/src/tmux/screen-redraw.c

Source
/* $OpenBSD: screen-redraw.c,v 1.171 2026/10/21 07:38:05 nicm Exp $ */

/*
 * Copyright (c) 2026 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 <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "tmux.h"

/*
 * Draw the visible area of a window to a client.
 *
 * A scene is built for the client and cached (in struct client). When the
 * offset or size of the visible part of the window changes, the scene is
 * invalidated. It is also invalidated when the generation number is increased;
 * this is done at various points, such as when a pane is moved or resized. The
 * scene only includes the part of the client used for the window: panes, pane
 * status lines, borders, scrollbars, and any area outside the window. The
 * client status line is not included.
 *
 * A scene is made from spans. A span is a horizontal run of cells on one
 * visible line that can be drawn in the same way. Each span has a type, for
 * example: pane content or pane border cells or pane status line. A span also
 * includes enough additional data to draw it, but does not include items such
 * as the style and content - those are determined when it is drawn.
 *
 * Scenes are built in two stages:
 *
 * 1) redraw_build_cells fills a temporary grid of struct redraw_build_cell
 *    objects, one per visible cell. It marks pane contents, scrollbars,
 *    borders, pane status lines and any cells outside the window. Border cells
 *    may belong to multiple panes, so they may be marked multiple times, with
 *    each pane adding its own state.
 *
 * 2) redraw_make_scene takes the grid of struct redraw_build_cell objects and
 *    converts them into spans by joining adjacent cells that have the same
 *    type and data. These spans together make up the scene (struct
 *    redraw_scene).
 *
 * Once generated, a scene is redrawn by looping over some or all of the spans
 * (in redraw_draw), working out the style and content, and writing to the
 * client terminal. Until it is invalidated, the scene may be redrawn multiple
 * times without being rebuilt.
 */

/* Type of span in the scene. */
enum redraw_span_type {
  REDRAW_SPAN_PANE, /* inside a pane */
  REDRAW_SPAN_OUTSIDE,  /* outside the window */
  REDRAW_SPAN_EMPTY,  /* inside the window but nothing visible */
  REDRAW_SPAN_STATUS, /* pane status line */
  REDRAW_SPAN_BORDER, /* pane border */
  REDRAW_SPAN_SCROLLBAR,  /* pane scrollbar */
  REDRAW_SPAN_MENU, /* window menu */
};
#define REDRAW_SPAN_TYPES 7

/* Draw phases. */
enum redraw_phase {
  REDRAW_TEXT,
  REDRAW_IMAGES
};
#define REDRAW_PHASE_COUNT 2

/* Border connections to adjacent cells. */
#define REDRAW_BORDER_L 0x1
#define REDRAW_BORDER_R 0x2
#define REDRAW_BORDER_U 0x4
#define REDRAW_BORDER_D 0x8

/* Span flags. */
#define REDRAW_BORDER_IS_ARROW 0x1
#define REDRAW_SCROLLBAR_LEFT 0x2
#define REDRAW_SCROLLBAR_RIGHT 0x4
#define REDRAW_SCROLLBAR_OVERLAY 0x8

/* Draw operations. */
#define REDRAW_PANE 0x1
#define REDRAW_OUTSIDE 0x2
#define REDRAW_EMPTY 0x4
#define REDRAW_PANE_BORDER 0x8
#define REDRAW_PANE_STATUS 0x10
#define REDRAW_PANE_SCROLLBAR 0x20
#define REDRAW_STATUS 0x40
#define REDRAW_MENU 0x80
#define REDRAW_SIDE_STATUS 0x100

/* Draw everything. */
#define REDRAW_ALL 0x7fffffff
#define REDRAW_IS_ALL(flags) ((flags) == REDRAW_ALL)

/* UTF-8 isolate characters. */
#define REDRAW_START_ISOLATE "\342\201\246"
#define REDRAW_END_ISOLATE "\342\201\251"

/* Data for a span. */
struct redraw_span_data {
  enum redraw_span_type type;

  union {
    struct {
      /* Pane this span belongs to. */
      struct window_pane  *wp;

      /* Position of span inside the pane. */
      u_int      px;
      u_int      py;
    } p; /* pane */

    struct {
      /* Adjacent panes on each side. */
      struct window_pane  *top_wp;
      struct window_pane  *bottom_wp;
      struct window_pane  *left_wp;
      struct window_pane  *right_wp;

      /*
       * The pane this span belongs if that is known when the
       * scene is built. This is used for the half coloured
       * active pane indicator.
       */
      struct window_pane  *style_wp;

      /* Cell type for this span. */
      int      cell_type;
      int      cell_mask;

      /* Line styles for this span. */
      enum pane_lines    top_lines;
      enum pane_lines    bottom_lines;
      enum pane_lines    left_lines;
      enum pane_lines    right_lines;

      /* Flags for this span. */
      int      flags;
    } b; /* pane border */

    struct {
      /* The pane and the offset into the status line. */
      struct window_pane  *wp;
      u_int      offset;
      int      cell_type;
    } st; /* pane status line */

    struct {
      /* Pane this span belongs to. */
      struct window_pane  *wp;

      /* Line within the scrollbar. */
      u_int      y;

      /* Full height of scrollbar. */
      u_int      height;

      /* Flags for this span. */
      int      flags;
    } sb; /* pane scrollbar */

    struct {
      /* Menu this span belongs to. */
      struct menu_data  *md;

      /* Position of span inside the menu. */
      u_int      px;
      u_int      py;
    } m; /* menu */
  };
};

/* A span of cells of the same type inside a line. */
struct redraw_span {
  u_int       x;
  u_int       width;
  struct redraw_span_data   data;

  TAILQ_ENTRY(redraw_span)  entry;
};
TAILQ_HEAD(redraw_spans, redraw_span);

/* A visible line on the client. */
struct redraw_line {
  struct redraw_spans spans[REDRAW_SPAN_TYPES];
};

/* A scene representing all the spans on the client. */
struct redraw_scene {
  struct client   *c;
  struct window   *w;
  struct redraw_line  *lines;

  uint64_t     generation;
  u_int      sx;
  u_int      sy;
  u_int      ox;
  u_int      oy;
};

/* A damaged rectangle in a window. */
struct redraw_damage {
  u_int        x;
  u_int        y;
  u_int        sx;
  u_int        sy;

  int        flags;
#define REDRAW_DAMAGE_SCROLL 0x1

  TAILQ_ENTRY(redraw_damage)   entry;
};

/*
 * If there are more damage rectangles than this, they are collapsed into
 * one.
 */
#define REDRAW_DAMAGE_MAX 16

/* Cell for building the scene. */
struct redraw_build_cell {
  struct redraw_span_data  data;
};
static struct redraw_build_cell *redraw_cells;
static size_t      redraw_ncells;

/*
 * We can reuse the same pane status lines during one damage redraw, but when
 * we enter a new one, the client or format variables may have changed, so we
 * need to make them again. The generation is increased so this happens.
 */
static u_int  redraw_status_generation;

/* Context for building the scene. */
struct redraw_build_ctx {
  struct client       *c;
  struct window       *w;

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

  int          ind;

  struct redraw_build_cell    *cells;
};

/* Context for redrawing. */
struct redraw_draw_ctx {
  struct redraw_scene *scene;

  struct window_pane  *active;
  struct window_pane  *marked;

  u_int      status_lines;
  u_int      side_left;
  enum pane_lines    pane_lines;
  struct grid_cell   default_gc;

  int      flags;
#define REDRAW_ISOLATES 0x1
#define REDRAW_DEFAULT_SET 0x2
#define REDRAW_STATUS_TOP 0x4
};

/* Make redraw flags into a string. */
static const char *
redraw_flags_to_string(int flags)
{
  static char s[128];

  *s = '\0';
  if (flags & REDRAW_STATUS)
    strlcat(s, "status ", sizeof s);
  if (flags & REDRAW_PANE)
    strlcat(s, "pane ", sizeof s);
  if (flags & REDRAW_PANE_BORDER)
    strlcat(s, "border ", sizeof s);
  if (flags & REDRAW_PANE_STATUS)
    strlcat(s, "pane-status ", sizeof s);
  if (flags & REDRAW_PANE_SCROLLBAR)
    strlcat(s, "scrollbar ", sizeof s);
  if (flags & REDRAW_MENU)
    strlcat(s, "menu ", sizeof s);
  if (REDRAW_IS_ALL(flags))
    strlcat(s, "all ", sizeof s);
  if (*s != '\0')
    s[strlen(s) - 1] = '\0';
  return (s);
}

/* Get window offset and expand size to cover any part outside the window. */
static void
redraw_get_window_offset(struct client *c, u_int *ox, u_int *oy, u_int *sx,
    u_int *sy)
{
  u_int tty_sx, tty_sy;

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

  tty_sx = c->tty.sx - status_side_size(c);
  tty_sy = c->tty.sy - status_line_size(c);
  if (*sx < tty_sx)
    *sx = tty_sx;
  if (*sy < tty_sy)
    *sy = tty_sy;
}

/* Initialize the context for building scene. */
static void
redraw_set_context(struct client *c, struct redraw_build_ctx *bctx)
{
  struct session  *s = c->session;
  struct window *w = s->curw->window;

  memset(bctx, 0, sizeof *bctx);
  bctx->c = c;
  bctx->w = w;
  redraw_get_window_offset(c, &bctx->ox, &bctx->oy, &bctx->sx, &bctx->sy);

  bctx->ind = options_get_number(w->options, "pane-border-indicators");
}

/* Return a cell. */
static struct redraw_build_cell *
redraw_get_build_cell(struct redraw_build_ctx *bctx, u_int x, u_int y)
{
  return (&bctx->cells[(y * bctx->sx) + x]);
}

