screen.c - tmux - Rivoreo Source Code Repositories

 /* $Id: screen.c,v 1.63 2008-06-29 07:04:30 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.
  *
  * A screen is stored as three arrays of lines of 8-bit values, one for the
  * actual characters (data), one for attributes and one for colours. Three
  * seperate blocks means memset and friends can be used. Each array is y by x
  * in size, row then column order. Sizes are 0-based. There is an additional
  * array of u_ints with the size of each line.
  *
  * Each screen has a history starting at the beginning of the arrays and
  * extending for hsize lines. Beyond that is the screen display of size
  * dy:
  *
  * ----------- array base
  * |         |
  * | history |
  * ----------- array base + hsize
  * |         |
  * | display |
  * |         |
  * ----------- array base + hsize + dy
  *
  * The screen_x/screen_y macros are used to convert a cell on the displayed
  * area to an absolute position in the arrays.
  *
  * Screen handling code is split into four files:
  *
  *	screen.c: Creation/deletion, utility functions, and basic functions to
  *		  manipulate the screen based on offsets from the base.
  *	screen-display.c: Basic functions for manipulating the displayed
  *			  part of the screen. x,y coordinates passed to these
  *			  are relative to the display. These are largely
  *			  utility functions for screen-write.c.
  *	screen-redraw.c: Functions for redrawing all or part of a screen to
  *			 one or more ttys. A context is filled via one of the
  *			 screen_redraw_start* variants which sets up (removes
  *			 cursor etc) and figures out which tty_write_* function
  *			 to use to write to the terminals, then the other
  *			 screen_redraw_* functions are used to draw the screen,
  *			 and screen_redraw_stop used to reset the cursor and
  *			 clean up. These are used when changing window and a
  *			 few other bits (status line).
  * 	screen-write.c: Functions for modifying (writing into) the screen and
  *			optionally simultaneously updating one or more ttys.
  *			These are used in much the same way as the redraw
  *			functions. These are used to update when parsing
  *			input from the window (input.c) and for the various
  *			other modes which maintain private screens.
  *
  * If you're thinking this all seems too complicated, that's because it is :-/.
  */

 /* Colour to string. */
 const char *
 screen_colourstring(u_char c)
 {
 	switch (c) {
 	case 0:
 		return ("black");
 	case 1:
 		return ("red");
 	case 2:
 		return ("green");
 	case 3:
 		return ("yellow");
 	case 4:
 		return ("blue");
 	case 5:
 		return ("magenta");
 	case 6:
 		return ("cyan");
 	case 7:
 		return ("white");
 	case 8:
 		return ("default");
 	}
 	return (NULL);
 }

 /* String to colour. */
 u_char
 screen_stringcolour(const char *s)
 {
 	if (strcasecmp(s, "black") == 0 || (s[0] == '0' && s[1] == '\0'))
 		return (0);
 	if (strcasecmp(s, "red") == 0 || (s[0] == '1' && s[1] == '\0'))
 		return (1);
 	if (strcasecmp(s, "green") == 0 || (s[0] == '2' && s[1] == '\0'))
 		return (2);
 	if (strcasecmp(s, "yellow") == 0 || (s[0] == '3' && s[1] == '\0'))
 		return (3);
 	if (strcasecmp(s, "blue") == 0 || (s[0] == '4' && s[1] == '\0'))
 		return (4);
 	if (strcasecmp(s, "magenta") == 0 || (s[0] == '5' && s[1] == '\0'))
 		return (5);
 	if (strcasecmp(s, "cyan") == 0 || (s[0] == '6' && s[1] == '\0'))
 		return (6);
 	if (strcasecmp(s, "white") == 0 || (s[0] == '7' && s[1] == '\0'))
 		return (7);
 	if (strcasecmp(s, "default") == 0 || (s[0] == '8' && s[1] == '\0'))
 		return (8);
 	return (255);
 }

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

 	s->rupper = 0;
 	s->rlower = s->dy - 1;

 	s->hsize = 0;
 	s->hlimit = hlimit;

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

 	s->mode = MODE_CURSOR|MODE_KCURSOR|MODE_KKEYPAD;
 	s->title = xstrdup("");

 	s->grid_data = xmalloc(dy * (sizeof *s->grid_data));
 	s->grid_attr = xmalloc(dy * (sizeof *s->grid_attr));
 	s->grid_colr = xmalloc(dy * (sizeof *s->grid_colr));
 	s->grid_size = xmalloc(dy * (sizeof *s->grid_size));
 	screen_make_lines(s, 0, dy);

 	screen_clear_selection(s);
 }

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

 	s->rupper = 0;
 	s->rlower = s->dy - 1;

