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<HTML>
<HEAD>
Here is a sample program to motivate the discussion:
<PRE>
+#include <stdlib.h>
#include <curses.h>
#include <signal.h>
<H3><A NAME="xterm">Using NCURSES under XTERM</A></H3>
-A resize operation in X sends SIGWINCH to the application running under xterm.
-The <CODE>ncurses</CODE> library provides an experimental signal
-handler, but in general does not catch this signal, because it cannot
-know how you want the screen re-painted. You will usually have to write the
-SIGWINCH handler yourself. Ncurses can give you some help. <P>
+A resize operation in X sends <CODE>SIGWINCH</CODE> to the application running
+under xterm.
-The easiest way to code your SIGWINCH handler is to have it do an
-<CODE>endwin</CODE>, followed by an <CODE>refresh</CODE> and a screen repaint you code
-yourself. The <CODE>refresh</CODE> will pick up the new screen size from the
+The easiest way to handle <CODE>SIGWINCH</CODE>
+is to do an <CODE>endwin</CODE>,
+followed by an <CODE>refresh</CODE> and a screen repaint you code
+yourself.
+The <CODE>refresh</CODE> will pick up the new screen size from the
xterm's environment. <P>
That is the standard way, of course (it even works with some vendor's curses
are limited to the new screen dimensions, and pads <CODE>stdscr</CODE>
with blanks if the screen is larger. <P>
-Finally, ncurses can be configured to provide its own SIGWINCH handler,
-based on <CODE>resizeterm</CODE>.
+The <CODE>ncurses</CODE> library provides a SIGWINCH signal handler,
+which pushes a <CODE>KEY_RESIZE</CODE> via the wgetch() calls.
+When <CODE>ncurses</CODE> returns that code,
+it calls <code>resizeterm</CODE>
+to update the size of the standard screen's window, repainting that
+(filling with blanks or truncating as needed).
+It also resizes other windows,
+but its effect may be less satisfactory because it cannot
+know how you want the screen re-painted.
+You will usually have to write special-purpose code to handle
+<CODE>KEY_RESIZE</CODE> yourself.
<H3><A NAME="screens">Handling Multiple Terminal Screens</A></H3>
To understand why this is a problem, remember that screen updates are
calculated between two representations of the <EM>entire</EM> display. The
-documentation says that when you refresh a window, it is first copied to to the
+documentation says that when you refresh a window, it is first copied to the
virtual screen, and then changes are calculated to update the physical screen
(and applied to the terminal). But "copied to" is not very specific, and
subtle differences in how copying works can produce different behaviors in the
from the last page goes to the first, and <CODE>REQ_PREV_PAGE</CODE> from
the first page goes to the last.
-<H3><A NAME="#ffield">Inter-Field Navigation Requests</A></H3>
+<H3><A NAME="ffield">Inter-Field Navigation Requests</A></H3>
These requests handle navigation between fields on the same page.
go to B only if A, B, and C <EM>all</EM> share the same first line;
otherwise it will skip over B to C.
-<H3><A NAME="#fifield">Intra-Field Navigation Requests</A></H3>
+<H3><A NAME="fifield">Intra-Field Navigation Requests</A></H3>
These requests drive movement of the edit cursor within the currently
selected field.
projects / ncurses.git / blobdiff