/* Reset cell to either empty or outside the window. */
static void
redraw_reset_cell(struct redraw_build_ctx *bctx, u_int x, u_int y)
{
  struct redraw_build_cell  *bc = redraw_get_build_cell(bctx, x, y);
  struct window     *w = bctx->w;

  memset(bc, 0, sizeof *bc);
  if (bctx->ox + x < w->sx && bctx->oy + y < w->sy)
    bc->data.type = REDRAW_SPAN_EMPTY;
  else
    bc->data.type = REDRAW_SPAN_OUTSIDE;
}

/* Convert window position to scene position. Return 0 if outside the scene. */
static int
redraw_window_to_scene(struct redraw_build_ctx *bctx, int wx, int wy,
    u_int *x, u_int *y)
{
  int sx, sy;

  if (wx < 0 || wy < 0)
    return (0);
  if ((u_int)wx > bctx->w->sx || (u_int)wy > bctx->w->sy)
    return (0);
  if (wx < (int)bctx->ox || wy < (int)bctx->oy)
    return (0);

  sx = wx - (int)bctx->ox;
  sy = wy - (int)bctx->oy;

  if ((u_int)sx >= bctx->sx || (u_int)sy >= bctx->sy)
    return (0);
  *x = sx;
  *y = sy;
  return (1);
}

/*
 * Convert pane position to scene position. Return 0 if outside the scene. A
 * floating pane is clipped to the window edge.
 */
static int
redraw_pane_to_scene(struct redraw_build_ctx *bctx, struct window_pane *wp,
    int px, int py, u_int *x, u_int *y)
{
  int wx = wp->xoff + px, wy = wp->yoff + py;
  int left, right, top, bottom;

  if (window_pane_is_floating(wp)) {
    left = wp->xoff - 1;
    right = wp->xoff + wp->sx;
    top = wp->yoff - 1;
    bottom = wp->yoff + wp->sy;

    if (left < 0 && wx < 0)
      return (0);
    if (right > (int)bctx->w->sx && wx >= (int)bctx->w->sx)
      return (0);
    if (top < 0 && wy < 0)
      return (0);
    if (bottom > (int)bctx->w->sy && wy >= (int)bctx->w->sy)
      return (0);
  }
  return (redraw_window_to_scene(bctx, wx, wy, x, y));
}

/* Convert redraw border mask to a border cell type. */
static int
redraw_get_cell_type(int mask)
{
  switch (mask) {
  case REDRAW_BORDER_L|REDRAW_BORDER_R|REDRAW_BORDER_U|REDRAW_BORDER_D:
    return (CELL_LRUD);
  case REDRAW_BORDER_L|REDRAW_BORDER_R|REDRAW_BORDER_U:
    return (CELL_LRU);
  case REDRAW_BORDER_L|REDRAW_BORDER_R|REDRAW_BORDER_D:
    return (CELL_LRD);
  case REDRAW_BORDER_L|REDRAW_BORDER_R:
  case REDRAW_BORDER_L:
  case REDRAW_BORDER_R:
    return (CELL_LR);
  case REDRAW_BORDER_L|REDRAW_BORDER_U|REDRAW_BORDER_D:
    return (CELL_ULD);
  case REDRAW_BORDER_L|REDRAW_BORDER_U:
    return (CELL_LU);
  case REDRAW_BORDER_L|REDRAW_BORDER_D:
    return (CELL_LD);
  case REDRAW_BORDER_R|REDRAW_BORDER_U|REDRAW_BORDER_D:
    return (CELL_URD);
  case REDRAW_BORDER_R|REDRAW_BORDER_U:
    return (CELL_RU);
  case REDRAW_BORDER_R|REDRAW_BORDER_D:
    return (CELL_RD);
  case REDRAW_BORDER_U|REDRAW_BORDER_D:
  case REDRAW_BORDER_U:
  case REDRAW_BORDER_D:
    return (CELL_UD);
  }
  return (CELL_NONE);
}

/* Return if there are two panes for the border colour indicator. */
static int
redraw_check_two_pane_colours(struct window *w, enum layout_type *type)
{
  struct window_pane  *wp;
  u_int      count = 0;

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

/* Mark pane inside data. */
static void
redraw_mark_pane_inside(struct redraw_build_ctx *bctx, struct window_pane *wp)
{
  struct redraw_build_cell  *bc;
  u_int        px, py, x, y;

  for (py = 0; py < wp->sy; py++) {
    for (px = 0; px < wp->sx; px++) {
      if (!redraw_pane_to_scene(bctx, wp, px, py, &x, &y))
        continue;
      bc = redraw_get_build_cell(bctx, x, y);
      memset(bc, 0, sizeof *bc);
      bc->data.type = REDRAW_SPAN_PANE;
      bc->data.p.wp = wp;
      bc->data.p.px = px;
      bc->data.p.py = py;
    }
  }
}

/* Mark scrollbar data. */
static void
redraw_mark_pane_scrollbar(struct redraw_build_ctx *bctx,
    struct window_pane *wp, int sb_w, int sb_left, int overlay)
{
  struct redraw_build_cell  *bc;
  u_int        x, y;
  int        wx, wy, sx, ex;
  u_int        sy;

  if (sb_w == 0)
    return;

  if (overlay && sb_left) {
    sx = wp->xoff;
    ex = sx + sb_w - 1;
  } else if (overlay) {
    ex = wp->xoff + (int)wp->sx - 1;
    sx = ex - sb_w + 1;
  } else if (sb_left) {
    sx = wp->xoff - sb_w;
    ex = wp->xoff - 1;
  } else {
    sx = wp->xoff + (int)wp->sx;
    ex = sx + sb_w - 1;
  }

  for (sy = 0; sy < wp->sy; sy++) {
    wy = wp->yoff + (int)sy;
    for (wx = sx; wx <= ex; wx++) {
      if (!redraw_window_to_scene(bctx, wx, wy, &x,
          &y))
        continue;
      bc = redraw_get_build_cell(bctx, x, y);
      memset(bc, 0, sizeof *bc);
      bc->data.type = REDRAW_SPAN_SCROLLBAR;
      bc->data.sb.wp = wp;
      bc->data.sb.y = sy;
      bc->data.sb.height = wp->sy;
      if (sb_left)
        bc->data.sb.flags |= REDRAW_SCROLLBAR_LEFT;
      else
        bc->data.sb.flags |= REDRAW_SCROLLBAR_RIGHT;
      if (overlay)
        bc->data.sb.flags |= REDRAW_SCROLLBAR_OVERLAY;
    }
  }
}

/*
 * Return if span data belongs to pane, that is: is the cell adjacent to this
 * pane?
 */
static int
redraw_data_has_pane(struct redraw_span_data *data, struct window_pane *wp)
{
  if (data->b.top_wp == wp)
    return (1);
  if (data->b.bottom_wp == wp)
    return (1);
  if (data->b.left_wp == wp)
    return (1);
  if (data->b.right_wp == wp)
    return (1);
  return (0);
}

/*
 * Mark one border cell. If a non-border cell is marked as a border, replace
 * it. If it is already a border and this is not a floating pane, merge the
 * border mask and pane ownership.
 */
static void
redraw_mark_border_cell(struct redraw_build_ctx *bctx, int wx, int wy,
    struct window_pane *wp, int top_owner, int bottom_owner, int mask,
    enum pane_lines pane_lines, int floating)
{
  struct redraw_build_cell  *bc;
  u_int        x, y;
  int        reset = 0, side_owner, above, left;

  if (!redraw_window_to_scene(bctx, wx, wy, &x, &y))
    return;
  bc = redraw_get_build_cell(bctx, x, y);

  /*
   * If this is a tiled pane, only empty and border cells may be marked.
   * Border cells are merged and empty cells are updated.
   *
   * Floating panes may mark any existing cell type. All cells are reset
   * except borders that already belong to this pane, they need to be
   * merged.
   */
  if (!floating) {
    if (bc->data.type == REDRAW_SPAN_EMPTY ||
        bc->data.type == REDRAW_SPAN_OUTSIDE)
      reset = 1;
    else if (bc->data.type != REDRAW_SPAN_BORDER)
      return;
  } else {
    if (bc->data.type != REDRAW_SPAN_BORDER ||
        !redraw_data_has_pane(&bc->data, wp))
      reset = 1;
  }
  if (reset) {
    memset(bc, 0, sizeof *bc);
    bc->data.type = REDRAW_SPAN_BORDER;
  }

  /*
   * A corner cell can be shared by four tiled panes, two on each side,
   * and only one pane is kept for each side. So that none is lost
   * whatever order panes are marked in, a pane keeps its corner only on
   * the side clockwise from it: a pane above and to the left of the cell
   * is the top pane, above and to the right is the right pane, and so on.
   */
  side_owner = (mask & (REDRAW_BORDER_U|REDRAW_BORDER_D));
  if (!floating &&
      (mask == REDRAW_BORDER_L ||
      mask == REDRAW_BORDER_R ||
      mask == REDRAW_BORDER_U ||
      mask == REDRAW_BORDER_D)) {
    above = (wy >= wp->yoff + (int)wp->sy);
    left = (wx >= wp->xoff + (int)wp->sx);
    top_owner = (above && left);
    bottom_owner = (!above && !left);
    side_owner = (above != left);
  }

  if (top_owner) {
    bc->data.b.top_wp = wp;
    bc->data.b.top_lines = pane_lines;
  }
  if (bottom_owner) {
    bc->data.b.bottom_wp = wp;
    bc->data.b.bottom_lines = pane_lines;
  }

  if (side_owner) {
    if (wx < wp->xoff) {
      bc->data.b.right_wp = wp;
      bc->data.b.right_lines = pane_lines;
    } else if (wx >= wp->xoff + (int)wp->sx) {
      bc->data.b.left_wp = wp;
      bc->data.b.left_lines = pane_lines;
    }
  }

  mask |= bc->data.b.cell_mask;
  bc->data.b.cell_mask = mask;
  bc->data.b.cell_type = redraw_get_cell_type(mask);
}

