/* $OpenBSD$ */

/*
 * Copyright (c) 2007 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"

static void	screen_redraw_draw_borders(struct screen_redraw_ctx *);
static void	screen_redraw_draw_panes(struct screen_redraw_ctx *);
static void	screen_redraw_draw_status(struct screen_redraw_ctx *);
static void	screen_redraw_draw_pane(struct screen_redraw_ctx *,
		    struct window_pane *);
static void	screen_redraw_set_context(struct client *,
		    struct screen_redraw_ctx *);
static void	screen_redraw_draw_pane_scrollbars(struct screen_redraw_ctx *);
static void	screen_redraw_draw_scrollbar(struct screen_redraw_ctx *,
		    struct window_pane *, int, int, int, u_int, u_int, u_int);
static void	screen_redraw_draw_pane_scrollbar(struct screen_redraw_ctx *,
		    struct window_pane *);

#define START_ISOLATE "\342\201\246"
#define END_ISOLATE   "\342\201\251"

/* Border in relation to a pane. */
enum screen_redraw_border_type {
	SCREEN_REDRAW_OUTSIDE,
	SCREEN_REDRAW_INSIDE,
	SCREEN_REDRAW_BORDER_LEFT,
	SCREEN_REDRAW_BORDER_RIGHT,
	SCREEN_REDRAW_BORDER_TOP,
	SCREEN_REDRAW_BORDER_BOTTOM
};
#define BORDER_MARKERS "  +,.-"

/* Get cell border character. */
static void
screen_redraw_border_set(struct window *w, struct window_pane *wp,
    enum pane_lines pane_lines, int cell_type, struct grid_cell *gc)
{
	u_int	idx;

	if (cell_type == CELL_OUTSIDE && w->fill_character != NULL) {
		utf8_copy(&gc->data, &w->fill_character[0]);
		return;
	}

	switch (pane_lines) {
	case PANE_LINES_NUMBER:
		if (cell_type == CELL_OUTSIDE) {
			gc->attr |= GRID_ATTR_CHARSET;
			utf8_set(&gc->data, CELL_BORDERS[CELL_OUTSIDE]);
			break;
		}
		gc->attr &= ~GRID_ATTR_CHARSET;
		if (wp != NULL && window_pane_index(wp, &idx) == 0)
			utf8_set(&gc->data, '0' + (idx % 10));
		else
			utf8_set(&gc->data, '*');
		break;
	case PANE_LINES_DOUBLE:
		gc->attr &= ~GRID_ATTR_CHARSET;
		utf8_copy(&gc->data, tty_acs_double_borders(cell_type));
		break;
	case PANE_LINES_HEAVY:
		gc->attr &= ~GRID_ATTR_CHARSET;
		utf8_copy(&gc->data, tty_acs_heavy_borders(cell_type));
		break;
	case PANE_LINES_SIMPLE:
		gc->attr &= ~GRID_ATTR_CHARSET;
		utf8_set(&gc->data, SIMPLE_BORDERS[cell_type]);
		break;
	case PANE_LINES_SPACES:
		gc->attr &= ~GRID_ATTR_CHARSET;
		utf8_set(&gc->data, ' ');
		break;
	default:
		gc->attr |= GRID_ATTR_CHARSET;
		utf8_set(&gc->data, CELL_BORDERS[cell_type]);
		break;
	}
}

/* Return 1 if window has only two panes. */
static int
screen_redraw_two_panes(struct window *w, enum layout_type *type)
{
	struct window_pane	*wp;
	u_int			 count = 0;

	TAILQ_FOREACH(wp, &w->panes, entry) {
		if (wp->flags & PANE_FLOATING || wp->layout_cell == NULL)
			continue;
		count++;
		if (count > 2 || wp->layout_cell->parent == NULL)
			return (0);
		*type = wp->layout_cell->parent->type;
	}
	if (count <= 1)
		return (0);
	return (1);
}

/* Check if cell is on the border of a pane. */
static enum screen_redraw_border_type
screen_redraw_pane_border(struct screen_redraw_ctx *ctx, struct window_pane *wp,
    int px, int py)
{
	struct options	*oo = wp->window->options;
	int		 ex = wp->xoff + wp->sx, ey = wp->yoff + wp->sy;
	int		 hsplit = 0, vsplit = 0, pane_status = ctx->pane_status;
	int		 pane_scrollbars = ctx->pane_scrollbars, sb_w = 0;
	int		 sb_pos, sx = wp->sx, sy = wp->sy;
	enum layout_type split_type;

	if (pane_scrollbars != 0)
		sb_pos = ctx->pane_scrollbars_pos;
	else
		sb_pos = 0;

	/* Inside pane. */
	if (px >= wp->xoff && px < ex && py >= wp->yoff && py < ey)
		return (SCREEN_REDRAW_INSIDE);

	/* Are scrollbars enabled? */
	if (window_pane_show_scrollbar(wp, pane_scrollbars))
		sb_w = wp->scrollbar_style.width + wp->scrollbar_style.pad;

	/* Floating pane borders. */
	if (wp->flags & PANE_FLOATING) {
		if (py >= wp->yoff - 1 && py <= wp->yoff + sy) {
			if (sb_pos == PANE_SCROLLBARS_LEFT) {
				if (px == wp->xoff - 1 - sb_w)
					return (SCREEN_REDRAW_BORDER_LEFT);
				if (px == wp->xoff + sx)
					return (SCREEN_REDRAW_BORDER_RIGHT);
			} else { /* PANE_SCROLLBARS_RIGHT or none. */
				if (px == wp->xoff - 1)
					return (SCREEN_REDRAW_BORDER_LEFT);
				if (px == wp->xoff + sx + sb_w)
					return (SCREEN_REDRAW_BORDER_RIGHT);
			}
		}
		if (px >= wp->xoff && px <= wp->xoff + sx) {
			if (py == wp->yoff - 1)
				return (SCREEN_REDRAW_BORDER_TOP);
			if (py == wp->yoff + sy)
				return (SCREEN_REDRAW_BORDER_BOTTOM);
		}
		return (SCREEN_REDRAW_OUTSIDE);
	}

	/* Get pane indicator. */
	switch (options_get_number(oo, "pane-border-indicators")) {
	case PANE_BORDER_COLOUR:
	case PANE_BORDER_BOTH:
		if (screen_redraw_two_panes(wp->window, &split_type)) {
			hsplit = (split_type == LAYOUT_LEFTRIGHT);
			vsplit = (split_type == LAYOUT_TOPBOTTOM);
		}
		break;
	}

