text: /* $OpenBSD$ */
  
  /*
   * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
   *
   * 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 "tmux.h"
  
  /*
   * Grid data. This is the basic data structure that represents what is shown on
   * screen.
   *
   * A grid is a grid of cells (struct grid_cell). Lines are not allocated until
   * cells in that line are written to. The grid is split into history and
   * viewable data with the history starting at row (line) 0 and extending to
   * (hsize - 1); from hsize to hsize + (sy - 1) is the viewable data. All
   * functions in this file work on absolute coordinates, grid-view.c has
   * functions which work on the screen data.
   */
  
  /* Default grid cell data. */
  const struct grid_cell grid_default_cell = {
  	0, 0, 8, 8, { { ' ' }, 0, 1, 1 }
  };
  
  /* Cleared grid cell data. */
  const struct grid_cell grid_cleared_cell = {
  	GRID_FLAG_CLEARED, 0, 8, 8, { { ' ' }, 0, 1, 1 }
  };
  static const struct grid_cell_entry grid_cleared_entry = {
  	GRID_FLAG_CLEARED, { .data = { 0, 8, 8, ' ' } }
  };
  
  static void	grid_empty_line(struct grid *, u_int, u_int);
  
  /* Store cell in entry. */
  static void
  grid_store_cell(struct grid_cell_entry *gce, const struct grid_cell *gc,
      u_char c)
  {
  	gce->flags = (gc->flags & ~GRID_FLAG_CLEARED);
  
  	gce->data.fg = gc->fg & 0xff;
  	if (gc->fg & COLOUR_FLAG_256)
  		gce->flags |= GRID_FLAG_FG256;
  
  	gce->data.bg = gc->bg & 0xff;
  	if (gc->bg & COLOUR_FLAG_256)
  		gce->flags |= GRID_FLAG_BG256;
  
  	gce->data.attr = gc->attr;
  	gce->data.data = c;
  }
  
  /* Check if a cell should be an extended cell. */
  static int
  grid_need_extended_cell(const struct grid_cell_entry *gce,
      const struct grid_cell *gc)
  {
  	if (gce->flags & GRID_FLAG_EXTENDED)
  		return (1);
  	if (gc->attr > 0xff)
  		return (1);
  	if (gc->data.size != 1 || gc->data.width != 1)
  		return (1);
  	if ((gc->fg & COLOUR_FLAG_RGB) || (gc->bg & COLOUR_FLAG_RGB))
  		return (1);
  	return (0);
  }
  
  /* Get an extended cell. */
  static void
  grid_get_extended_cell(struct grid_line *gl, struct grid_cell_entry *gce,
      int flags)
  {
  	u_int at = gl->extdsize + 1;
  
  	gl->extddata = xreallocarray(gl->extddata, at, sizeof *gl->extddata);
  	gl->extdsize = at;
  
  	gce->offset = at - 1;
  	gce->flags = (flags | GRID_FLAG_EXTENDED);
  }
  
  /* Set cell as extended. */
  static struct grid_cell *
  grid_extended_cell(struct grid_line *gl, struct grid_cell_entry *gce,
      const struct grid_cell *gc)
  {
  	struct grid_cell	*gcp;
  	int			 flags = (gc->flags & ~GRID_FLAG_CLEARED);
  
  	if (~gce->flags & GRID_FLAG_EXTENDED)
  		grid_get_extended_cell(gl, gce, flags);
  	else if (gce->offset >= gl->extdsize)
  		fatalx("offset too big");
  	gl->flags |= GRID_LINE_EXTENDED;
  
  	gcp = &gl->extddata[gce->offset];
  	memcpy(gcp, gc, sizeof *gcp);
  	gcp->flags = flags;
  	return (gcp);
  }
  
  /* Free up unused extended cells. */
  static void
  grid_compact_line(struct grid_line *gl)
  {
  	int			 new_extdsize = 0;
  	struct grid_cell	*new_extddata;
  	struct grid_cell_entry	*gce;
  	struct grid_cell	*gc;
  	u_int			 px, idx;
  
  	if (gl->extdsize == 0)
  		return;
  
  	for (px = 0; px < gl->cellsize; px++) {
  		gce = &gl->celldata[px];
  		if (gce->flags & GRID_FLAG_EXTENDED)
  			new_extdsize++;
  	}
  
  	if (new_extdsize == 0) {
  		free(gl->extddata);
  		gl->extddata = NULL;
  		gl->extdsize = 0;
  		return;
  	}
  	new_extddata = xreallocarray(NULL, new_extdsize, sizeof *gl->extddata);
  
  	idx = 0;
  	for (px = 0; px < gl->cellsize; px++) {
  		gce = &gl->celldata[px];
  		if (gce->flags & GRID_FLAG_EXTENDED) {
  			gc = &gl->extddata[gce->offset];
  			memcpy(&new_extddata[idx], gc, sizeof *gc);
  			gce->offset = idx++;
  		}
  	}
  
  	free(gl->extddata);
  	gl->extddata = new_extddata;
  	gl->extdsize = new_extdsize;
  }
  
  /* Get line data. */
  struct grid_line *
  grid_get_line(struct grid *gd, u_int line)
  {
  	return (&gd->linedata[line]);
  }
  
  /* Adjust number of lines. */
  void
  grid_adjust_lines(struct grid *gd, u_int lines)
  {
  	gd->linedata = xreallocarray(gd->linedata, lines, sizeof *gd->linedata);
  }
  