/*
 * Mark border cells for a pane status line, keeping the border cell type for
 * drawing.
 */
static void
redraw_mark_border_status(struct redraw_build_ctx *bctx, struct window_pane *wp,
    __unused int left, int right, int top, int bottom)
{
  struct redraw_build_cell  *bc;
  u_int        x, y, off = 0;
  int        pane_status, wy, sx, ex, wx, cell_type;

  pane_status = window_pane_get_pane_status(wp);
  if (pane_status == PANE_STATUS_OFF)
    return;
  if (pane_status == PANE_STATUS_TOP)
    wy = top;
  else
    wy = bottom;

  sx = wp->xoff + 2;
  ex = right - 1;
  if (sx > ex)
    return;

  for (wx = sx; wx <= ex; wx++, off++) {
    if (!redraw_window_to_scene(bctx, wx, wy, &x, &y))
      continue;
    bc = redraw_get_build_cell(bctx, x, y);
    if (bc->data.type != REDRAW_SPAN_BORDER)
      continue;
    cell_type = bc->data.b.cell_type;

    bc->data.type = REDRAW_SPAN_STATUS;
    bc->data.st.wp = wp;
    bc->data.st.offset = off;
    bc->data.st.cell_type = cell_type;
  }
}

/* Mark existing border cells where indicator arrows will be drawn. */
static void
redraw_mark_border_arrows(struct redraw_build_ctx *bctx, struct window_pane *wp,
    int left, int right, int top, int bottom)
{
  struct redraw_build_cell  *bc;
  u_int        x, y;
  int        wx, wy;

  if (bctx->ind != PANE_BORDER_ARROWS && bctx->ind != PANE_BORDER_BOTH)
    return;

  wx = wp->xoff + 1;
  if (wx >= left && wx <= right) {
    wy = top;
    if (redraw_window_to_scene(bctx, wx, wy, &x, &y)) {
      bc = redraw_get_build_cell(bctx, x, y);
      if (bc->data.type == REDRAW_SPAN_BORDER)
        bc->data.b.flags |= REDRAW_BORDER_IS_ARROW;
    }
    wy = bottom;
    if (redraw_window_to_scene(bctx, wx, wy, &x, &y)) {
      bc = redraw_get_build_cell(bctx, x, y);
      if (bc->data.type == REDRAW_SPAN_BORDER)
        bc->data.b.flags |= REDRAW_BORDER_IS_ARROW;
    }
  }

  wy = wp->yoff + 1;
  if (wy >= top && wy <= bottom) {
    wx = left;
    if (redraw_window_to_scene(bctx, wx, wy, &x, &y)) {
      bc = redraw_get_build_cell(bctx, x, y);
      if (bc->data.type == REDRAW_SPAN_BORDER)
        bc->data.b.flags |= REDRAW_BORDER_IS_ARROW;
    }
    wx = right;
    if (redraw_window_to_scene(bctx, wx, wy, &x, &y)) {
      bc = redraw_get_build_cell(bctx, x, y);
      if (bc->data.type == REDRAW_SPAN_BORDER)
        bc->data.b.flags |= REDRAW_BORDER_IS_ARROW;
    }
  }
}

/* Mark pane borders. */
static void
redraw_mark_pane_borders(struct redraw_build_ctx *bctx, struct window_pane *wp,
    int sb_w, int sb_left)
{
  enum pane_lines pane_lines = window_pane_get_pane_lines(wp);
  int   pane_status, left, right, top, bottom, wx, wy;
  int   mark_top, mark_bottom, mark_left, mark_right, mask = 0;
  int   floating = window_pane_is_floating(wp);

  if (floating && pane_lines == PANE_LINES_NONE)
    return;
  pane_status = window_pane_get_pane_status(wp);

  left = wp->xoff - 1;
  right = wp->xoff + wp->sx;
  if (sb_w != 0) {
    if (sb_left)
      left -= sb_w;
    else
      right += sb_w;
  }
  top = wp->yoff - 1;
  bottom = wp->yoff + wp->sy;

  mark_left = (left >= 0);
  mark_top = (top >= 0);

  if (floating) {
    mark_right = (right < (int)bctx->w->sx);
    mark_bottom = (bottom < (int)bctx->w->sy);
    if (left < 0)
      left = 0;
    if (right >= (int)bctx->w->sx)
      right = (int)bctx->w->sx - 1;
    if (top < 0)
      top = 0;
    if (bottom >= (int)bctx->w->sy)
      bottom = (int)bctx->w->sy - 1;
  } else {
    mark_right = (right <= (int)bctx->w->sx);
    mark_bottom = (bottom <= (int)bctx->w->sy);
    if (pane_status == PANE_STATUS_TOP && bottom < (int)bctx->w->sy)
      mark_bottom = 0;
    else if (pane_status == PANE_STATUS_BOTTOM)
      mark_top = 0;
  }

  if (mark_top) {
    for (wx = left; wx <= right; wx++) {
      mask = 0;
      if (wx > left)
        mask |= REDRAW_BORDER_L;
      if (wx < right)
        mask |= REDRAW_BORDER_R;
      redraw_mark_border_cell(bctx, wx, top, wp, 0, 1, mask,
          pane_lines, floating);
    }
  }
  if (mark_bottom) {
    for (wx = left; wx <= right; wx++) {
      mask = 0;
      if (wx > left)
        mask |= REDRAW_BORDER_L;
      if (wx < right)
        mask |= REDRAW_BORDER_R;
      redraw_mark_border_cell(bctx, wx, bottom, wp, 1, 0,
          mask, pane_lines, floating);
    }
  }
  if (mark_left) {
    for (wy = top; wy <= bottom; wy++) {
      mask = 0;
      if (wy > top)
        mask |= REDRAW_BORDER_U;
      if (wy < bottom)
        mask |= REDRAW_BORDER_D;
      redraw_mark_border_cell(bctx, left, wy, wp, 0, 0, mask,
          pane_lines, floating);
    }
  }
  if (mark_right) {
    for (wy = top; wy <= bottom; wy++) {
      mask = 0;
      if (wy > top)
        mask |= REDRAW_BORDER_U;
      if (wy < bottom)
        mask |= REDRAW_BORDER_D;
      redraw_mark_border_cell(bctx, right, wy, wp, 0, 0, mask,
          pane_lines, floating);
    }
  }

  redraw_mark_border_status(bctx, wp, left, right, top, bottom);
  redraw_mark_border_arrows(bctx, wp, left, right, top, bottom);
}

/*
 * Mark an entire pane in the build grid. Floating panes overwrite anything
 * already below them.
 */
static void
redraw_mark_pane(struct redraw_build_ctx *bctx, struct window_pane *wp)
{
  struct style  *sb_style = &wp->scrollbar_style;
  int    sb_w = 0, sb_left = 0, overlay = 0;

  if (!window_pane_is_visible(wp))
    return;

  if (window_pane_scrollbar_visible(wp)) {
    overlay = window_pane_scrollbar_overlay(wp);
    if (!overlay)
      sb_w = sb_style->width + sb_style->pad;
    else {
      sb_w = sb_style->width + sb_style->pad;
      if (sb_w > (int)wp->sx) {
        sb_w = sb_style->width;
        if (sb_w > (int)wp->sx)
          sb_w = wp->sx;
      }
    }
  }
  if (sb_w != 0 && bctx->w->sb_pos == PANE_SCROLLBARS_LEFT)
    sb_left = 1;

  redraw_mark_pane_inside(bctx, wp);
  redraw_mark_pane_borders(bctx, wp, overlay ? 0 : sb_w, sb_left);
  redraw_mark_pane_scrollbar(bctx, wp, sb_w, sb_left, overlay);
}

/* Choose the pane that will provide the border style for two-pane layouts. */
static void
redraw_mark_two_pane_colours(struct redraw_build_ctx *bctx)
{
  struct redraw_build_cell  *bc;
  struct redraw_span_data   *sd;
  enum layout_type     type;
  u_int        x, y, wx, wy;

  if (bctx->ind != PANE_BORDER_COLOUR && bctx->ind != PANE_BORDER_BOTH)
    return;
  if (!redraw_check_two_pane_colours(bctx->w, &type))
    return;

  for (y = 0; y < bctx->sy; y++) {
    for (x = 0; x < bctx->sx; x++) {
      bc = redraw_get_build_cell(bctx, x, y);
      if (bc->data.type != REDRAW_SPAN_BORDER)
        continue;
      sd = &bc->data;

      wx = bctx->ox + x;
      wy = bctx->oy + y;

      if (type == LAYOUT_LEFTRIGHT &&
          sd->b.left_wp != NULL &&
          sd->b.right_wp != NULL) {
        if (wy <= bctx->w->sy / 2)
          sd->b.style_wp = sd->b.left_wp;
        else
          sd->b.style_wp = sd->b.right_wp;
      } else if (type == LAYOUT_TOPBOTTOM &&
          sd->b.top_wp != NULL &&
          sd->b.bottom_wp != NULL) {
        if (wx <= bctx->w->sx / 2)
          sd->b.style_wp = sd->b.top_wp;
        else
          sd->b.style_wp = sd->b.bottom_wp;
      }
    }
  }
}

