screen.c - tmux - Rivoreo Source Code Repositories

 /* $Id: screen.c,v 1.15 2007-09-29 18:48:04 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 <string.h>

 #include "tmux.h"

 /*
  * Virtual screen and basic terminal emulator.
  *
  * XXX Much of this file sucks.
  */

 void	 screen_free_lines(struct screen *, u_int, u_int);
 void	 screen_make_lines(struct screen *, u_int, u_int);
 void	 screen_move_lines(struct screen *, u_int, u_int, u_int);
 void	 screen_fill_lines(
 	     struct screen *, u_int, u_int, u_char, u_char, u_char);

 #define screen_last_y(s) ((s)->sy - 1)
 #define screen_last_x(s) ((s)->sx - 1)

 #define screen_range_y(lx, rx) (((rx) - (lx)) + 1)
 #define screen_range_x(ux, lx) (((lx) - (ux)) + 1)

 #define screen_offset_y(py, ny) ((py) + (ny) - 1)
 #define screen_offset_x(px, nx) ((px) + (nx) - 1)

 /* Create a new screen. */
 void
 screen_create(struct screen *s, u_int sx, u_int sy)
 {
 	s->sx = sx;
 	s->sy = sy;
 	s->cx = 0;
 	s->cy = 0;

 	s->ry_upper = 0;
 	s->ry_lower = screen_last_y(s);

 	s->attr = SCREEN_DEFATTR;
 	s->colr = SCREEN_DEFCOLR;

 	s->mode = MODE_CURSOR;
 	*s->title = '\0';

 	s->grid_data = xmalloc(sy * (sizeof *s->grid_data));
 	s->grid_attr = xmalloc(sy * (sizeof *s->grid_attr));
 	s->grid_colr = xmalloc(sy * (sizeof *s->grid_colr));
 	screen_make_lines(s, 0, sy);
 	screen_fill_screen(s, SCREEN_DEFDATA, 0, SCREEN_DEFCOLR);
 }

 /* Resize screen. */
 void
 screen_resize(struct screen *s, u_int sx, u_int sy)
 {
 	u_int	i, ox, oy, ny;

 	if (sx == s->sx || sy == s->sy)
 		return;

 	if (sx < 1)
 		sx = 1;
 	if (sy < 1)
 		sy = 1;

 	ox = s->sx;
 	oy = s->sy;
 	s->sx = sx;
 	s->sy = sy;

 	log_debug("resizing screen (%u, %u) -> (%u, %u)", ox, oy, sx, sy);

 	if (sy < oy) {
 		ny = oy - sy;
 		if (ny > s->cy)
 			ny = s->cy;

 		if (ny != 0) {
 			log_debug("removing %u lines from top", ny);
 			for (i = 0; i < ny; i++) {
 				log_debug("freeing line %u", i);
 				xfree(s->grid_data[i]);
 				xfree(s->grid_attr[i]);
 				xfree(s->grid_colr[i]);
 			}
 			memmove(s->grid_data, s->grid_data + ny,
 			    (oy - ny) * (sizeof *s->grid_data));
 			memmove(s->grid_attr, s->grid_attr + ny,
 			    (oy - ny) * (sizeof *s->grid_attr));
 			memmove(s->grid_colr, s->grid_colr + ny,
 			    (oy - ny) * (sizeof *s->grid_colr));
 			s->cy -= ny;
 		}
 		if (ny < oy - sy) {
 			log_debug(
 			    "removing %u lines from bottom", oy - sy - ny);
 			for (i = sy; i < oy - ny; i++) {
 				log_debug("freeing line %u", i);
 				  xfree(s->grid_data[i]);
 				  xfree(s->grid_attr[i]);
 				  xfree(s->grid_colr[i]);
 			}
 			if (s->cy >= sy)
 				s->cy = sy - 1;
 		}
 	}
 	if (sy != oy) {
 		s->grid_data = xrealloc(s->grid_data, sy, sizeof *s->grid_data);
 		s->grid_attr = xrealloc(s->grid_attr, sy, sizeof *s->grid_attr);
 		s->grid_colr = xrealloc(s->grid_colr, sy, sizeof *s->grid_colr);
 	}
 	if (sy > oy) {
 		for (i = oy; i < sy; i++) {
 			log_debug("allocating line %u", i);
 			s->grid_data[i] = xmalloc(sx);
 			s->grid_attr[i] = xmalloc(sx);
 			s->grid_colr[i] = xmalloc(sx);
 			screen_fill_line(s, i,
 			    SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 		}
 		sy = oy;
 	}

 	if (sx != ox) {
 		for (i = 0; i < sy; i++) {
 			log_debug("adjusting line %u to %u", i, sx);
 			s->grid_data[i] = xrealloc(s->grid_data[i], sx, 1);
 			s->grid_attr[i] = xrealloc(s->grid_attr[i], sx, 1);
 			s->grid_colr[i] = xrealloc(s->grid_colr[i], sx, 1);
 			if (sx > ox) {
 				screen_fill_end_of_line(s, ox, i,
 				    SCREEN_DEFDATA, SCREEN_DEFATTR,
 				    SCREEN_DEFCOLR);
 			}
 		}
 		if (s->cx >= sx)
 			s->cx = sx - 1;
 	}
 }

 /* Draw a set of lines on the screen. */
 void
 screen_draw(struct screen *s, struct buffer *b, u_int uy, u_int ly)
 {
 	u_char		 attr, colr;
 	size_t		 size;
 	u_int		 i, j;
 	uint16_t	 n;

 	if (uy > screen_last_y(s) || ly > screen_last_y(s) || ly < uy)
 		fatalx("bad range");