  /* Copy default into a cell. */
  static void
  grid_clear_cell(struct grid *gd, u_int px, u_int py, u_int bg)
  {
  	struct grid_line	*gl = &gd->linedata[py];
  	struct grid_cell_entry	*gce = &gl->celldata[px];
  	struct grid_cell	*gc;
  
  	memcpy(gce, &grid_cleared_entry, sizeof *gce);
  	if (bg & COLOUR_FLAG_RGB) {
  		grid_get_extended_cell(gl, gce, gce->flags);
  		gl->flags |= GRID_LINE_EXTENDED;
  
  		gc = &gl->extddata[gce->offset];
  		memcpy(gc, &grid_cleared_cell, sizeof *gc);
  		gc->bg = bg;
  	} else {
  		if (bg & COLOUR_FLAG_256)
  			gce->flags |= GRID_FLAG_BG256;
  		gce->data.bg = bg;
  	}
  }
  
  /* Check grid y position. */
  static int
  grid_check_y(struct grid *gd, const char* from, u_int py)
  {
  	if (py >= gd->hsize + gd->sy) {
  		log_debug("%s: y out of range: %u", from, py);
  		return (-1);
  	}
  	return (0);
  }
  
  /* Compare grid cells. Return 1 if equal, 0 if not. */
  int
  grid_cells_equal(const struct grid_cell *gca, const struct grid_cell *gcb)
  {
  	if (gca->fg != gcb->fg || gca->bg != gcb->bg)
  		return (0);
  	if (gca->attr != gcb->attr || gca->flags != gcb->flags)
  		return (0);
  	if (gca->data.width != gcb->data.width)
  		return (0);
  	if (gca->data.size != gcb->data.size)
  		return (0);
  	return (memcmp(gca->data.data, gcb->data.data, gca->data.size) == 0);
  }
  
  /* Free one line. */
  static void
  grid_free_line(struct grid *gd, u_int py)
  {
  	free(gd->linedata[py].celldata);
  	gd->linedata[py].celldata = NULL;
  	free(gd->linedata[py].extddata);
  	gd->linedata[py].extddata = NULL;
  }
  
  /* Free several lines. */
  static void
  grid_free_lines(struct grid *gd, u_int py, u_int ny)
  {
  	u_int	yy;
  
  	for (yy = py; yy < py + ny; yy++)
  		grid_free_line(gd, yy);
  }
  
  /* Create a new grid. */
  struct grid *
  grid_create(u_int sx, u_int sy, u_int hlimit)
  {
  	struct grid	*gd;
  
  	gd = xmalloc(sizeof *gd);
  	gd->sx = sx;
  	gd->sy = sy;
  
  	gd->flags = GRID_HISTORY;
  
  	gd->hscrolled = 0;
  	gd->hsize = 0;
  	gd->hlimit = hlimit;
  
  	if (gd->sy != 0)
  		gd->linedata = xcalloc(gd->sy, sizeof *gd->linedata);
  	else
  		gd->linedata = NULL;
  
  	return (gd);
  }
  
  /* Destroy grid. */
  void
  grid_destroy(struct grid *gd)
  {
  	grid_free_lines(gd, 0, gd->hsize + gd->sy);
  
  	free(gd->linedata);
  
  	free(gd);
  }
  
  /* Compare grids. */
  int
  grid_compare(struct grid *ga, struct grid *gb)
  {
  	struct grid_line	*gla, *glb;
  	struct grid_cell	 gca, gcb;
  	u_int			 xx, yy;
  
  	if (ga->sx != gb->sx || ga->sy != gb->sy)
  		return (1);
  
  	for (yy = 0; yy < ga->sy; yy++) {
  		gla = &ga->linedata[yy];
  		glb = &gb->linedata[yy];
  		if (gla->cellsize != glb->cellsize)
  			return (1);
  		for (xx = 0; xx < gla->cellsize; xx++) {
  			grid_get_cell(ga, xx, yy, &gca);
  			grid_get_cell(gb, xx, yy, &gcb);
  			if (!grid_cells_equal(&gca, &gcb))
  				return (1);
  		}
  	}
  
  	return (0);
  }
  
  /* Trim lines from the history. */
  static void
  grid_trim_history(struct grid *gd, u_int ny)
  {
  	grid_free_lines(gd, 0, ny);
  	memmove(&gd->linedata[0], &gd->linedata[ny],
  	    (gd->hsize + gd->sy - ny) * (sizeof *gd->linedata));
  }
  
  /*
   * Collect lines from the history if at the limit. Free the top (oldest) 10%
   * and shift up.
   */
  void
  grid_collect_history(struct grid *gd)
  {
  	u_int	ny;
  
  	if (gd->hsize == 0 || gd->hsize < gd->hlimit)
  		return;
  
  	ny = gd->hlimit / 10;
  	if (ny < 1)
  		ny = 1;
  	if (ny > gd->hsize)
  		ny = gd->hsize;
  
  	/*
  	 * Free the lines from 0 to ny then move the remaining lines over
  	 * them.
  	 */
  	grid_trim_history(gd, ny);
  
  	gd->hsize -= ny;
  	if (gd->hscrolled > gd->hsize)
  		gd->hscrolled = gd->hsize;
  }
  
  /*
   * Scroll the entire visible screen, moving one line into the history. Just
   * allocate a new line at the bottom and move the history size indicator.
   */
  void
  grid_scroll_history(struct grid *gd, u_int bg)
  {
  	u_int	yy;
  
  	yy = gd->hsize + gd->sy;
  	gd->linedata = xreallocarray(gd->linedata, yy + 1,
  	    sizeof *gd->linedata);
  	grid_empty_line(gd, yy, bg);
  
  	gd->hscrolled++;
  	grid_compact_line(&gd->linedata[gd->hsize]);
  	gd->hsize++;
  }
  