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

 	s->mode = MODE_CURSOR|MODE_KCURSOR|MODE_KKEYPAD;

 	screen_display_fill_area(s, 0, 0,
 	    screen_size_x(s), screen_size_y(s), ' ', 0, 0x88);

 	screen_clear_selection(s);
 }

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

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

 	ox = s->dx;
 	oy = s->dy;
 	if (sx == ox && sy == oy)
 		return;

 	/*
 	 * X dimension.
 	 */
 	if (sx != ox) {
 		/*
 		 * If getting smaller, nuke any data in lines over the new
 		 * size.
 		 */
 		if (sx < ox) {
 			for (i = s->hsize; i < s->hsize + oy; i++) {
 				if (s->grid_size[i] > sx)
 					screen_reduce_line(s, i, sx);
 			}
 		}

 		if (s->cx >= sx)
 			s->cx = sx - 1;
 		s->dx = sx;
 	}

 	/*
 	 * Y dimension.
 	 */
 	if (sy == oy)
 		return;

 	/* Size decreasing. */
 	if (sy < oy) {
  		ny = oy - sy;
 		if (s->cy != 0) {
 			/*
 			 * The cursor is not at the start. Try to remove as
 			 * many lines as possible from the top. (Up to the
 			 * cursor line.)
 			 */
 			my = s->cy;
 			if (my > ny)
 				my = ny;

 			screen_free_lines(s, s->hsize, my);
 			screen_move_lines(s, s->hsize, s->hsize + my, oy - my);

 			s->cy -= my;
 			oy -= my;
 		}

  		ny = oy - sy;
 		if (ny > 0) {
 			/*
 			 * Remove any remaining lines from the bottom.
 			 */
 			screen_free_lines(s, s->hsize + oy - ny, ny);
 			if (s->cy >= sy)
 				s->cy = sy - 1;
 		}
 	}

 	/* Resize line arrays. */
 	ny = s->hsize + sy;
 	s->grid_data = xrealloc(s->grid_data, ny, sizeof *s->grid_data);
 	s->grid_attr = xrealloc(s->grid_attr, ny, sizeof *s->grid_attr);
 	s->grid_colr = xrealloc(s->grid_colr, ny, sizeof *s->grid_colr);
 	s->grid_size = xrealloc(s->grid_size, ny, sizeof *s->grid_size);
 	s->dy = sy;

 	/* Size increasing. */
 	if (sy > oy)
 		screen_make_lines(s, s->hsize + oy, sy - oy);

 	s->rupper = 0;
 	s->rlower = s->dy - 1;
 }

 /* Expand line. */
 void
 screen_expand_line(struct screen *s, u_int py, u_int nx)
 {
 	u_int	ox;

 	ox = s->grid_size[py];
 	s->grid_size[py] = nx;

 	s->grid_data[py] = xrealloc(s->grid_data[py], 1, nx);
 	memset(&s->grid_data[py][ox], SCREEN_DEFDATA, nx - ox);
 	s->grid_attr[py] = xrealloc(s->grid_attr[py], 1, nx);
 	memset(&s->grid_attr[py][ox], SCREEN_DEFATTR, nx - ox);
 	s->grid_colr[py] = xrealloc(s->grid_colr[py], 1, nx);
 	memset(&s->grid_colr[py][ox], SCREEN_DEFCOLR, nx - ox);
 }

 /* Reduce line. */
 void
 screen_reduce_line(struct screen *s, u_int py, u_int nx)
 {
 	s->grid_size[py] = nx;

 	s->grid_data[py] = xrealloc(s->grid_data[py], 1, nx);
 	s->grid_attr[py] = xrealloc(s->grid_attr[py], 1, nx);
 	s->grid_colr[py] = xrealloc(s->grid_colr[py], 1, nx);
 }

 /* Get cell. */
 void
 screen_get_cell(struct screen *s,
     u_int cx, u_int cy, u_char *data, u_char *attr, u_char *colr)
 {
 	if (cx >= s->grid_size[cy]) {
 		*data = SCREEN_DEFDATA;
 		*attr = SCREEN_DEFATTR;
 		*colr = SCREEN_DEFCOLR;
 	} else {
 		*data = s->grid_data[cy][cx];
 		*attr = s->grid_attr[cy][cx];
 		*colr = s->grid_colr[cy][cx];
 	}

 	if (screen_check_selection(s, cx, cy))
 		*attr |= ATTR_REVERSE;
 }

 /* Set a cell. */
 void
 screen_set_cell(struct screen *s,
     u_int cx, u_int cy, u_char data, u_char attr, u_char colr)
 {
 	if (cx >= s->grid_size[cy])
 		screen_expand_line(s, cy, cx + 1);

