PP
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| 109 | Not obvious from the description,
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| 110 | most implementations clear the screen after \fBwclear\fP
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| 111 | even for a subwindow or derived window.
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| 112 | If you do not want to clear the screen during the next \fBwrefresh\fP,
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| 113 | use \fBwerase\fP instead.
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| 114 | .SH SEE ALSO
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| 115 | \fBcurses\fR(3X),
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| 116 | \fBcurs_outopts\fR(3X),
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| 117 | \fBcurs_refresh\fR(3X),
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| 118 | \fBcurs_variables\fR(3X)
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