  /* Clear the history. */
  void
  grid_clear_history(struct grid *gd)
  {
  	grid_trim_history(gd, gd->hsize);
  
  	gd->hscrolled = 0;
  	gd->hsize = 0;
  
  	gd->linedata = xreallocarray(gd->linedata, gd->sy,
  	    sizeof *gd->linedata);
  }
  
  /* Scroll a region up, moving the top line into the history. */
  void
  grid_scroll_history_region(struct grid *gd, u_int upper, u_int lower, u_int bg)
  {
  	struct grid_line	*gl_history, *gl_upper;
  	u_int			 yy;
  
  	/* Create a space for a new line. */
  	yy = gd->hsize + gd->sy;
  	gd->linedata = xreallocarray(gd->linedata, yy + 1,
  	    sizeof *gd->linedata);
  
  	/* Move the entire screen down to free a space for this line. */
  	gl_history = &gd->linedata[gd->hsize];
  	memmove(gl_history + 1, gl_history, gd->sy * sizeof *gl_history);
  
  	/* Adjust the region and find its start and end. */
  	upper++;
  	gl_upper = &gd->linedata[upper];
  	lower++;
  
  	/* Move the line into the history. */
  	memcpy(gl_history, gl_upper, sizeof *gl_history);
  
  	/* Then move the region up and clear the bottom line. */
  	memmove(gl_upper, gl_upper + 1, (lower - upper) * sizeof *gl_upper);
  	grid_empty_line(gd, lower, bg);
  
  	/* Move the history offset down over the line. */
  	gd->hscrolled++;
  	gd->hsize++;
  }
  
  /* Expand line to fit to cell. */
  static void
  grid_expand_line(struct grid *gd, u_int py, u_int sx, u_int bg)
  {
  	struct grid_line	*gl;
  	u_int			 xx;
  
  	gl = &gd->linedata[py];
  	if (sx <= gl->cellsize)
  		return;
  
  	if (sx < gd->sx / 4)
  		sx = gd->sx / 4;
  	else if (sx < gd->sx / 2)
  		sx = gd->sx / 2;
  	else
  		sx = gd->sx;
  
  	gl->celldata = xreallocarray(gl->celldata, sx, sizeof *gl->celldata);
  	for (xx = gl->cellsize; xx < sx; xx++)
  		grid_clear_cell(gd, xx, py, bg);
  	gl->cellsize = sx;
  }
  
  /* Empty a line and set background colour if needed. */
  static void
  grid_empty_line(struct grid *gd, u_int py, u_int bg)
  {
  	memset(&gd->linedata[py], 0, sizeof gd->linedata[py]);
  	if (!COLOUR_DEFAULT(bg))
  		grid_expand_line(gd, py, gd->sx, bg);
  }
  
  /* Peek at grid line. */
  const struct grid_line *
  grid_peek_line(struct grid *gd, u_int py)
  {
  	if (grid_check_y(gd, __func__, py) != 0)
  		return (NULL);
  	return (&gd->linedata[py]);
  }
  
  /* Get cell from line. */
  static void
  grid_get_cell1(struct grid_line *gl, u_int px, struct grid_cell *gc)
  {
  	struct grid_cell_entry	*gce = &gl->celldata[px];
  
  	if (gce->flags & GRID_FLAG_EXTENDED) {
  		if (gce->offset >= gl->extdsize)
  			memcpy(gc, &grid_default_cell, sizeof *gc);
  		else
  			memcpy(gc, &gl->extddata[gce->offset], sizeof *gc);
  		return;
  	}
  
  	gc->flags = gce->flags & ~(GRID_FLAG_FG256|GRID_FLAG_BG256);
  	gc->attr = gce->data.attr;
  	gc->fg = gce->data.fg;
  	if (gce->flags & GRID_FLAG_FG256)
  		gc->fg |= COLOUR_FLAG_256;
  	gc->bg = gce->data.bg;
  	if (gce->flags & GRID_FLAG_BG256)
  		gc->bg |= COLOUR_FLAG_256;
  	utf8_set(&gc->data, gce->data.data);
  }
  
  /* Get cell for reading. */
  void
  grid_get_cell(struct grid *gd, u_int px, u_int py, struct grid_cell *gc)
  {
  	if (grid_check_y(gd, __func__, py) != 0 ||
  	    px >= gd->linedata[py].cellsize)
  		memcpy(gc, &grid_default_cell, sizeof *gc);
  	else
  		grid_get_cell1(&gd->linedata[py], px, gc);
  }
  
  /* Set cell at relative position. */
  void
  grid_set_cell(struct grid *gd, u_int px, u_int py, const struct grid_cell *gc)
  {
  	struct grid_line	*gl;
  	struct grid_cell_entry	*gce;
  
  	if (grid_check_y(gd, __func__, py) != 0)
  		return;
  
  	grid_expand_line(gd, py, px + 1, 8);
  
  	gl = &gd->linedata[py];
  	if (px + 1 > gl->cellused)
  		gl->cellused = px + 1;
  
  	gce = &gl->celldata[px];
  	if (grid_need_extended_cell(gce, gc))
  		grid_extended_cell(gl, gce, gc);
  	else
  		grid_store_cell(gce, gc, gc->data.data[0]);
  }
  