 	/* XXX. This is naive and rough right now. */
 	attr = 0;
 	colr = SCREEN_DEFCOLR;

 	input_store_two(b, CODE_SCROLLREGION, s->ry_upper + 1, s->ry_lower + 1);

 	input_store_zero(b, CODE_CURSOROFF);

 	input_store_one(b, CODE_ATTRIBUTES, 0);

 	for (j = uy; j <= ly; j++) {
 		input_store_two(b, CODE_CURSORMOVE, j + 1, 1);

 		for (i = 0; i <= screen_last_x(s); i++) {
 			size = BUFFER_USED(b);
 			input_store_one(b, CODE_ATTRIBUTES, 0);

 			n = 0;
 			if (s->grid_attr[j][i] != attr) {
 				attr = s->grid_attr[j][i];
 				n += screen_store_attributes(b, attr);
 				if (attr == 0)
 					colr = SCREEN_DEFCOLR;
 			}
 			if (s->grid_colr[j][i] != colr) {
 				colr = s->grid_colr[j][i];
 				n += screen_store_colours(b, colr);
 			}
 			if (n == 0)
 				buffer_reverse_add(b, 4);
 			else {
 				size = BUFFER_USED(b) - size;
 				memcpy(BUFFER_IN(b) - size + 2, &n, 2);
 			}

 			input_store8(b, s->grid_data[j][i]);
 		}
 	}

 	size = BUFFER_USED(b);
 	input_store_one(b, CODE_ATTRIBUTES, 0);
 	n = screen_store_attributes(b, s->attr);
 	n += screen_store_colours(b, s->colr);
 	size = BUFFER_USED(b) - size;
 	memcpy(BUFFER_IN(b) - size + 2, &n, 2);

 	input_store_two(b, CODE_CURSORMOVE, s->cy + 1, s->cx + 1);

 	if (s->mode & MODE_CURSOR)
 		input_store_zero(b, CODE_CURSORON);
 }

 /* Store screen atttributes in buffer. */
 size_t
 screen_store_attributes(struct buffer *b, u_char attr)
 {
 	size_t	n;

 	if (attr == 0) {
 		input_store16(b, 0);
 		return (1);
 	}

 	n = 0;
 	if (attr & ATTR_BRIGHT) {
 		input_store16(b, 1);
 		n++;
 	}
 	if (attr & ATTR_DIM) {
 		input_store16(b, 2);
 		n++;
 	}
 	if (attr & ATTR_ITALICS) {
 		input_store16(b, 3);
 		n++;
 	}
 	if (attr & ATTR_UNDERSCORE) {
 		input_store16(b, 4);
 		n++;
 	}
 	if (attr & ATTR_BLINK) {
 		input_store16(b, 5);
 		n++;
 	}
 	if (attr & ATTR_REVERSE) {
 		input_store16(b, 7);
 		n++;
 	}
 	if (attr & ATTR_HIDDEN) {
 		input_store16(b, 8);
 		n++;
 	}
 	return (n);
 }

 /* Store screen colours in buffer. */
 size_t
 screen_store_colours(struct buffer *b, u_char colr)
 {
 	uint16_t	v;

 	v = colr >> 4;
 	if (v == 8)
 		v = 9;
 	input_store16(b, 30 + v);
 	v = colr & 0xf;
 	if (v == 8)
 		v = 9;
 	input_store16(b, 40 + v);

 	return (2);
 }

 /* Make a range of lines. */
 void
 screen_make_lines(struct screen *s, u_int py, u_int ny)
 {
 	u_int	i;

 	log_debug("making lines %u,%u", py, ny);

 	if (py > screen_last_y(s) || py + ny - 1 > screen_last_y(s))
 		fatalx("bad range");

 	for (i = py; i < py + ny; i++) {
 		s->grid_data[i] = xmalloc(s->sx);
 		s->grid_attr[i] = xmalloc(s->sx);
 		s->grid_colr[i] = xmalloc(s->sx);
 	}
 }

 /* Free a range of lines. */
 void
 screen_free_lines(struct screen *s, u_int py, u_int ny)
 {
 	u_int	i;

 	log_debug("freeing lines %u,%u", py, ny);

 	if (py > screen_last_y(s) || py + ny - 1 > screen_last_y(s))
 		fatalx("bad range");

 	for (i = py; i < py + ny; i++) {
 		xfree(s->grid_data[i]);
 		xfree(s->grid_attr[i]);
 		xfree(s->grid_colr[i]);
 	}
 }

 /* Move a range of lines. */
 void
 screen_move_lines(struct screen *s, u_int dy, u_int py, u_int ny)
 {
 	log_debug("moving lines %u,%u to %u", py, ny, dy);

 	if (py > screen_last_y(s) || py + ny - 1 > screen_last_y(s))
 		fatalx("bad range");
 	if (dy > screen_last_y(s) || dy == py)
 		fatalx("bad destination");
 	if (dy + ny - 1 > screen_last_y(s))
 		fatalx("bad size");

 	memmove(
 	    &s->grid_data[dy], &s->grid_data[py], ny * (sizeof *s->grid_data));
 	memmove(
 	    &s->grid_attr[dy], &s->grid_attr[py], ny * (sizeof *s->grid_attr));
 	memmove(
 	    &s->grid_colr[dy], &s->grid_colr[py], ny * (sizeof *s->grid_colr));
 }

 /* Fill a range of lines. */
 void
 screen_fill_lines(
     struct screen *s, u_int py, u_int ny, u_char data, u_char attr, u_char colr)
 {
 	u_int	i;

 	log_debug("filling lines %u,%u", py, ny);

 	if (py > screen_last_y(s) || py + ny - 1 > screen_last_y(s))
 		fatalx("bad range");

 	for (i = py; i < py + ny; i++)
 		screen_fill_line(s, i, data, attr, colr);
 }

 /* Write a single character to the screen at the cursor and move forward. */
 void
 screen_write_character(struct screen *s, u_char ch)
 {
 	if (s->cx > screen_last_x(s)) {
 		s->cx = 0;
 		screen_cursor_down_scroll(s);
 	}

 	s->grid_data[s->cy][s->cx] = ch;
 	s->grid_attr[s->cy][s->cx] = s->attr;
 	s->grid_colr[s->cy][s->cx] = s->colr;

 	s->cx++;
 }

 /* Move cursor up and scroll if necessary. */
 void
 screen_cursor_up_scroll(struct screen *s)
 {
 	if (s->cy == s->ry_upper)
 		screen_scroll_region_down(s);
 	else if (s->cy > 0)
 		s->cy--;
 }