	/*
	 * Left/right borders. The sy / 2 test is to colour only half the
	 * active window's border when there are two panes.
	 */
	if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
		if (sb_pos == PANE_SCROLLBARS_LEFT) {
			if (wp->xoff - sb_w == 0 && px == sx + sb_w) {
				if (!hsplit || (hsplit && py <= sy / 2))
					return (SCREEN_REDRAW_BORDER_RIGHT);
			}
			if (wp->xoff - sb_w != 0) {
				if (px == wp->xoff - sb_w - 1 &&
				    (!hsplit || (hsplit && py > sy / 2)))
					return (SCREEN_REDRAW_BORDER_LEFT);
				if (px == wp->xoff + sx + sb_w - 1)
					return (SCREEN_REDRAW_BORDER_RIGHT);
			}
		} else { /* sb_pos == PANE_SCROLLBARS_RIGHT or disabled */
			if (wp->xoff == 0 && px == sx + sb_w) {
				if (!hsplit || (hsplit && py <= sy / 2))
					return (SCREEN_REDRAW_BORDER_RIGHT);
			}
			if (wp->xoff != 0) {
				if (px == wp->xoff - 1 &&
				    (!hsplit || (hsplit && py > sy / 2)))
					return (SCREEN_REDRAW_BORDER_LEFT);
				if (px == wp->xoff + sx + sb_w)
					return (SCREEN_REDRAW_BORDER_RIGHT);
			}
		}
	}

	/* Top/bottom borders. */
	if (vsplit && pane_status == PANE_STATUS_OFF && sb_w == 0) {
		if (wp->yoff == 0 && py == sy && px <= sx / 2)
			return (SCREEN_REDRAW_BORDER_BOTTOM);
		if (wp->yoff != 0 && py == wp->yoff - 1 && px > sx / 2)
			return (SCREEN_REDRAW_BORDER_TOP);
	} else {
		if (sb_pos == PANE_SCROLLBARS_LEFT) {
			if ((wp->xoff - sb_w == 0 || px >= wp->xoff - sb_w) &&
			    (px <= ex || (sb_w != 0 && px < ex + sb_w))) {
				if (wp->yoff != 0 && py == wp->yoff - 1)
					return (SCREEN_REDRAW_BORDER_TOP);
				if (py == ey)
					return (SCREEN_REDRAW_BORDER_BOTTOM);
			}
		} else { /* sb_pos == PANE_SCROLLBARS_RIGHT */
			if ((wp->xoff == 0 || px >= wp->xoff) &&
			    (px <= ex || (sb_w != 0 && px < ex + sb_w))) {
				if (pane_status != PANE_STATUS_BOTTOM &&
				    wp->yoff != 0 &&
				    py == wp->yoff - 1)
					return (SCREEN_REDRAW_BORDER_TOP);
				if (pane_status != PANE_STATUS_TOP && py == ey)
					return (SCREEN_REDRAW_BORDER_BOTTOM);
			}
		}
	}

	/* Outside pane. */
	return (SCREEN_REDRAW_OUTSIDE);
}

/* Check if a cell is on a border. */
static int
screen_redraw_cell_border(struct screen_redraw_ctx *ctx, struct window_pane *wp,
    int px, int py)
{
	struct client		*c = ctx->c;
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp2;
	int			 sx = w->sx, sy = w->sy, sb_w, sb_pos, floating;

	if (ctx->pane_scrollbars != 0)
		sb_pos = ctx->pane_scrollbars_pos;
	else
		sb_pos = 0;
	sb_w = wp->scrollbar_style.width + wp->scrollbar_style.pad;

	if (ctx->pane_status == PANE_STATUS_BOTTOM)
		sy--;

	floating = (wp->flags & PANE_FLOATING);
	if (!floating) {
		/* Outside the window? */
		if (px > sx || py > sy)
			return (0);

		/* On the window border? */
		if (px == sx || py == sy)
			return (1);
	}

	/*
	 * If checking a cell from a tiled pane, ignore floating panes because
	 * tqo side-by-side or top-bottom panes share a border which is used to
	 * do split colouring. Essentially, treat all tiled panes as being in a
	 * single z-index.
	 *
	 * If checking a cell from a floating pane, only check cells from this
	 * floating pane, again, essentially only this z-index.
	 */

	/* Check all the panes. */
	TAILQ_FOREACH(wp2, &w->z_index, zentry) {
		if (!window_pane_visible(wp2) ||
		    (!floating && (wp2->flags & PANE_FLOATING)) ||
		    (floating && wp2 != wp))
			continue;
		if (sb_pos == PANE_SCROLLBARS_LEFT) {
			if ((px < wp2->xoff - 1 - sb_w ||
			    px > wp2->xoff + (int)wp2->sx) &&
			    (py < wp2->yoff - 1 ||
			    py > wp2->yoff + (int)wp2->sy))
				continue;
		} else { /* PANE_SCROLLBARS_RIGHT or off. */
			if ((px < wp2->xoff - 1 ||
			    px > wp2->xoff + (int)wp2->sx + sb_w) &&
			    (py < wp2->yoff - 1 ||
			    py > wp2->yoff + (int)wp2->sy))
				continue;
		}
		switch (screen_redraw_pane_border(ctx, wp2, px, py)) {
		case SCREEN_REDRAW_INSIDE:
			return (0);
		case SCREEN_REDRAW_OUTSIDE:
			break;
		default:
			return (1);
		}
	}

	return (0);
}

/* Work out type of border cell from surrounding cells. */
static int
screen_redraw_type_of_cell(struct screen_redraw_ctx *ctx,
    struct window_pane *wp, int px, int py)
{
	struct client	*c = ctx->c;
	struct window	*w = c->session->curw->window;
	int		 pane_status = ctx->pane_status, borders = 0;
	int		 sx = w->sx, sy = w->sy;

	/* Is this outside the window? */
	if (pane_status == PANE_STATUS_BOTTOM)
		sy--;
	if (px > sx || py > sy)
		return (CELL_OUTSIDE);

	/*
	 * Construct a bitmask of whether the cells to the left (bit 8), right,
	 * top, and bottom (bit 1) of this cell are borders.
	 *
	 * bits 8 4 2 1:     2
	 *		   8 + 4
	 *		     1
	 */
	if (~wp->flags & PANE_FLOATING) {
		if (px == 0 || screen_redraw_cell_border(ctx, wp, px - 1, py))
			borders |= 8;
		if (px <= sx && screen_redraw_cell_border(ctx, wp, px + 1, py))
			borders |= 4;
		if (pane_status == PANE_STATUS_TOP) {
			if (py != 0 &&
			    screen_redraw_cell_border(ctx, wp, px, py - 1))
				borders |= 2;
			if (screen_redraw_cell_border(ctx, wp, px, py + 1))
				borders |= 1;
		} else if (pane_status == PANE_STATUS_BOTTOM) {
			if (py == 0 ||
			    screen_redraw_cell_border(ctx, wp, px, py - 1))
				borders |= 2;
			if (py != sy &&
			    screen_redraw_cell_border(ctx, wp, px, py + 1))
				borders |= 1;
		} else {
			if (py == 0 ||
			    screen_redraw_cell_border(ctx, wp, px, py - 1))
				borders |= 2;
			if (screen_redraw_cell_border(ctx, wp, px, py + 1))
				borders |= 1;
		}
	} else {
		if (screen_redraw_cell_border(ctx, wp, px - 1, py))
			borders |= 8;
		if (px <= sx && screen_redraw_cell_border(ctx, wp, px + 1, py))
			borders |= 4;
		if (pane_status == PANE_STATUS_TOP) {
			if (py != 0 &&
			    screen_redraw_cell_border(ctx, wp, px, py - 1))
				borders |= 2;
			if (screen_redraw_cell_border(ctx, wp, px, py + 1))
				borders |= 1;
		} else if (pane_status == PANE_STATUS_BOTTOM) {
			if (screen_redraw_cell_border(ctx, wp, px, py - 1))
				borders |= 2;
			if (py != sy &&
			    screen_redraw_cell_border(ctx, wp, px, py + 1))
				borders |= 1;
		} else {
			if (screen_redraw_cell_border(ctx, wp, px, py - 1))
				borders |= 2;
			if (screen_redraw_cell_border(ctx, wp, px, py + 1))
				borders |= 1;
		}
	}