  /* Set cells at relative position. */
  void
  grid_set_cells(struct grid *gd, u_int px, u_int py, const struct grid_cell *gc,
      const char *s, size_t slen)
  {
  	struct grid_line	*gl;
  	struct grid_cell_entry	*gce;
  	struct grid_cell	*gcp;
  	u_int			 i;
  
  	if (grid_check_y(gd, __func__, py) != 0)
  		return;
  
  	grid_expand_line(gd, py, px + slen, 8);
  
  	gl = &gd->linedata[py];
  	if (px + slen > gl->cellused)
  		gl->cellused = px + slen;
  
  	for (i = 0; i < slen; i++) {
  		gce = &gl->celldata[px + i];
  		if (grid_need_extended_cell(gce, gc)) {
  			gcp = grid_extended_cell(gl, gce, gc);
  			utf8_set(&gcp->data, s[i]);
  		} else
  			grid_store_cell(gce, gc, s[i]);
  	}
  }
  
  /* Clear area. */
  void
  grid_clear(struct grid *gd, u_int px, u_int py, u_int nx, u_int ny, u_int bg)
  {
  	struct grid_line	*gl;
  	u_int			 xx, yy;
  
  	if (nx == 0 || ny == 0)
  		return;
  
  	if (px == 0 && nx == gd->sx) {
  		grid_clear_lines(gd, py, ny, bg);
  		return;
  	}
  
  	if (grid_check_y(gd, __func__, py) != 0)
  		return;
  	if (grid_check_y(gd, __func__, py + ny - 1) != 0)
  		return;
  
  	for (yy = py; yy < py + ny; yy++) {
  		gl = &gd->linedata[yy];
  		if (px + nx >= gd->sx && px < gl->cellused)
  			gl->cellused = px;
  		if (px > gl->cellsize && COLOUR_DEFAULT(bg))
  			continue;
  		if (px + nx >= gl->cellsize && COLOUR_DEFAULT(bg)) {
  			gl->cellsize = px;
  			continue;
  		}
  		grid_expand_line(gd, yy, px + nx, 8); /* default bg first */
  		for (xx = px; xx < px + nx; xx++)
  			grid_clear_cell(gd, xx, yy, bg);
  	}
  }
  
  /* Clear lines. This just frees and truncates the lines. */
  void
  grid_clear_lines(struct grid *gd, u_int py, u_int ny, u_int bg)
  {
  	u_int	yy;
  
  	if (ny == 0)
  		return;
  
  	if (grid_check_y(gd, __func__, py) != 0)
  		return;
  	if (grid_check_y(gd, __func__, py + ny - 1) != 0)
  		return;
  
  	for (yy = py; yy < py + ny; yy++) {
  		grid_free_line(gd, yy);
  		grid_empty_line(gd, yy, bg);
  	}
  }
  
  /* Move a group of lines. */
  void
  grid_move_lines(struct grid *gd, u_int dy, u_int py, u_int ny, u_int bg)
  {
  	u_int	yy;
  
  	if (ny == 0 || py == dy)
  		return;
  
  	if (grid_check_y(gd, __func__, py) != 0)
  		return;
  	if (grid_check_y(gd, __func__, py + ny - 1) != 0)
  		return;
  	if (grid_check_y(gd, __func__, dy) != 0)
  		return;
  	if (grid_check_y(gd, __func__, dy + ny - 1) != 0)
  		return;
  
  	/* Free any lines which are being replaced. */
  	for (yy = dy; yy < dy + ny; yy++) {
  		if (yy >= py && yy < py + ny)
  			continue;
  		grid_free_line(gd, yy);
  	}
  
  	memmove(&gd->linedata[dy], &gd->linedata[py],
  	    ny * (sizeof *gd->linedata));
  
  	/*
  	 * Wipe any lines that have been moved (without freeing them - they are
  	 * still present).
  	 */
  	for (yy = py; yy < py + ny; yy++) {
  		if (yy < dy || yy >= dy + ny)
  			grid_empty_line(gd, yy, bg);
  	}
  }
  
  /* Move a group of cells. */
  void
  grid_move_cells(struct grid *gd, u_int dx, u_int px, u_int py, u_int nx,
      u_int bg)
  {
  	struct grid_line	*gl;
  	u_int			 xx;
  
  	if (nx == 0 || px == dx)
  		return;
  
  	if (grid_check_y(gd, __func__, py) != 0)
  		return;
  	gl = &gd->linedata[py];
  
  	grid_expand_line(gd, py, px + nx, 8);
  	grid_expand_line(gd, py, dx + nx, 8);
  	memmove(&gl->celldata[dx], &gl->celldata[px],
  	    nx * sizeof *gl->celldata);
  	if (dx + nx > gl->cellused)
  		gl->cellused = dx + nx;
  
  	/* Wipe any cells that have been moved. */
  	for (xx = px; xx < px + nx; xx++) {
  		if (xx >= dx && xx < dx + nx)
  			continue;
  		grid_clear_cell(gd, xx, py, bg);
  	}
  }
  
  /* Get ANSI foreground sequence. */
  static size_t
  grid_string_cells_fg(const struct grid_cell *gc, int *values)
  {
  	size_t	n;
  	u_char	r, g, b;
  
  	n = 0;
  	if (gc->fg & COLOUR_FLAG_256) {
  		values[n++] = 38;
  		values[n++] = 5;
  		values[n++] = gc->fg & 0xff;
  	} else if (gc->fg & COLOUR_FLAG_RGB) {
  		values[n++] = 38;
  		values[n++] = 2;
  		colour_split_rgb(gc->fg, &r, &g, &b);
  		values[n++] = r;
  		values[n++] = g;
  		values[n++] = b;
  	} else {
  		switch (gc->fg) {
  		case 0:
  		case 1:
  		case 2:
  		case 3:
  		case 4:
  		case 5:
  		case 6:
  		case 7:
  			values[n++] = gc->fg + 30;
  			break;
  		case 8:
  			values[n++] = 39;
  			break;
  		case 90:
  		case 91:
  		case 92:
  		case 93:
  		case 94:
  		case 95:
  		case 96:
  		case 97:
  			values[n++] = gc->fg;
  			break;
  		}
  	}
  	return (n);
  }
  