 /* Move cursor down and scroll if necessary. */
 void
 screen_cursor_down_scroll(struct screen *s)
 {
 	if (s->cy == s->ry_lower)
 		screen_scroll_region_up(s);
 	else if (s->cy < screen_last_y(s))
 		s->cy++;
 }

 /* Scroll region up. */
 void
 screen_scroll_region_up(struct screen *s)
 {
 	log_debug("scrolling region up: %u:%u", s->ry_upper, s->ry_lower);

 	/*
 	 * Scroll scrolling region up:
 	 * 	- delete ry_upper
 	 *	- move ry_upper + 1 to ry_lower to ry_upper
 	 *	- make new line at ry_lower
 	 *
 	 * Example: region is 12 to 24.
 	 *	ry_lower = 24, ry_upper = 12
 	 *	screen_free_lines(s, 12, 1);
 	 *	screen_move_lines(s, 12, 13, 12);
 	 *	screen_make_lines(s, 24, 1);
 	 */

 	screen_free_lines(s, s->ry_upper, 1);

 	if (s->ry_upper != s->ry_lower) {
 		screen_move_lines(s,
 		    s->ry_upper, s->ry_upper + 1, s->ry_lower - s->ry_upper);
 	}

 	screen_make_lines(s, s->ry_lower, 1);
 	screen_fill_lines(
 	    s, s->ry_lower, 1, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 }

 /* Scroll region down. */
 void
 screen_scroll_region_down(struct screen *s)
 {
 	log_debug("scrolling region down: %u:%u", s->ry_upper, s->ry_lower);

 	/*
 	 * Scroll scrolling region down:
 	 * 	- delete ry_lower
 	 *	- move ry_upper to ry_lower - 1 to ry_upper + 1
 	 *	- make new line at ry_upper
 	 *
 	 * Example: region is 12 to 24.
 	 *	ry_lower = 24, ry_upper = 12
 	 *	screen_free_lines(s, 24, 1);
 	 *	screen_move_lines(s, 13, 12, 12);
 	 *	screen_make_lines(s, 12, 1);
 	 */

 	screen_free_lines(s, s->ry_lower, 1);

 	if (s->ry_upper != s->ry_lower) {
 		screen_move_lines(s,
 		    s->ry_upper + 1, s->ry_upper, s->ry_lower - s->ry_upper);
 	}

 	screen_make_lines(s, s->ry_upper, 1);
 	screen_fill_lines(
 	    s, s->ry_upper, 1, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 }

 /* Scroll screen up. */
 void
 screen_scroll_up(struct screen *s, u_int ny)
 {
 	screen_delete_lines(s, 0, ny);
 }

 /* Scroll screen down. */
 void
 screen_scroll_down(struct screen *s, u_int ny)
 {
 	screen_insert_lines(s, 0, ny);
 }

 /* Fill entire screen. */
 void
 screen_fill_screen(struct screen *s, u_char data, u_char attr, u_char colr)
 {
 	screen_fill_end_of_screen(s, 0, 0, data, attr, colr);
 }

 /* Fill single line. */
 void
 screen_fill_line(
     struct screen *s, u_int py, u_char data, u_char attr, u_char colr)
 {
 	screen_fill_end_of_line(s, 0, py, data, attr, colr);
 }

 /* Fill to end of screen. */
 void
 screen_fill_end_of_screen(
     struct screen *s, u_int px, u_int py, u_char data, u_char attr, u_char colr)
 {
 	if (py > screen_last_y(s))
 		return;

 	if (px != 0) {
 		screen_fill_end_of_line(s, px, py, data, attr, colr);
 		if (py++ > screen_last_y(s))
 			return;
 	}

 	while (py <= screen_last_y(s)) {
 		screen_fill_line(s, py, data, attr, colr);
 		py++;
 	}
 }

 /* Fill to end of line. */
 void
 screen_fill_end_of_line(
     struct screen *s, u_int px, u_int py, u_char data, u_char attr, u_char colr)
 {
 	if (px > screen_last_x(s))
 		return;
 	if (py > screen_last_y(s))
 		return;

 	memset(&s->grid_data[py][px], data, s->sx - px);
 	memset(&s->grid_attr[py][px], attr, s->sx - px);
 	memset(&s->grid_colr[py][px], colr, s->sx - px);
 }

 /* Fill to start of line. */
 void
 screen_fill_start_of_line(
     struct screen *s, u_int px, u_int py, u_char data, u_char attr, u_char colr)
 {
 	if (px > screen_last_x(s))
 		return;
 	if (py > screen_last_y(s))
 		return;

 	memset(s->grid_data[py], data, px);
 	memset(s->grid_attr[py], attr, px);
 	memset(s->grid_colr[py], colr, px);
 }

 /* Insert lines. */
 void
 screen_insert_lines(struct screen *s, u_int py, u_int ny)
 {
 	if (py > screen_last_y(s))
 		return;

 	if (py + ny > screen_last_y(s))
 		ny = screen_last_y(s) - py;
 	log_debug("inserting lines: %u,%u", py, ny);

 	/*
 	 * Insert range of ny lines at py:
 	 *	- Free ny lines from end of screen.
 	 *	- Move from py to end of screen - ny to py + ny.
 	 *	- Create ny lines at py.
 	 *
 	 * Example: insert 2 lines at 4.
 	 *	sy = 10, py = 4, ny = 2
 	 *	screen_free_lines(s, 8, 2);	- delete lines 8,9
 	 *	screen_move_lines(s, 6, 4, 4);	- move 4,5,6,7 to 6,7,8,9
 	 *	screen_make_lines(s, 4, 2);	- make lines 4,5
 	 */

 	screen_free_lines(s, s->sy - ny, ny);

 	if (py != screen_last_y(s))
 		screen_move_lines(s, py + ny, py, s->sy - py - ny);

 	screen_make_lines(s, py, ny);
 	screen_fill_lines(
 	    s, py, ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 }