	/*
	 * Figure out what kind of border this cell is. Only one bit set
	 * doesn't make sense (can't have a border cell with no others
	 * connected).
	 */
	switch (borders) {
	case 15:	/* 1111, left right top bottom */
		return (CELL_JOIN);
	case 14:	/* 1110, left right top */
		return (CELL_BOTTOMJOIN);
	case 13:	/* 1101, left right bottom */
		return (CELL_TOPJOIN);
	case 12:	/* 1100, left right */
		return (CELL_LEFTRIGHT);
	case 11:	/* 1011, left top bottom */
		return (CELL_RIGHTJOIN);
	case 10:	/* 1010, left top */
		return (CELL_BOTTOMRIGHT);
	case 9:		/* 1001, left bottom */
		return (CELL_TOPRIGHT);
	case 7:		/* 0111, right top bottom */
		return (CELL_LEFTJOIN);
	case 6:		/* 0110, right top */
		return (CELL_BOTTOMLEFT);
	case 5:		/* 0101, right bottom */
		return (CELL_TOPLEFT);
	case 3:		/* 0011, top bottom */
		return (CELL_TOPBOTTOM);
	}
	return (CELL_OUTSIDE);
}

/* Check if cell inside a pane. */
static int
screen_redraw_check_cell(struct screen_redraw_ctx *ctx, int px, int py,
    struct window_pane **wpp)
{
	struct client		*c = ctx->c;
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp, *start;
	int			 sx = w->sx, sy = w->sy;
	int			 pane_status = ctx->pane_status;
	int			 border, pane_scrollbars = ctx->pane_scrollbars;
	int			 pane_status_line, tiled_only = 0, left, right;
	int			 sb_pos = ctx->pane_scrollbars_pos, sb_w;

	*wpp = NULL;

	/* Outside the pane. */
	if (px > sx || py > sy)
		return (CELL_OUTSIDE);

	/* Find pane higest in z-index at this point. */
	TAILQ_FOREACH(wp, &w->z_index, zentry) {
		if (wp->flags & PANE_FLOATING && (px >= sx || py >= sy)) {
			/* Clip floating panes to window. */
			continue;
		}
		sb_w = wp->scrollbar_style.width + wp->scrollbar_style.pad;
		if (sb_pos == PANE_SCROLLBARS_LEFT) {
			if ((px >= wp->xoff - 1 - sb_w &&
			    px <= wp->xoff + (int)wp->sx) &&
			    (py >= wp->yoff - 1 &&
			    py <= wp->yoff + (int)wp->sy))
				break;
		} else { /* PANE_SCROLLBARS_RIGHT or none. */
			if ((px >= wp->xoff - 1 &&
			    px <= wp->xoff + (int)wp->sx + sb_w) &&
			    (py >= wp->yoff - 1 &&
			    py <= wp->yoff + (int)wp->sy))
				break;
		}
	}
	if (wp != NULL)
		start = wp;
	else
		start = wp = server_client_get_pane(c);
	if (wp == NULL)
		return (CELL_OUTSIDE);

	/* On the window border. */
	if (px == sx || py == sy)
		return (screen_redraw_type_of_cell(ctx, wp, px, py));

	/*
	 * If this is a tiled pane, then only check other tiled panes. This is
	 * necessary if there are two side-by-side or top-bottom panes with a
	 * shared border and half the shared border is the active border.
	 */
	if (~wp->flags & PANE_FLOATING)
		tiled_only = 1;
	do { /* Loop until back to wp == start.*/
		if (!window_pane_visible(wp) ||
		    (tiled_only && (wp->flags & PANE_FLOATING)))
			goto next;
		*wpp = wp;

		sb_w = wp->scrollbar_style.width + wp->scrollbar_style.pad;
		if (sb_pos == PANE_SCROLLBARS_LEFT) {
			if ((px < wp->xoff - 1 - sb_w ||
			     px > wp->xoff + (int)wp->sx) &&
			    (py < wp->yoff - 1 ||
			    py > wp->yoff + (int)wp->sy))
				goto next;
		} else { /* PANE_SCROLLBARS_RIGHT or none. */
			if ((px < wp->xoff - 1 ||
			     px > wp->xoff + (int)wp->sx + sb_w) &&
			    (py < wp->yoff - 1 ||
			     py > wp->yoff + (int)wp->sy))
				goto next;
		}

		/*
		 * Pane border status inside top/bottom border is CELL_INSIDE
		 * so it doesn't get overdrawn by a border line.
		 */
		if (pane_status != PANE_STATUS_OFF) {
			if (pane_status == PANE_STATUS_TOP)
				pane_status_line = wp->yoff - 1;
			else
				pane_status_line = wp->yoff + (int)wp->sy;
			left = wp->xoff + 2;
			right = wp->xoff + 2 + (int)wp->status_size - 1;
			if (py == pane_status_line + (int)ctx->oy &&
			    px >= left &&
			    px <= right)
				return (CELL_INSIDE);
		}

		/* Check if CELL_SCROLLBAR. */
		if (window_pane_show_scrollbar(wp, pane_scrollbars)) {
			/*
			 * Check if py could lie within a scrollbar. If the
			 * pane is at the top then py == 0 to sy; if the pane
			 * is not at the top, then yoff to yoff + sy.
			 */
			sb_w = wp->scrollbar_style.width +
			    wp->scrollbar_style.pad;
			if ((wp->yoff == 0 && py < (int)wp->sy) ||
			    (py >= wp->yoff &&
			     py < wp->yoff + (int)wp->sy)) {
				/* Check if px lies within a scrollbar. */
				if ((sb_pos == PANE_SCROLLBARS_RIGHT &&
				    (px >= wp->xoff + (int)wp->sx &&
				    px < wp->xoff + (int)wp->sx + sb_w)) ||
				    (sb_pos == PANE_SCROLLBARS_LEFT &&
				    (px >= wp->xoff - sb_w &&
				    px < wp->xoff)))
					return (CELL_SCROLLBAR);
			}
		}