  /* Get ANSI background sequence. */
  static size_t
  grid_string_cells_bg(const struct grid_cell *gc, int *values)
  {
  	size_t	n;
  	u_char	r, g, b;
  
  	n = 0;
  	if (gc->bg & COLOUR_FLAG_256) {
  		values[n++] = 48;
  		values[n++] = 5;
  		values[n++] = gc->bg & 0xff;
  	} else if (gc->bg & COLOUR_FLAG_RGB) {
  		values[n++] = 48;
  		values[n++] = 2;
  		colour_split_rgb(gc->bg, &r, &g, &b);
  		values[n++] = r;
  		values[n++] = g;
  		values[n++] = b;
  	} else {
  		switch (gc->bg) {
  		case 0:
  		case 1:
  		case 2:
  		case 3:
  		case 4:
  		case 5:
  		case 6:
  		case 7:
  			values[n++] = gc->bg + 40;
  			break;
  		case 8:
  			values[n++] = 49;
  			break;
  		case 100:
  		case 101:
  		case 102:
  		case 103:
  		case 104:
  		case 105:
  		case 106:
  		case 107:
  			values[n++] = gc->bg - 10;
  			break;
  		}
  	}
  	return (n);
  }
  
  /*
   * Returns ANSI code to set particular attributes (colour, bold and so on)
   * given a current state.
   */
  static void
  grid_string_cells_code(const struct grid_cell *lastgc,
      const struct grid_cell *gc, char *buf, size_t len, int escape_c0)
  {
  	int	oldc[64], newc[64], s[128];
  	size_t	noldc, nnewc, n, i;
  	u_int	attr = gc->attr, lastattr = lastgc->attr;
  	char	tmp[64];
  
  	struct {
  		u_int	mask;
  		u_int	code;
  	} attrs[] = {
  		{ GRID_ATTR_BRIGHT, 1 },
  		{ GRID_ATTR_DIM, 2 },
  		{ GRID_ATTR_ITALICS, 3 },
  		{ GRID_ATTR_UNDERSCORE, 4 },
  		{ GRID_ATTR_BLINK, 5 },
  		{ GRID_ATTR_REVERSE, 7 },
  		{ GRID_ATTR_HIDDEN, 8 },
  		{ GRID_ATTR_STRIKETHROUGH, 9 },
  		{ GRID_ATTR_UNDERSCORE_2, 42 },
  		{ GRID_ATTR_UNDERSCORE_3, 43 },
  		{ GRID_ATTR_UNDERSCORE_4, 44 },
  		{ GRID_ATTR_UNDERSCORE_5, 45 },
  		{ GRID_ATTR_OVERLINE, 53 },
  	};
  	n = 0;
  
  	/* If any attribute is removed, begin with 0. */
  	for (i = 0; i < nitems(attrs); i++) {
  		if (!(attr & attrs[i].mask) && (lastattr & attrs[i].mask)) {
  			s[n++] = 0;
  			lastattr &= GRID_ATTR_CHARSET;
  			break;
  		}
  	}
  	/* For each attribute that is newly set, add its code. */
  	for (i = 0; i < nitems(attrs); i++) {
  		if ((attr & attrs[i].mask) && !(lastattr & attrs[i].mask))
  			s[n++] = attrs[i].code;
  	}
  
  	/* Write the attributes. */
  	*buf = '\0';
  	if (n > 0) {
  		if (escape_c0)
  			strlcat(buf, "\\033[", len);
  		else
  			strlcat(buf, "\033[", len);
  		for (i = 0; i < n; i++) {
  			if (s[i] < 10)
  				xsnprintf(tmp, sizeof tmp, "%d", s[i]);
  			else {
  				xsnprintf(tmp, sizeof tmp, "%d:%d", s[i] / 10,
  				    s[i] % 10);
  			}
  			strlcat(buf, tmp, len);
  			if (i + 1 < n)
  				strlcat(buf, ";", len);
  		}
  		strlcat(buf, "m", len);
  	}
  
  	/* If the foreground colour changed, write its parameters. */
  	nnewc = grid_string_cells_fg(gc, newc);
  	noldc = grid_string_cells_fg(lastgc, oldc);
  	if (nnewc != noldc ||
  	    memcmp(newc, oldc, nnewc * sizeof newc[0]) != 0 ||
  	    (n != 0 && s[0] == 0)) {
  		if (escape_c0)
  			strlcat(buf, "\\033[", len);
  		else
  			strlcat(buf, "\033[", len);
  		for (i = 0; i < nnewc; i++) {
  			if (i + 1 < nnewc)
  				xsnprintf(tmp, sizeof tmp, "%d;", newc[i]);
  			else
  				xsnprintf(tmp, sizeof tmp, "%d", newc[i]);
  			strlcat(buf, tmp, len);
  		}
  		strlcat(buf, "m", len);
  	}
  
