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Support for windows larger than visible on the attached client. This has
been a limitation for a long time.

There are two new options, window-size and default-size, and a new
command, resize-window. The force-width and force-height options and the
session_width and session_height formats have been removed.

The new window-size option tells tmux how to work out the size of
windows: largest means it picks the size of the largest session,
smallest the smallest session (similar to the old behaviour) and manual
means that it does not automatically resize windows. The default is
currently largest but this may change. aggressive-resize modifies the
choice of session for largest and smallest as it did before.

If a window is in a session attached to a client that is too small, only
part of the window is shown. tmux attempts to keep the cursor visible,
so the part of the window displayed is changed as the cursor moves (with
a small delay, to try and avoid excess redrawing when applications
redraw status lines or similar that are not currently visible). The
offset of the visible portion of the window is shown in status-right.

Drawing windows which are larger than the client is not as efficient as
those which fit, particularly when the cursor moves, so it is
recommended to avoid using this on slow machines or networks (set
window-size to smallest or manual).

The resize-window command can be used to resize a window manually. If it
is used, the window-size option is automatically set to manual for the
window (undo this with "setw -u window-size"). resize-window works in a
similar way to resize-pane (-U -D -L -R -x -y flags) but also has -a and
-A flags. -a sets the window to the size of the smallest client (what it
would be if window-size was smallest) and -A the largest.

For the same behaviour as force-width or force-height, use resize-window
-x or -y, and "setw -u window-size" to revert to automatic sizing..

If the global window-size option is set to manual, the default-size
option is used for new windows. If -x or -y is used with new-session,
that sets the default-size option for the new session.

The maximum size of a window is 10000x10000. But expect applications to
complain and much higher memory use if making a window excessively
big. The minimum size is the size required for the current layout
including borders.

The refresh-client command can be used to pan around a window, -U -D -L
-R moves up, down, left or right and -c returns to automatic cursor
tracking. The position is reset when the current window is changed.

/* $OpenBSD: screen-redraw.c,v 1.55 2018/10/18 08:38:01 nicm Exp $ */

/*
 * 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"

struct screen_redraw_ctx {
	struct client	*c;

	u_int		 lines;
	int		 top;

	int		 pane_status;

	u_int		 sx;
	u_int		 sy;
	u_int		 ox;
	u_int		 oy;
};

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_draw_number(struct screen_redraw_ctx *,
		    struct window_pane *);

#define CELL_INSIDE 0
#define CELL_LEFTRIGHT 1
#define CELL_TOPBOTTOM 2
#define CELL_TOPLEFT 3
#define CELL_TOPRIGHT 4
#define CELL_BOTTOMLEFT 5
#define CELL_BOTTOMRIGHT 6
#define CELL_TOPJOIN 7
#define CELL_BOTTOMJOIN 8
#define CELL_LEFTJOIN 9
#define CELL_RIGHTJOIN 10
#define CELL_JOIN 11
#define CELL_OUTSIDE 12

#define CELL_BORDERS " xqlkmjwvtun~"

#define CELL_STATUS_OFF 0
#define CELL_STATUS_TOP 1
#define CELL_STATUS_BOTTOM 2

/* Check if cell is on the border of a particular pane. */
static int
screen_redraw_cell_border1(struct window_pane *wp, u_int px, u_int py)
{
	/* Inside pane. */
	if (px >= wp->xoff && px < wp->xoff + wp->sx &&
	    py >= wp->yoff && py < wp->yoff + wp->sy)
		return (0);

	/* Left/right borders. */
	if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= wp->yoff + wp->sy) {
		if (wp->xoff != 0 && px == wp->xoff - 1)
			return (1);
		if (px == wp->xoff + wp->sx)
			return (2);
	}

	/* Top/bottom borders. */
	if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= wp->xoff + wp->sx) {
		if (wp->yoff != 0 && py == wp->yoff - 1)
			return (3);
		if (py == wp->yoff + wp->sy)
			return (4);
	}

