/src/tmux/layout.c

Source
/* $OpenBSD: layout.c,v 1.98 2026/08/25 18:38:05 nicm Exp $ */

/*
 * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
 * Copyright (c) 2016 Stephen Kent <smkent@smkent.net>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>

#include "tmux.h"

/*
 * The window layout is a tree of cells each of which can be one of: a
 * left-right container for a list of cells, a top-bottom container for a list
 * of cells, or a container for a window pane. 'Node' will be used to refer to
 * a cell which contains a list of cells, and 'leaf' to refer to a cell that
 * contains a window pane. A leaf is considered to be 'tiled' if it is to be
 * drawn as a part of the tiled layout. A 'neighbour' is a sibling that is also
 * tiled or a node that contains a tiled leaf in a subtree. A cell's 'split'
 * size refers to the side that is shortened when splitting it, determined by
 * the parent's type.
 *
 * Each window has a pointer to the root of its layout tree (containing its
 * panes), every pane has a pointer back to the cell containing it, and each
 * cell a pointer to its parent cell. Every cell has a position in the root
 * layout tree. This position is retained through cell state changes such as
 * floating or hiding.
 */

static u_int  layout_resize_check(struct window *, struct layout_cell *,
        enum layout_type);
static int  layout_resize_pane_grow(struct window *, struct layout_cell *,
        enum layout_type, int, int);
static int  layout_resize_pane_shrink(struct window *, struct layout_cell *,
        enum layout_type, int);
static u_int  layout_new_pane_size(struct window *, u_int,
        struct layout_cell *, enum layout_type, u_int, u_int,
        u_int);
static int  layout_set_size_check(struct window *, struct layout_cell *,
        enum layout_type, int);
static void layout_resize_child_cells(struct window *,
        struct layout_cell *);

/* Initializes cell geometry to sentinel values. */
static void
layout_geometry_init(struct layout_geometry *lg)
{
  lg->sx = UINT_MAX;
  lg->sy = UINT_MAX;
  lg->xoff = INT_MAX;
  lg->yoff = INT_MAX;
}

/* Create a new layout cell. */
struct layout_cell *
layout_create_cell(struct layout_cell *lcparent)
{
  struct layout_cell  *lc;

  lc = xcalloc(1, sizeof *lc);
  lc->type = LAYOUT_WINDOWPANE;
  lc->parent = lcparent;
  TAILQ_INIT(&lc->cells);

  layout_geometry_init(&lc->g);
  layout_geometry_init(&lc->fg);

  return (lc);
}

/* Free a layout cell. */
void
layout_free_cell(struct layout_cell *lc, int only_nodes)
{
  struct layout_cell  *lcchild, *lcnext;

  if (lc == NULL || (only_nodes && lc->type == LAYOUT_WINDOWPANE))
    return;

  switch (lc->type) {
  case LAYOUT_LEFTRIGHT:
  case LAYOUT_TOPBOTTOM:
    lcchild = TAILQ_FIRST(&lc->cells);
    while (lcchild != NULL) {
      lcnext = TAILQ_NEXT(lcchild, entry);
      if (!only_nodes || lcchild->type != LAYOUT_WINDOWPANE) {
        TAILQ_REMOVE(&lc->cells, lcchild, entry);
        layout_free_cell(lcchild, only_nodes);
      }
      lcchild = lcnext;
    }
    break;
  case LAYOUT_WINDOWPANE:
    if (lc->wp != NULL) {
      lc->wp->layout_cell->parent = NULL;
      lc->wp->layout_cell = NULL;
    }
    break;
  }

  free(lc);
}

/* Log a cell. */
void
layout_print_cell(struct layout_cell *lc, const char *hdr, u_int n)
{
  struct layout_cell  *lcchild;
  const char    *type;

  if (lc == NULL)
    return;

  switch (lc->type) {
  case LAYOUT_LEFTRIGHT:
    type = "LEFTRIGHT";
    break;
  case LAYOUT_TOPBOTTOM:
    type = "TOPBOTTOM";
    break;
  case LAYOUT_WINDOWPANE:
    type = "WINDOWPANE";
    break;
  default:
    type = "UNKNOWN";
    break;
  }
  log_debug("%s:%*s%p type %s [parent %p] wp=%p [%d,%d %ux%u]", hdr, n,
      " ", lc, type, lc->parent, lc->wp, lc->g.xoff, lc->g.yoff, lc->g.sx,
      lc->g.sy);
  switch (lc->type) {
  case LAYOUT_LEFTRIGHT:
  case LAYOUT_TOPBOTTOM:
    TAILQ_FOREACH(lcchild, &lc->cells, entry)
      layout_print_cell(lcchild, hdr, n + 1);
    break;
  case LAYOUT_WINDOWPANE:
    break;
  }
}