  	/* If the background colour changed, append its parameters. */
  	nnewc = grid_string_cells_bg(gc, newc);
  	noldc = grid_string_cells_bg(lastgc, oldc);
  	if (nnewc != noldc ||
  	    memcmp(newc, oldc, nnewc * sizeof newc[0]) != 0 ||
  	    (n != 0 && s[0] == 0)) {
  		if (escape_c0)
  			strlcat(buf, "\\033[", len);
  		else
  			strlcat(buf, "\033[", len);
  		for (i = 0; i < nnewc; i++) {
  			if (i + 1 < nnewc)
  				xsnprintf(tmp, sizeof tmp, "%d;", newc[i]);
  			else
  				xsnprintf(tmp, sizeof tmp, "%d", newc[i]);
  			strlcat(buf, tmp, len);
  		}
  		strlcat(buf, "m", len);
  	}
  
  	/* Append shift in/shift out if needed. */
  	if ((attr & GRID_ATTR_CHARSET) && !(lastattr & GRID_ATTR_CHARSET)) {
  		if (escape_c0)
  			strlcat(buf, "\\016", len); /* SO */
  		else
  			strlcat(buf, "\016", len);  /* SO */
  	}
  	if (!(attr & GRID_ATTR_CHARSET) && (lastattr & GRID_ATTR_CHARSET)) {
  		if (escape_c0)
  			strlcat(buf, "\\017", len); /* SI */
  		else
  			strlcat(buf, "\017", len);  /* SI */
  	}
  }
  
  /* Convert cells into a string. */
  char *
  grid_string_cells(struct grid *gd, u_int px, u_int py, u_int nx,
      struct grid_cell **lastgc, int with_codes, int escape_c0, int trim)
  {
  	struct grid_cell	 gc;
  	static struct grid_cell	 lastgc1;
  	const char		*data;
  	char			*buf, code[128];
  	size_t			 len, off, size, codelen;
  	u_int			 xx;
  	const struct grid_line	*gl;
  
  	if (lastgc != NULL && *lastgc == NULL) {
  		memcpy(&lastgc1, &grid_default_cell, sizeof lastgc1);
  		*lastgc = &lastgc1;
  	}
  
  	len = 128;
  	buf = xmalloc(len);
  	off = 0;
  
  	gl = grid_peek_line(gd, py);
  	for (xx = px; xx < px + nx; xx++) {
  		if (gl == NULL || xx >= gl->cellsize)
  			break;
  		grid_get_cell(gd, xx, py, &gc);
  		if (gc.flags & GRID_FLAG_PADDING)
  			continue;
  
  		if (with_codes) {
  			grid_string_cells_code(*lastgc, &gc, code, sizeof code,
  			    escape_c0);
  			codelen = strlen(code);
  			memcpy(*lastgc, &gc, sizeof **lastgc);
  		} else
  			codelen = 0;
  
  		data = gc.data.data;
  		size = gc.data.size;
  		if (escape_c0 && size == 1 && *data == '\\') {
  			data = "\\\\";
  			size = 2;
  		}
  
  		while (len < off + size + codelen + 1) {
  			buf = xreallocarray(buf, 2, len);
  			len *= 2;
  		}
  
  		if (codelen != 0) {
  			memcpy(buf + off, code, codelen);
  			off += codelen;
  		}
  		memcpy(buf + off, data, size);
  		off += size;
  	}
  
  	if (trim) {
  		while (off > 0 && buf[off - 1] == ' ')
  			off--;
  	}
  	buf[off] = '\0';
  
  	return (buf);
  }
  
  /*
   * Duplicate a set of lines between two grids. Both source and destination
   * should be big enough.
   */
  void
  grid_duplicate_lines(struct grid *dst, u_int dy, struct grid *src, u_int sy,
      u_int ny)
  {
  	struct grid_line	*dstl, *srcl;
  	u_int			 yy;
  
  	if (dy + ny > dst->hsize + dst->sy)
  		ny = dst->hsize + dst->sy - dy;
  	if (sy + ny > src->hsize + src->sy)
  		ny = src->hsize + src->sy - sy;
  	grid_free_lines(dst, dy, ny);
  
  	for (yy = 0; yy < ny; yy++) {
  		srcl = &src->linedata[sy];
  		dstl = &dst->linedata[dy];
  
  		memcpy(dstl, srcl, sizeof *dstl);
  		if (srcl->cellsize != 0) {
  			dstl->celldata = xreallocarray(NULL,
  			    srcl->cellsize, sizeof *dstl->celldata);
  			memcpy(dstl->celldata, srcl->celldata,
  			    srcl->cellsize * sizeof *dstl->celldata);
  		} else
  			dstl->celldata = NULL;
  
  		if (srcl->extdsize != 0) {
  			dstl->extdsize = srcl->extdsize;
  			dstl->extddata = xreallocarray(NULL, dstl->extdsize,
  			    sizeof *dstl->extddata);
  			memcpy(dstl->extddata, srcl->extddata, dstl->extdsize *
  			    sizeof *dstl->extddata);
  		}
  
  		sy++;
  		dy++;
  	}
  }
  
  /* Mark line as dead. */
  static void
  grid_reflow_dead(struct grid_line *gl)
  {
  	memset(gl, 0, sizeof *gl);
  	gl->flags = GRID_LINE_DEAD;
  }
  
  /* Add lines, return the first new one. */
  static struct grid_line *
  grid_reflow_add(struct grid *gd, u_int n)
  {
  	struct grid_line	*gl;
  	u_int			 sy = gd->sy + n;
  
  	gd->linedata = xreallocarray(gd->linedata, sy, sizeof *gd->linedata);
  	gl = &gd->linedata[gd->sy];
  	memset(gl, 0, n * (sizeof *gl));
  	gd->sy = sy;
  	return (gl);
  }
  