	/* Outside pane. */
	return (-1);
}

/* Check if a cell is on the pane border. */
static int
screen_redraw_cell_border(struct client *c, u_int px, u_int py)
{
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp;
	int			 retval;

	/* Check all the panes. */
	TAILQ_FOREACH(wp, &w->panes, entry) {
		if (!window_pane_visible(wp))
			continue;
		if ((retval = screen_redraw_cell_border1(wp, px, py)) != -1)
			return (!!retval);
	}

	return (0);
}

/* Check if cell inside a pane. */
static int
screen_redraw_check_cell(struct client *c, u_int px, u_int py, int pane_status,
    struct window_pane **wpp)
{
	struct window		*w = c->session->curw->window;
	struct window_pane	*wp;
	int			 borders;
	u_int			 right, line;

	*wpp = NULL;

	if (px > w->sx || py > w->sy)
		return (CELL_OUTSIDE);

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

			if (pane_status == CELL_STATUS_TOP)
				line = wp->yoff - 1;
			else
				line = wp->yoff + wp->sy;
			right = wp->xoff + 2 + wp->status_size - 1;

			if (py == line && px >= wp->xoff + 2 && px <= right)
				return (CELL_INSIDE);
		}
	}

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

		/* If outside the pane and its border, skip it. */
		if ((wp->xoff != 0 && px < wp->xoff - 1) ||
		    px > wp->xoff + wp->sx ||
		    (wp->yoff != 0 && py < wp->yoff - 1) ||
		    py > wp->yoff + wp->sy)
			continue;

		/* If definitely inside, return so. */
		if (!screen_redraw_cell_border(c, px, py))
			return (CELL_INSIDE);

		/*
		 * Construct a bitmask of whether the cells to the left (bit
		 * 4), right, top, and bottom (bit 1) of this cell are borders.
		 */
		borders = 0;
		if (px == 0 || screen_redraw_cell_border(c, px - 1, py))
			borders |= 8;
		if (px <= w->sx && screen_redraw_cell_border(c, px + 1, py))
			borders |= 4;
		if (pane_status == CELL_STATUS_TOP) {
			if (py != 0 && screen_redraw_cell_border(c, px, py - 1))
				borders |= 2;
		} else {
			if (py == 0 || screen_redraw_cell_border(c, px, py - 1))
				borders |= 2;
		}
		if (py <= w->sy && screen_redraw_cell_border(c, 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_TOPBOTTOM);
		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_LEFTRIGHT);
		}
	}

	return (CELL_OUTSIDE);
}

/* Check if the border of a particular pane. */
static int
screen_redraw_check_is(u_int px, u_int py, int type, int pane_status,
    struct window *w, struct window_pane *wantwp, struct window_pane *wp)
{
	int	border;

	/* Is this off the active pane border? */
	border = screen_redraw_cell_border1(wantwp, px, py);
	if (border == 0 || border == -1)
		return (0);
	if (pane_status == CELL_STATUS_TOP && border == 4)
		return (0);
	if (pane_status == CELL_STATUS_BOTTOM && border == 3)
		return (0);

	/* If there are more than two panes, that's enough. */
	if (window_count_panes(w) != 2)
		return (1);

	/* Else if the cell is not a border cell, forget it. */
	if (wp == NULL || (type == CELL_OUTSIDE || type == CELL_INSIDE))
		return (1);

	/* With status lines mark the entire line. */
	if (pane_status != CELL_STATUS_OFF)
		return (1);

	/* Check if the pane covers the whole width. */
	if (wp->xoff == 0 && wp->sx == w->sx) {
		/* This can either be the top pane or the bottom pane. */
		if (wp->yoff == 0) { /* top pane */
			if (wp == wantwp)
				return (px <= wp->sx / 2);
			return (px > wp->sx / 2);
		}
		return (0);
	}

