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Automatically reflow wrapped lines when a pane is resized, requested by
many over the years and finally implemented by Richard Woodbury.

/* $OpenBSD: screen.c,v 1.24 2013/02/05 11:08:59 nicm Exp $ */

/*
 * Copyright (c) 2007 Nicholas Marriott <nicm@users.sourceforge.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "tmux.h"

void	screen_resize_x(struct screen *, u_int);
void	screen_resize_y(struct screen *, u_int);

/* Create a new screen. */
void
screen_init(struct screen *s, u_int sx, u_int sy, u_int hlimit)
{
	char hn[MAXHOSTNAMELEN];

	s->grid = grid_create(sx, sy, hlimit);

	if (gethostname(hn, MAXHOSTNAMELEN) == 0)
		s->title = xstrdup(hn);
	else
		s->title = xstrdup("");

	s->cstyle = 0;
	s->ccolour = xstrdup("");
	s->tabs = NULL;

	screen_reinit(s);
}

/* Reinitialise screen. */
void
screen_reinit(struct screen *s)
{
	s->cx = 0;
	s->cy = 0;

	s->rupper = 0;
	s->rlower = screen_size_y(s) - 1;

	s->mode = MODE_CURSOR | MODE_WRAP;

	screen_reset_tabs(s);

	grid_clear_lines(s->grid, s->grid->hsize, s->grid->sy);

	screen_clear_selection(s);
}

/* Destroy a screen. */
void
screen_free(struct screen *s)
{
	free(s->tabs);
	free(s->title);
	free(s->ccolour);
	grid_destroy(s->grid);
}

/* Reset tabs to default, eight spaces apart. */
void
screen_reset_tabs(struct screen *s)
{
	u_int	i;

	free(s->tabs);

	if ((s->tabs = bit_alloc(screen_size_x(s))) == NULL)
		fatal("bit_alloc failed");
	for (i = 8; i < screen_size_x(s); i += 8)
		bit_set(s->tabs, i);
}

/* Set screen cursor style. */
void
screen_set_cursor_style(struct screen *s, u_int style)
{
	if (style <= 6)
		s->cstyle = style;
}

/* Set screen cursor colour. */
void
screen_set_cursor_colour(struct screen *s, const char *colour_string)
{
	free(s->ccolour);
	s->ccolour = xstrdup(colour_string);
}

/* Set screen title. */
void
screen_set_title(struct screen *s, const char *title)
{
	char	tmp[BUFSIZ];

	strlcpy(tmp, title, sizeof tmp);

	free(s->title);
	s->title = xstrdup(tmp);
}

/* Resize screen. */
void
screen_resize(struct screen *s, u_int sx, u_int sy, int reflow)
{
	if (sx < 1)
		sx = 1;
	if (sy < 1)
		sy = 1;

	if (sx != screen_size_x(s)) {
		screen_resize_x(s, sx);

		/*
		 * It is unclear what should happen to tabs on resize. xterm
		 * seems to try and maintain them, rxvt resets them. Resetting
		 * is simpler and more reliable so let's do that.
		 */
		screen_reset_tabs(s);
	}

	if (sy != screen_size_y(s))
		screen_resize_y(s, sy);

	if (reflow)
		screen_reflow(s, sx);
}

void
screen_resize_x(struct screen *s, u_int sx)
{
	struct grid		*gd = s->grid;

	if (sx == 0)
		fatalx("zero size");

	/*
	 * Treat resizing horizontally simply: just ensure the cursor is
	 * on-screen and change the size. Don't bother to truncate any lines -
	 * then the data should be accessible if the size is then incrased.
	 *
	 * The only potential wrinkle is if UTF-8 double-width characters are
	 * left in the last column, but UTF-8 terminals should deal with this
	 * sanely.
	 */
	if (s->cx >= sx)
		s->cx = sx - 1;
	gd->sx = sx;
}

void
screen_resize_y(struct screen *s, u_int sy)
{
	struct grid	*gd = s->grid;
	u_int		 needed, available, oldy, i;

	if (sy == 0)
		fatalx("zero size");
	oldy = screen_size_y(s);

	/*
	 * When resizing:
	 *
	 * If the height is decreasing, delete lines from the bottom until
	 * hitting the cursor, then push lines from the top into the history.
	 *
	 * When increasing, pull as many lines as possible from the history to
	 * the top, then fill the remaining with blanks at the bottom.
	 */

	/* Size decreasing. */
	if (sy < oldy) {
		needed = oldy - sy;

		/* Delete as many lines as possible from the bottom. */
		available = oldy - 1 - s->cy;
		if (available > 0) {
			if (available > needed)
				available = needed;
			grid_view_delete_lines(gd, oldy - available, available);
		}
		needed -= available;

