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Pads can be used when a large window is needed, only 74 part of which is to be visible on the screen. Pads are not 75 automatically refreshed by scrolling or input-echoing operations. 76 77 Pads cannot be refreshed with <STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG>; use <STRONG>prefresh</STRONG> or 78 <STRONG>pnoutrefresh</STRONG> instead. 79 80 81</PRE><H3><a name="h3-newpad">newpad</a></H3><PRE> 82 <STRONG>newpad</STRONG> creates and returns a pointer to a new pad data structure with 83 the given number of lines, <EM>nlines</EM>, and columns, <EM>ncols</EM>. 84 85 86</PRE><H3><a name="h3-subpad">subpad</a></H3><PRE> 87 <STRONG>subpad</STRONG> creates and returns a pointer to a subwindow within a pad with 88 the given number of lines, <EM>nlines</EM>, and columns, <EM>ncols</EM>. Unlike 89 <STRONG><A HREF="subwin.3x.html">subwin(3x)</A></STRONG>, which uses screen coordinates, the new pad is placed at 90 position (<EM>begin</EM><STRONG>_</STRONG><EM>y</EM>, <EM>begin</EM><STRONG>_</STRONG><EM>x</EM>) relative to its parent. Thus, changes made 91 to one pad can affect both. When operating on a subpad, it is often 92 necessary to call <STRONG><A HREF="curs_touch.3x.html">touchwin(3x)</A></STRONG> or <STRONG><A HREF="curs_touch.3x.html">touchline(3x)</A></STRONG> on <EM>parent</EM> before 93 calling <STRONG>prefresh</STRONG>. 94 95 96</PRE><H3><a name="h3-prefresh_pnoutrefresh">prefresh, pnoutrefresh</a></H3><PRE> 97 <STRONG>prefresh</STRONG> and <STRONG>pnoutrefresh</STRONG> are analogous to <STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG> and 98 <STRONG><A HREF="curs_refresh.3x.html">wnoutrefresh(3x)</A></STRONG> except that they operate on pads rather than windows. 99 They require additional parameters are needed to indicate what portions 100 of the pad and screen are involved. 101 102 <STRONG>o</STRONG> <EM>pminrow</EM> and <EM>pmincol</EM> specify the upper left-hand corner of a 103 rectangular view of the pad. 104 105 <STRONG>o</STRONG> <EM>sminrow</EM>, <EM>smincol</EM>, <EM>smaxrow</EM>, and <EM>smaxcol</EM> specify the vertices of the 106 rectangle to be displayed on the screen. 107 108 The lower right-hand corner of the rectangle to be displayed in the pad 109 is calculated from the screen coordinates, since the rectangles must be 110 the same size. Both rectangles must be entirely contained within their 111 respective structures. <EM>curses</EM> treats negative values of any of these 112 parameters as zero. 113 114 115</PRE><H3><a name="h3-pechochar">pechochar</a></H3><PRE> 116 <STRONG>pechochar</STRONG> is functionally equivalent to calling <STRONG><A HREF="curs_addch.3x.html">waddch(3x)</A></STRONG> followed by 117 <STRONG>prefresh</STRONG>. It suggests to the <EM>curses</EM> optimizer that only a single 118 character is being output; a considerable performance benefit may be 119 thus enjoyed. The location of the character <EM>ch</EM> written to the pad is 120 used to populate the arguments to <STRONG>prefresh</STRONG>. 121 122 123</PRE><H3><a name="h3-pecho_wchar">pecho_wchar</a></H3><PRE> 124 <STRONG>pecho_wchar</STRONG> is functionally equivalent to calling <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG> followed 125 by <STRONG>prefresh</STRONG>. It suggests to the <EM>curses</EM> optimizer that only a single 126 wide character is being output; a considerable performance benefit may 127 be thus enjoyed. The location of the character <EM>wch</EM> written to the pad 128 is used to populate the arguments to <STRONG>prefresh</STRONG>. 129 130 131</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE> 132 Functions that return an integer return <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> (SVr4 133 specifies only "an integer value other than <STRONG>ERR</STRONG>") upon successful 134 completion. 135 136 Functions that return pointers return <STRONG>NULL</STRONG> on error, and set <STRONG>errno</STRONG> to 137 <STRONG>ENOMEM</STRONG>. 138 139 X/Open Curses does not specify any error conditions. In this 140 implementation 141 142 <STRONG>prefresh</STRONG> and <STRONG>pnoutrefresh</STRONG> 143 return an error if the window pointer is null, or if the window 144 is not really a pad or if the area to refresh extends off- 145 screen or if the minimum coordinates are greater than the 146 maximum. 147 148 <STRONG>pechochar</STRONG> 149 returns an error if the window is not really a pad, and the 150 associated call to <STRONG>wechochar</STRONG> returns an error. 