	/* Check if the pane covers the whole height. */
	if (wp->yoff == 0 && wp->sy == w->sy) {
		/* This can either be the left pane or the right pane. */
		if (wp->xoff == 0) { /* left pane */
			if (wp == wantwp)
				return (py <= wp->sy / 2);
			return (py > wp->sy / 2);
		}
		return (0);
	}

	return (1);
}

/* Update pane status. */
static int
screen_redraw_make_pane_status(struct client *c, struct window *w,
    struct window_pane *wp)
{
	struct grid_cell	 gc;
	const char		*fmt;
	struct format_tree	*ft;
	char			*out;
	size_t			 outlen;
	struct screen_write_ctx	 ctx;
	struct screen		 old;

	if (wp == w->active)
		style_apply(&gc, w->options, "pane-active-border-style");
	else
		style_apply(&gc, w->options, "pane-border-style");

	fmt = options_get_string(w->options, "pane-border-format");

	ft = format_create(c, NULL, FORMAT_PANE|wp->id, 0);
	format_defaults(ft, c, NULL, NULL, wp);

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

	out = format_expand(ft, fmt);
	outlen = screen_write_cstrlen("%s", out);
	if (outlen > wp->sx - 4)
		outlen = wp->sx - 4;
	screen_resize(&wp->status_screen, outlen, 1, 0);

	screen_write_start(&ctx, NULL, &wp->status_screen);
	screen_write_cursormove(&ctx, 0, 0);
	screen_write_clearline(&ctx, 8);
	screen_write_cnputs(&ctx, outlen, &gc, "%s", out);
	screen_write_stop(&ctx);

	free(out);
	format_free(ft);

	wp->status_size = outlen;

	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;
	u_int			 i, x, width, xoff, yoff, size;

	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 == CELL_STATUS_TOP)
			yoff = wp->yoff - 1;
		else
			yoff = wp->yoff + wp->sy;
		xoff = wp->xoff + 2;

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

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

		if (ctx->top)
			yoff += ctx->lines;
		tty_draw_line(tty, NULL, s, i, 0, width, x, yoff - ctx->oy);
	}
	tty_cursor(tty, 0, 0);
}

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

	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 (options_get_number(wo, "pane-border-status") != CELL_STATUS_OFF) {
		redraw = 0;
		TAILQ_FOREACH(wp, &w->panes, entry) {
			if (screen_redraw_make_pane_status(c, w, wp))
				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;

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

	ctx->lines = status_line_size(c);
	if (c->message_string != NULL || c->prompt_string != NULL)
		ctx->lines = (ctx->lines == 0) ? 1 : ctx->lines;
	if (ctx->lines != 0 && options_get_number(oo, "status-position") == 0)
		ctx->top = 1;
	ctx->pane_status = options_get_number(wo, "pane-border-status");

	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->lines, ctx->top);
}

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

	if (c->flags & CLIENT_SUSPENDED)
		return;

	flags = screen_redraw_update(c, c->flags);
	screen_redraw_set_context(c, &ctx);

	if (flags & (CLIENT_REDRAWWINDOW|CLIENT_REDRAWBORDERS)) {
		if (ctx.pane_status != CELL_STATUS_OFF)
			screen_redraw_draw_pane_status(&ctx);
		screen_redraw_draw_borders(&ctx);
	}
	if (flags & CLIENT_REDRAWWINDOW)
		screen_redraw_draw_panes(&ctx);
	if (ctx.lines != 0 &&
	    (flags & (CLIENT_REDRAWSTATUS|CLIENT_REDRAWSTATUSALWAYS)))
		screen_redraw_draw_status(&ctx);
	tty_reset(&c->tty);
}

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

	if (!window_pane_visible(wp))
		return;

	screen_redraw_set_context(c, &ctx);

	screen_redraw_draw_pane(&ctx, wp);
	tty_reset(&c->tty);
}

/* Draw a border cell. */
static void
screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j,
    struct grid_cell *m_active_gc, struct grid_cell *active_gc,
    struct grid_cell *m_other_gc, struct grid_cell *other_gc)
{
	struct client		*c = ctx->c;
	struct session		*s = c->session;
	struct window		*w = s->curw->window;
	struct tty		*tty = &c->tty;
	struct window_pane	*wp;
	struct window_pane	*active = w->active;
	struct window_pane	*marked = marked_pane.wp;
	u_int			 type, x = ctx->ox + i, y = ctx->oy + j;
	int			 flag, pane_status = ctx->pane_status;