 /* Insert lines in region. */
 void
 screen_insert_lines_region(struct screen *s, u_int py, u_int ny)
 {
 	if (py < s->ry_upper || py > s->ry_lower)
 		return;
 	if (py + ny > s->ry_lower)
 		ny = s->ry_lower - py;
 	log_debug("inserting lines in region: %u,%u (%u,%u)", py, ny,
 	    s->ry_upper, s->ry_lower);

 	/*
 	 * Insert range of ny lines at py:
 	 *	- Free ny lines from end of screen.
 	 *	- Move from py to end of screen - ny to py + ny.
 	 *	- Create ny lines at py.
 	 *
 	 * Example: insert 2 lines at 4.
 	 *	ryu = 11, ryl = 16, py = 13, ny = 2
 	 *	screen_free_lines(s, 15, 2);	- delete lines 15,16
 	 *	screen_move_lines(s, 13, 15, 2);- move 13,14 to 15,16
 	 *	screen_make_lines(s, 13, 2);	- make lines 13,14
 	 */

 	screen_free_lines(s, (s->ry_upper + 1) - ny, ny);

 	if (py != s->ry_upper)
 		screen_move_lines(s, py + ny, py, (s->ry_upper + 1) - py - ny);

 	screen_make_lines(s, py, ny);
 	screen_fill_lines(
 	    s, py, ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 }

 /* Delete lines. */
 void
 screen_delete_lines(struct screen *s, u_int py, u_int ny)
 {
 	if (py > screen_last_y(s))
 		return;

 	if (py + ny > screen_last_y(s))
 		ny = screen_last_y(s) - py;
 	log_debug("deleting lines: %u,%u", py, ny);

 	/*
 	 * Delete range of ny lines at py:
 	 * 	- Free ny lines at py.
 	 *	- Move from py + ny to end of screen to py.
 	 *	- Free and recreate last ny lines.
 	 *
 	 * Example: delete lines 3,4.
 	 *	sy = 10, py = 3, ny = 2
 	 *	screen_free_lines(s, 3, 2);	- delete lines 3,4
 	 *	screen_move_lines(s, 3, 5, 5);	- move 5,6,7,8,9 to 3
 	 *	screen_make_lines(s, 8, 2);	- make lines 8,9
 	 */

 	screen_free_lines(s, py, ny);

 	if (py != screen_last_y(s))
 		screen_move_lines(s, py, py + ny, s->sy - py - ny);

 	screen_make_lines(s, s->sy - ny, ny);
 	screen_fill_lines(
 	    s, s->sy - ny, ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 }

 /* Delete lines inside scroll region. */
 void
 screen_delete_lines_region(struct screen *s, u_int py, u_int ny)
 {
 	if (py < s->ry_upper || py > s->ry_lower)
 		return;
 	if (py + ny > s->ry_lower)
 		ny = s->ry_lower - py;
 	log_debug("deleting lines in region: %u,%u (%u,%u)", py, ny,
 	    s->ry_upper, s->ry_lower);

 	/*
 	 * Delete range of ny lines at py:
 	 * 	- Free ny lines at py.
 	 *	- Move from py + ny to end of region to py.
 	 *	- Free and recreate last ny lines.
 	 *
 	 * Example: delete lines 13,14.
 	 *	ryu = 11, ryl = 16, py = 13, ny = 2
 	 *	screen_free_lines(s, 13, 2);	- delete lines 13,14
 	 *	screen_move_lines(s, 15, 16, 2);- move 15,16 to 13
 	 *	screen_make_lines(s, 15, 16);	- make lines 15,16
 	 */

 	screen_free_lines(s, py, ny);

 	if (py != s->ry_lower)
 		screen_move_lines(s, py, py + ny, (s->ry_lower + 1) - py - ny);

 	screen_make_lines(s, (s->ry_lower + 1) - ny, ny);
 	screen_fill_lines(s, (s->ry_lower + 1) - ny,
 	    ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
 }

 /* Insert characters. */
 void
 screen_insert_characters(struct screen *s, u_int px, u_int py, u_int nx)
 {
 	u_int	lx, rx;

 	if (px > screen_last_x(s) || py > screen_last_y(s))
 		return;

 	lx = px;
 	rx = screen_offset_x(px, nx);
 	if (rx > screen_last_x(s))
 		rx = screen_last_x(s);

 	/*
 	 * Inserting a range from lx to rx, inclusive.
 	 *
 	 * - If rx is not the last x, move from lx to rx + 1.
 	 * - Clear the range from lx to rx.
 	 */
 	if (rx != screen_last_x(s)) {
 		nx = screen_range_x(rx + 1, screen_last_x(s));
 		memmove(&s->grid_data[py][rx + 1], &s->grid_data[py][lx], nx);
 		memmove(&s->grid_attr[py][rx + 1], &s->grid_attr[py][lx], nx);
 		memmove(&s->grid_colr[py][rx + 1], &s->grid_colr[py][lx], nx);
 	}
 	memset(&s->grid_data[py][lx], SCREEN_DEFDATA, screen_range_x(lx, rx));
 	memset(&s->grid_attr[py][lx], SCREEN_DEFATTR, screen_range_x(lx, rx));
 	memset(&s->grid_colr[py][lx], SCREEN_DEFCOLR, screen_range_x(lx, rx));
 }

 /* Delete characters. */
 void
 screen_delete_characters(struct screen *s, u_int px, u_int py, u_int nx)
 {
 	u_int	lx, rx;

 	if (px > screen_last_x(s) || py > screen_last_y(s))
 		return;

 	lx = px;
 	rx = screen_offset_x(px, nx);
 	if (rx > screen_last_x(s))
 		rx = screen_last_x(s);

 	/*
 	 * Deleting the range from lx to rx, inclusive.
 	 *
 	 * - If rx is not the last x, move the range from rx + 1 to lx.
 	 * - Clear the range from the last x - (rx - lx)  to the last x.
 	 */

 	if (rx != screen_last_x(s)) {
 		nx = screen_range_x(rx + 1, screen_last_x(s));
 		memmove(&s->grid_data[py][lx], &s->grid_data[py][rx + 1], nx);
 		memmove(&s->grid_attr[py][lx], &s->grid_attr[py][rx + 1], nx);
 		memmove(&s->grid_colr[py][lx], &s->grid_colr[py][rx + 1], nx);
 	}