/* Search for a cell by the border position. */
struct layout_cell *
layout_search_by_border(struct layout_cell *lc, u_int x, u_int y)
{
  struct layout_cell  *lcchild, *last = NULL;

  TAILQ_FOREACH(lcchild, &lc->cells, entry) {
    if ((int)x >= lcchild->g.xoff &&
        (int)x < lcchild->g.xoff + (int)lcchild->g.sx &&
        (int)y >= lcchild->g.yoff &&
        (int)y < lcchild->g.yoff + (int)lcchild->g.sy) {
      /* Inside the cell - recurse. */
      return (layout_search_by_border(lcchild, x, y));
    }

    if (last == NULL) {
      last = lcchild;
      continue;
    }

    switch (lc->type) {
    case LAYOUT_LEFTRIGHT:
      if ((int)x < lcchild->g.xoff &&
          (int)x >= last->g.xoff + (int)last->g.sx)
        return (last);
      break;
    case LAYOUT_TOPBOTTOM:
      if ((int)y < lcchild->g.yoff &&
          (int)y >= last->g.yoff + (int)last->g.sy)
        return (last);
      break;
    case LAYOUT_WINDOWPANE:
      break;
    }

    last = lcchild;
  }

  return (NULL);
}

/* Set cell size. */
void
layout_set_size(struct layout_cell *lc, u_int sx, u_int sy, int xoff, int yoff)
{
  lc->g.sx = sx;
  lc->g.sy = sy;

  lc->g.xoff = xoff;
  lc->g.yoff = yoff;
}

/* Make a cell a leaf cell. */
void
layout_make_leaf(struct layout_cell *lc, struct window_pane *wp)
{
  lc->type = LAYOUT_WINDOWPANE;

  TAILQ_INIT(&lc->cells);

  wp->layout_cell = lc;
  lc->wp = wp;
}

/* Make a cell a node cell. */
void
layout_make_node(struct layout_cell *lc, enum layout_type type)
{
  if (type == LAYOUT_WINDOWPANE)
    fatalx("bad layout type");
  lc->type = type;

  TAILQ_INIT(&lc->cells);

  if (lc->wp != NULL)
    lc->wp->layout_cell = NULL;
  lc->wp = NULL;
}

/* Fix z-indexes. */
void
layout_fix_zindexes(struct window *w, struct layout_cell *lc)
{
  struct layout_cell  *lcchild;

  if (lc == NULL)
    return;

  switch (lc->type) {
  case LAYOUT_WINDOWPANE:
    TAILQ_INSERT_TAIL(&w->z_index, lc->wp, zentry);
    break;
  case LAYOUT_LEFTRIGHT:
  case LAYOUT_TOPBOTTOM:
    TAILQ_FOREACH(lcchild, &lc->cells, entry)
      layout_fix_zindexes(w, lcchild);
    return;
  default:
    fatalx("bad layout type");
  }
}

int
layout_cell_is_tiled(struct layout_cell *lc)
{
  int is_leaf = lc->type == LAYOUT_WINDOWPANE;
  int is_floating = lc->flags & LAYOUT_CELL_FLOATING;

  return is_leaf && !is_floating;
}

static int
layout_cell_has_tiled_child(struct layout_cell *lc)
{
  struct layout_cell      *lcchild;

  if (lc->type == LAYOUT_WINDOWPANE)
    return (0);

  TAILQ_FOREACH(lcchild, &lc->cells, entry) {
    if (layout_cell_is_tiled(lcchild) ||
        layout_cell_has_tiled_child(lcchild))
      return (1);
  }
  return (0);
}

static int
layout_cell_is_first_tiled(struct layout_cell *lc)
{
  struct layout_cell      *lcchild, *lcparent = lc->parent;

  if (lcparent == NULL)
    return (layout_cell_is_tiled(lc));

  TAILQ_FOREACH(lcchild, &lcparent->cells, entry) {
    if (layout_cell_is_tiled(lcchild) ||
        layout_cell_has_tiled_child(lcchild))
      break;
  }

  return (lcchild == lc);
}

static struct layout_cell *
layout_cell_get_first_tiled(struct layout_cell *lc)
{
  struct layout_cell  *lcchild, *lcchild2;

  if (layout_cell_is_tiled(lc))
    return (lc);
  if (lc->type == LAYOUT_WINDOWPANE)
    return (NULL);