	type = screen_redraw_check_cell(c, x, y, pane_status, &wp);
	if (type == CELL_INSIDE)
		return;
	flag = screen_redraw_check_is(x, y, type, pane_status, w, active, wp);

	if (server_is_marked(s, s->curw, marked_pane.wp) &&
	    screen_redraw_check_is(x, y, type, pane_status, w, marked, wp)) {
		if (flag)
			tty_attributes(tty, m_active_gc, NULL);
		else
			tty_attributes(tty, m_other_gc, NULL);
	} else if (flag)
		tty_attributes(tty, active_gc, NULL);
	else
		tty_attributes(tty, other_gc, NULL);
	if (ctx->top)
		tty_cursor(tty, i, ctx->lines + j);
	else
		tty_cursor(tty, i, j);
	tty_putc(tty, CELL_BORDERS[type]);
}

/* 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 tty		*tty = &c->tty;
	struct options		*oo = w->options;
	struct grid_cell	 m_active_gc, active_gc, m_other_gc, other_gc;
	u_int		 	 i, j;

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

	style_apply(&other_gc, oo, "pane-border-style");
	style_apply(&active_gc, oo, "pane-active-border-style");
	active_gc.attr = other_gc.attr = GRID_ATTR_CHARSET;

	memcpy(&m_other_gc, &other_gc, sizeof m_other_gc);
	m_other_gc.attr ^= GRID_ATTR_REVERSE;
	memcpy(&m_active_gc, &active_gc, sizeof m_active_gc);
	m_active_gc.attr ^= GRID_ATTR_REVERSE;

	for (j = 0; j < tty->sy - ctx->lines; j++) {
		for (i = 0; i < tty->sx; i++) {
			screen_redraw_draw_borders_cell(ctx, i, j,
			    &m_active_gc, &active_gc, &m_other_gc, &other_gc);
		}
	}
}

/* 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))
			continue;
		screen_redraw_draw_pane(ctx, wp);
		if (c->flags & CLIENT_IDENTIFY)
			screen_redraw_draw_number(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.status;
	u_int		 i, y;

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

	if (ctx->top)
		y = 0;
	else
		y = c->tty.sy - ctx->lines;
	for (i = 0; i < ctx->lines; i++)
		tty_draw_line(tty, NULL, s, 0, i, UINT_MAX, 0, y + i);
}

/* 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;
	u_int		 i, j, top, x, y, width;

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

	if (wp->xoff + wp->sx <= ctx->ox || wp->xoff >= ctx->ox + ctx->sx)
		return;
	if (ctx->top)
		top = ctx->lines;
	else
		top = 0;

	s = wp->screen;
	for (j = 0; j < wp->sy; j++) {
		if (wp->yoff + j < ctx->oy || wp->yoff + j >= ctx->oy + ctx->sy)
			continue;
		y = top + wp->yoff + j - ctx->oy;

		if (wp->xoff >= ctx->ox &&
		    wp->xoff + wp->sx <= ctx->ox + ctx->sx) {
			/* All visible. */
			i = 0;
			x = wp->xoff - ctx->ox;
			width = wp->sx;
		} else if (wp->xoff < ctx->ox &&
		    wp->xoff + wp->sx > ctx->ox + ctx->sx) {
			/* Both left and right not visible. */
			i = ctx->ox;
			x = 0;
			width = ctx->sx;
		} else if (wp->xoff < ctx->ox) {
			/* Left not visible. */
			i = ctx->ox - wp->xoff;
			x = 0;
			width = wp->sx - i;
		} else {
			/* Right not visible. */
			i = 0;
			x = wp->xoff - ctx->ox;
			width = ctx->sx - x;
		}
		log_debug("%s: %s %%%u line %u,%u at %u,%u, width %u",
		    __func__, c->name, wp->id, i, j, x, y, width);

		tty_draw_line(tty, wp, s, i, j, width, x, y);
	}
}

/* Draw number on a pane. */
static void
screen_redraw_draw_number(struct screen_redraw_ctx *ctx, struct window_pane *wp)
{
	struct client		*c = ctx->c;
	struct tty		*tty = &c->tty;
	struct session		*s = c->session;
	struct options		*oo = s->options;
	struct window		*w = wp->window;
	struct grid_cell	 gc;
	u_int			 idx, px, py, i, j, xoff, yoff, sx, sy;
	int			 colour, active_colour;
	char			 buf[16], *ptr;
	size_t			 len;