 	/* If lx == rx, then nx = 1. */
 	nx = screen_range_x(lx, rx);
 	memset(&s->grid_data[py][s->sx - nx], SCREEN_DEFDATA, nx);
 	memset(&s->grid_attr[py][s->sx - nx], SCREEN_DEFATTR, nx);
 	memset(&s->grid_colr[py][s->sx - nx], SCREEN_DEFCOLR, nx);
 }
	/* $Id: screen.c,v 1.15 2007-09-29 18:48:04 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 <string.h>

	#include "tmux.h"

	/*
	* Virtual screen and basic terminal emulator.
	*
	* XXX Much of this file sucks.
	*/

	void screen_free_lines(struct screen *, u_int, u_int);
	void screen_make_lines(struct screen *, u_int, u_int);
	void screen_move_lines(struct screen *, u_int, u_int, u_int);
	void screen_fill_lines(
	struct screen *, u_int, u_int, u_char, u_char, u_char);

	#define screen_last_y(s) ((s)->sy - 1)
	#define screen_last_x(s) ((s)->sx - 1)

	#define screen_range_y(lx, rx) (((rx) - (lx)) + 1)
	#define screen_range_x(ux, lx) (((lx) - (ux)) + 1)

	#define screen_offset_y(py, ny) ((py) + (ny) - 1)
	#define screen_offset_x(px, nx) ((px) + (nx) - 1)

	/* Create a new screen. */
	void
	screen_create(struct screen *s, u_int sx, u_int sy)
	{
	s->sx = sx;
	s->sy = sy;
	s->cx = 0;
	s->cy = 0;

	s->ry_upper = 0;
	s->ry_lower = screen_last_y(s);

	s->attr = SCREEN_DEFATTR;
	s->colr = SCREEN_DEFCOLR;

	s->mode = MODE_CURSOR;
	*s->title = '\0';

	s->grid_data = xmalloc(sy * (sizeof *s->grid_data));
	s->grid_attr = xmalloc(sy * (sizeof *s->grid_attr));
	s->grid_colr = xmalloc(sy * (sizeof *s->grid_colr));
	screen_make_lines(s, 0, sy);
	screen_fill_screen(s, SCREEN_DEFDATA, 0, SCREEN_DEFCOLR);
	}

	/* Resize screen. */
	void
	screen_resize(struct screen *s, u_int sx, u_int sy)
	{
	u_int i, ox, oy, ny;

	if (sx == s->sx \|\| sy == s->sy)
	return;

	if (sx < 1)
	sx = 1;
	if (sy < 1)
	sy = 1;

	ox = s->sx;
	oy = s->sy;
	s->sx = sx;
	s->sy = sy;

	log_debug("resizing screen (%u, %u) -> (%u, %u)", ox, oy, sx, sy);

	if (sy < oy) {
	ny = oy - sy;
	if (ny > s->cy)
	ny = s->cy;

	if (ny != 0) {
	log_debug("removing %u lines from top", ny);
	for (i = 0; i < ny; i++) {
	log_debug("freeing line %u", i);
	xfree(s->grid_data[i]);
	xfree(s->grid_attr[i]);
	xfree(s->grid_colr[i]);
	}
	memmove(s->grid_data, s->grid_data + ny,
	(oy - ny) * (sizeof *s->grid_data));
	memmove(s->grid_attr, s->grid_attr + ny,
	(oy - ny) * (sizeof *s->grid_attr));
	memmove(s->grid_colr, s->grid_colr + ny,
	(oy - ny) * (sizeof *s->grid_colr));
	s->cy -= ny;
	}
	if (ny < oy - sy) {
	log_debug(
	"removing %u lines from bottom", oy - sy - ny);
	for (i = sy; i < oy - ny; i++) {
	log_debug("freeing line %u", i);
	xfree(s->grid_data[i]);
	xfree(s->grid_attr[i]);
	xfree(s->grid_colr[i]);
	}
	if (s->cy >= sy)
	s->cy = sy - 1;
	}
	}
	if (sy != oy) {
	s->grid_data = xrealloc(s->grid_data, sy, sizeof *s->grid_data);
	s->grid_attr = xrealloc(s->grid_attr, sy, sizeof *s->grid_attr);
	s->grid_colr = xrealloc(s->grid_colr, sy, sizeof *s->grid_colr);
	}
	if (sy > oy) {
	for (i = oy; i < sy; i++) {
	log_debug("allocating line %u", i);
	s->grid_data[i] = xmalloc(sx);
	s->grid_attr[i] = xmalloc(sx);
	s->grid_colr[i] = xmalloc(sx);
	screen_fill_line(s, i,
	SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}
	sy = oy;
	}

	if (sx != ox) {
	for (i = 0; i < sy; i++) {
	log_debug("adjusting line %u to %u", i, sx);
	s->grid_data[i] = xrealloc(s->grid_data[i], sx, 1);
	s->grid_attr[i] = xrealloc(s->grid_attr[i], sx, 1);
	s->grid_colr[i] = xrealloc(s->grid_colr[i], sx, 1);
	if (sx > ox) {
	screen_fill_end_of_line(s, ox, i,
	SCREEN_DEFDATA, SCREEN_DEFATTR,
	SCREEN_DEFCOLR);
	}
	}
	if (s->cx >= sx)
	s->cx = sx - 1;
	}
	}

	/* Draw a set of lines on the screen. */
	void
	screen_draw(struct screen s, struct buffer b, u_int uy, u_int ly)
	{
	u_char attr, colr;
	size_t size;
	u_int i, j;
	uint16_t n;

	if (uy > screen_last_y(s) \|\| ly > screen_last_y(s) \|\| ly < uy)
	fatalx("bad range");