		/*
		 * If definitely inside, return. If not on border, skip.
		 * Otherwise work out the cell.
		 */
		border = screen_redraw_pane_border(ctx, wp, px, py);
		if (border == SCREEN_REDRAW_INSIDE)
			return (CELL_INSIDE);
		if (border == SCREEN_REDRAW_OUTSIDE)
			goto next;
		return (screen_redraw_type_of_cell(ctx, wp, px, py));

	next:
		wp = TAILQ_NEXT(wp, zentry);
		if (wp == NULL)
			wp = TAILQ_FIRST(&w->z_index);
	} while (wp != start);

	return (CELL_OUTSIDE);
}

/* Check if the border of a particular pane. */
static int
screen_redraw_check_is(struct screen_redraw_ctx *ctx, int px, int py,
    struct window_pane *wp)
{
	enum screen_redraw_border_type	border;

	if (wp == NULL)
		return (0); /* No active pane. */
	border = screen_redraw_pane_border(ctx, wp, px, py);
	if (border != SCREEN_REDRAW_INSIDE && border != SCREEN_REDRAW_OUTSIDE)
		return (1);
	return (0);
}

/* Update pane status. */
static int
screen_redraw_make_pane_status(struct client *c, struct window_pane *wp,
    struct screen_redraw_ctx *rctx, enum pane_lines pane_lines)
{
	struct window		*w = wp->window;
	struct grid_cell	 gc;
	const char		*fmt, *border_option;
	struct format_tree	*ft;
	struct style_line_entry	*sle = &wp->border_status_line;
	char			*expanded;
	int			 pane_status = rctx->pane_status, sb_w = 0;
	int			 pane_scrollbars = rctx->pane_scrollbars;
	int			 max_width;
	u_int			 width, i, cell_type, px, py;
	struct screen_write_ctx	 ctx;
	struct screen		 old;

	if (window_pane_show_scrollbar(wp, pane_scrollbars))
		sb_w = wp->scrollbar_style.width + wp->scrollbar_style.pad;

	ft = format_create(c, NULL, FORMAT_PANE|wp->id, FORMAT_STATUS);
	format_defaults(ft, c, c->session, c->session->curw, wp);

	if (wp == server_client_get_pane(c))
		border_option = "pane-active-border-style";
	else
		border_option = "pane-border-style";
	style_apply(&gc, w->options, border_option, ft);
	if (options_get_only(wp->options, border_option) != NULL)
		style_add(&gc, wp->options, border_option, ft);
	fmt = options_get_string(wp->options, "pane-border-format");

	expanded = format_expand_time(ft, fmt);
	if (wp->sx < 4)
		width = 0;
	else
		width = wp->sx + sb_w - 2;
	max_width = (int)w->sx - (wp->xoff + 2) - sb_w;
	if (max_width < 0) max_width = 0;
	if (width > (u_int)max_width) width = (u_int)max_width;
	wp->status_size = width;

	memcpy(&old, &wp->status_screen, sizeof old);
	screen_init(&wp->status_screen, width, 1, 0);
	wp->status_screen.mode = 0;

	screen_write_start(&ctx, &wp->status_screen);

	for (i = 0; i < width; i++) {
		px = wp->xoff + 2 + i;
		if (pane_status == PANE_STATUS_TOP)
			py = wp->yoff - 1;
		else
			py = wp->yoff + wp->sy;
		cell_type = screen_redraw_type_of_cell(rctx, wp, px, py);
		screen_redraw_border_set(w, wp, pane_lines, cell_type, &gc);
		screen_write_cell(&ctx, &gc);
	}
	gc.attr &= ~GRID_ATTR_CHARSET;

	screen_write_cursormove(&ctx, 0, 0, 0);
	style_ranges_free(&sle->ranges);
	format_draw(&ctx, &gc, width, expanded, &sle->ranges, 0);

	screen_write_stop(&ctx);
	format_free(ft);

	free(sle->expanded);
	sle->expanded = expanded;

	if (grid_compare(wp->status_screen.grid, old.grid) == 0) {
		screen_free(&old);
		return (0);
	}
	screen_free(&old);
	return (1);
}

/* Draw pane status. */
static void
screen_redraw_draw_pane_status(struct screen_redraw_ctx *ctx)
{
	struct client		*c = ctx->c;
	struct window		*w = c->session->curw->window;
	struct tty		*tty = &c->tty;
	struct window_pane	*wp;
	struct screen		*s;
	struct visible_ranges	*r;
	struct visible_range	*ri;
	u_int			 i, l, x, width, size;
	int			 xoff, yoff;

	log_debug("%s: %s @%u", __func__, c->name, w->id);

	TAILQ_FOREACH(wp, &w->panes, entry) {
		if (!window_pane_visible(wp))
			continue;
		s = &wp->status_screen;

		size = wp->status_size;
		if (ctx->pane_status == PANE_STATUS_TOP)
			yoff = wp->yoff - 1;
		else
			yoff = wp->yoff + wp->sy;
		xoff = wp->xoff + 2;

		if (xoff + (int)size <= ctx->ox ||
		    xoff >= ctx->ox + (int)ctx->sx ||
		    yoff < ctx->oy ||
		    yoff >= ctx->oy + (int)ctx->sy)
			continue;

		if (xoff >= ctx->ox && xoff + size <= ctx->ox + ctx->sx) {
			/* All visible. */
			l = 0;
			x = xoff - ctx->ox;
			width = size;
		} else if (xoff < ctx->ox && xoff + size > ctx->ox + ctx->sx) {
			/* Both left and right not visible. */
			l = ctx->ox;
			x = 0;
			width = ctx->sx;
		} else if (xoff < ctx->ox) {
			/* Left not visible. */
			l = ctx->ox - xoff;
			x = 0;
			width = size - i;
		} else {
			/* Right not visible. */
			l = 0;
			x = xoff - ctx->ox;
			width = size - x;
		}

		r = screen_redraw_get_visible_ranges(wp, x, yoff, width, NULL);
		if (ctx->statustop)
			yoff += ctx->statuslines;
		for (i = 0; i < r->used; i++) {
			ri = &r->ranges[i];
			if (ri->nx == 0)
				continue;
			tty_draw_line(tty, s, l + (ri->px - x), 0, ri->nx,
			    ri->px, yoff - ctx->oy,
			    &grid_default_cell, NULL);
		}
	}
	tty_cursor(tty, 0, 0);
}

