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- * @Id: curs_variables.3x,v 1.8 2015/08/22 23:33:22 tom Exp @
+ * @Id: curs_variables.3x,v 1.13 2019/06/01 22:51:21 tom Exp @
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This variable holds the number of milliseconds to wait after reading an
escape character, to distinguish between an individual escape character
entered on the keyboard from escape sequences sent by cursor- and func-
- tion-keys (see <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>.
+ tion-keys (see <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>).
</PRE><H3><a name="h3-LINES">LINES</a></H3><PRE>
This implementation of curses uses a special window <STRONG>curscr</STRONG> to record
its updates to the terminal screen.
+ This is referred to as the "physical screen" in the <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>
+ and <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG> manual pages.
+
</PRE><H3><a name="h3-The-New-Screen">The New Screen</a></H3><PRE>
- This implementation of curses uses a special window <STRONG>newscr</STRONG> to hold up-
+ This implementation of curses uses a special window <STRONG>newscr</STRONG> to hold up-
dates to the terminal screen before applying them to <STRONG>curscr</STRONG>.
+ This is referred to as the "virtual screen" in the <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>,
+ <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG> and <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG> manual pages.
+
</PRE><H3><a name="h3-The-Standard-Screen">The Standard Screen</a></H3><PRE>
Upon initializing curses, a default window called <STRONG>stdscr</STRONG>, which is the
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- ESCDELAY and TABSIZE are extensions, not provided in most other imple-
- mentations of curses.
+ <STRONG>TABSIZE</STRONG> is a feature of SVr4 curses which is not documented by X/Open
+ curses.
+
+ <STRONG>o</STRONG> In SVr4 curses, <STRONG>TABSIZE</STRONG> is initially set from the terminal descrip-
+ tion's <STRONG>init_tabs</STRONG> capability. After that, it can be altered by the
+ applications using SVr4 curses.
+
+ SVr4 curses uses the current value of <STRONG>TABSIZE</STRONG> to compute the posi-
+ tion of tabstops for updating both the virtual screen with <STRONG>add-</STRONG>
+ <STRONG><A HREF="addch.3x.html">ch(3x)</A></STRONG> as well as the physical screen with <STRONG><A HREF="curs_terminfo.3x.html">mvcur(3x)</A></STRONG>.
+
+ <STRONG>o</STRONG> This implementation uses the current value of <STRONG>TABSIZE</STRONG> only for up-
+ dating the virtual screen. It uses the terminal description's <STRONG>it</STRONG>
+ (<STRONG>init_tabs</STRONG>) capability for computing hardware tabs (i.e., tab stops
+ on the physical screen).
+
+ <STRONG>o</STRONG> Other implementations differ. For instance, NetBSD curses allows
+ <STRONG>TABSIZE</STRONG> to be set through an environment variable. This implemen-
+ tation does not.
+
+ NetBSD curses does not support hardware tabs; it uses the <STRONG>init_tabs</STRONG>
+ capability and the <STRONG>TABSIZE</STRONG> variable only for updating the virtual
+ screen.
- ESCDELAY is an extension in AIX curses:
+ <STRONG>ESCDELAY</STRONG> is an extension in AIX curses:
- <STRONG>o</STRONG> In AIX, the units for ESCDELAY are <EM>fifths</EM> of a millisecond.
+ <STRONG>o</STRONG> In AIX, the units for <STRONG>ESCDELAY</STRONG> are <EM>fifths</EM> of a millisecond.
- <STRONG>o</STRONG> The default value for AIX's ESCDELAY is 0.1 seconds.
+ <STRONG>o</STRONG> The default value for AIX's <STRONG>ESCDELAY</STRONG> is 0.1 seconds.
- <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for ESCDELAY; this im-
+ <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for <STRONG>ESCDELAY</STRONG>; this im-
plementation currently has no upper limit.
- This implementation has long used ESCDELAY with units of milliseconds,
- making it impossible to be completely compatible with AIX. Likewise,
- most users have either decided to override the value, or rely upon its
+ This implementation has long used <STRONG>ESCDELAY</STRONG> with units of milliseconds,
+ making it impossible to be completely compatible with AIX. Likewise,
+ most users have either decided to override the value, or rely upon its
default value.
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