	/* XXX. This is naive and rough right now. */
	attr = 0;
	colr = SCREEN_DEFCOLR;

	input_store_two(b, CODE_SCROLLREGION, s->ry_upper + 1, s->ry_lower + 1);

	input_store_zero(b, CODE_CURSOROFF);

	input_store_one(b, CODE_ATTRIBUTES, 0);

	for (j = uy; j <= ly; j++) {
	input_store_two(b, CODE_CURSORMOVE, j + 1, 1);

	for (i = 0; i <= screen_last_x(s); i++) {
	size = BUFFER_USED(b);
	input_store_one(b, CODE_ATTRIBUTES, 0);

	n = 0;
	if (s->grid_attr[j][i] != attr) {
	attr = s->grid_attr[j][i];
	n += screen_store_attributes(b, attr);
	if (attr == 0)
	colr = SCREEN_DEFCOLR;
	}
	if (s->grid_colr[j][i] != colr) {
	colr = s->grid_colr[j][i];
	n += screen_store_colours(b, colr);
	}
	if (n == 0)
	buffer_reverse_add(b, 4);
	else {
	size = BUFFER_USED(b) - size;
	memcpy(BUFFER_IN(b) - size + 2, &n, 2);
	}

	input_store8(b, s->grid_data[j][i]);
	}
	}

	size = BUFFER_USED(b);
	input_store_one(b, CODE_ATTRIBUTES, 0);
	n = screen_store_attributes(b, s->attr);
	n += screen_store_colours(b, s->colr);
	size = BUFFER_USED(b) - size;
	memcpy(BUFFER_IN(b) - size + 2, &n, 2);

	input_store_two(b, CODE_CURSORMOVE, s->cy + 1, s->cx + 1);

	if (s->mode & MODE_CURSOR)
	input_store_zero(b, CODE_CURSORON);
	}

	/* Store screen atttributes in buffer. */
	size_t
	screen_store_attributes(struct buffer *b, u_char attr)
	{
	size_t n;

	if (attr == 0) {
	input_store16(b, 0);
	return (1);
	}

	n = 0;
	if (attr & ATTR_BRIGHT) {
	input_store16(b, 1);
	n++;
	}
	if (attr & ATTR_DIM) {
	input_store16(b, 2);
	n++;
	}
	if (attr & ATTR_ITALICS) {
	input_store16(b, 3);
	n++;
	}
	if (attr & ATTR_UNDERSCORE) {
	input_store16(b, 4);
	n++;
	}
	if (attr & ATTR_BLINK) {
	input_store16(b, 5);
	n++;
	}
	if (attr & ATTR_REVERSE) {
	input_store16(b, 7);
	n++;
	}
	if (attr & ATTR_HIDDEN) {
	input_store16(b, 8);
	n++;
	}
	return (n);
	}

	/* Store screen colours in buffer. */
	size_t
	screen_store_colours(struct buffer *b, u_char colr)
	{
	uint16_t v;

	v = colr >> 4;
	if (v == 8)
	v = 9;
	input_store16(b, 30 + v);
	v = colr & 0xf;
	if (v == 8)
	v = 9;
	input_store16(b, 40 + v);

	return (2);
	}

	/* Make a range of lines. */
	void
	screen_make_lines(struct screen *s, u_int py, u_int ny)
	{
	u_int i;

	log_debug("making lines %u,%u", py, ny);

	if (py > screen_last_y(s) \|\| py + ny - 1 > screen_last_y(s))
	fatalx("bad range");

	for (i = py; i < py + ny; i++) {
	s->grid_data[i] = xmalloc(s->sx);
	s->grid_attr[i] = xmalloc(s->sx);
	s->grid_colr[i] = xmalloc(s->sx);
	}
	}

	/* Free a range of lines. */
	void
	screen_free_lines(struct screen *s, u_int py, u_int ny)
	{
	u_int i;

	log_debug("freeing lines %u,%u", py, ny);

	if (py > screen_last_y(s) \|\| py + ny - 1 > screen_last_y(s))
	fatalx("bad range");

	for (i = py; i < py + ny; i++) {
	xfree(s->grid_data[i]);
	xfree(s->grid_attr[i]);
	xfree(s->grid_colr[i]);
	}
	}

	/* Move a range of lines. */
	void
	screen_move_lines(struct screen *s, u_int dy, u_int py, u_int ny)
	{
	log_debug("moving lines %u,%u to %u", py, ny, dy);

	if (py > screen_last_y(s) \|\| py + ny - 1 > screen_last_y(s))
	fatalx("bad range");
	if (dy > screen_last_y(s) \|\| dy == py)
	fatalx("bad destination");
	if (dy + ny - 1 > screen_last_y(s))
	fatalx("bad size");

	memmove(
	&s->grid_data[dy], &s->grid_data[py], ny * (sizeof *s->grid_data));
	memmove(
	&s->grid_attr[dy], &s->grid_attr[py], ny * (sizeof *s->grid_attr));
	memmove(
	&s->grid_colr[dy], &s->grid_colr[py], ny * (sizeof *s->grid_colr));
	}

	/* Fill a range of lines. */
	void
	screen_fill_lines(
	struct screen *s, u_int py, u_int ny, u_char data, u_char attr, u_char colr)
	{
	u_int i;

	log_debug("filling lines %u,%u", py, ny);

	if (py > screen_last_y(s) \|\| py + ny - 1 > screen_last_y(s))
	fatalx("bad range");

	for (i = py; i < py + ny; i++)
	screen_fill_line(s, i, data, attr, colr);
	}

	/* Write a single character to the screen at the cursor and move forward. */
	void
	screen_write_character(struct screen *s, u_char ch)
	{
	if (s->cx > screen_last_x(s)) {
	s->cx = 0;
	screen_cursor_down_scroll(s);
	}

	s->grid_data[s->cy][s->cx] = ch;
	s->grid_attr[s->cy][s->cx] = s->attr;
	s->grid_colr[s->cy][s->cx] = s->colr;

	s->cx++;
	}

	/* Move cursor up and scroll if necessary. */
	void
	screen_cursor_up_scroll(struct screen *s)
	{
	if (s->cy == s->ry_upper)
	screen_scroll_region_down(s);
	else if (s->cy > 0)
	s->cy--;
	}