  TAILQ_FOREACH(lcchild, &lc->cells, entry) {
    if (layout_cell_is_tiled(lcchild))
      return (lcchild);
    if (lcchild->type != LAYOUT_WINDOWPANE) {
      lcchild2 = layout_cell_get_first_tiled(lcchild);
      if (lcchild2 != NULL)
        return (lcchild2);
    }
  }
  return (NULL);
}

/* Fix cell offsets for a child cell. */
static void
layout_fix_offsets1(struct layout_cell *lc)
{
  struct layout_cell  *lcchild;
  int      xoff, yoff;

  if (lc->type == LAYOUT_LEFTRIGHT) {
    xoff = lc->g.xoff;
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      if (!layout_cell_is_tiled(lcchild) &&
          !layout_cell_has_tiled_child(lcchild))
        continue;
      lcchild->g.xoff = xoff;
      lcchild->g.yoff = lc->g.yoff;
      if (lcchild->type != LAYOUT_WINDOWPANE)
        layout_fix_offsets1(lcchild);
      xoff += lcchild->g.sx + 1;
    }
  } else {
    yoff = lc->g.yoff;
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      if (!layout_cell_is_tiled(lcchild) &&
          !layout_cell_has_tiled_child(lcchild))
        continue;
      lcchild->g.xoff = lc->g.xoff;
      lcchild->g.yoff = yoff;
      if (lcchild->type != LAYOUT_WINDOWPANE)
        layout_fix_offsets1(lcchild);
      yoff += lcchild->g.sy + 1;
    }
  }
}

/* Update cell offsets based on their sizes. */
void
layout_fix_offsets(struct window *w)
{
  struct layout_cell  *lc = w->layout_root;

  /* Root consists of a single floating cell */
  if (lc->flags & LAYOUT_CELL_FLOATING)
    return;

  lc->g.xoff = 0;
  lc->g.yoff = 0;

  layout_fix_offsets1(lc);
}

static int
layout_cell_is_last_tiled(struct layout_cell *lc)
{
  struct layout_cell      *lcchild, *lcparent = lc->parent;

  if (lcparent == NULL)
    return (layout_cell_is_tiled(lc));

  TAILQ_FOREACH_REVERSE(lcchild, &lcparent->cells, layout_cells, entry) {
    if (layout_cell_is_tiled(lcchild) ||
        layout_cell_has_tiled_child(lcchild))
      break;
  }

  return (lcchild == lc);
}

/* Is this a top cell? */
static int
layout_cell_is_top(struct layout_cell *root, struct layout_cell *lc)
{
  struct layout_cell  *next;

  while (lc != root) {
    next = lc->parent;
    if (next == NULL)
      return (0);
    if (next->type == LAYOUT_TOPBOTTOM &&
        !layout_cell_is_first_tiled(lc))
      return (0);
    lc = next;
  }
  return (1);
}

/* Is this a bottom cell? */
static int
layout_cell_is_bottom(struct layout_cell *root, struct layout_cell *lc)
{
  struct layout_cell  *next;

  while (lc != root) {
    next = lc->parent;
    if (next == NULL)
      return (0);
    if (next->type == LAYOUT_TOPBOTTOM &&
        !layout_cell_is_last_tiled(lc))
      return (0);
    lc = next;
  }
  return (1);
}

/*
 * Returns 1 if we need to add an extra line for the pane status line. This is
 * the case for the most upper or lower panes only.
 */
int
layout_add_horizontal_border(struct layout_cell *root, struct layout_cell *lc,
    int status)
{
  if (status == PANE_STATUS_TOP)
    return (layout_cell_is_top(root, lc));
  if (status == PANE_STATUS_BOTTOM)
    return (layout_cell_is_bottom(root, lc));
  return (0);
}

/* Update pane offsets and sizes based on their cells. */
void
layout_fix_panes(struct window *w, struct window_pane *skip)
{
  struct window_pane  *wp;
  struct layout_cell  *lc, *root = w->layout_root;
  int      status, sb_w, sb_pad;
  int      old_xoff, old_yoff, changed = 0;
  u_int      sx, sy, old_sx, old_sy;