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

 /* Destroy a screen. */
 void
 screen_destroy(struct screen *s)
 {
 	xfree(s->title);
 	screen_free_lines(s, 0, s->dy + s->hsize);
 	xfree(s->grid_data);
 	xfree(s->grid_attr);
 	xfree(s->grid_colr);
 	xfree(s->grid_size);
 }

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

 	for (i = py; i < py + ny; i++) {
 		s->grid_data[i] = NULL;
 		s->grid_attr[i] = NULL;
 		s->grid_colr[i] = NULL;
 		s->grid_size[i] = 0;
 	}
 }

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

 	for (i = py; i < py + ny; i++) {
 		if (s->grid_data[i] != NULL)
 			xfree(s->grid_data[i]);
 		s->grid_data[i] = NULL;
 		if (s->grid_attr[i] != NULL)
 			xfree(s->grid_attr[i]);
 		s->grid_attr[i] = NULL;
 		if (s->grid_colr[i] != NULL)
 			xfree(s->grid_colr[i]);
 		s->grid_colr[i] = NULL;
 		s->grid_size[i] = 0;
 	}
 }

 /* Move a range of lines. */
 void
 screen_move_lines(struct screen *s, u_int dy, u_int py, u_int ny)
 {
 	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));
 	memmove(
 	    &s->grid_size[dy], &s->grid_size[py], ny * (sizeof *s->grid_size));
 }

 /* Fill an area. */
 void
 screen_fill_area(struct screen *s, u_int px, u_int py,
     u_int nx, u_int ny, u_char data, u_char attr, u_char colr)
 {
 	u_int	i, j;

 	for (i = py; i < py + ny; i++) {
 		for (j = px; j < px + nx; j++)
 			screen_set_cell(s, j, i, data, attr, colr);
 	}
 }

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

 	sel->flag = 1;
 	if (ey < sy || (sy == ey && ex < sx)) {
 		sel->sx = ex; sel->sy = ey;
 		sel->ex = sx; sel->ey = sy;
 	} else {
 		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 || py < sel->sy || py > sel->ey)
 		return (0);

 	if (py == sel->sy && py == sel->ey) {
 		if (px < sel->sx || px > sel->ex)
 			return (0);
 		return (1);
 	}

 	if ((py == sel->sy && px < sel->sx) || (py == sel->ey && px > sel->ex))
 		return (0);
 	return (1);
 }
	/* $Id: screen.c,v 1.63 2008-06-29 07:04:30 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.
	*
	* A screen is stored as three arrays of lines of 8-bit values, one for the
	* actual characters (data), one for attributes and one for colours. Three
	* seperate blocks means memset and friends can be used. Each array is y by x
	* in size, row then column order. Sizes are 0-based. There is an additional
	* array of u_ints with the size of each line.
	*
	* Each screen has a history starting at the beginning of the arrays and
	* extending for hsize lines. Beyond that is the screen display of size
	* dy:
	*
	* ----------- array base
	* \| \|
	* \| history \|
	* ----------- array base + hsize
	* \| \|
	* \| display \|
	* \| \|
	* ----------- array base + hsize + dy
	*
	* The screen_x/screen_y macros are used to convert a cell on the displayed
	* area to an absolute position in the arrays.
	*
	* Screen handling code is split into four files:
	*
	* screen.c: Creation/deletion, utility functions, and basic functions to
	* manipulate the screen based on offsets from the base.
	* screen-display.c: Basic functions for manipulating the displayed
	* part of the screen. x,y coordinates passed to these
	* are relative to the display. These are largely
	* utility functions for screen-write.c.
	* screen-redraw.c: Functions for redrawing all or part of a screen to
	* one or more ttys. A context is filled via one of the
	* screen_redraw_start* variants which sets up (removes
	* cursor etc) and figures out which tty_write_* function
	* to use to write to the terminals, then the other
	* screen_redraw_* functions are used to draw the screen,
	* and screen_redraw_stop used to reset the cursor and
	* clean up. These are used when changing window and a
	* few other bits (status line).
	* screen-write.c: Functions for modifying (writing into) the screen and
	* optionally simultaneously updating one or more ttys.
	* These are used in much the same way as the redraw
	* functions. These are used to update when parsing
	* input from the window (input.c) and for the various
	* other modes which maintain private screens.
	*
	* If you're thinking this all seems too complicated, that's because it is :-/.
	*/