/* Update status line and change flags if unchanged. */
static uint64_t
screen_redraw_update(struct screen_redraw_ctx *ctx, uint64_t flags)
{
	struct client			*c = ctx->c;
	struct window			*w = c->session->curw->window;
	struct window_pane		*wp;
	int				 redraw;
	enum pane_lines			 lines;

	if (c->message_string != NULL)
		redraw = status_message_redraw(c);
	else if (c->prompt_string != NULL)
		redraw = status_prompt_redraw(c);
	else
		redraw = status_redraw(c);
	if (!redraw && (~flags & CLIENT_REDRAWSTATUSALWAYS))
		flags &= ~CLIENT_REDRAWSTATUS;

	if (c->overlay_draw != NULL)
		flags |= CLIENT_REDRAWOVERLAY;

	if (ctx->pane_status != PANE_STATUS_OFF) {
		lines = ctx->pane_lines;
		redraw = 0;
		TAILQ_FOREACH(wp, &w->panes, entry) {
			if (screen_redraw_make_pane_status(c, wp, ctx, lines))
				redraw = 1;
		}
		if (redraw)
			flags |= CLIENT_REDRAWBORDERS;
	}

	return (flags);
}

/* Set up redraw context. */
static void
screen_redraw_set_context(struct client *c, struct screen_redraw_ctx *ctx)
{
	struct session	*s = c->session;
	struct options	*oo = s->options;
	struct window	*w = s->curw->window;
	struct options	*wo = w->options;
	u_int		 lines;

	memset(ctx, 0, sizeof *ctx);
	ctx->c = c;

	lines = status_line_size(c);
	if (c->message_string != NULL || c->prompt_string != NULL)
		lines = (lines == 0) ? 1 : lines;
	if (lines != 0 && options_get_number(oo, "status-position") == 0)
		ctx->statustop = 1;
	ctx->statuslines = lines;

	ctx->pane_status = options_get_number(wo, "pane-border-status");
	ctx->pane_lines = options_get_number(wo, "pane-border-lines");

	ctx->pane_scrollbars = options_get_number(wo, "pane-scrollbars");
	ctx->pane_scrollbars_pos = options_get_number(wo,
	    "pane-scrollbars-position");

	tty_window_offset(&c->tty, &ctx->ox, &ctx->oy, &ctx->sx, &ctx->sy);

	log_debug("%s: %s @%u ox=%u oy=%u sx=%u sy=%u %u/%d", __func__, c->name,
	    w->id, ctx->ox, ctx->oy, ctx->sx, ctx->sy, ctx->statuslines,
	    ctx->statustop);
}

/* Redraw entire screen. */
void
screen_redraw_screen(struct client *c)
{
	struct screen_redraw_ctx	ctx;
	uint64_t			flags;

	if (c->flags & CLIENT_SUSPENDED)
		return;

	screen_redraw_set_context(c, &ctx);

	flags = screen_redraw_update(&ctx, c->flags);
	if ((flags & CLIENT_ALLREDRAWFLAGS) == 0)
		return;

	tty_sync_start(&c->tty);
	tty_update_mode(&c->tty, c->tty.mode, NULL);

	if (flags & (CLIENT_REDRAWWINDOW|CLIENT_REDRAWBORDERS)) {
		log_debug("%s: redrawing borders", c->name);
		screen_redraw_draw_borders(&ctx);
		if (ctx.pane_status != PANE_STATUS_OFF)
			screen_redraw_draw_pane_status(&ctx);
		screen_redraw_draw_pane_scrollbars(&ctx);
	}
	if (flags & CLIENT_REDRAWWINDOW) {
		log_debug("%s: redrawing panes", c->name);
		screen_redraw_draw_panes(&ctx);
		screen_redraw_draw_pane_scrollbars(&ctx);
	}
	if (ctx.statuslines != 0 &&
	    (flags & (CLIENT_REDRAWSTATUS|CLIENT_REDRAWSTATUSALWAYS))) {
		log_debug("%s: redrawing status", c->name);
		screen_redraw_draw_status(&ctx);
	}
	if (c->overlay_draw != NULL && (flags & CLIENT_REDRAWOVERLAY)) {
		log_debug("%s: redrawing overlay", c->name);
		c->overlay_draw(c, c->overlay_data, &ctx);
	}

	tty_reset(&c->tty);
}

/* Redraw a single pane and its scrollbar. */
void
screen_redraw_pane(struct client *c, struct window_pane *wp,
    int redraw_scrollbar_only)
{
	struct screen_redraw_ctx	ctx;

	if (!window_pane_visible(wp))
		return;

	screen_redraw_set_context(c, &ctx);
	tty_sync_start(&c->tty);
	tty_update_mode(&c->tty, c->tty.mode, NULL);

	if (!redraw_scrollbar_only)
		screen_redraw_draw_pane(&ctx, wp);

	if (window_pane_show_scrollbar(wp, ctx.pane_scrollbars))
		screen_redraw_draw_pane_scrollbar(&ctx, wp);

	tty_reset(&c->tty);
}

/* Get border cell style. */
static const struct grid_cell *
screen_redraw_draw_borders_style(struct screen_redraw_ctx *ctx, u_int x,
    u_int y, struct window_pane *wp)
{
	struct client		*c = ctx->c;
	struct session		*s = c->session;
	struct window		*w = s->curw->window;
	struct window_pane	*active = server_client_get_pane(c);
	struct options		*wo = w->options;
	const char		*border_opt;
	struct format_tree	*ft;

	if (wp->border_gc_set)
		return (&wp->border_gc);
	wp->border_gc_set = 1;

	ft = format_create_defaults(NULL, c, s, s->curw, wp);

	border_opt = screen_redraw_check_is(ctx, x, y, active) ?
	    "pane-active-border-style" : "pane-border-style";

	/* Window-level baseline. */
	style_apply(&wp->border_gc, wo, border_opt, ft);

	/* Floating pane window default overrides window baseline. */
	if (wp->flags & PANE_FLOATING)
		style_add(&wp->border_gc, wo, "floating-pane-border-style", ft);

	/* Per-pane override (set via new-pane -S or set-option -p). */
	if (options_get_only(wp->options, border_opt) != NULL)
		style_add(&wp->border_gc, wp->options, border_opt, ft);

	format_free(ft);
	return (&wp->border_gc);
}

/* Draw arrow indicator if enabled. */
static void
screen_redraw_draw_border_arrows(struct screen_redraw_ctx *ctx, int i,
    int j, u_int cell_type, struct window_pane *wp,
    struct window_pane *active, struct grid_cell *gc)
{
	struct client		*c = ctx->c;
	struct session		*s = c->session;
	struct window		*w = s->curw->window;
	struct options		*oo = w->options;
	u_int			 x = ctx->ox + i, y = ctx->oy + j;
	int			 value, arrows = 0, border;
	enum layout_type	 type;

	if (wp == NULL)
		return;
	if (i != wp->xoff + 1 && j != wp->yoff + 1)
		return;

	value = options_get_number(oo, "pane-border-indicators");
	if (value != PANE_BORDER_ARROWS && value != PANE_BORDER_BOTH)
		return;

	border = screen_redraw_pane_border(ctx, active, x, y);
	if (border == SCREEN_REDRAW_INSIDE)
		return;