  TAILQ_FOREACH(wp, &w->panes, entry) {
    if ((lc = wp->layout_cell) == NULL || wp == skip)
      continue;

    old_xoff = wp->xoff;
    old_yoff = wp->yoff;
    old_sx = wp->sx;
    old_sy = wp->sy;

    wp->xoff = lc->g.xoff;
    wp->yoff = lc->g.yoff;
    sx = lc->g.sx;
    sy = lc->g.sy;

    status = window_pane_get_pane_status(wp);
    if (!window_pane_is_floating(wp) &&
        layout_add_horizontal_border(root, lc, status)) {
      if (status == PANE_STATUS_TOP)
        wp->yoff++;
      if (sy > 1)
        sy--;
    }

    if (window_pane_scrollbar_reserve(wp)) {
      sb_w = wp->scrollbar_style.width;
      sb_pad = wp->scrollbar_style.pad;
      if (sb_w < 1)
        sb_w = 1;
      if (sb_pad < 0)
        sb_pad = 0;
      if (w->sb_pos == PANE_SCROLLBARS_LEFT) {
        if ((int)sx - sb_w - sb_pad < PANE_MINIMUM) {
          wp->xoff = wp->xoff +
              (int)sx - PANE_MINIMUM;
          sx = PANE_MINIMUM;
        } else {
          sx = sx - sb_w - sb_pad;
          wp->xoff = wp->xoff + sb_w + sb_pad;
        }
      } else /* sb_pos == PANE_SCROLLBARS_RIGHT */
        if ((int)sx - sb_w - sb_pad < PANE_MINIMUM)
          sx = PANE_MINIMUM;
        else
          sx = sx - sb_w - sb_pad;
      wp->flags |= PANE_REDRAWSCROLLBAR;
    }

    window_pane_resize(wp, sx, sy);

    if (wp->xoff != old_xoff ||
        wp->yoff != old_yoff ||
        wp->sx != old_sx ||
        wp->sy != old_sy)
      changed = 1;
  }
  if (changed)
    redraw_invalidate_scene(w);
}

/* Count the number of available cells in a layout. */
u_int
layout_count_cells(struct layout_cell *lc)
{
  struct layout_cell  *lcchild;
  u_int      count = 0;

  switch (lc->type) {
  case LAYOUT_WINDOWPANE:
    return (1);
  case LAYOUT_LEFTRIGHT:
  case LAYOUT_TOPBOTTOM:
    TAILQ_FOREACH(lcchild, &lc->cells, entry)
      count += layout_count_cells(lcchild);
    return (count);
  default:
    fatalx("bad layout type");
  }
}

/* Calculate how much size is available to be removed from a cell. */
static u_int
layout_resize_check(struct window *w, struct layout_cell *lc,
    enum layout_type type)
{
  struct layout_cell  *lcchild, *root = w->layout_root;
  struct style    *sb_style = &w->active->scrollbar_style;
  u_int      available, minimum;
  int      status;

  status = window_get_pane_status(w);

  /* Floating cells do not take space from the tiled layout. */
  if (!layout_cell_is_tiled(lc) && !layout_cell_has_tiled_child(lc))
    return (0);

  if (lc->type == LAYOUT_WINDOWPANE) {
    /* Space available in this cell only. */
    if (type == LAYOUT_LEFTRIGHT) {
      available = lc->g.sx;
      if (w->sb == PANE_SCROLLBARS_ALWAYS)
        minimum = PANE_MINIMUM + sb_style->width +
            sb_style->pad;
      else
        minimum = PANE_MINIMUM;
    } else {
      available = lc->g.sy;
      if (layout_add_horizontal_border(root, lc, status))
        minimum = PANE_MINIMUM + 1;
      else
        minimum = PANE_MINIMUM;
    }
    if (available > minimum)
      available -= minimum;
    else
      available = 0;
  } else if (lc->type == type) {
    /* Same type: total of available space in all child cells. */
    available = 0;
    TAILQ_FOREACH(lcchild, &lc->cells, entry)
      available += layout_resize_check(w, lcchild, type);
  } else {
    /* Different type: minimum of available space in child cells. */
    minimum = UINT_MAX;
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      if (!layout_cell_is_tiled(lcchild) &&
          !layout_cell_has_tiled_child(lcchild))
        continue;
      available = layout_resize_check(w, lcchild, type);
      if (available < minimum)
        minimum = available;
    }
    available = minimum;
  }

  return (available);
}

/*
 * Adjust cell size evenly, including altering its children. This function
 * expects the change to have already been bounded to the space available.
 */
void
layout_resize_adjust(struct window *w, struct layout_cell *lc,
    enum layout_type type, int change)
{
  struct layout_cell  *lcchild;
  int      changed;