	/* Colour to string. */
	const char *
	screen_colourstring(u_char c)
	{
	switch (c) {
	case 0:
	return ("black");
	case 1:
	return ("red");
	case 2:
	return ("green");
	case 3:
	return ("yellow");
	case 4:
	return ("blue");
	case 5:
	return ("magenta");
	case 6:
	return ("cyan");
	case 7:
	return ("white");
	case 8:
	return ("default");
	}
	return (NULL);
	}

	/* String to colour. */
	u_char
	screen_stringcolour(const char *s)
	{
	if (strcasecmp(s, "black") == 0 \|\| (s[0] == '0' && s[1] == '\0'))
	return (0);
	if (strcasecmp(s, "red") == 0 \|\| (s[0] == '1' && s[1] == '\0'))
	return (1);
	if (strcasecmp(s, "green") == 0 \|\| (s[0] == '2' && s[1] == '\0'))
	return (2);
	if (strcasecmp(s, "yellow") == 0 \|\| (s[0] == '3' && s[1] == '\0'))
	return (3);
	if (strcasecmp(s, "blue") == 0 \|\| (s[0] == '4' && s[1] == '\0'))
	return (4);
	if (strcasecmp(s, "magenta") == 0 \|\| (s[0] == '5' && s[1] == '\0'))
	return (5);
	if (strcasecmp(s, "cyan") == 0 \|\| (s[0] == '6' && s[1] == '\0'))
	return (6);
	if (strcasecmp(s, "white") == 0 \|\| (s[0] == '7' && s[1] == '\0'))
	return (7);
	if (strcasecmp(s, "default") == 0 \|\| (s[0] == '8' && s[1] == '\0'))
	return (8);
	return (255);
	}

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

	s->rupper = 0;
	s->rlower = s->dy - 1;

	s->hsize = 0;
	s->hlimit = hlimit;

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

	s->mode = MODE_CURSOR\|MODE_KCURSOR\|MODE_KKEYPAD;
	s->title = xstrdup("");

	s->grid_data = xmalloc(dy * (sizeof *s->grid_data));
	s->grid_attr = xmalloc(dy * (sizeof *s->grid_attr));
	s->grid_colr = xmalloc(dy * (sizeof *s->grid_colr));
	s->grid_size = xmalloc(dy * (sizeof *s->grid_size));
	screen_make_lines(s, 0, dy);

	screen_clear_selection(s);
	}

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

	s->rupper = 0;
	s->rlower = s->dy - 1;

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

	s->mode = MODE_CURSOR\|MODE_KCURSOR\|MODE_KKEYPAD;

	screen_display_fill_area(s, 0, 0,
	screen_size_x(s), screen_size_y(s), ' ', 0, 0x88);

	screen_clear_selection(s);
	}

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

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

	ox = s->dx;
	oy = s->dy;
	if (sx == ox && sy == oy)
	return;

	/*
	* X dimension.
	*/
	if (sx != ox) {
	/*
	* If getting smaller, nuke any data in lines over the new
	* size.
	*/
	if (sx < ox) {
	for (i = s->hsize; i < s->hsize + oy; i++) {
	if (s->grid_size[i] > sx)
	screen_reduce_line(s, i, sx);
	}
	}

	if (s->cx >= sx)
	s->cx = sx - 1;
	s->dx = sx;
	}

	/*
	* Y dimension.
	*/
	if (sy == oy)
	return;

	/* Size decreasing. */
	if (sy < oy) {
	ny = oy - sy;
	if (s->cy != 0) {
	/*
	* The cursor is not at the start. Try to remove as
	* many lines as possible from the top. (Up to the
	* cursor line.)
	*/
	my = s->cy;
	if (my > ny)
	my = ny;

	screen_free_lines(s, s->hsize, my);
	screen_move_lines(s, s->hsize, s->hsize + my, oy - my);

	s->cy -= my;
	oy -= my;
	}

	ny = oy - sy;
	if (ny > 0) {
	/*
	* Remove any remaining lines from the bottom.
	*/
	screen_free_lines(s, s->hsize + oy - ny, ny);
	if (s->cy >= sy)
	s->cy = sy - 1;
	}
	}

	/* Resize line arrays. */
	ny = s->hsize + sy;
	s->grid_data = xrealloc(s->grid_data, ny, sizeof *s->grid_data);
	s->grid_attr = xrealloc(s->grid_attr, ny, sizeof *s->grid_attr);
	s->grid_colr = xrealloc(s->grid_colr, ny, sizeof *s->grid_colr);
	s->grid_size = xrealloc(s->grid_size, ny, sizeof *s->grid_size);
	s->dy = sy;