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

	if (wp->xoff >= ctx->ox && wp->xoff + wp->sx <= ctx->ox + ctx->sx) {
		/* All visible. */
		xoff = wp->xoff - ctx->ox;
		sx = wp->sx;
	} else if (wp->xoff < ctx->ox &&
	    wp->xoff + wp->sx > ctx->ox + ctx->sx) {
		/* Both left and right not visible. */
		xoff = 0;
		sx = ctx->sx;
	} else if (wp->xoff < ctx->ox) {
		/* Left not visible. */
		xoff = 0;
		sx = wp->sx - (ctx->ox - wp->xoff);
	} else {
		/* Right not visible. */
		xoff = wp->xoff - ctx->ox;
		sx = wp->sx - xoff;
	}
	if (wp->yoff >= ctx->oy && wp->yoff + wp->sy <= ctx->oy + ctx->sy) {
		/* All visible. */
		yoff = wp->yoff - ctx->oy;
		sy = wp->sy;
	} else if (wp->yoff < ctx->oy &&
	    wp->yoff + wp->sy > ctx->oy + ctx->sy) {
		/* Both top and bottom not visible. */
		yoff = 0;
		sy = ctx->sy;
	} else if (wp->yoff < ctx->oy) {
		/* Top not visible. */
		yoff = 0;
		sy = wp->sy - (ctx->oy - wp->yoff);
	} else {
		/* Bottom not visible. */
		yoff = wp->yoff - ctx->oy;
		sy = wp->sy - yoff;
	}

	if (ctx->top)
		yoff += ctx->lines;
	px = sx / 2;
	py = sy / 2;

	if (window_pane_index(wp, &idx) != 0)
		fatalx("index not found");
	len = xsnprintf(buf, sizeof buf, "%u", idx);

	if (sx < len)
		return;
	colour = options_get_number(oo, "display-panes-colour");
	active_colour = options_get_number(oo, "display-panes-active-colour");

	if (sx < len * 6 || sy < 5) {
		tty_cursor(tty, xoff + px - len / 2, yoff + py);
		goto draw_text;
	}

	px -= len * 3;
	py -= 2;

	memcpy(&gc, &grid_default_cell, sizeof gc);
	if (w->active == wp)
		gc.bg = active_colour;
	else
		gc.bg = colour;
	gc.flags |= GRID_FLAG_NOPALETTE;

	tty_attributes(tty, &gc, wp);
	for (ptr = buf; *ptr != '\0'; ptr++) {
		if (*ptr < '0' || *ptr > '9')
			continue;
		idx = *ptr - '0';

		for (j = 0; j < 5; j++) {
			for (i = px; i < px + 5; i++) {
				tty_cursor(tty, xoff + i, yoff + py + j);
				if (window_clock_table[idx][j][i - px])
					tty_putc(tty, ' ');
			}
		}
		px += 6;
	}

	len = xsnprintf(buf, sizeof buf, "%ux%u", wp->sx, wp->sy);
	if (sx < len || sy < 6)
		return;
	tty_cursor(tty, xoff + sx - len, yoff);

draw_text:
	memcpy(&gc, &grid_default_cell, sizeof gc);
	if (w->active == wp)
		gc.fg = active_colour;
	else
		gc.fg = colour;
	gc.flags |= GRID_FLAG_NOPALETTE;

	tty_attributes(tty, &gc, wp);
	tty_puts(tty, buf);

	tty_cursor(tty, 0, 0);
}