  /* Move a line across. */
  static struct grid_line *
  grid_reflow_move(struct grid *gd, struct grid_line *from)
  {
  	struct grid_line	*to;
  
  	to = grid_reflow_add(gd, 1);
  	memcpy(to, from, sizeof *to);
  	grid_reflow_dead(from);
  	return (to);
  }
  
  /* Join line below onto this one. */
  static void
  grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,
      u_int width, int already)
  {
  	struct grid_line	*gl, *from = NULL;
  	struct grid_cell	 gc;
  	u_int			 lines, left, i, to, line, want = 0;
  	u_int			 at;
  	int			 wrapped = 1;
  
  	/*
  	 * Add a new target line.
  	 */
  	if (!already) {
  		to = target->sy;
  		gl = grid_reflow_move(target, &gd->linedata[yy]);
  	} else {
  		to = target->sy - 1;
  		gl = &target->linedata[to];
  	}
  	at = gl->cellused;
  
  	/*
  	 * Loop until no more to consume or the target line is full.
  	 */
  	lines = 0;
  	for (;;) {
  		/*
  		 * If this is now the last line, there is nothing more to be
  		 * done.
  		 */
  		if (yy + 1 + lines == gd->hsize + gd->sy)
  			break;
  		line = yy + 1 + lines;
  
  		/* If the next line is empty, skip it. */
  		if (~gd->linedata[line].flags & GRID_LINE_WRAPPED)
  			wrapped = 0;
  		if (gd->linedata[line].cellused == 0) {
  			if (!wrapped)
  				break;
  			lines++;
  			continue;
  		}
  
  		/*
  		 * Is the destination line now full? Copy the first character
  		 * separately because we need to leave "from" set to the last
  		 * line if this line is full.
  		 */
  		grid_get_cell1(&gd->linedata[line], 0, &gc);
  		if (width + gc.data.width > sx)
  			break;
  		width += gc.data.width;
  		grid_set_cell(target, at, to, &gc);
  		at++;
  
  		/* Join as much more as possible onto the current line. */
  		from = &gd->linedata[line];
  		for (want = 1; want < from->cellused; want++) {
  			grid_get_cell1(from, want, &gc);
  			if (width + gc.data.width > sx)
  				break;
  			width += gc.data.width;
  
  			grid_set_cell(target, at, to, &gc);
  			at++;
  		}
  		lines++;
  
  		/*
  		 * If this line wasn't wrapped or we didn't consume the entire
  		 * line, don't try to join any further lines.
  		 */
  		if (!wrapped || want != from->cellused || width == sx)
  			break;
  	}
  	if (lines == 0)
  		return;
  
  	/*
  	 * If we didn't consume the entire final line, then remove what we did
  	 * consume. If we consumed the entire line and it wasn't wrapped,
  	 * remove the wrap flag from this line.
  	 */
  	left = from->cellused - want;
  	if (left != 0) {
  		grid_move_cells(gd, 0, want, yy + lines, left, 8);
  		from->cellsize = from->cellused = left;
  		lines--;
  	} else if (!wrapped)
  		gl->flags &= ~GRID_LINE_WRAPPED;
  
  	/* Remove the lines that were completely consumed. */
  	for (i = yy + 1; i < yy + 1 + lines; i++) {
  		free(gd->linedata[i].celldata);
  		free(gd->linedata[i].extddata);
  		grid_reflow_dead(&gd->linedata[i]);
  	}
  
  	/* Adjust scroll position. */
  	if (gd->hscrolled > to + lines)
  		gd->hscrolled -= lines;
  	else if (gd->hscrolled > to)
  		gd->hscrolled = to;
  }
  
  /* Split this line into several new ones */
  static void
  grid_reflow_split(struct grid *target, struct grid *gd, u_int sx, u_int yy,
      u_int at)
  {
  	struct grid_line	*gl = &gd->linedata[yy], *first;
  	struct grid_cell	 gc;
  	u_int			 line, lines, width, i, xx;
  	u_int			 used = gl->cellused;
  	int			 flags = gl->flags;
  
  	/* How many lines do we need to insert? We know we need at least two. */
  	if (~gl->flags & GRID_LINE_EXTENDED)
  		lines = 1 + (gl->cellused - 1) / sx;
  	else {
  		lines = 2;
  		width = 0;
  		for (i = at; i < used; i++) {
  			grid_get_cell1(gl, i, &gc);
  			if (width + gc.data.width > sx) {
  				lines++;
  				width = 0;
  			}
  			width += gc.data.width;
  		}
  	}
  
  	/* Insert new lines. */
  	line = target->sy + 1;
  	first = grid_reflow_add(target, lines);
  
  	/* Copy sections from the original line. */
  	width = 0;
  	xx = 0;
  	for (i = at; i < used; i++) {
  		grid_get_cell1(gl, i, &gc);
  		if (width + gc.data.width > sx) {
  			target->linedata[line].flags |= GRID_LINE_WRAPPED;
  
  			line++;
  			width = 0;
  			xx = 0;
  		}
  		width += gc.data.width;
  		grid_set_cell(target, xx, line, &gc);
  		xx++;
  	}
  	if (flags & GRID_LINE_WRAPPED)
  		target->linedata[line].flags |= GRID_LINE_WRAPPED;
  
  	/* Move the remainder of the original line. */
  	gl->cellsize = gl->cellused = at;
  	gl->flags |= GRID_LINE_WRAPPED;
  	memcpy(first, gl, sizeof *first);
  	grid_reflow_dead(gl);
  
