/************************************************************************ 
 * 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.				*
 *									*
 * See the file maintain.er for details of the current maintainer.	*
 ************************************************************************/

#include <curspriv.h>

RCSID("$Id: refresh.c,v 1.54 2007/07/10 20:56:03 wmcbrine Exp $")

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

  Name:								refresh

  Synopsis:
	int refresh(void);
	int wrefresh(WINDOW *win);
	int wnoutrefresh(WINDOW *win);
	int doupdate(void);
	int redrawwin(WINDOW *win);
	int wredrawln(WINDOW *win, int beg_line, int num_lines);

  Description:
	wrefresh() copies the named window to the physical terminal 
	screen, taking into account what is already there in order to 
	optimize cursor movement. refresh() does the same, using stdscr. 
	These routines must be called to get any output on the terminal, 
	as other routines only manipulate data structures. Unless 
	leaveok() has been enabled, the physical cursor of the terminal 
	is left at the location of the window's cursor.

	wnoutrefresh() and doupdate() allow multiple updates with more 
	efficiency than wrefresh() alone. wrefresh() works by first 
	calling wnoutrefresh(), which copies the named window to the 
	virtual screen.  It then calls doupdate(), which compares the 
	virtual screen to the physical screen and does the actual 
	update. A series of calls to wrefresh() will result in 
	alternating calls to wnoutrefresh() and doupdate(), causing 
	several bursts of output to the screen.  By first calling 
	wnoutrefresh() for each window, it is then possible to call 
	doupdate() only once.

	In PDCurses, redrawwin() is equivalent to touchwin(), and 
	wredrawln() is the same as touchline(). In some other curses 
	implementations, there's a subtle distinction, but it has no 
	meaning in PDCurses.

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

  Portability				     X/Open    BSD    SYS V
	refresh					Y	Y	Y
	wrefresh				Y	Y	Y
	wnoutrefresh				Y	Y	Y
	doupdate				Y	Y	Y
	redrawwin				Y	-      4.0
	wredrawln				Y	-      4.0

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

#include <string.h>

int wnoutrefresh(WINDOW *win)
{
	int begy, begx;		/* window's place on screen   */
	int i, j;

	PDC_LOG(("wnoutrefresh() - called: win=%p\n", win));

	if ( !win || (win->_flags & (_PAD|_SUBPAD)) )
		return ERR;

	begy = win->_begy;
	begx = win->_begx;

	for (i = 0, j = begy; i < win->_maxy; i++, j++)
	{
		if (win->_firstch[i] != _NO_CHANGE)
		{
			chtype *src = win->_y[i];
			chtype *dest = curscr->_y[j] + begx;

			int first = win->_firstch[i];	/* first changed */
			int last = win->_lastch[i];	/* last changed  */

			/* ignore areas on the outside that are marked 
			   as changed, but really aren't */

			while (first <= last && src[first] == dest[first])
				first++;

			while (last >= first && src[last] == dest[last])
				last--;

			/* if any have really changed... */

			if (first <= last)
			{
				memcpy(dest + first, src + first,
					(last - first + 1) * sizeof(chtype));

				first += begx; 
				last += begx;

				if (first < curscr->_firstch[j] ||
				    curscr->_firstch[j] == _NO_CHANGE)
					curscr->_firstch[j] = first;

				if (last > curscr->_lastch[j])
					curscr->_lastch[j] = last;
			}

			win->_firstch[i] = _NO_CHANGE;	/* updated now */
		}

		win->_lastch[i] = _NO_CHANGE;		/* updated now */
	}

	if (win->_clear)
		win->_clear = FALSE;

	if (!win->_leaveit)
	{
		curscr->_cury = win->_cury + begy;
		curscr->_curx = win->_curx + begx;
	}

	return OK;
}

int doupdate(void)
{
	int y;
	bool clearall;

	PDC_LOG(("doupdate() - called\n"));

	if (!curscr)
		return ERR;

	if (isendwin())			/* coming back after endwin() called */
	{
		reset_prog_mode();
		clearall = TRUE;
		SP->alive = TRUE;	/* so isendwin() result is correct */
	}
	else
		clearall = curscr->_clear;

	for (y = 0; y < SP->lines; y++)
	{
		PDC_LOG(("doupdate() - Transforming line %d of %d: %s\n",
			y, SP->lines, (curscr->_firstch[y] != _NO_CHANGE) ?
			"Yes" : "No"));

		if (clearall || curscr->_firstch[y] != _NO_CHANGE)
		{
			int first, last;

			chtype *src = curscr->_y[y];
			chtype *dest = pdc_lastscr->_y[y];

			if (clearall)
			{
				first = 0;
				last = COLS - 1;
			}
			else
			{
				first = curscr->_firstch[y];
				last = curscr->_lastch[y];
			}

			while (first <= last)
			{
				int len = 0;

				/* build up a run of changed cells; if 
				   two runs are separated by a single 
				   unchanged cell, ignore the break */

				if (clearall)
					len = last - first + 1;
				else
					while (first + len <= last &&

						(src[first + len] !=
						dest[first + len] ||

						(len && first + len < last &&
						 src[first + len + 1] !=
						dest[first + len + 1]) ))

							len++;

				/* update the screen, and pdc_lastscr */

				if (len)
				{
					PDC_transform_line(y, first, len,
						src + first);

					memcpy(dest + first, src + first,
						len * sizeof(chtype));

					first += len;
				}

				/* skip over runs of unchanged cells */

				while (first <= last &&
					src[first] == dest[first])
						first++;
			}

			curscr->_firstch[y] = _NO_CHANGE;
			curscr->_lastch[y] = _NO_CHANGE;
		}
	}

	curscr->_clear = FALSE;

	if (SP->visibility)
		PDC_gotoyx(curscr->_cury, curscr->_curx);

	SP->cursrow = curscr->_cury;
	SP->curscol = curscr->_curx;

	return OK;
}

int wrefresh(WINDOW *win)
{
	bool save_clear;

	PDC_LOG(("wrefresh() - called\n"));

	if ( !win || (win->_flags & (_PAD|_SUBPAD)) )
		return ERR;

	save_clear = win->_clear;

	if (win == curscr)
		curscr->_clear = TRUE;
	else
		wnoutrefresh(win);

	if (save_clear && win->_maxy == SP->lines && win->_maxx == SP->cols)
		curscr->_clear = TRUE;

	return doupdate();
}

int refresh(void)
{
	PDC_LOG(("refresh() - called\n"));

	return wrefresh(stdscr);
}

int wredrawln(WINDOW *win, int start, int num)
{
	int i;

	PDC_LOG(("wredrawln() - called: win=%p start=%d num=%d\n",
		win, start, num));

	if (!win || start > win->_maxy || start + num > win->_maxy)
		return ERR;

	for (i = start; i < start + num; i++)
	{
		win->_firstch[i] = 0;
		win->_lastch[i] = win->_maxx - 1;
	}

	return OK;
}

int redrawwin(WINDOW *win)
{
	PDC_LOG(("redrawwin() - called: win=%p\n", win));

	if (!win)
		return ERR;

	return wredrawln(win, 0, win->_maxy);
}