/* Mark the window menu above all panes. */
static void
redraw_mark_menu(struct redraw_build_ctx *bctx)
{
  struct menu_data    *md = bctx->w->menu;
  struct redraw_build_cell  *bc;
  u_int        px, py, x, y, sx, sy;

  if (md == NULL)
    return;

  sx = menu_width(md);
  sy = menu_height(md);
  for (py = 0; py < sy; py++) {
    for (px = 0; px < sx; px++) {
      if (!redraw_window_to_scene(bctx, menu_x(md) + px,
          menu_y(md) + py, &x, &y))
        continue;
      bc = redraw_get_build_cell(bctx, x, y);
      memset(bc, 0, sizeof *bc);
      bc->data.type = REDRAW_SPAN_MENU;
      bc->data.m.md = md;
      bc->data.m.px = px;
      bc->data.m.py = py;
    }
  }
}

/* Return true if two adjacent build cells can be joined into one span. */
static int
redraw_compare_data(struct redraw_build_cell *a, struct redraw_build_cell *b)
{
  struct redraw_span_data *ad = &a->data, *bd = &b->data;

  if (ad->type != bd->type)
    return (0);

  switch (ad->type) {
  case REDRAW_SPAN_PANE:
    if (ad->p.wp != bd->p.wp ||
        ad->p.py != bd->p.py ||
        ad->p.px + 1 != bd->p.px)
      return (0);
    return (1);
  case REDRAW_SPAN_BORDER:
    if (ad->b.top_wp != bd->b.top_wp ||
        ad->b.bottom_wp != bd->b.bottom_wp ||
        ad->b.left_wp != bd->b.left_wp ||
        ad->b.right_wp != bd->b.right_wp ||
        ad->b.style_wp != bd->b.style_wp ||
        ad->b.top_lines != bd->b.top_lines ||
        ad->b.bottom_lines != bd->b.bottom_lines ||
        ad->b.left_lines != bd->b.left_lines ||
        ad->b.right_lines != bd->b.right_lines ||
        ad->b.cell_type != bd->b.cell_type ||
        ad->b.cell_mask != bd->b.cell_mask ||
        ad->b.flags != bd->b.flags)
      return (0);
    if (ad->b.flags & REDRAW_BORDER_IS_ARROW)
      return (0);
    return (1);
  case REDRAW_SPAN_STATUS:
    if (ad->st.wp != bd->st.wp ||
        ad->st.offset + 1 != bd->st.offset ||
        ad->st.cell_type != bd->st.cell_type)
      return (0);
    return (1);
  case REDRAW_SPAN_SCROLLBAR:
    if (ad->sb.wp != bd->sb.wp ||
        ad->sb.y != bd->sb.y ||
        ad->sb.height != bd->sb.height ||
        ad->sb.flags != bd->sb.flags)
      return (0);
    return (1);
  case REDRAW_SPAN_MENU:
    if (ad->m.md != bd->m.md ||
        ad->m.py != bd->m.py ||
        ad->m.px + 1 != bd->m.px)
      return (0);
    return (1);
  case REDRAW_SPAN_OUTSIDE:
  case REDRAW_SPAN_EMPTY:
    return (1);
  }
  return (0);
}

/* Build the temporary cells for a redraw scene. */
static void
redraw_build_cells(struct redraw_build_ctx *bctx)
{
  struct window   *w = bctx->w;
  struct window_pane  *wp;
  size_t       ncells;
  u_int      x, y;

  if (bctx->sx != 0 && bctx->sy > SIZE_MAX / bctx->sx)
    fatalx("%s: too many cells", __func__);
  ncells = (size_t)bctx->sx * bctx->sy;
  if (ncells > redraw_ncells) {
    redraw_cells = xreallocarray(redraw_cells, ncells,
        sizeof *redraw_cells);
    redraw_ncells = ncells;
  }

  bctx->cells = redraw_cells;
  for (y = 0; y < bctx->sy; y++) {
    for (x = 0; x < bctx->sx; x++)
      redraw_reset_cell(bctx, x, y);
  }

  TAILQ_FOREACH_REVERSE(wp, &w->z_index, window_panes_zindex, zentry)
    redraw_mark_pane(bctx, wp);
  redraw_mark_two_pane_colours(bctx);
  redraw_mark_menu(bctx);
}

/*
 * Build and return a redraw scene for a client. The caller owns the scene and
 * must free it with redraw_free_scene.
 */
static struct redraw_scene *
redraw_make_scene(struct client *c)
{
  struct session      *s = c->session;
  struct window     *w = s->curw->window;
  struct redraw_build_ctx    bctx;
  struct redraw_scene   *scene;
  struct redraw_build_cell  *bc, *last;
  struct redraw_line    *line;
  struct redraw_span    *span;
  enum redraw_span_type    type;
  u_int        x, y, x0;

  if (c->flags & CLIENT_SUSPENDED)
    return (NULL);

  redraw_set_context(c, &bctx);

  log_debug("%s: building @%u scene (%ux%u %u,%u; generation %llu)",
      c->name, w->id, bctx.sx, bctx.sy, bctx.ox, bctx.oy,
      (unsigned long long)w->redraw_scene_generation);

  redraw_build_cells(&bctx);

  scene = xcalloc(1, sizeof *scene);
  scene->c = c;
  scene->w = w;
  scene->lines = xcalloc(bctx.sy, sizeof *scene->lines);
  scene->generation = w->redraw_scene_generation;
  scene->sx = bctx.sx;
  scene->sy = bctx.sy;
  scene->ox = bctx.ox;
  scene->oy = bctx.oy;

  for (y = 0; y < bctx.sy; y++) {
    line = &scene->lines[y];
    for (type = 0; type < REDRAW_SPAN_TYPES; type++)
      TAILQ_INIT(&line->spans[type]);

    x = 0;
    while (x < bctx.sx) {
      x0 = x;
      last = redraw_get_build_cell(&bctx, x, y);
      x++;

      while (x < bctx.sx) {
        bc = redraw_get_build_cell(&bctx, x, y);
        if (!redraw_compare_data(last, bc))
          break;
        last = bc;
        x++;
      }
      bc = redraw_get_build_cell(&bctx, x0, y);
      type = bc->data.type;

      span = xcalloc(1, sizeof *span);
      span->x = x0;
      span->width = x - x0;
      span->data = bc->data;

      TAILQ_INSERT_TAIL(&line->spans[type], span, entry);
    }
  }

  log_debug("%s: finished building @%u scene", c->name, w->id);
  return (scene);
}

/* Free a scene. */
void
redraw_free_scene(struct redraw_scene *scene)
{
  struct redraw_spans *spans;
  struct redraw_span  *span, *span1;
  u_int      y, type;

  if (scene == NULL)
    return;

  for (y = 0; y < scene->sy; y++) {
    for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
      spans = &scene->lines[y].spans[type];
      TAILQ_FOREACH_SAFE(span, spans, entry, span1) {
        TAILQ_REMOVE(spans, span, entry);
        free(span);
      }
    }
  }
  free(scene->lines);
  free(scene);
}

/* Does a client's cached scene show this window? */
int
redraw_client_has_window(struct client *c, struct window *w)
{
  return (c->redraw_scene != NULL && c->redraw_scene->w == w);
}

/*
 * Mark a window's cached redraw scenes as out of date. Generations are unique
 * across all windows so a scene can never match a new window that reuses the
 * address of a freed one.
 */
void
redraw_invalidate_scene(struct window *w)
{
  static uint64_t next_generation;

  w->redraw_scene_generation = ++next_generation;
}

/* Free all pending damage for a window. */
void
redraw_free_damage(struct window *w)
{
  struct redraw_damage  *rd, *rd1;

  TAILQ_FOREACH_SAFE(rd, &w->damage, entry, rd1) {
    TAILQ_REMOVE(&w->damage, rd, entry);
    free(rd);
  }
  w->damage_count = 0;
  w->scroll_pending = 0;
}

/* Collapse all pending damage for a window into one rectangle. */
static void
redraw_collapse_damage(struct window *w)
{
  struct redraw_damage  *rd, *rd1, *first;
  u_int      x0, y0, x1, y1;

  first = TAILQ_FIRST(&w->damage);
  if (first == NULL)
    return;
  x0 = first->x;
  y0 = first->y;
  x1 = first->x + first->sx;
  y1 = first->y + first->sy;

  TAILQ_FOREACH_SAFE(rd, &w->damage, entry, rd1) {
    if (rd->x < x0)
      x0 = rd->x;
    if (rd->y < y0)
      y0 = rd->y;
    if (rd->x + rd->sx > x1)
      x1 = rd->x + rd->sx;
    if (rd->y + rd->sy > y1)
      y1 = rd->y + rd->sy;
    first->flags &= rd->flags;
    if (rd != first) {
      TAILQ_REMOVE(&w->damage, rd, entry);
      free(rd);
    }
  }

  first->x = x0;
  first->y = y0;
  first->sx = x1 - x0;
  first->sy = y1 - y0;
  w->damage_count = 1;
}

/* Record window damage, merging nearby rectangles and limiting the count. */
static void
redraw_apply_window_damage(struct window *w, u_int x, u_int y, u_int sx,
    u_int sy, int flags)
{
  struct redraw_damage  *rd;
  u_int      x0, y0, x1, y1, area, union_area;

  if (x >= w->sx || y >= w->sy)
    return;
  if (x + sx > w->sx)
    sx = w->sx - x;
  if (y + sy > w->sy)
    sy = w->sy - y;
  if (sx == 0 || sy == 0)
    return;