  /* Adjust the cell size. */
  if (type == LAYOUT_LEFTRIGHT)
    lc->g.sx += change;
  else
    lc->g.sy += change;

  /* If this is a leaf cell, that is all that is necessary. */
  if (type == LAYOUT_WINDOWPANE)
    return;

  /* Child cell runs in a different direction. */
  if (lc->type != type) {
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      if (!layout_cell_is_tiled(lcchild) &&
          !layout_cell_has_tiled_child(lcchild))
        continue;
      layout_resize_adjust(w, lcchild, type, change);
    }
    return;
  }

  /*
   * If a node doesn't contain any tiled cells, there is nothing to do.
   */
  if (!layout_cell_has_tiled_child(lc))
    return;

  /*
   * Child cell runs in the same direction. Adjust each child equally
   * until no further change is possible.
   */
  while (change != 0) {
    changed = 0;
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      if (change == 0)
        break;
      if (!layout_cell_is_tiled(lcchild) &&
          !layout_cell_has_tiled_child(lcchild))
        continue;
      if (change > 0) {
        layout_resize_adjust(w, lcchild, type, 1);
        change--;
        changed = 1;
        continue;
      }
      if (layout_resize_check(w, lcchild, type) > 0) {
        layout_resize_adjust(w, lcchild, type, -1);
        change++;
        changed = 1;
      }
    }
    if (!changed)
      break;
  }
}

/* Resizes a cell to a specified size */
void
layout_resize_set_size(struct window *w, struct layout_cell *lc,
    enum layout_type type, u_int size)
{
  int change;

  if (type == LAYOUT_LEFTRIGHT)
    change = size - lc->g.sx;
  else
    change = size - lc->g.sy;
  layout_resize_adjust(w, lc, type, change);
}

/* Find and return the nearest neighbour to a cell in a specific direction. */
static struct layout_cell *
layout_cell_get_neighbour_dir(struct layout_cell *lc, int direction)
{
  struct layout_cell  *lcn = lc;

  while (1) {
    if (direction)
      lcn = TAILQ_NEXT(lcn, entry);
    else
      lcn = TAILQ_PREV(lcn, layout_cells, entry);

    if (lcn == NULL ||
        layout_cell_is_tiled(lcn) ||
        layout_cell_has_tiled_child(lcn))
      return (lcn);
  }
}

/*
 * Find and return the nearest neighbour. Prefers cells "after" the specified
 * cell. This behavior defines how cell dimensions are redistributed when a cell
 * is hidden/shown and floated/tiled.
 */
struct layout_cell *
layout_cell_get_neighbour(struct layout_cell *lc)
{
  struct layout_cell  *lcother, *lcparent = lc->parent;
  int      direction = 1;

  if (lcparent == NULL)
    return (NULL);

  if (lc == TAILQ_LAST(&lcparent->cells, layout_cells))
    direction = !direction;

  lcother = layout_cell_get_neighbour_dir(lc, direction);
  if (lcother == NULL)
    lcother = layout_cell_get_neighbour_dir(lc, !direction);

  return (lcother);
}


/* Destroy a cell and redistribute the space. */
void
layout_destroy_cell(struct window *w, struct layout_cell *lc,
    struct layout_cell **lcroot)
{
  struct layout_cell  *lcother = NULL, *lcparent;
  int      change;

  /* If no parent, this is the last pane in a window. */
  lcparent = lc->parent;
  if (lcparent == NULL) {
    if (lc->wp != NULL)
      *lcroot = NULL;
    layout_free_cell(lc, 0);
    return;
  }

  if (!layout_cell_is_tiled(lc)) {
    TAILQ_REMOVE(&lcparent->cells, lc, entry);
    layout_free_cell(lc, 0);
    goto out;
  }

  lcother = layout_cell_get_neighbour(lc);
  if (lcother != NULL) {
    if (lcparent->type == LAYOUT_LEFTRIGHT)
      change = lc->g.sx + 1;
    else
      change = lc->g.sy + 1;
    layout_resize_adjust(w, lcother, lcparent->type, change);
  } else
    layout_remove_tile(w, lcparent);