	/* Size increasing. */
	if (sy > oy)
	screen_make_lines(s, s->hsize + oy, sy - oy);

	s->rupper = 0;
	s->rlower = s->dy - 1;
	}

	/* Expand line. */
	void
	screen_expand_line(struct screen *s, u_int py, u_int nx)
	{
	u_int ox;

	ox = s->grid_size[py];
	s->grid_size[py] = nx;

	s->grid_data[py] = xrealloc(s->grid_data[py], 1, nx);
	memset(&s->grid_data[py][ox], SCREEN_DEFDATA, nx - ox);
	s->grid_attr[py] = xrealloc(s->grid_attr[py], 1, nx);
	memset(&s->grid_attr[py][ox], SCREEN_DEFATTR, nx - ox);
	s->grid_colr[py] = xrealloc(s->grid_colr[py], 1, nx);
	memset(&s->grid_colr[py][ox], SCREEN_DEFCOLR, nx - ox);
	}

	/* Reduce line. */
	void
	screen_reduce_line(struct screen *s, u_int py, u_int nx)
	{
	s->grid_size[py] = nx;

	s->grid_data[py] = xrealloc(s->grid_data[py], 1, nx);
	s->grid_attr[py] = xrealloc(s->grid_attr[py], 1, nx);
	s->grid_colr[py] = xrealloc(s->grid_colr[py], 1, nx);
	}

	/* Get cell. */
	void
	screen_get_cell(struct screen *s,
	u_int cx, u_int cy, u_char data, u_char attr, u_char *colr)
	{
	if (cx >= s->grid_size[cy]) {
	*data = SCREEN_DEFDATA;
	*attr = SCREEN_DEFATTR;
	*colr = SCREEN_DEFCOLR;
	} else {
	*data = s->grid_data[cy][cx];
	*attr = s->grid_attr[cy][cx];
	*colr = s->grid_colr[cy][cx];
	}

	if (screen_check_selection(s, cx, cy))
	*attr \|= ATTR_REVERSE;
	}

	/* Set a cell. */
	void
	screen_set_cell(struct screen *s,
	u_int cx, u_int cy, u_char data, u_char attr, u_char colr)
	{
	if (cx >= s->grid_size[cy])
	screen_expand_line(s, cy, cx + 1);

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

	/* Destroy a screen. */
	void
	screen_destroy(struct screen *s)
	{
	xfree(s->title);
	screen_free_lines(s, 0, s->dy + s->hsize);
	xfree(s->grid_data);
	xfree(s->grid_attr);
	xfree(s->grid_colr);
	xfree(s->grid_size);
	}

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

	for (i = py; i < py + ny; i++) {
	s->grid_data[i] = NULL;
	s->grid_attr[i] = NULL;
	s->grid_colr[i] = NULL;
	s->grid_size[i] = 0;
	}
	}

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

	for (i = py; i < py + ny; i++) {
	if (s->grid_data[i] != NULL)
	xfree(s->grid_data[i]);
	s->grid_data[i] = NULL;
	if (s->grid_attr[i] != NULL)
	xfree(s->grid_attr[i]);
	s->grid_attr[i] = NULL;
	if (s->grid_colr[i] != NULL)
	xfree(s->grid_colr[i]);
	s->grid_colr[i] = NULL;
	s->grid_size[i] = 0;
	}
	}

	/* Move a range of lines. */
	void
	screen_move_lines(struct screen *s, u_int dy, u_int py, u_int ny)
	{
	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));
	memmove(
	&s->grid_size[dy], &s->grid_size[py], ny * (sizeof *s->grid_size));
	}

	/* Fill an area. */
	void
	screen_fill_area(struct screen *s, u_int px, u_int py,
	u_int nx, u_int ny, u_char data, u_char attr, u_char colr)
	{
	u_int i, j;

	for (i = py; i < py + ny; i++) {
	for (j = px; j < px + nx; j++)
	screen_set_cell(s, j, i, data, attr, colr);
	}
	}

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

	sel->flag = 1;
	if (ey < sy \|\| (sy == ey && ex < sx)) {
	sel->sx = ex; sel->sy = ey;
	sel->ex = sx; sel->ey = sy;
	} else {
	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 \|\| py < sel->sy \|\| py > sel->ey)
	return (0);

	if (py == sel->sy && py == sel->ey) {
	if (px < sel->sx \|\| px > sel->ex)
	return (0);
	return (1);
	}

	if ((py == sel->sy && px < sel->sx) \|\| (py == sel->ey && px > sel->ex))
	return (0);
	return (1);
	}