  TAILQ_FOREACH(rd, &w->damage, entry) {
    if (x > rd->x + rd->sx || rd->x > x + sx ||
        y > rd->y + rd->sy || rd->y > y + sy)
      continue;

    x0 = (x < rd->x) ? x : rd->x;
    y0 = (y < rd->y) ? y : rd->y;
    x1 = (x + sx > rd->x + rd->sx) ? x + sx : rd->x + rd->sx;
    y1 = (y + sy > rd->y + rd->sy) ? y + sy : rd->y + rd->sy;

    area = sx * sy + rd->sx * rd->sy;
    union_area = (x1 - x0) * (y1 - y0);
    if (union_area > 2 * area)
      continue;

    rd->x = x0;
    rd->y = y0;
    rd->sx = x1 - x0;
    rd->sy = y1 - y0;
    rd->flags &= flags;
    return;
  }

  rd = xcalloc(1, sizeof *rd);
  rd->x = x;
  rd->y = y;
  rd->sx = sx;
  rd->sy = sy;
  rd->flags = flags;
  TAILQ_INSERT_TAIL(&w->damage, rd, entry);
  if (++w->damage_count > REDRAW_DAMAGE_MAX)
    redraw_collapse_damage(w);
}

/* Record ordinary window damage. */
void
redraw_damage_window(struct window *w, u_int x, u_int y, u_int sx, u_int sy)
{
  redraw_apply_window_damage(w, x, y, sx, sy, 0);
}

/* Record damage caused by terminal scrolling. */
void
redraw_damage_scroll(struct window *w, u_int x, u_int y, u_int sx, u_int sy)
{
  if (!w->scroll_pending) {
    w->scroll_generation++;
    w->scroll_pending = 1;
  }
  redraw_apply_window_damage(w, x, y, sx, sy, REDRAW_DAMAGE_SCROLL);
}

/* Remember whether this client used terminal scrolling for the damage. */
void
redraw_scroll_result(struct tty *tty, const struct tty_ctx *ctx, int failed)
{
  struct window_pane  *wp = ctx->arg;
  struct window   *w;

  if (wp == NULL)
    return;
  w = wp->window;
  if (!w->scroll_pending)
    return;
  if (tty->scroll_window != w ||
      tty->scroll_generation != w->scroll_generation) {
    tty->scroll_window = w;
    tty->scroll_generation = w->scroll_generation;
    tty->scroll_failed = 0;
  }
  if (failed)
    tty->scroll_failed = 1;
}

/* Mark all cached redraw scenes as out of date. */
void
redraw_invalidate_all_scenes(void)
{
  struct window *w;

  RB_FOREACH(w, windows, &windows)
    redraw_invalidate_scene(w);
}

/* Get the cached redraw scene, rebuilding it if needed. */
static struct redraw_scene *
redraw_get_scene(struct client *c)
{
  struct redraw_scene *scene = c->redraw_scene;
  struct window   *w = c->session->curw->window;
  const char    *reason = NULL;
  u_int      ox, oy, sx, sy;

  redraw_get_window_offset(c, &ox, &oy, &sx, &sy);
  if (scene == NULL)
    reason = "missing";
  else if (scene->w != w)
    reason = "window changed";
  else if (scene->generation != w->redraw_scene_generation)
    reason = "generation changed";
  else if (scene->ox != ox || scene->oy != oy)
    reason = "offset changed";
  else if (scene->sx != sx || scene->sy != sy)
    reason = "size changed";
  if (reason != NULL) {
    log_debug("%s: @%u scene invalid: %s", c->name, w->id, reason);
    redraw_free_scene(scene);
    scene = redraw_make_scene(c);
    c->redraw_scene = scene;
  }
  return (scene);
}

/* Draw a pane span. */
static void
redraw_draw_pane_span(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, u_int x, u_int y, u_int n)
{
  struct redraw_scene *scene = dctx->scene;
  struct client   *c = scene->c;
  struct tty    *tty = &c->tty;
  struct window_pane  *wp = span->data.p.wp;
  struct screen   *s = wp->screen;
  struct grid_cell   defaults;
  struct tty_style_ctx   style_ctx;
  u_int      px, py;

  tty_default_colours(&defaults, wp, &style_ctx.dim);
  style_ctx.defaults = &defaults;
  style_ctx.palette = &wp->palette;
  style_ctx.hyperlinks = s->hyperlinks;

  px = span->data.p.px + (x - dctx->side_left - span->x);
  py = span->data.p.py;
  tty_draw_line(tty, s, px, py, n, x, y, &style_ctx);
}

/* Get default border style for spans without a pane. */
static void
redraw_get_default_border_style(struct redraw_draw_ctx *dctx,
    struct grid_cell *gc, enum pane_lines *pane_lines)
{
  struct redraw_scene *scene = dctx->scene;
  struct client   *c = scene->c;
  struct session    *s = c->session;
  struct options    *oo = scene->w->options;
  struct format_tree  *ft;
  struct grid_cell  *dgc = &dctx->default_gc;

  if (~dctx->flags & REDRAW_DEFAULT_SET) {
    ft = format_create_defaults(NULL, c, s, s->curw, NULL);
    memcpy(dgc, &grid_default_cell, sizeof *dgc);
    style_add(dgc, oo, "pane-border-style", ft);
    format_free(ft);
    dctx->pane_lines = options_get_number(oo, "pane-border-lines");
    dctx->flags |= REDRAW_DEFAULT_SET;
  }
  memcpy(gc, dgc, sizeof *gc);
  *pane_lines = dctx->pane_lines;
}

/*
 * For this border span, pick the pane whose border style should colour it.
 * Prefer an explicitly assigned style owner, then the active adjacent pane,
 * then any adjacent pane.
 */
static struct window_pane *
redraw_get_pane_for_border_style(struct redraw_draw_ctx *dctx,
    struct redraw_span *span)
{
  struct window_pane  *active = dctx->active;

  if (span->data.type != REDRAW_SPAN_BORDER)
    return (NULL);

  if (span->data.b.style_wp != NULL)
    return (span->data.b.style_wp);
  if (active != NULL && redraw_data_has_pane(&span->data, active))
    return (active);

  if (span->data.b.top_wp != NULL)
    return (span->data.b.top_wp);
  if (span->data.b.bottom_wp != NULL)
    return (span->data.b.bottom_wp);
  if (span->data.b.left_wp != NULL)
    return (span->data.b.left_wp);
  if (span->data.b.right_wp != NULL)
    return (span->data.b.right_wp);
  return (NULL);
}

/* Draw arrow indicator if this border span is an arrow cell. */
static void
redraw_draw_border_arrow(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, struct grid_cell *gc)
{
  struct window_pane  *active = dctx->active;
  char       ch;

  if (span->data.type != REDRAW_SPAN_BORDER || active == NULL)
    return;
  if (~span->data.b.flags & REDRAW_BORDER_IS_ARROW)
    return;

  if (span->data.b.left_wp == active)
    ch = ',';
  else if (span->data.b.right_wp == active)
    ch = '+';
  else if (span->data.b.top_wp == active)
    ch = '-';
  else if (span->data.b.bottom_wp == active)
    ch = '.';
  else
    return;

  utf8_set(&gc->data, ch);
  gc->attr |= GRID_ATTR_CHARSET;
}

/* Draw a border span. */
static void
redraw_draw_border_span(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, u_int x, u_int y, u_int n)
{
  struct redraw_scene *scene = dctx->scene;
  struct client   *c = scene->c;
  struct tty    *tty = &c->tty;
  struct window   *w = scene->w;
  struct window_pane  *wp = NULL;
  struct grid_cell   gc;
  enum pane_lines    pane_lines;
  u_int      i, cell_type;
  int      isolates = 0;

  if (span->data.type != REDRAW_SPAN_BORDER)
    cell_type = CELL_NONE;
  else {
    wp = redraw_get_pane_for_border_style(dctx, span);
    cell_type = span->data.b.cell_type;
  }

  if (wp == NULL) {
    redraw_get_default_border_style(dctx, &gc, &pane_lines);
    if (span->data.type == REDRAW_SPAN_OUTSIDE)
      window_get_fill_cell(w, 0, &gc);
    else if (span->data.type == REDRAW_SPAN_EMPTY)
      window_get_fill_cell(w, 1, &gc);
    else {
      if (span->data.type != REDRAW_SPAN_BORDER)
        pane_lines = PANE_LINES_SINGLE;
      window_get_border_cell(NULL, pane_lines, cell_type, &gc);
    }
  } else {
    window_pane_get_border_style(wp, c, &gc);
    window_pane_get_border_cell(wp, cell_type, &gc);
  }

  if (span->data.type == REDRAW_SPAN_BORDER &&
      dctx->marked != NULL &&
      redraw_data_has_pane(&span->data, dctx->marked))
    gc.attr ^= GRID_ATTR_REVERSE;
  redraw_draw_border_arrow(dctx, span, &gc);

  if (cell_type == CELL_UD && (dctx->flags & REDRAW_ISOLATES))
    isolates = 1;
  tty_cursor(tty, x, y);
  if (isolates)
    tty_puts(tty, REDRAW_END_ISOLATE);
  for (i = 0; i < n; i++)
    tty_cell(tty, &gc, NULL);
  if (isolates)
    tty_puts(tty, REDRAW_START_ISOLATE);
}

/* Draw a pane status span. */
static void
redraw_draw_status_span(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, u_int x, u_int y, u_int n)
{
  struct redraw_scene *scene = dctx->scene;
  struct client   *c = scene->c;
  struct tty    *tty = &c->tty;
  struct window_pane  *wp = span->data.st.wp;
  struct screen   *s = &wp->status_screen;
  u_int      px, sx = screen_size_x(s);

  px = span->data.st.offset + (x - dctx->side_left - span->x);
  if (px < sx) {
    if (n > sx - px)
      n = sx - px;
    tty_draw_line(tty, s, px, 0, n, x, y, NULL);
  }
}