  /* Remove this from the parent's list. */
  TAILQ_REMOVE(&lcparent->cells, lc, entry);
  layout_free_cell(lc, 0);

out:
  /*
   * If the parent now has one cell, remove the parent from the tree and
   * replace it by that cell.
   */
  lc = TAILQ_FIRST(&lcparent->cells);
  if (lc != NULL && TAILQ_NEXT(lc, entry) == NULL) {
    TAILQ_REMOVE(&lcparent->cells, lc, entry);

    lc->parent = lcparent->parent;
    if (lc->parent == NULL) {
      if (layout_cell_is_tiled(lc)) {
        lc->g.xoff = 0;
        lc->g.yoff = 0;
      }
      *lcroot = lc;
    } else
      TAILQ_REPLACE(&lc->parent->cells, lcparent, lc, entry);

    layout_free_cell(lcparent, 0);
  }
}

/* Initialize layout for pane. */
void
layout_init(struct window *w, struct window_pane *wp)
{
  struct layout_cell  *lc;

  lc = w->layout_root = layout_create_cell(NULL);
  layout_set_size(lc, w->sx, w->sy, 0, 0);
  layout_make_leaf(lc, wp);
  layout_fix_panes(w, NULL);
}

/* Free layout for pane. */
void
layout_free(struct window *w, int only_nodes)
{
  layout_free_cell(w->layout_root, only_nodes);
}

/* Resize the entire layout after window resize. */
void
layout_resize(struct window *w, u_int sx, u_int sy)
{
  struct layout_cell  *lc = w->layout_root;
  int      xlimit, ylimit, xchange, ychange;

  /*
   * Adjust horizontally. Do not attempt to reduce the layout lower than
   * the minimum (more than the amount returned by layout_resize_check).
   *
   * This can mean that the window size is smaller than the total layout
   * size: redrawing this is handled at a higher level, but it does leave
   * a problem with growing the window size here: if the current size is
   * < the minimum, growing proportionately by adding to each pane is
   * wrong as it would keep the layout size larger than the window size.
   * Instead, spread the difference between the minimum and the new size
   * out proportionately - this should leave the layout fitting the new
   * window size.
   */
  if (lc->type == LAYOUT_WINDOWPANE && (lc->flags & LAYOUT_CELL_FLOATING))
    return;
  xchange = sx - lc->g.sx;
  xlimit = layout_resize_check(w, lc, LAYOUT_LEFTRIGHT);
  if (xchange < 0 && xchange < -xlimit)
    xchange = -xlimit;
  if (xlimit == 0) {
    if (sx <= lc->g.sx) /* lc->g.sx is minimum possible */
      xchange = 0;
    else
      xchange = sx - lc->g.sx;
  }
  if (xchange != 0)
    layout_resize_adjust(w, lc, LAYOUT_LEFTRIGHT, xchange);

  /* Adjust vertically in a similar fashion. */
  ychange = sy - lc->g.sy;
  ylimit = layout_resize_check(w, lc, LAYOUT_TOPBOTTOM);
  if (ychange < 0 && ychange < -ylimit)
    ychange = -ylimit;
  if (ylimit == 0) {
    if (sy <= lc->g.sy) /* lc->g.sy is minimum possible */
      ychange = 0;
    else
      ychange = sy - lc->g.sy;
  }
  if (ychange != 0)
    layout_resize_adjust(w, lc, LAYOUT_TOPBOTTOM, ychange);

  /* Fix cell offsets. */
  layout_fix_offsets(w);
  layout_fix_panes(w, NULL);
}

/* Resize a pane to an absolute size. */
void
layout_resize_pane_to(struct window_pane *wp, enum layout_type type,
    u_int new_size)
{
  struct layout_cell     *lc, *lcparent;
  int     change, size;

  lc = wp->layout_cell;

  /* Find next parent of the same type. */
  lcparent = lc->parent;
  while (lcparent != NULL && lcparent->type != type) {
    lc = lcparent;
    lcparent = lc->parent;
  }
  if (lcparent == NULL)
    return;

  /* Work out the size adjustment. */
  if (type == LAYOUT_LEFTRIGHT)
    size = lc->g.sx;
  else
    size = lc->g.sy;
  if (layout_cell_is_last_tiled(lc))
    change = size - new_size;
  else
    change = new_size - size;

  /* Resize the pane. */
  layout_resize_pane(wp, type, change, 1);
}

/* Resize a floating pane to an absolute size. */
int
layout_resize_floating_pane_to(struct window_pane *wp, enum layout_type type,
    u_int size, char **cause)
{
  struct layout_cell  *lc = wp->layout_cell;

  if (~lc->flags & LAYOUT_CELL_FLOATING) {
    *cause = xstrdup("pane is not floating");
    return (-1);
  }

  if (window_pane_get_pane_lines(wp) != PANE_LINES_NONE &&
      size >= PANE_MINIMUM + 2)
    size -= 2;
  if (size < PANE_MINIMUM || size > PANE_MAXIMUM) {
    *cause = xstrdup("size is too big or too small");
    return (-1);
  }

  if (type == LAYOUT_TOPBOTTOM) {
    if (lc->g.sy == size)
      return (0);
    lc->g.sy = size;
  } else {
    if (lc->g.sx == size)
      return (0);
    lc->g.sx = size;
  }
  redraw_invalidate_scene(wp->window);
  return (0);
}

