Move the ripoffline logic out of screen.c and into ripoffline.c.
Store ripped off lines in the SCREEN structure so we can repaint then
when the terminal is resized.
Fix mvwin(3) so it can move windows in the ripped off area.


(roy)

/*	$NetBSD: ripoffline.c,v 1.1 2017/01/11 20:43:03 roy Exp $	*/

/*-
 * Copyright (c) 2017 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Roy Marples.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: ripoffline.c,v 1.1 2017/01/11 20:43:03 roy Exp $");
#endif				/* not lint */

#include "curses.h"
#include "curses_private.h"

/* List of ripoffline calls */
static struct ripoff {
	int	nlines;
	int	(*init)(WINDOW *, int);
} ripoffs[MAX_RIPS];
static int nrips;

/*
 * ripoffline --
 *	Ripoff a line from the top of bottom of stdscr.
 *	Must be called before initscr or newterm.
 */
int
ripoffline(int line, int (*init)(WINDOW *, int))
{

#ifdef DEBUG
	__CTRACE(__CTRACE_SCREEN, "ripoffline: %d\n", line);
#endif

	if (nrips >= MAX_RIPS || init == NULL)
		return ERR; /* This makes sense, but not standards compliant. */
	if (line == 0)
		return OK;
	ripoffs[nrips].nlines = line < 0 ? -1 : 1;
	ripoffs[nrips++].init = init;
	return OK;
}

/*
 * __rippedlines --
 *	Returns the number of ripped lines from the screen.
 */
int
__rippedlines(const SCREEN *screen)
{
	const struct __ripoff *rip;
	int i, n;

	n = 0;
	for (i = 0, rip = screen->ripped; i < screen->nripped; i++, rip++) {
		if (rip->nlines < 0)
			n += -rip->nlines;
		else
			n += rip->nlines;
	}
	return n;
}

/*
 * __ripoffscreen --
 *	Rips lines from the screen by creating a WINDOW per ripoffline call.
 *	Although the POSIX API only allows for one line WINDOWS to be created,
 *	this implemenation allows for N lines if needed.
 */
int
__ripoffscreen(SCREEN *screen, int *rtop)
{
	int i, nlines;
	const struct ripoff *srip;
	struct __ripoff *rip;
	WINDOW *w;

	*rtop = 0;
	rip = screen->ripped;
	for (i = 0, srip = ripoffs; i < nrips; i++, srip++) {
		nlines = srip->nlines < 0 ? -srip->nlines : srip->nlines;
		w = __newwin(screen, nlines, 0,
		    srip->nlines < 0 ? LINES - nlines : *rtop,
		    0, FALSE);
		if (w != NULL) {
			rip->win = w;
			rip->nlines = srip->nlines;
			rip++;
			screen->nripped++;
			if (rip->nlines > 0)
				(*rtop) += rip->nlines;
			LINES -= nlines;
		}
		if (srip->init(w, COLS) == ERR)
			return ERR;
#ifdef DEBUG
		if (w != NULL)
			__CTRACE(__CTRACE_SCREEN,
			    "newterm: ripped %d lines from the %s\n",
			    nlines, srip->nlines < 0 ? "bottom" : "top");
#endif
	}
	nrips = 0; /* Reset the stack. */
	return OK;
}

/*
 * __ripoffresize --
 *	Called from resizeterm to ensure the ripped off lines are correctly
 *	placed and refreshed.
 */
void
__ripoffresize(SCREEN *screen)
{
	int rbot = _cursesi_screen->LINES, i;
	struct __ripoff *rip;

	for (i = 0, rip = _cursesi_screen->ripped;
	     i < _cursesi_screen->nripped;
	     i++, rip++)
	{
		if (rip->nlines > 0)
			touchwin(rip->win);
		else {
			/* Reposition the lower windows. */
			mvwin(rip->win, rbot + rip->nlines, 0);
			rbot += rip->nlines;
		}
		wnoutrefresh(rip->win);
	}
}