/* Draw a scrollbar span. */
static void
redraw_draw_scrollbar_span(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, u_int x, u_int y, u_int n)
{
  struct redraw_scene *scene = dctx->scene;
  struct window_pane  *wp = span->data.sb.wp;
  struct screen   *s = wp->screen;
  struct tty    *tty = &scene->c->tty;
  struct style    *sb_style = &wp->scrollbar_style;
  struct grid_cell   gc, slgc, pad_gc, *gcp;
  double       pct_view;
  u_int      total_height, slider_h, slider_y;
  u_int      sb_h = span->data.sb.height;
  u_int      sb_y = span->data.sb.y;
  u_int      i, off, sb_w, sb_pad;
  int      cm_y, cm_size;

  if (window_pane_mode(wp) == WINDOW_PANE_NO_MODE) {
    total_height = screen_size_y(s) + screen_hsize(s);
    if (total_height == 0)
      return;
    pct_view = (double)sb_h / total_height;
    slider_h = (double)sb_h * pct_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;
    if (total_height == 0)
      return;
    pct_view = (double)sb_h / total_height;
    slider_h = (double)sb_h * pct_view;
    slider_y = (sb_h + 1) * ((double)cm_y / total_height);
  }

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

  wp->sb_slider_y = slider_y;
  wp->sb_slider_h = slider_h;

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

  sb_w = sb_style->width;
  sb_pad = sb_style->pad;
  off = x - dctx->side_left - span->x;

  tty_cursor(tty, x, y);
  for (i = 0; i < n; i++) {
    if (span->data.sb.flags & REDRAW_SCROLLBAR_LEFT) {
      if (off + i >= sb_w && off + i < sb_w + sb_pad) {
        tty_cell(tty, &pad_gc, NULL);
        continue;
      }
    } else {
      if (off + i < sb_pad) {
        tty_cell(tty, &pad_gc, NULL);
        continue;
      }
    }

    if (sb_y >= slider_y && sb_y < slider_y + slider_h)
      gcp = &slgc;
    else
      gcp = &gc;
    tty_cell(tty, gcp, NULL);
  }
}

/* Draw a menu span. */
static void
redraw_draw_menu_span(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, u_int x, u_int y, u_int n)
{
  struct redraw_scene *scene = dctx->scene;
  struct tty    *tty = &scene->c->tty;
  struct screen   *s = menu_screen(span->data.m.md);
  u_int      px;

#ifdef ENABLE_IMAGES
  image_redraw_start(tty, x, y, n, 1);
#endif
  px = span->data.m.px + (x - dctx->side_left - span->x);
  tty_draw_line(tty, s, px, span->data.m.py, n, x, y, NULL);
}

/* Draw a span. */
static void
redraw_draw_span(struct redraw_draw_ctx *dctx, struct redraw_span *span,
    u_int y, enum redraw_phase phase)
{
  struct redraw_span_data *data = &span->data;
  enum redraw_span_type  type = data->type;
  u_int      x = dctx->side_left + span->x;
  u_int      width = span->width;

  if (type == REDRAW_SPAN_STATUS && ~data->st.wp->flags & PANE_NEWSTATUS)
    return;
  if (phase != REDRAW_TEXT && type != REDRAW_SPAN_PANE)
    return;

  switch (span->data.type) {
  case REDRAW_SPAN_PANE:
    if (phase == REDRAW_TEXT)
      redraw_draw_pane_span(dctx, span, x, y, width);
#ifdef ENABLE_IMAGES
    else {
      image_draw_line(&dctx->scene->c->tty, data->p.wp->screen,
          data->p.px, data->p.py, width, x, y);
    }
#endif
    break;
  case REDRAW_SPAN_BORDER:
  case REDRAW_SPAN_EMPTY:
  case REDRAW_SPAN_OUTSIDE:
    redraw_draw_border_span(dctx, span, x, y, width);
    break;
  case REDRAW_SPAN_STATUS:
    redraw_draw_status_span(dctx, span, x, y, width);
    break;
  case REDRAW_SPAN_SCROLLBAR:
    redraw_draw_scrollbar_span(dctx, span, x, y, width);
    break;
  case REDRAW_SPAN_MENU:
    redraw_draw_menu_span(dctx, span, x, y, width);
    break;
  }
}

/* Draw pane lines. */
static void
redraw_draw_pane_lines(struct redraw_draw_ctx *dctx, struct window_pane *wp,
    int flags)
{
  struct redraw_scene *scene = dctx->scene;
  struct redraw_line  *line;
  struct redraw_spans *spans;
  struct redraw_span  *span;
  enum redraw_phase  phase;
  u_int      cy;
  int      y, top, bottom;

  top = wp->yoff - (int)scene->oy;
  if (top < 0)
    top = 0;
  bottom = wp->yoff + (int)wp->sy - (int)scene->oy;
  if (bottom < 0)
    bottom = 0;
  if (bottom > (int)scene->sy)
    bottom = scene->sy;

#ifdef ENABLE_IMAGES
  /* Erase only pane-owned spans so overlapping panes remain intact. */
  if (flags & REDRAW_PANE) {
    for (y = top; y < bottom; y++) {
      line = &scene->lines[y];
      if (dctx->flags & REDRAW_STATUS_TOP)
        cy = dctx->status_lines + y;
      else
        cy = y;
      spans = &line->spans[REDRAW_SPAN_PANE];
      TAILQ_FOREACH(span, spans, entry) {
        if (span->data.p.wp == wp) {
          image_redraw_start(&scene->c->tty,
              dctx->side_left + span->x, cy,
              span->width, 1);
        }
      }
    }
  }
#endif

  /* Draw each phase. */
  for (phase = 0; phase < REDRAW_PHASE_COUNT; phase++) {
    for (y = top; y < bottom; y++) {
      line = &scene->lines[y];
      if (dctx->flags & REDRAW_STATUS_TOP)
        cy = dctx->status_lines + y;
      else
        cy = y;
      if (flags & REDRAW_PANE) {
        spans = &line->spans[REDRAW_SPAN_PANE];
        TAILQ_FOREACH(span, spans, entry) {
          if (span->data.p.wp != wp)
            continue;
          redraw_draw_span(dctx, span, cy, phase);
        }
      }
      if (phase == REDRAW_TEXT &&
          (flags & REDRAW_PANE_SCROLLBAR)) {
        spans = &line->spans[REDRAW_SPAN_SCROLLBAR];
        TAILQ_FOREACH(span, spans, entry) {
          if (span->data.sb.wp != wp)
            continue;
          redraw_draw_span(dctx, span, cy, phase);
        }
      }
    }
#ifdef ENABLE_IMAGES
    image_draw_flush(&scene->c->tty);
#endif
  }
}

/* Return whether to draw a span type in this phase for these flags. */
static int
redraw_should_draw(enum redraw_span_type type, int flags,
    enum redraw_phase phase)
{
  if (phase != REDRAW_TEXT && type != REDRAW_SPAN_PANE)
    return (0);
  if (REDRAW_IS_ALL(flags))
    return (1);

  switch (type) {
  case REDRAW_SPAN_PANE:
    return (flags & REDRAW_PANE);
  case REDRAW_SPAN_OUTSIDE:
    return (flags & REDRAW_OUTSIDE);
  case REDRAW_SPAN_EMPTY:
    return (flags & REDRAW_EMPTY);
  case REDRAW_SPAN_BORDER:
    return (flags & REDRAW_PANE_BORDER);
  case REDRAW_SPAN_STATUS:
    return (flags & REDRAW_PANE_STATUS);
  case REDRAW_SPAN_SCROLLBAR:
    return (flags & REDRAW_PANE_SCROLLBAR);
  case REDRAW_SPAN_MENU:
    return (flags & REDRAW_MENU);
  default:
    return (0);
  }
}

/* Draw lines. */
static void
redraw_draw_lines(struct redraw_draw_ctx *dctx, int flags)
{
  struct redraw_scene *scene = dctx->scene;
  struct redraw_line  *line;
  struct redraw_spans *spans;
  struct redraw_span  *span;
  enum redraw_phase  phase;
  u_int      y, cy, type;

  /* Draw each phase. */
  for (phase = 0; phase < REDRAW_PHASE_COUNT; phase++) {
    for (y = 0; y < scene->sy; y++) {
      line = &scene->lines[y];
      if (dctx->flags & REDRAW_STATUS_TOP)
        cy = dctx->status_lines + y;
      else
        cy = y;
      for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
        if (!redraw_should_draw(type, flags, phase))
          continue;
        spans = &line->spans[type];
        TAILQ_FOREACH(span, spans, entry)
          redraw_draw_span(dctx, span, cy, phase);
      }
    }
#ifdef ENABLE_IMAGES
    image_draw_flush(&scene->c->tty);
#endif
  }
}

/* Draw menu spans. */
static void
redraw_draw_menu_lines(struct redraw_draw_ctx *dctx)
{
  struct redraw_scene *scene = dctx->scene;
  struct redraw_line  *line;
  struct redraw_span  *span;
  u_int      y, cy;

  for (y = 0; y < scene->sy; y++) {
    line = &scene->lines[y];
    if (dctx->flags & REDRAW_STATUS_TOP)
      cy = dctx->status_lines + y;
    else
      cy = y;
    TAILQ_FOREACH(span, &line->spans[REDRAW_SPAN_MENU], entry)
      redraw_draw_span(dctx, span, cy, REDRAW_TEXT);
  }
}