/* Resize a floating pane relative to its current size. */
int
layout_resize_floating_pane(struct window_pane *wp, enum layout_type type,
    int change, int opposite, char **cause)
{
  struct layout_cell  *lc = wp->layout_cell;
  u_int      size;

  if (~lc->flags & LAYOUT_CELL_FLOATING) {
    *cause = xstrdup("pane is not floating");
    return (-1);
  }
  if (change == 0)
    return (0);

  if (type == LAYOUT_TOPBOTTOM) {
    size = lc->g.sy + change;
    if (size < PANE_MINIMUM || size > PANE_MAXIMUM) {
      *cause = xstrdup("change is too big or too small");
      return (-1);
    }
    lc->g.sy = size;
    if (opposite)
      lc->g.yoff -= change;
  } else {
    size = lc->g.sx + change;
    if (size < PANE_MINIMUM || size > PANE_MAXIMUM) {
      *cause = xstrdup("change is too big or too small");
      return (-1);
    }
    lc->g.sx = size;
    if (opposite)
      lc->g.xoff -= change;
  }
  redraw_invalidate_scene(wp->window);
  return (0);
}

/* Resize a layout cell. */
void
layout_resize_layout(struct window *w, struct layout_cell *lc,
    enum layout_type type, int change, int opposite)
{
  int needed, size;

  /* Grow or shrink the cell. */
  needed = change;
  while (needed != 0) {
    if (change > 0) {
      size = layout_resize_pane_grow(w, lc, type, needed,
          opposite);
      needed -= size;
    } else {
      size = layout_resize_pane_shrink(w, lc, type, needed);
      needed += size;
    }

    if (size == 0) /* no more change possible */
      break;
  }

  /* Fix cell offsets. */
  layout_fix_offsets(w);
  layout_fix_panes(w, NULL);
  events_fire_window("window-layout-changed", w);
}

/* Resize a single pane within the layout. */
void
layout_resize_pane(struct window_pane *wp, enum layout_type type, int change,
    int opposite)
{
  struct layout_cell  *lc = wp->layout_cell, *lcparent;

  /* Find next parent of the same type. */
  lcparent = lc->parent;
  while (lcparent != NULL && lcparent->type != type) {
    lc = lcparent;
    lcparent = lc->parent;
  }
  if (lcparent == NULL)
    return;

  /* If this is the last tiled cell, move back one. */
  if (layout_cell_is_last_tiled(lc)) {
    lc = layout_cell_get_neighbour_dir(lc, 0);
    if (lc == NULL)
      return;
  }

  layout_resize_layout(wp->window, lc, type, change, opposite);
}

/* Helper function to grow pane. */
static int
layout_resize_pane_grow(struct window *w, struct layout_cell *lc,
    enum layout_type type, int needed, int opposite)
{
  struct layout_cell  *lcadd, *lcremove;
  u_int      size = 0;

  /* Growing. Always add to the current cell. */
  lcadd = lc;

  /* Look towards the tail for a suitable cell for reduction. */
  lcremove = layout_cell_get_neighbour_dir(lc, 1);
  while (lcremove != NULL) {
    size = layout_resize_check(w, lcremove, type);
    if (size > 0)
      break;
    lcremove = layout_cell_get_neighbour_dir(lcremove, 1);
  }

  /* If none found, look towards the head. */
  if (opposite && lcremove == NULL) {
    lcremove = layout_cell_get_neighbour_dir(lc, 0);
    while (lcremove != NULL) {
      size = layout_resize_check(w, lcremove, type);
      if (size > 0)
        break;
      lcremove = layout_cell_get_neighbour_dir(lcremove, 0);
    }
  }
  if (lcremove == NULL)
    return (0);

  /* Change the cells. */
  if (size > (u_int) needed)
    size = needed;
  layout_resize_adjust(w, lcadd, type, size);
  layout_resize_adjust(w, lcremove, type, -size);
  return (size);
}