	/* Move cursor down and scroll if necessary. */
	void
	screen_cursor_down_scroll(struct screen *s)
	{
	if (s->cy == s->ry_lower)
	screen_scroll_region_up(s);
	else if (s->cy < screen_last_y(s))
	s->cy++;
	}

	/* Scroll region up. */
	void
	screen_scroll_region_up(struct screen *s)
	{
	log_debug("scrolling region up: %u:%u", s->ry_upper, s->ry_lower);

	/*
	* Scroll scrolling region up:
	* - delete ry_upper
	* - move ry_upper + 1 to ry_lower to ry_upper
	* - make new line at ry_lower
	*
	* Example: region is 12 to 24.
	* ry_lower = 24, ry_upper = 12
	* screen_free_lines(s, 12, 1);
	* screen_move_lines(s, 12, 13, 12);
	* screen_make_lines(s, 24, 1);
	*/

	screen_free_lines(s, s->ry_upper, 1);

	if (s->ry_upper != s->ry_lower) {
	screen_move_lines(s,
	s->ry_upper, s->ry_upper + 1, s->ry_lower - s->ry_upper);
	}

	screen_make_lines(s, s->ry_lower, 1);
	screen_fill_lines(
	s, s->ry_lower, 1, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}

	/* Scroll region down. */
	void
	screen_scroll_region_down(struct screen *s)
	{
	log_debug("scrolling region down: %u:%u", s->ry_upper, s->ry_lower);

	/*
	* Scroll scrolling region down:
	* - delete ry_lower
	* - move ry_upper to ry_lower - 1 to ry_upper + 1
	* - make new line at ry_upper
	*
	* Example: region is 12 to 24.
	* ry_lower = 24, ry_upper = 12
	* screen_free_lines(s, 24, 1);
	* screen_move_lines(s, 13, 12, 12);
	* screen_make_lines(s, 12, 1);
	*/

	screen_free_lines(s, s->ry_lower, 1);

	if (s->ry_upper != s->ry_lower) {
	screen_move_lines(s,
	s->ry_upper + 1, s->ry_upper, s->ry_lower - s->ry_upper);
	}

	screen_make_lines(s, s->ry_upper, 1);
	screen_fill_lines(
	s, s->ry_upper, 1, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}

	/* Scroll screen up. */
	void
	screen_scroll_up(struct screen *s, u_int ny)
	{
	screen_delete_lines(s, 0, ny);
	}

	/* Scroll screen down. */
	void
	screen_scroll_down(struct screen *s, u_int ny)
	{
	screen_insert_lines(s, 0, ny);
	}

	/* Fill entire screen. */
	void
	screen_fill_screen(struct screen *s, u_char data, u_char attr, u_char colr)
	{
	screen_fill_end_of_screen(s, 0, 0, data, attr, colr);
	}

	/* Fill single line. */
	void
	screen_fill_line(
	struct screen *s, u_int py, u_char data, u_char attr, u_char colr)
	{
	screen_fill_end_of_line(s, 0, py, data, attr, colr);
	}

	/* Fill to end of screen. */
	void
	screen_fill_end_of_screen(
	struct screen *s, u_int px, u_int py, u_char data, u_char attr, u_char colr)
	{
	if (py > screen_last_y(s))
	return;

	if (px != 0) {
	screen_fill_end_of_line(s, px, py, data, attr, colr);
	if (py++ > screen_last_y(s))
	return;
	}

	while (py <= screen_last_y(s)) {
	screen_fill_line(s, py, data, attr, colr);
	py++;
	}
	}

	/* Fill to end of line. */
	void
	screen_fill_end_of_line(
	struct screen *s, u_int px, u_int py, u_char data, u_char attr, u_char colr)
	{
	if (px > screen_last_x(s))
	return;
	if (py > screen_last_y(s))
	return;

	memset(&s->grid_data[py][px], data, s->sx - px);
	memset(&s->grid_attr[py][px], attr, s->sx - px);
	memset(&s->grid_colr[py][px], colr, s->sx - px);
	}

	/* Fill to start of line. */
	void
	screen_fill_start_of_line(
	struct screen *s, u_int px, u_int py, u_char data, u_char attr, u_char colr)
	{
	if (px > screen_last_x(s))
	return;
	if (py > screen_last_y(s))
	return;

	memset(s->grid_data[py], data, px);
	memset(s->grid_attr[py], attr, px);
	memset(s->grid_colr[py], colr, px);
	}

	/* Insert lines. */
	void
	screen_insert_lines(struct screen *s, u_int py, u_int ny)
	{
	if (py > screen_last_y(s))
	return;

	if (py + ny > screen_last_y(s))
	ny = screen_last_y(s) - py;
	log_debug("inserting lines: %u,%u", py, ny);

	/*
	* Insert range of ny lines at py:
	* - Free ny lines from end of screen.
	* - Move from py to end of screen - ny to py + ny.
	* - Create ny lines at py.
	*
	* Example: insert 2 lines at 4.
	* sy = 10, py = 4, ny = 2
	* screen_free_lines(s, 8, 2); - delete lines 8,9
	* screen_move_lines(s, 6, 4, 4); - move 4,5,6,7 to 6,7,8,9
	* screen_make_lines(s, 4, 2); - make lines 4,5
	*/

	screen_free_lines(s, s->sy - ny, ny);

	if (py != screen_last_y(s))
	screen_move_lines(s, py + ny, py, s->sy - py - ny);

	screen_make_lines(s, py, ny);
	screen_fill_lines(
	s, py, ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}

	/* Insert lines in region. */
	void
	screen_insert_lines_region(struct screen *s, u_int py, u_int ny)
	{
	if (py < s->ry_upper \|\| py > s->ry_lower)
	return;
	if (py + ny > s->ry_lower)
	ny = s->ry_lower - py;
	log_debug("inserting lines in region: %u,%u (%u,%u)", py, ny,
	s->ry_upper, s->ry_lower);

