/************************************************************************ 
 * This file is part of PDCurses. PDCurses is public domain software;	*
 * you may use it for any purpose. This software is provided AS IS with	*
 * NO WARRANTY whatsoever.						*
 *									*
 * If you use PDCurses in an application, an acknowledgement would be	*
 * appreciated, but is not mandatory. If you make corrections or	*
 * enhancements to PDCurses, please forward them to the current		*
 * maintainer for the benefit of other users.				*
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 * See the file maintain.er for details of the current maintainer.	*
 ************************************************************************/

#include <curspriv.h>

RCSID("$Id: scroll.c,v 1.34 2007/06/24 00:50:34 wmcbrine Exp $")

/*man-start**************************************************************

  Name:								scroll

  Synopsis:
	int scroll(WINDOW *win);
	int scrl(int n);
	int wscrl(WINDOW *win, int n);

  Description:
	scroll() causes the window to scroll up one line.  This involves 
	moving the lines in the window data strcture.
 
	With a positive n, scrl() and wscrl() scroll the window up n 
	lines (line i + n becomes i); otherwise they scroll the window 
	down n lines.
 
	For these functions to work, scrolling must be enabled via 
	scrollok(). Note also that scrolling is not allowed if the 
	supplied window is a pad.

  Return Value:
	All functions return OK on success and ERR on error.

  Portability				     X/Open    BSD    SYS V
	scroll					Y	Y	Y
	scrl					Y	-      4.0
	wscrl					Y	-      4.0

**man-end****************************************************************/

int wscrl(WINDOW *win, int n)
{
	int i, l, dir, start, end;
	chtype blank, *temp;

	/* Check if window scrolls. Valid for window AND pad */

	if (!win || !win->_scroll || !n)
		return ERR;

	blank = win->_bkgd;

	if (n > 0)
	{
		start = win->_tmarg;
		end = win->_bmarg;
		dir = 1;
	}
	else
	{
		start = win->_bmarg;
		end = win->_tmarg;
		dir = -1;
	}

	for (l = 0; l < (n * dir); l++) 
	{
		temp = win->_y[start];

		/* re-arrange line pointers */

		for (i = start; i != end; i += dir)
			win->_y[i] = win->_y[i + dir];

		win->_y[end] = temp;

		/* make a blank line */

		for (i = 0; i < win->_maxx; i++)
			*temp++ = blank;
	}

	touchline(win, win->_tmarg, win->_bmarg - win->_tmarg + 1);

	PDC_sync(win);
	return OK;
}

int scrl(int n)
{
	PDC_LOG(("scrl() - called\n"));

	return wscrl(stdscr, n);
}

int scroll(WINDOW *win)
{
	PDC_LOG(("scroll() - called\n"));

	return wscrl(win, 1);
}