151 152 <STRONG>pecho_wchar</STRONG> 153 returns an error if the window is not really a pad, and the 154 associated call to <STRONG>wecho_wchar</STRONG> returns an error. 155 156 157</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE> 158 <STRONG>pechochar</STRONG> may be a macro. 159 160 161</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> 162 BSD <EM>curses</EM> has no <EM>pad</EM> feature. 163 164 SVr2 <EM>curses</EM> (1986) provided the <STRONG>newpad</STRONG> and related functions, 165 documenting them in a single line each. SVr3 (1987) provided more 166 extensive documentation. 167 168 The documentation does not explain the term <EM>pad</EM>. However, the Apollo 169 <EM>Aegis</EM> workstation operating system supported a graphical <EM>pad</EM> feature: 170 171 <STRONG>o</STRONG> These graphical pads could be much larger than the computer's 172 display. 173 174 <STRONG>o</STRONG> The read-only output from a command could be scrolled back to 175 inspect, and select text from the pad. 176 177 The two uses may be related. 178 179 X/Open Curses, Issue 4 describes these functions, without significant 180 change from the SVr3 documentation. It describes no error conditions. 181 The behavior of <STRONG>subpad</STRONG> if the parent window is not a pad is 182 undocumented, and is not checked by the vendor Unix implementations: 183 184 <STRONG>o</STRONG> SVr4 <EM>curses</EM> sets a flag in the <EM>WINDOW</EM> structure in <STRONG>newpad</STRONG> which 185 tells if the window is a <EM>pad</EM>. 186 187 However, it uses this information only in <STRONG>waddch</STRONG> (to decide if it 188 should call <STRONG>wrefresh</STRONG>) and <STRONG>wscrl</STRONG> (to avoid scrolling a pad), and 189 does not check in <STRONG>wrefresh</STRONG> to ensure that the pad is refreshed 190 properly. 191 192 <STRONG>o</STRONG> Solaris <EM>xcurses</EM> checks whether a window is a pad in <STRONG>wnoutrefresh</STRONG>, 193 returning <STRONG>ERR</STRONG> in that case. 194 195 However, it only sets the flag for subwindows if the parent window 196 is a pad. Its <STRONG>newpad</STRONG> function does not set this information. 197 Consequently, the check will never fail. 198 199 It makes no comparable check in <STRONG>pnoutrefresh</STRONG>, though interestingly 200 enough, a comment in the source code states that the lack of a 201 check was an MKS extension. 202 203 <STRONG>o</STRONG> NetBSD 7 <EM>curses</EM> sets a flag in the <EM>WINDOW</EM> structure for <STRONG>newpad</STRONG> and 204 <STRONG>subpad</STRONG>, using this to help with the distinction between 205 <STRONG>wnoutrefresh</STRONG> and <STRONG>pnoutrefresh</STRONG>. 206 207 It does not check for the case where a subwindow is created in a 208 pad using <STRONG>subwin</STRONG> or <STRONG>derwin</STRONG>. 209 210 The <STRONG>dupwin</STRONG> function returns a regular window when duplicating a 211 pad. Likewise, <STRONG>getwin</STRONG> always returns a window, even if the saved 212 data was from a pad. 213 214 This implementation 215 216 <STRONG>o</STRONG> sets a flag in the <EM>WINDOW</EM> structure for <STRONG>newpad</STRONG> and <STRONG>subpad</STRONG>, 217 218 <STRONG>o</STRONG> allows a <STRONG>subwin</STRONG> or <STRONG>derwin</STRONG> call to succeed having a pad parent by 219 forcing the subwindow to be a pad, 220 221 <STRONG>o</STRONG> checks in both <STRONG>wnoutrefresh</STRONG> and <STRONG>pnoutrefresh</STRONG> to ensure that pads 222 and windows are handled distinctly, and 223 224 <STRONG>o</STRONG> ensures that <STRONG>dupwin</STRONG> and <STRONG>getwin</STRONG> treat pads versus windows 225 consistently. 226 227 228</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> 229 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_touch.3x.html">curs_touch(3x)</A></STRONG> 230 231 232 233ncurses 6.5 2024-04-27 <STRONG><A HREF="curs_pad.3x.html">curs_pad(3x)</A></STRONG> 234</PRE> 235<div class="nav"> 236<ul> 237<li><a href="#h2-NAME">NAME</a></li> 238<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li> 239<li><a href="#h2-DESCRIPTION">DESCRIPTION</a> 240<ul> 241<li><a href="#h3-newpad">newpad</a></li> 242<li><a href="#h3-subpad">subpad</a></li> 243<li><a href="#h3-prefresh_pnoutrefresh">prefresh, pnoutrefresh</a></li> 244<li><a href="#h3-pechochar">pechochar</a></li> 245<li><a href="#h3-pecho_wchar">pecho_wchar</a></li> 246</ul> 247</li> 248<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li> 249<li><a href="#h2-NOTES">NOTES</a></li> 250<li><a href="#h2-PORTABILITY">PORTABILITY</a></li> 251<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> 252</ul> 253</div> 254</BODY> 255</HTML> 256