	if (i == wp->xoff + 1) {
		if (border == SCREEN_REDRAW_OUTSIDE) {
			if (screen_redraw_two_panes(wp->window, &type)) {
				if (active == TAILQ_FIRST(&w->panes))
					border = SCREEN_REDRAW_BORDER_BOTTOM;
				else
					border = SCREEN_REDRAW_BORDER_TOP;
				arrows = 1;
			}
		} else {
			if (cell_type == CELL_LEFTRIGHT)
				arrows = 1;
			else if (cell_type == CELL_TOPJOIN &&
			    border == SCREEN_REDRAW_BORDER_BOTTOM)
				arrows = 1;
			else if (cell_type == CELL_BOTTOMJOIN &&
			    border == SCREEN_REDRAW_BORDER_TOP)
				arrows = 1;
		}
	}
	if (j == wp->yoff + 1) {
		if (border == SCREEN_REDRAW_OUTSIDE) {
			if (screen_redraw_two_panes(wp->window, &type)) {
				if (active == TAILQ_FIRST(&w->panes))
					border = SCREEN_REDRAW_BORDER_RIGHT;
				else
					border = SCREEN_REDRAW_BORDER_LEFT;
				arrows = 1;
			}
		} else {
			if (cell_type == CELL_TOPBOTTOM)
				arrows = 1;
			else if (cell_type == CELL_LEFTJOIN &&
			    border == SCREEN_REDRAW_BORDER_RIGHT)
				arrows = 1;
			else if (cell_type == CELL_RIGHTJOIN &&
			    border == SCREEN_REDRAW_BORDER_LEFT)
				arrows = 1;
		}
	}
	if (arrows) {
		gc->attr |= GRID_ATTR_CHARSET;
		utf8_set(&gc->data, BORDER_MARKERS[border]);
	}
}

/* Draw a border cell. */
static void
screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j)
{
	struct client		*c = ctx->c;
	struct session		*s = c->session;
	struct window		*w = s->curw->window;
	struct options		*oo = w->options;
	struct tty		*tty = &c->tty;
	struct format_tree	*ft;
	struct window_pane	*wp, *active = server_client_get_pane(c);
	struct grid_cell	 gc;
	const struct grid_cell	*tmp;
	u_int			 cell_type;
	u_int			 x = ctx->ox + i, y = ctx->oy + j;
	int			 isolates;
	struct visible_ranges	*r;

	if (c->overlay_check != NULL) {
		r = c->overlay_check(c, c->overlay_data, x, y, 1);
		if (server_client_ranges_is_empty(r))
			return;
	}

	cell_type = screen_redraw_check_cell(ctx, x, y, &wp);
	if (cell_type == CELL_INSIDE || cell_type == CELL_SCROLLBAR)
		return;

	if (wp == NULL || cell_type == CELL_OUTSIDE) {
		if (!ctx->no_pane_gc_set) {
			ft = format_create_defaults(NULL, c, s, s->curw, NULL);
			memcpy(&ctx->no_pane_gc, &grid_default_cell, sizeof gc);
			style_add(&ctx->no_pane_gc, oo, "pane-border-style",
			    ft);
			format_free(ft);
			ctx->no_pane_gc_set = 1;
		}
		memcpy(&gc, &ctx->no_pane_gc, sizeof gc);
	} else {
		tmp = screen_redraw_draw_borders_style(ctx, x, y, wp);
		if (tmp == NULL)
			return;
		memcpy(&gc, tmp, sizeof gc);

		if (server_is_marked(s, s->curw, marked_pane.wp) &&
		    screen_redraw_check_is(ctx, x, y, marked_pane.wp))
			gc.attr ^= GRID_ATTR_REVERSE;
	}
	screen_redraw_border_set(w, wp, ctx->pane_lines, cell_type, &gc);

	if (cell_type == CELL_TOPBOTTOM &&
	    (c->flags & CLIENT_UTF8) &&
	    tty_term_has(tty->term, TTYC_BIDI))
		isolates = 1;
	else
		isolates = 0;

	if (ctx->statustop)
		tty_cursor(tty, i, ctx->statuslines + j);
	else
		tty_cursor(tty, i, j);
	if (isolates)
		tty_puts(tty, END_ISOLATE);

	screen_redraw_draw_border_arrows(ctx, i, j, cell_type, wp, active, &gc);

	tty_cell(tty, &gc, &grid_default_cell, NULL, NULL);
	if (isolates)
		tty_puts(tty, START_ISOLATE);
}

/* Draw the borders. */
static void
screen_redraw_draw_borders(struct screen_redraw_ctx *ctx)
{
	struct client		*c = ctx->c;
	struct session		*s = c->session;
	struct window		*w = s->curw->window;
	struct window_pane	*wp;
	u_int			 i, j;

	log_debug("%s: %s @%u", __func__, c->name, w->id);

	TAILQ_FOREACH(wp, &w->panes, entry)
		wp->border_gc_set = 0;

	for (j = 0; j < c->tty.sy - ctx->statuslines; j++) {
		for (i = 0; i < c->tty.sx; i++)
			screen_redraw_draw_borders_cell(ctx, i, j);
	}
}

/* Draw the panes. */
static void
screen_redraw_draw_panes(struct screen_redraw_ctx *ctx)
{
	struct client		*c = ctx->c;
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp;

	log_debug("%s: %s @%u", __func__, c->name, w->id);

	TAILQ_FOREACH(wp, &w->panes, entry) {
		if (window_pane_visible(wp))
			screen_redraw_draw_pane(ctx, wp);
	}
}

/* Draw the status line. */
static void
screen_redraw_draw_status(struct screen_redraw_ctx *ctx)
{
	struct client	*c = ctx->c;
	struct window	*w = c->session->curw->window;
	struct tty	*tty = &c->tty;
	struct screen	*s = c->status.active;
	u_int		 i, y;

	log_debug("%s: %s @%u", __func__, c->name, w->id);

	if (ctx->statustop)
		y = 0;
	else
		y = c->tty.sy - ctx->statuslines;
	for (i = 0; i < ctx->statuslines; i++) {
		tty_draw_line(tty, s, 0, i, UINT_MAX, 0, y + i,
		    &grid_default_cell, NULL);
	}
}

/*
 * Check if a single character is within a visible range (not obscured by a
 * floating pane).
 */
int
screen_redraw_is_visible(struct visible_ranges *r, u_int px)
{
	u_int			 i;
	struct visible_range	*ri;

	if (r == NULL)
		return (1);
	for (i = 0; i < r->used; i++) {
		ri = &r->ranges[i];
		if (ri->nx != 0 && px >= ri->px && px <= ri->px + ri->nx)
			return (1);
	}
	return (0);
}

/*
 * Construct ranges array for the line at starting at px,py of width cells of
 * base_wp that are unobsructed.
 */
struct visible_ranges *
screen_redraw_get_visible_ranges(struct window_pane *base_wp, u_int px,
    u_int py, u_int width, struct visible_ranges *r)
{
	struct window_pane		*wp;
	struct window			*w;
	struct visible_range		*ri;
	static struct visible_ranges	 sr = { NULL, 0, 0 };
	int				 found_self, sb, sb_w, sb_pos;
	u_int				 lb, rb, tb, bb;
	u_int				 i, s;

	if (base_wp == NULL) {
		if (r != NULL)
			return (r);