/* Get line for pane status line. */
static int
redraw_pane_status_line(struct redraw_draw_ctx *dctx,
    struct window_pane *wp, u_int *line)
{
  struct redraw_scene *scene = dctx->scene;
  int      pane_status, wy;

  pane_status = window_pane_get_pane_status(wp);
  if (pane_status == PANE_STATUS_OFF)
    return (0);

  if (pane_status == PANE_STATUS_TOP)
    wy = (int)wp->yoff - 1;
  else
    wy = (int)wp->yoff + wp->sy;
  if (wy < 0 || wy < (int)scene->oy)
    return (0);
  if ((u_int)wy >= scene->oy + scene->sy)
    return (0);
  *line = wy - scene->oy;
  return (1);
}

/* Get available width for pane status line. */
static u_int
redraw_pane_status_width(struct redraw_draw_ctx *dctx,
    struct window_pane *wp, struct redraw_span **first)
{
  struct redraw_scene *scene = dctx->scene;
  struct redraw_span  *span;
  u_int      y, width = 0, end;

  if (!redraw_pane_status_line(dctx, wp, &y))
    return (0);

  *first = NULL;
  TAILQ_FOREACH(span, &scene->lines[y].spans[REDRAW_SPAN_STATUS], entry) {
    if (span->data.st.wp == wp) {
      if (*first == NULL)
          *first = span;
      end = span->data.st.offset + span->width;
      if (end > width)
        width = end;
    }
  }
  return (width);
}

/* Set up draw context. */
static void
redraw_set_draw_context(struct redraw_draw_ctx *dctx,
    struct redraw_scene *scene)
{
  struct client *c = scene->c;
  struct session  *s = c->session;
  struct options  *oo = s->options;
  struct tty  *tty = &c->tty;
  u_int    lines;

  memset(dctx, 0, sizeof *dctx);
  dctx->scene = scene;

  if (server_is_marked(s, s->curw, marked_pane.wp))
    dctx->marked = marked_pane.wp;
  dctx->active = s->curw->window->active;

  lines = status_line_size(c);
  if (options_get_number(oo, "status-position") == 0)
    dctx->flags |= REDRAW_STATUS_TOP;
  dctx->status_lines = lines;

  if (status_side_at_column(c) == 0)
    dctx->side_left = status_side_size(c);

  if ((c->flags & CLIENT_UTF8) && tty_term_has(tty->term, TTYC_BIDI))
    dctx->flags |= REDRAW_ISOLATES;
}

/* Build a pane prompt. */
static void
redraw_make_pane_prompt(struct window_pane *wp, struct screen *screen)
{
  struct screen_write_ctx  ctx;
  struct prompt_draw_data  pdd;

  screen_init(screen, wp->sx, 1, 0);
  screen_write_start(&ctx, screen);
  pdd.ctx = &ctx;
  pdd.cursor_x = &wp->prompt_cx;
  pdd.area_x = 0;
  pdd.area_width = wp->sx;
  pdd.prompt_line = 0;
  prompt_draw(wp->prompt, &pdd);
  screen_write_stop(&ctx);
}

/* Draw a pane's prompt over its content. */
static void
redraw_draw_pane_prompt(struct redraw_draw_ctx *dctx, struct window_pane *wp)
{
  struct redraw_scene *scene = dctx->scene;
  struct client   *c = scene->c;
  struct tty    *tty = &c->tty;
  struct screen    screen;
  int      ox = scene->ox, oy = scene->oy;
  int      sx = scene->sx, sy = scene->sy;
  int      line, cy, px, offset, width, wy;
  u_int      side_left = dctx->side_left;

  if (wp->prompt == NULL || wp->sx == 0 || wp->sy == 0)
    return;

  if (~dctx->flags & REDRAW_STATUS_TOP)
    wy = wp->yoff + (int)wp->sy - 1;
  else
    wy = wp->yoff;
  if (wy < oy || wy >= oy + sy)
    return;
  line = wy - oy;
  if (dctx->flags & REDRAW_STATUS_TOP)
    cy = dctx->status_lines + line;
  else
    cy = line;

  if (wp->xoff + (int)wp->sx <= ox || wp->xoff >= ox + sx)
    return;
  if (wp->xoff < ox) {
    offset = ox - wp->xoff;
    px = 0;
  } else {
    offset = 0;
    px = wp->xoff - ox;
  }
  width = wp->sx - offset;
  if (px + width > sx)
    width = sx - px;

#ifdef ENABLE_IMAGES
  image_redraw_start(tty, side_left + px, cy, width, 1);
#endif
  redraw_make_pane_prompt(wp, &screen);
  tty_draw_line(tty, &screen, offset, 0, width, side_left + px, cy, NULL);
  screen_free(&screen);
}

/* Draw scene to client. */
static void
redraw_draw(struct client *c, struct window_pane *wp, int flags)
{
  struct redraw_draw_ctx   dctx;
  struct session    *s = c->session;
  struct window   *w = s->curw->window;
  struct tty    *tty = &c->tty;
  struct screen   *sl;
  struct redraw_scene *scene;
  struct window_pane  *loop;
  u_int      width, i, y, lines, side_width;
  int      side_x;
  struct redraw_span  *first;
  int      redraw;

  if (c->flags & CLIENT_SUSPENDED)
    return;

  if (flags & REDRAW_STATUS) {
    if (c->message_string != NULL)
      redraw = status_message_redraw(c);
    else if (c->prompt != NULL)
      redraw = status_prompt_redraw(c);
    else
      redraw = status_redraw(c);
    if (!redraw &&
        (~c->flags & CLIENT_REDRAWSTATUSALWAYS) &&
        !REDRAW_IS_ALL(flags)) {
      flags &= ~REDRAW_STATUS;
      if (flags == 0)
        return;
    }
  }

  if (flags & REDRAW_SIDE_STATUS) {
    if (!status_side_redraw(c) &&
        (~c->flags & CLIENT_REDRAWSTATUSALWAYS) &&
        !REDRAW_IS_ALL(flags)) {
      flags &= ~REDRAW_SIDE_STATUS;
      if (flags == 0)
        return;
    }
  }

  if (log_get_level() != 0) {
    log_debug("%s: starting @%u redraw (%s)", c->name, w->id,
        redraw_flags_to_string(flags));
  }

  scene = redraw_get_scene(c);
  if (scene == NULL)
    return;
  redraw_set_draw_context(&dctx, scene);
  if (w->menu != NULL)
    menu_update(w->menu);

  if (flags & (REDRAW_PANE_BORDER|REDRAW_PANE_STATUS)) {
    TAILQ_FOREACH(loop, &scene->w->panes, entry) {
      loop->border_gc_set = 0;
      loop->active_border_gc_set = 0;
    }
  }

  if (flags & REDRAW_PANE_STATUS) {
    redraw = 0;
    TAILQ_FOREACH(loop, &scene->w->panes, entry) {
      if (REDRAW_IS_ALL(flags))
        loop->flags |= PANE_NEWSTATUS;
      else
        loop->flags &= ~PANE_NEWSTATUS;

      width = redraw_pane_status_width(&dctx, loop, &first);
      if (width == 0)
        continue;

      if (window_make_pane_status(loop, c, width, first)) {
        loop->flags |= PANE_NEWSTATUS;
        redraw = 1;
      }
    }
    if (!redraw && !REDRAW_IS_ALL(flags)) {
      flags &= ~REDRAW_PANE_STATUS;
      if (flags == 0)
        return;
    }
  }

  if (flags & REDRAW_PANE) {
    if (wp != NULL) {
      if (wp->base.mode & MODE_SYNC)
        screen_write_stop_sync(wp);
      screen_write_sync_clear_dirty(wp);
    } else {
      TAILQ_FOREACH(loop, &scene->w->panes, entry) {
        if (!window_pane_is_visible(loop))
          continue;
        if (loop->base.mode & MODE_SYNC)
          screen_write_stop_sync(loop);
        screen_write_sync_clear_dirty(loop);
      }
    }
  }
  tty_sync_start(tty); /* end in server_client_reset_state */
#ifdef ENABLE_IMAGES
  if (wp == NULL && (flags & REDRAW_PANE)) {
    y = 0;
    if (dctx.flags & REDRAW_STATUS_TOP)
      y = dctx.status_lines;
    image_redraw_start(tty, dctx.side_left, y, scene->sx,
        scene->sy);
  }
#endif
  tty_update_mode(tty, tty->mode & ~CURSOR_MODES, NULL);

  if (wp != NULL)
    redraw_draw_pane_lines(&dctx, wp, flags);
  else
    redraw_draw_lines(&dctx, flags);

  if (flags & REDRAW_PANE) {
    if (wp != NULL)
      redraw_draw_pane_prompt(&dctx, wp);
    else {
      TAILQ_FOREACH(loop, &scene->w->panes, entry) {
        if (window_pane_is_visible(loop))
          redraw_draw_pane_prompt(&dctx, loop);
      }
    }
  }
  if (w->menu != NULL && (flags & REDRAW_MENU))
    redraw_draw_menu_lines(&dctx);

  if (flags & REDRAW_SIDE_STATUS) {
    side_width = status_side_size(c);
    side_x = status_side_at_column(c);
    if (side_width != 0 && side_x != -1) {
      if (dctx.flags & REDRAW_STATUS_TOP)
        y = dctx.status_lines;
      else
        y = 0;
      for (i = 0; i < status_side_rows(c); i++) {
        tty_draw_line(tty, &c->side_status.screen, 0, i,
            side_width, side_x, y + i, NULL);
      }
    }
  }

  if (flags & REDRAW_STATUS) {
    lines = dctx.status_lines;
    if (c->message_string != NULL || c->prompt != NULL)
      lines = (lines == 0 ? 1 : lines);
    if (dctx.flags & REDRAW_STATUS_TOP)
      y = 0;
    else
      y = c->tty.sy - lines;
    sl = c->status.active;
    for (i = 0; i < lines; i++)
      tty_draw_line(tty, sl, 0, i, tty->sx, 0, y + i, NULL);
  }