  	/* Adjust the scroll position. */
  	if (yy <= gd->hscrolled)
  		gd->hscrolled += lines - 1;
  
  	/*
  	 * If the original line had the wrapped flag and there is still space
  	 * in the last new line, try to join with the next lines.
  	 */
  	if (width < sx && (flags & GRID_LINE_WRAPPED))
  		grid_reflow_join(target, gd, sx, yy, width, 1);
  }
  
  /* Reflow lines on grid to new width. */
  void
  grid_reflow(struct grid *gd, u_int sx)
  {
  	struct grid		*target;
  	struct grid_line	*gl;
  	struct grid_cell	 gc;
  	u_int			 yy, width, i, at, first;
  
  	/*
  	 * Create a destination grid. This is just used as a container for the
  	 * line data and may not be fully valid.
  	 */
  	target = grid_create(gd->sx, 0, 0);
  
  	/*
  	 * Loop over each source line.
  	 */
  	for (yy = 0; yy < gd->hsize + gd->sy; yy++) {
  		gl = &gd->linedata[yy];
  		if (gl->flags & GRID_LINE_DEAD)
  			continue;
  
  		/*
  		 * Work out the width of this line. first is the width of the
  		 * first character, at is the point at which the available
  		 * width is hit, and width is the full line width.
  		 */
  		first = at = width = 0;
  		if (~gl->flags & GRID_LINE_EXTENDED) {
  			first = 1;
  			width = gl->cellused;
  			if (width > sx)
  				at = sx;
  			else
  				at = width;
  		} else {
  			for (i = 0; i < gl->cellused; i++) {
  				grid_get_cell1(gl, i, &gc);
  				if (i == 0)
  					first = gc.data.width;
  				if (at == 0 && width + gc.data.width > sx)
  					at = i;
  				width += gc.data.width;
  			}
  		}
  
  		/*
  		 * If the line is exactly right or the first character is wider
  		 * than the targe width, just move it across unchanged.
  		 */
  		if (width == sx || first > sx) {
  			grid_reflow_move(target, gl);
  			continue;
  		}
  
  		/*
  		 * If the line is too big, it needs to be split, whether or not
  		 * it was previously wrapped.
  		 */
  		if (width > sx) {
  			grid_reflow_split(target, gd, sx, yy, at);
  			continue;
  		}
  
  		/*
  		 * If the line was previously wrapped, join as much as possible
  		 * of the next line.
  		 */
  		if (gl->flags & GRID_LINE_WRAPPED)
  			grid_reflow_join(target, gd, sx, yy, width, 0);
  		else
  			grid_reflow_move(target, gl);
  	}
  
  	/*
  	 * Replace the old grid with the new.
  	 */
  	if (target->sy < gd->sy)
  		grid_reflow_add(target, gd->sy - target->sy);
  	gd->hsize = target->sy - gd->sy;
  	if (gd->hscrolled > gd->hsize)
  		gd->hscrolled = gd->hsize;
  	free(gd->linedata);
  	gd->linedata = target->linedata;
  	free(target);
  }
  
  /* Convert to position based on wrapped lines. */
  void
  grid_wrap_position(struct grid *gd, u_int px, u_int py, u_int *wx, u_int *wy)
  {
  	u_int	ax = 0, ay = 0, yy;
  
  	for (yy = 0; yy < py; yy++) {
  		if (gd->linedata[yy].flags & GRID_LINE_WRAPPED)
  			ax += gd->linedata[yy].cellused;
  		else {
  			ax = 0;
  			ay++;
  		}
  	}
  	if (px >= gd->linedata[yy].cellused)
  		ax = UINT_MAX;
  	else
  		ax += px;
  	*wx = ax;
  	*wy = ay;
  }
  
  /* Convert position based on wrapped lines back. */
  void
  grid_unwrap_position(struct grid *gd, u_int *px, u_int *py, u_int wx, u_int wy)
  {
  	u_int	yy, ax = 0, ay = 0;
  
  	for (yy = 0; yy < gd->hsize + gd->sy - 1; yy++) {
  		if (ay == wy)
  			break;
  		if (gd->linedata[yy].flags & GRID_LINE_WRAPPED)
  			ax += gd->linedata[yy].cellused;
  		else {
  			ax = 0;
  			ay++;
  		}
  	}
  
  	/*
  	 * yy is now 0 on the unwrapped line which contains wx. Walk forwards
  	 * until we find the end or the line now containing wx.
  	 */
  	if (wx == UINT_MAX) {
  		while (gd->linedata[yy].flags & GRID_LINE_WRAPPED)
  			yy++;
  		wx = gd->linedata[yy].cellused;
  	} else {
  		while (gd->linedata[yy].flags & GRID_LINE_WRAPPED) {
  			if (wx < gd->linedata[yy].cellused)
  				break;
  			wx -= gd->linedata[yy].cellused;
  			yy++;
  		}
  	}
  	*px = wx;
  	*py = yy;
  }
  
  /* Get length of line. */
  u_int
  grid_line_length(struct grid *gd, u_int py)
  {
  	struct grid_cell	gc;
  	u_int			px;
  
  	px = grid_get_line(gd, py)->cellsize;
  	if (px > gd->sx)
  		px = gd->sx;
  	while (px > 0) {
  		grid_get_cell(gd, px - 1, py, &gc);
  		if (gc.data.size != 1 || *gc.data.data != ' ')
  			break;
  		px--;
  	}
  	return (px);
  }
  