		/* Return static range as last resort. */
		if (sr.ranges == NULL)
			sr.ranges = xcalloc(1, sizeof *sr.ranges);
		sr.ranges[0].px = px;
		sr.ranges[0].nx = width;
		sr.size = 1;
		sr.used = 1;
		return (&sr);
	}

	if (r == NULL) {
		/* Start with the entire width of the range. */
		server_client_ensure_ranges(&base_wp->r, 1);
		r = &base_wp->r;
		r->ranges[0].px = px;
		r->ranges[0].nx = width;
		r->used = 1;
	}

	w = base_wp->window;
	sb = options_get_number(w->options, "pane-scrollbars");
	sb_pos = options_get_number(w->options, "pane-scrollbars-position");

	found_self = 0;
	TAILQ_FOREACH_REVERSE(wp, &w->z_index, window_panes_zindex, zentry) {
		if (wp == base_wp) {
			found_self = 1;
			continue;
		}

		tb = wp->yoff > 0 ? wp->yoff - 1 : 0;
		bb = wp->yoff + wp->sy;
		if (!found_self ||
		    !window_pane_visible(wp) ||
		    py < tb ||
		    py > bb)
			continue;
		if (~wp->flags & PANE_FLOATING && py == bb)
			continue;

		sb_w = wp->scrollbar_style.width + wp->scrollbar_style.pad;
		if (!window_pane_show_scrollbar(wp, sb))
			sb_w = sb_pos = 0;

		for (i = 0; i < r->used; i++) {
			ri = &r->ranges[i];
			if (sb_pos == PANE_SCROLLBARS_LEFT) {
				if (wp->xoff > sb_w)
					lb = wp->xoff - 1 - sb_w;
				else
					lb = 0;
			} else { /* PANE_SCROLLBARS_RIGHT or none. */
				if (wp->xoff > 0)
					lb = wp->xoff - 1;
				else
					lb = 0;
			}
			if (sb_pos == PANE_SCROLLBARS_LEFT)
				rb = wp->xoff + wp->sx;
			else /* PANE_SCROLLBARS_RIGHT or none. */
				rb = wp->xoff + wp->sx + sb_w;
			if (rb > w->sx)
				rb = w->sx - 1;

			if (lb > ri->px &&
			    lb < ri->px + ri->nx &&
			    rb >= ri->px + ri->nx)
			{
				/*
				 * If the left edge of floating pane falls
				 * inside this range and right edge covers up
				 * to right of range, then shrink left edge of
				 * range.
				 */
				ri->nx = lb - ri->px;
			}
			else if (rb >= ri->px &&
			    rb < ri->px + ri->nx &&
			    lb <= ri->px) {
				/*
				 * Else if the right edge of floating pane falls
				 * inside of this range and left edge covers
				 * the left of range, then move px forward to
				 * right edge of pane.
				 */
				ri->nx = ri->nx - (rb + 1 - ri->px);
				ri->px = ri->px + (rb + 1 - ri->px);
			}
			else if (lb > ri->px && rb < ri->px + ri->nx) {
				/*
				 * Else if pane fully inside range then split
				 * into 2 ranges.
				 */
				server_client_ensure_ranges(r, r->used + 1);
				for (s = r->used; s > i; s--) {
					memcpy(&r->ranges[s], &r->ranges[s - 1],
					    sizeof *r->ranges);
				}
				ri = &r->ranges[i];
				r->ranges[i + 1].px = rb + 1;
				r->ranges[i + 1].nx = ri->px + ri->nx - (rb + 1);
				/* ri->px was copied, unchanged. */
				ri->nx = lb - ri->px;
				r->used++;
			} else if (lb <= ri->px && rb >= ri->px + ri->nx) {
				/*
				 * If floating pane completely covers this range
				 * then delete it (make it 0 length).
				 */
				ri->nx = 0;
			} else {
				/*
				 * The range is already obscured, do
				 * nothing.
				 */
			}
		}
	}
	return (r);
}

/* Draw one pane. */
static void
screen_redraw_draw_pane(struct screen_redraw_ctx *ctx, struct window_pane *wp)
{
	struct client		*c = ctx->c;
	struct window		*w = c->session->curw->window;
	struct tty		*tty = &c->tty;
	struct screen		*s = wp->screen;
	struct colour_palette	*palette = &wp->palette;
	struct grid_cell	 defaults;
	u_int			 i, j, woy, wx, wy, py, width;
	struct visible_ranges	*r;
	struct visible_range	*ri;

	if (wp->base.mode & MODE_SYNC)
		screen_write_stop_sync(wp);

	log_debug("%s: %s @%u %%%u", __func__, c->name, w->id, wp->id);

	if (wp->xoff + (int)wp->sx <= ctx->ox ||
	    wp->xoff >= (int)ctx->ox + (int)ctx->sx)
		return;

	if (ctx->statustop)
		woy = ctx->statuslines;
	else
		woy = 0;
	for (j = 0; j < wp->sy; j++) {
		if (wp->yoff + (int)j < (int)ctx->oy ||
		    wp->yoff + (int)j >= (int)ctx->oy + (int)ctx->sy)
			continue;
		wy = wp->yoff + j;       /* y line within window w */
		py = woy + wy - ctx->oy; /* y line within tty */
		if (py > tty->sy) {
			/* Continue if this line is off of tty. */
			continue;
		}
		if (wp->xoff >= (int)ctx->ox &&
		    wp->xoff + (int)wp->sx <= (int)ctx->ox + (int)ctx->sx) {
			/* All visible. */
			i = 0;
			wx = (u_int)(wp->xoff - (int)ctx->ox);
			width = wp->sx;
		} else if (wp->xoff < (int)ctx->ox &&
		    wp->xoff + (int)wp->sx > (int)ctx->ox + (int)ctx->sx) {
			/* Both left and right not visible. */
			i = ctx->ox;
			wx = 0;
			width = ctx->sx;
		} else if (wp->xoff < (int)ctx->ox) {
			/* Left not visible. */
			i = (u_int)((int)ctx->ox - wp->xoff);
			wx = 0;
			width = wp->sx - i;
		} else {
			/* Right not visible. */
			i = 0;
			wx = (u_int)(wp->xoff - (int)ctx->ox);
			width = ctx->sx - wx;
		}
		log_debug("%s: %s %%%u line %u,%u at %u,%u, width %u",
		    __func__, c->name, wp->id, i, j, wx, wy, width);

		/* Get visible ranges of line before we draw it. */
		r = screen_redraw_get_visible_ranges(wp, wx, wy, width, NULL);
		tty_default_colours(&defaults, wp);
		for (i = 0; i < r->used; i++) {
			ri = &r->ranges[i];
			if (ri->nx == 0)
				continue;
			tty_draw_line(tty, s, ri->px - wp->xoff, j, ri->nx,
			    ri->px, py, &defaults, palette);
		}
	}