#ifdef ENABLE_IMAGES
  image_redraw_finish(tty);
#endif

  tty_reset(tty);

  log_debug("%s: finished @%u redraw", c->name, scene->w->id);
}

/* Get border cell type beneath status cell at offset x in pane status line. */
int
redraw_get_status_border_cell_type(struct redraw_span **spanp, u_int x)
{
  struct redraw_span  *span = *spanp;
  struct window_pane  *wp;
  u_int      start, end;

  if (span == NULL || span->data.type != REDRAW_SPAN_STATUS)
    return (CELL_LR);
  wp = span->data.st.wp;
  for (; span != NULL; span = TAILQ_NEXT(span, entry)) {
    if (span->data.type != REDRAW_SPAN_STATUS)
      continue;
    if (span->data.st.wp != wp)
      continue;

    start = span->data.st.offset;
    end = start + span->width;
    if (x >= start && x < end) {
      *spanp = span;
      return (span->data.st.cell_type);
    }

    if (start > x) {
      *spanp = span;
      break;
    }
  }
  if (span == NULL)
    *spanp = NULL;
  return (CELL_LR);
}

/* Draw screen. */
void
redraw_screen(struct client *c)
{
  int flags = 0;

  if (c->flags & CLIENT_REDRAWWINDOW)
    redraw_draw(c, NULL, REDRAW_ALL);
  else {
    if (c->flags & CLIENT_REDRAWBORDERS)
      flags |= (REDRAW_PANE_BORDER|REDRAW_PANE_STATUS);
    if (c->flags & (CLIENT_REDRAWSTATUS|CLIENT_REDRAWSTATUSALWAYS))
      flags |= (REDRAW_STATUS|REDRAW_PANE_STATUS|
          REDRAW_SIDE_STATUS);
    if (c->flags & CLIENT_REDRAWMENU)
      flags |= REDRAW_MENU;
    if (c->session->curw->window->menu != NULL)
      flags |= REDRAW_MENU;
    if (flags != 0)
      redraw_draw(c, NULL, flags);
  }
}

/* Draw a single pane. */
void
redraw_pane(struct client *c, struct window_pane *wp)
{
  redraw_draw(c, wp, REDRAW_PANE|REDRAW_PANE_SCROLLBAR);
  if (c->session->curw->window->menu != NULL)
    redraw_draw(c, NULL, REDRAW_MENU);
}

/* Draw a pane's scrollbar. */
void
redraw_pane_scrollbar(struct client *c, struct window_pane *wp)
{
  redraw_draw(c, wp, REDRAW_PANE_SCROLLBAR);
}

/* Rebuild damaged pane status. */
static void
redraw_damage_refresh_status(struct redraw_draw_ctx *dctx,
    struct window_pane *wp)
{
  struct redraw_span  *first;
  u_int      g = wp->status_generation, width;

  if ((wp->flags & PANE_NEWSTATUS) && g == redraw_status_generation)
    return;
  width = redraw_pane_status_width(dctx, wp, &first);
  if (width != 0) {
    window_make_pane_status(wp, dctx->scene->c, width, first);
    wp->flags |= PANE_NEWSTATUS;
    wp->status_generation = redraw_status_generation;
  }
}

/* Draw a pane's prompt over a damaged span. */
static void
redraw_damage_draw_pane_prompt(struct redraw_draw_ctx *dctx,
    struct redraw_span *span, u_int y)
{
  struct redraw_scene *scene = dctx->scene;
  struct window_pane  *wp = span->data.p.wp;
  struct tty    *tty = &scene->c->tty;
  struct screen    screen;
  u_int      px = span->data.p.px, width, prompt_y;
  u_int      x = dctx->side_left + span->x;

  if (wp->prompt == NULL || wp->sx == 0 || wp->sy == 0)
    return;
  if (dctx->flags & REDRAW_STATUS_TOP)
    prompt_y = 0;
  else
    prompt_y = wp->sy - 1;
  if (span->data.p.py != prompt_y)
    return;
  redraw_make_pane_prompt(wp, &screen);
  if (px < screen_size_x(&screen)) {
    width = span->width;
    if (width > screen_size_x(&screen) - px)
      width = screen_size_x(&screen) - px;
#ifdef ENABLE_IMAGES
    image_redraw_start(tty, x, y, width, 1);
#endif
    tty_draw_line(tty, &screen, px, 0, width, x, y, NULL);
  }
  screen_free(&screen);
}

/* Draw the spans intersecting a damaged rectangle. */
static void
redraw_draw_damage_rectangle(struct redraw_draw_ctx *dctx, u_int x, u_int y,
    u_int sx, u_int sy)
{
  struct redraw_scene *scene = dctx->scene;
  struct redraw_line  *line;
  struct redraw_spans *spans;
  struct redraw_span  *span;
  enum redraw_phase  phase;
  u_int      cy, yy, type;

  if (x >= scene->sx || y >= scene->sy)
    return;
  if (x + sx > scene->sx)
    sx = scene->sx - x;
  if (y + sy > scene->sy)
    sy = scene->sy - y;
  if (sx == 0 || sy == 0)
    return;

#ifdef ENABLE_IMAGES
  /* Clear old image pixels on all damaged spans. */
  for (yy = y; yy < y + sy; yy++) {
    line = &scene->lines[yy];
    if (dctx->flags & REDRAW_STATUS_TOP)
      cy = dctx->status_lines + yy;
    else
      cy = yy;
    for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
      if (type == REDRAW_SPAN_STATUS)
        continue;
      spans = &line->spans[type];
      TAILQ_FOREACH(span, spans, entry) {
        if (span->x >= x + sx)
          continue;
        if (span->x + span->width <= x)
          continue;
        image_redraw_start(&scene->c->tty,
            dctx->side_left + span->x, cy,
            span->width, 1);
      }
    }
  }
#endif

  /* Draw each phase in the damaged spans. */
  for (phase = 0; phase < REDRAW_PHASE_COUNT; phase++) {
    for (yy = y; yy < y + sy; yy++) {
      line = &scene->lines[yy];
      if (dctx->flags & REDRAW_STATUS_TOP)
        cy = dctx->status_lines + yy;
      else
        cy = yy;
      for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
        if (phase != REDRAW_TEXT &&
            type != REDRAW_SPAN_PANE)
          continue;
        if (type == REDRAW_SPAN_STATUS)
          continue;
        spans = &line->spans[type];
        TAILQ_FOREACH(span, spans, entry) {
          if (span->x >= x + sx)
            continue;
          if (span->x + span->width <= x)
            continue;
          redraw_draw_span(dctx, span, cy, phase);
        }
      }
    }
#ifdef ENABLE_IMAGES
    image_draw_flush(&scene->c->tty);
#endif
  }

  /* Draw prompts and pane status lines last. */
  for (yy = y; yy < y + sy; yy++) {
    line = &scene->lines[yy];
    if (dctx->flags & REDRAW_STATUS_TOP)
      cy = dctx->status_lines + yy;
    else
      cy = yy;
    spans = &line->spans[REDRAW_SPAN_PANE];
    TAILQ_FOREACH(span, spans, entry) {
      if (span->x >= x + sx)
        continue;
      if (span->x + span->width <= x)
        continue;
      redraw_damage_draw_pane_prompt(dctx, span, cy);
    }
    spans = &line->spans[REDRAW_SPAN_STATUS];
    TAILQ_FOREACH(span, spans, entry) {
      if (span->x >= x + sx)
        continue;
      if (span->x + span->width <= x)
        continue;
      redraw_damage_refresh_status(dctx, span->data.st.wp);
      redraw_draw_span(dctx, span, cy, REDRAW_TEXT);
    }
  }
#ifdef ENABLE_IMAGES
  image_redraw_finish(&scene->c->tty);
#endif
}

/* Draw pending window damage on this client. */
void
redraw_client_damage(struct client *c)
{
  struct window   *w = c->session->curw->window;
  struct tty    *tty = &c->tty;
  struct window_pane  *wp;
  struct redraw_scene *scene;
  struct redraw_draw_ctx   dctx;
  struct redraw_damage  *rd;
  u_int      ox, oy, sx, sy, x0, y0, x1, y1;

  if (TAILQ_EMPTY(&w->damage))
    return;
  redraw_status_generation++;

  scene = redraw_get_scene(c);
  if (scene == NULL)
    return;
  redraw_set_draw_context(&dctx, scene);
  redraw_get_window_offset(c, &ox, &oy, &sx, &sy);

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

  tty_sync_start(tty);
  tty_update_mode(tty, tty->mode & ~CURSOR_MODES, NULL);

  TAILQ_FOREACH(rd, &w->damage, entry) {
#ifdef ENABLE_IMAGES
    if ((rd->flags & REDRAW_DAMAGE_SCROLL) &&
        (image_backend_get_flags(tty) & IMAGE_BACKEND_SCROLLS) &&
        tty->scroll_window == w &&
        tty->scroll_generation == w->scroll_generation &&
        !tty->scroll_failed)
      continue;
#endif
    x0 = (rd->x > ox) ? rd->x : ox;
    y0 = (rd->y > oy) ? rd->y : oy;
    x1 = (rd->x + rd->sx < ox + sx) ? rd->x + rd->sx : ox + sx;
    y1 = (rd->y + rd->sy < oy + sy) ? rd->y + rd->sy : oy + sy;
    if (x0 < x1 && y0 < y1) {
      redraw_draw_damage_rectangle(&dctx, x0 - ox, y0 - oy,
          x1 - x0, y1 - y0);
    }
  }
}

Coverage Report

Created: 2026-10-28 06:08