		/*
		 * Now just increase the history size, if possible, to take
		 * over the lines which are left. If history is off, delete
		 * lines from the top.
		 *
		 * XXX Should apply history limit?
		 */
		available = s->cy;
		if (gd->flags & GRID_HISTORY)
			gd->hsize += needed;
		else if (needed > 0 && available > 0) {
			if (available > needed)
				available = needed;
			grid_view_delete_lines(gd, 0, available);
		}
		s->cy -= needed;
	}

	/* Resize line arrays. */
	gd->linedata = xrealloc(
	    gd->linedata, gd->hsize + sy, sizeof *gd->linedata);

	/* Size increasing. */
	if (sy > oldy) {
		needed = sy - oldy;

		/*
		 * Try to pull as much as possible out of the history, if is
		 * is enabled.
		 */
		available = gd->hsize;
		if (gd->flags & GRID_HISTORY && available > 0) {
			if (available > needed)
				available = needed;
			gd->hsize -= available;
			s->cy += available;
		} else
			available = 0;
		needed -= available;

		/* Then fill the rest in with blanks. */
		for (i = gd->hsize + sy - needed; i < gd->hsize + sy; i++)
			memset(&gd->linedata[i], 0, sizeof gd->linedata[i]);
	}

	/* Set the new size, and reset the scroll region. */
	gd->sy = sy;
	s->rupper = 0;
	s->rlower = screen_size_y(s) - 1;
}

/* Set selection. */
void
screen_set_selection(struct screen *s, u_int sx, u_int sy,
    u_int ex, u_int ey, u_int rectflag, struct grid_cell *gc)
{
	struct screen_sel	*sel = &s->sel;

	memcpy(&sel->cell, gc, sizeof sel->cell);
	sel->flag = 1;
	sel->rectflag = rectflag;

	sel->sx = sx; sel->sy = sy;
	sel->ex = ex; sel->ey = ey;
}

/* Clear selection. */
void
screen_clear_selection(struct screen *s)
{
	struct screen_sel	*sel = &s->sel;

	sel->flag = 0;
}

/* Check if cell in selection. */
int
screen_check_selection(struct screen *s, u_int px, u_int py)
{
	struct screen_sel	*sel = &s->sel;

	if (!sel->flag)
		return (0);

	if (sel->rectflag) {
		if (sel->sy < sel->ey) {
			/* start line < end line -- downward selection. */
			if (py < sel->sy || py > sel->ey)
				return (0);
		} else if (sel->sy > sel->ey) {
			/* start line > end line -- upward selection. */
			if (py > sel->sy || py < sel->ey)
				return (0);
		} else {
			/* starting line == ending line. */
			if (py != sel->sy)
				return (0);
		}

		/*
		 * Need to include the selection start row, but not the cursor
		 * row, which means the selection changes depending on which
		 * one is on the left.
		 */
		if (sel->ex < sel->sx) {
			/* Cursor (ex) is on the left. */
			if (px < sel->ex)
				return (0);

			if (px > sel->sx)
				return (0);
		} else {
			/* Selection start (sx) is on the left. */
			if (px < sel->sx)
				return (0);

			if (px > sel->ex)
				return (0);
		}
	} else {
		/*
		 * Like emacs, keep the top-left-most character, and drop the
		 * bottom-right-most, regardless of copy direction.
		 */
		if (sel->sy < sel->ey) {
			/* starting line < ending line -- downward selection. */
			if (py < sel->sy || py > sel->ey)
				return (0);

			if ((py == sel->sy && px < sel->sx)
			    || (py == sel->ey && px > sel->ex))
				return (0);
		} else if (sel->sy > sel->ey) {
			/* starting line > ending line -- upward selection. */
			if (py > sel->sy || py < sel->ey)
				return (0);

			if ((py == sel->sy && px >= sel->sx)
			    || (py == sel->ey && px < sel->ex))
				return (0);
		} else {
			/* starting line == ending line. */
			if (py != sel->sy)
				return (0);

			if (sel->ex < sel->sx) {
				/* cursor (ex) is on the left */
				if (px > sel->sx || px < sel->ex)
					return (0);
			} else {
				/* selection start (sx) is on the left */
				if (px < sel->sx || px > sel->ex)
					return (0);
			}
		}
	}

	return (1);
}

/* Reflow wrapped lines. */
void
screen_reflow(struct screen *s, u_int sx)
{
	struct grid	*old, *new;

	old = s->grid;
	new = grid_create(old->sx, old->sy, old->hlimit);

	s->cy -= grid_reflow(new, old, sx);
	s->grid = new;

	grid_destroy(old);
}