#ifdef ENABLE_SIXEL
	tty_draw_images(c, wp, s);
#endif
}

/* Draw the panes scrollbars */
static void
screen_redraw_draw_pane_scrollbars(struct screen_redraw_ctx *ctx)
{
	struct client		*c = ctx->c;
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp;

	log_debug("%s: %s @%u", __func__, c->name, w->id);

	TAILQ_FOREACH(wp, &w->panes, entry) {
		if (window_pane_show_scrollbar(wp, ctx->pane_scrollbars) &&
		    window_pane_visible(wp))
			screen_redraw_draw_pane_scrollbar(ctx, wp);
	}
}

/* Calculate position and size of pane scrollbar. */
void
screen_redraw_draw_pane_scrollbar(struct screen_redraw_ctx *ctx,
    struct window_pane *wp)
{
	struct screen	*s = wp->screen;
	double		 percent_view;
	u_int		 sb = ctx->pane_scrollbars, total_height, sb_h = wp->sy;
	u_int		 sb_pos = ctx->pane_scrollbars_pos, slider_h, slider_y;
	int		 sb_w = wp->scrollbar_style.width;
	int		 sb_pad = wp->scrollbar_style.pad;
	int		 cm_y, cm_size, xoff = wp->xoff;
	int		 sb_x, sb_y = (int)(wp->yoff); /* sb top */

	if (window_pane_mode(wp) == WINDOW_PANE_NO_MODE) {
		if (sb == PANE_SCROLLBARS_MODAL)
			return;
		/* Show slider at the bottom of the scrollbar. */
		total_height = screen_size_y(s) + screen_hsize(s);
		percent_view = (double)sb_h / total_height;
		slider_h = (double)sb_h * percent_view;
		slider_y = sb_h - slider_h;
	} else {
		if (TAILQ_FIRST(&wp->modes) == NULL)
			return;
		if (window_copy_get_current_offset(wp, &cm_y, &cm_size) == 0)
			return;
		total_height = cm_size + sb_h;
		percent_view = (double)sb_h / (cm_size + sb_h);
		slider_h = (double)sb_h * percent_view;
		slider_y = (sb_h + 1) * ((double)cm_y / (total_height));
	}

	if (sb_pos == PANE_SCROLLBARS_LEFT)
		sb_x = xoff - sb_w - sb_pad;
	else
		sb_x = xoff + wp->sx;

	if (slider_h < 1)
		slider_h = 1;
	if (slider_y >= sb_h)
		slider_y = sb_h - 1;

	screen_redraw_draw_scrollbar(ctx, wp, sb_pos, sb_x, sb_y, sb_h,
	    slider_h, slider_y);

	/* Store current position and height of the slider */
	wp->sb_slider_y = slider_y;  /* top of slider y pos in scrollbar */
	wp->sb_slider_h = slider_h;  /* height of slider */
}

/* Draw pane scrollbar. */
static void
screen_redraw_draw_scrollbar(struct screen_redraw_ctx *ctx,
    struct window_pane *wp, int sb_pos, int sb_x, int sb_y, u_int sb_h,
    u_int slider_h, u_int slider_y)
{
	struct client		*c = ctx->c;
	struct tty		*tty = &c->tty;
	struct grid_cell	 gc, slgc, *gcp;
	struct style		*sb_style = &wp->scrollbar_style;
	u_int			 i, j, imin = 0, jmin = 0, imax, jmax;
	u_int			 sb_w = sb_style->width, sb_pad = sb_style->pad;
	int			 px, py, wx, wy, ox, oy, sx, sy, sb_tty_y;
	int			 xoff = wp->xoff;
	int			 yoff = wp->yoff;
	struct visible_ranges	*r;

	/*
	 * Size and offset of window relative to tty. Status at top offsets
	 * window downward.
	 */
	sx = ctx->sx;
	sy = tty->sy - ctx->statuslines;
	ox = ctx->ox;
	oy = ctx->oy;
	if (ctx->statustop) {
		sb_y += ctx->statuslines;
		sy += ctx->statuslines;	/* height of window */
		oy += ctx->statuslines;	/* top of window */
	}

	gc = sb_style->gc;
	memcpy(&slgc, &gc, sizeof slgc);
	slgc.fg = gc.bg;
	slgc.bg = gc.fg;

	if (sb_x + (int)sb_w < 0 || sb_x >= sx || sb_y >= sy) {
		/* Whole scrollbar is off screen. */
		return;
	}
	if (sb_x < 0) {
		/* Part of scrollbar on screen. */
		imin = - sb_x;
	}
	imax = sb_w + sb_pad;
	if ((int)imax + sb_x > sx) {
		if (sb_x > sx) {
			/* Whole scrollbar off screen. */
			return;
		}
		imax = sx - sb_x;
	}
	jmax = sb_h;
	if ((int)jmax + sb_y > sy) {
		if (sb_y >= sy)
			return;
		jmax = sy - sb_y;
	}

	/*
	 * sb_y is a window coordinate; convert to tty coordinate by
	 * subtracting the pan offset oy.
	 */
	sb_tty_y = sb_y - oy; /* scrollbar top in tty coordinates */
	if (sb_tty_y > (int)sy) {
		/* Whole scrollbar is off screen. */
		return;
	}
	if (sb_tty_y < 0) {
		/* Scrollbar starts above visible area; skip those rows. */
		jmin = -sb_tty_y;
	}
	if (sb_tty_y + (int)sb_h <= 0) {
		/* Whole scrollbar above visible area. */
		return;
	}
	jmax = sb_h;
	if (sb_tty_y + (int)jmax > (int)sy) {
		/* Clip to height of tty. */
		jmax = sy - sb_tty_y;
	}

	for (j = jmin; j < jmax; j++) {
		wy = sb_y + j;	   /* window y coordinate */
		py = sb_tty_y + j;/* tty y coordinate */
		r = tty_check_overlay_range(tty, sb_x, wy, imax);
		r = screen_redraw_get_visible_ranges(wp, sb_x, wy, imax, r);
		for (i = imin; i < imax; i++) {
			px = sb_x + ox + i; /* tty x coordinate */
			wx = sb_x + i;	    /* window x coordinate */
			if (wx < xoff - (int)sb_w - (int)sb_pad ||
			    px >= sx || px < 0 ||
			    wy < yoff - 1 ||
			    py >= sy || py < 0 ||
			    !screen_redraw_is_visible(r, wx))
				continue;
			tty_cursor(tty, px, py);
			if ((sb_pos == PANE_SCROLLBARS_LEFT &&
			    i >= sb_w && i < sb_w + sb_pad) ||
			    (sb_pos == PANE_SCROLLBARS_RIGHT &&
			    i < sb_pad)) {
				tty_cell(tty, &grid_default_cell,
				    &grid_default_cell, NULL, NULL);
			} else {
				if (j >= slider_y && j < slider_y + slider_h)
					gcp = &slgc;
				else
					gcp = &gc;
				tty_cell(tty, gcp, &grid_default_cell, NULL,
				    NULL);
			}
		}
	}
}