	/*
	* Insert range of ny lines at py:
	* - Free ny lines from end of screen.
	* - Move from py to end of screen - ny to py + ny.
	* - Create ny lines at py.
	*
	* Example: insert 2 lines at 4.
	* ryu = 11, ryl = 16, py = 13, ny = 2
	* screen_free_lines(s, 15, 2); - delete lines 15,16
	* screen_move_lines(s, 13, 15, 2);- move 13,14 to 15,16
	* screen_make_lines(s, 13, 2); - make lines 13,14
	*/

	screen_free_lines(s, (s->ry_upper + 1) - ny, ny);

	if (py != s->ry_upper)
	screen_move_lines(s, py + ny, py, (s->ry_upper + 1) - py - ny);

	screen_make_lines(s, py, ny);
	screen_fill_lines(
	s, py, ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}

	/* Delete lines. */
	void
	screen_delete_lines(struct screen *s, u_int py, u_int ny)
	{
	if (py > screen_last_y(s))
	return;

	if (py + ny > screen_last_y(s))
	ny = screen_last_y(s) - py;
	log_debug("deleting lines: %u,%u", py, ny);

	/*
	* Delete range of ny lines at py:
	* - Free ny lines at py.
	* - Move from py + ny to end of screen to py.
	* - Free and recreate last ny lines.
	*
	* Example: delete lines 3,4.
	* sy = 10, py = 3, ny = 2
	* screen_free_lines(s, 3, 2); - delete lines 3,4
	* screen_move_lines(s, 3, 5, 5); - move 5,6,7,8,9 to 3
	* screen_make_lines(s, 8, 2); - make lines 8,9
	*/

	screen_free_lines(s, py, ny);

	if (py != screen_last_y(s))
	screen_move_lines(s, py, py + ny, s->sy - py - ny);

	screen_make_lines(s, s->sy - ny, ny);
	screen_fill_lines(
	s, s->sy - ny, ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}

	/* Delete lines inside scroll region. */
	void
	screen_delete_lines_region(struct screen *s, u_int py, u_int ny)
	{
	if (py < s->ry_upper \|\| py > s->ry_lower)
	return;
	if (py + ny > s->ry_lower)
	ny = s->ry_lower - py;
	log_debug("deleting lines in region: %u,%u (%u,%u)", py, ny,
	s->ry_upper, s->ry_lower);

	/*
	* Delete range of ny lines at py:
	* - Free ny lines at py.
	* - Move from py + ny to end of region to py.
	* - Free and recreate last ny lines.
	*
	* Example: delete lines 13,14.
	* ryu = 11, ryl = 16, py = 13, ny = 2
	* screen_free_lines(s, 13, 2); - delete lines 13,14
	* screen_move_lines(s, 15, 16, 2);- move 15,16 to 13
	* screen_make_lines(s, 15, 16); - make lines 15,16
	*/

	screen_free_lines(s, py, ny);

	if (py != s->ry_lower)
	screen_move_lines(s, py, py + ny, (s->ry_lower + 1) - py - ny);

	screen_make_lines(s, (s->ry_lower + 1) - ny, ny);
	screen_fill_lines(s, (s->ry_lower + 1) - ny,
	ny, SCREEN_DEFDATA, SCREEN_DEFATTR, SCREEN_DEFCOLR);
	}

	/* Insert characters. */
	void
	screen_insert_characters(struct screen *s, u_int px, u_int py, u_int nx)
	{
	u_int lx, rx;

	if (px > screen_last_x(s) \|\| py > screen_last_y(s))
	return;

	lx = px;
	rx = screen_offset_x(px, nx);
	if (rx > screen_last_x(s))
	rx = screen_last_x(s);

	/*
	* Inserting a range from lx to rx, inclusive.
	*
	* - If rx is not the last x, move from lx to rx + 1.
	* - Clear the range from lx to rx.
	*/
	if (rx != screen_last_x(s)) {
	nx = screen_range_x(rx + 1, screen_last_x(s));
	memmove(&s->grid_data[py][rx + 1], &s->grid_data[py][lx], nx);
	memmove(&s->grid_attr[py][rx + 1], &s->grid_attr[py][lx], nx);
	memmove(&s->grid_colr[py][rx + 1], &s->grid_colr[py][lx], nx);
	}
	memset(&s->grid_data[py][lx], SCREEN_DEFDATA, screen_range_x(lx, rx));
	memset(&s->grid_attr[py][lx], SCREEN_DEFATTR, screen_range_x(lx, rx));
	memset(&s->grid_colr[py][lx], SCREEN_DEFCOLR, screen_range_x(lx, rx));
	}

	/* Delete characters. */
	void
	screen_delete_characters(struct screen *s, u_int px, u_int py, u_int nx)
	{
	u_int lx, rx;

	if (px > screen_last_x(s) \|\| py > screen_last_y(s))
	return;

	lx = px;
	rx = screen_offset_x(px, nx);
	if (rx > screen_last_x(s))
	rx = screen_last_x(s);

	/*
	* Deleting the range from lx to rx, inclusive.
	*
	* - If rx is not the last x, move the range from rx + 1 to lx.
	* - Clear the range from the last x - (rx - lx) to the last x.
	*/

	if (rx != screen_last_x(s)) {
	nx = screen_range_x(rx + 1, screen_last_x(s));
	memmove(&s->grid_data[py][lx], &s->grid_data[py][rx + 1], nx);
	memmove(&s->grid_attr[py][lx], &s->grid_attr[py][rx + 1], nx);
	memmove(&s->grid_colr[py][lx], &s->grid_colr[py][rx + 1], nx);
	}

	/* If lx == rx, then nx = 1. */
	nx = screen_range_x(lx, rx);
	memset(&s->grid_data[py][s->sx - nx], SCREEN_DEFDATA, nx);
	memset(&s->grid_attr[py][s->sx - nx], SCREEN_DEFATTR, nx);
	memset(&s->grid_colr[py][s->sx - nx], SCREEN_DEFCOLR, nx);
	}