/* Helper function to shrink pane. */
static int
layout_resize_pane_shrink(struct window *w, struct layout_cell *lc,
    enum layout_type type, int needed)
{
  struct layout_cell  *lcadd, *lcremove;
  u_int      size;

  /* Shrinking. Find cell to remove from by walking towards head. */
  lcremove = lc;
  do {
    size = layout_resize_check(w, lcremove, type);
    if (size != 0)
      break;
    lcremove = layout_cell_get_neighbour_dir(lcremove, 0);
  } while (lcremove != NULL);
  if (lcremove == NULL)
    return (0);

  /* And add onto the next cell (from the original cell). */
  lcadd = layout_cell_get_neighbour_dir(lc, 1);
  if (lcadd == NULL)
    return (0);

  /* Change the cells. */
  if (size > (u_int) -needed)
    size = -needed;
  layout_resize_adjust(w, lcadd, type, size);
  layout_resize_adjust(w, lcremove, type, -size);
  return (size);
}

/* Assign window pane to new cell. */
void
layout_assign_pane(struct layout_cell *lc, struct window_pane *wp,
    int do_not_resize)
{
  layout_make_leaf(lc, wp);
  if (do_not_resize)
    layout_fix_panes(wp->window, wp);
  else
    layout_fix_panes(wp->window, NULL);
}

/* Calculate the new pane size for resized parent. */
static u_int
layout_new_pane_size(struct window *w, u_int previous, struct layout_cell *lc,
    enum layout_type type, u_int size, u_int count_left, u_int size_left)
{
  u_int new_size, min, max, available;

  /* If this is the last cell, it can take all of the remaining size. */
  if (count_left == 1)
    return (size_left);

  /* How much is available in this parent? */
  available = layout_resize_check(w, lc, type);

  /*
   * Work out the minimum size of this cell and the new size
   * proportionate to the previous size.
   */
  min = (PANE_MINIMUM + 1) * (count_left - 1);
  if (type == LAYOUT_LEFTRIGHT) {
    if (lc->g.sx - available > min)
      min = lc->g.sx - available;
    new_size = (lc->g.sx * size) / previous;
  } else {
    if (lc->g.sy - available > min)
      min = lc->g.sy - available;
    new_size = (lc->g.sy * size) / previous;
  }

  /* Check against the maximum and minimum size. */
  max = size_left - min;
  if (new_size > max)
    new_size = max;
  if (new_size < PANE_MINIMUM)
    new_size = PANE_MINIMUM;
  return (new_size);
}

/* Check if the cell and all its children can be resized to a specific size. */
static int
layout_set_size_check(struct window *w, struct layout_cell *lc,
    enum layout_type type, int size)
{
  struct layout_cell  *lcchild;
  u_int      new_size, available, previous, count, idx;

  /* Cells with no children must just be bigger than minimum. */
  if (lc->type == LAYOUT_WINDOWPANE)
    return (size >= PANE_MINIMUM);
  available = size;

  /* Count number of children. */
  count = 0;
  TAILQ_FOREACH(lcchild, &lc->cells, entry)
    count++;

  /* Check new size will work for each child. */
  if (lc->type == type) {
    if (available < (count * 2) - 1)
      return (0);

    if (type == LAYOUT_LEFTRIGHT)
      previous = lc->g.sx;
    else
      previous = lc->g.sy;

    idx = 0;
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      new_size = layout_new_pane_size(w, previous, lcchild,
          type, size, count - idx, available);
      if (idx == count - 1) {
        if (new_size > available)
          return (0);
        available -= new_size;
      } else {
        if (new_size + 1 > available)
          return (0);
        available -= new_size + 1;
      }
      if (!layout_set_size_check(w, lcchild, type, new_size))
        return (0);
      idx++;
    }
  } else {
    TAILQ_FOREACH(lcchild, &lc->cells, entry) {
      if (lcchild->type == LAYOUT_WINDOWPANE)
        continue;
      if (!layout_set_size_check(w, lcchild, type, size))
        return (0);
    }
  }

  return (1);
}

/* Resize all child cells to fit within the current cell. */
static void
layout_resize_child_cells(struct window *w, struct layout_cell *lc)
{
  struct layout_cell  *lcchild;
  u_int      prev, available, count, idx;

  if (lc->type == LAYOUT_WINDOWPANE)
    return;

  /* What is the current size used? */
  count = 0;
  prev = 0;
  TAILQ_FOREACH(lcchild, &lc->cells, entry) {
    if (!layout_cell_is_tiled(lcchild) &&
        !layout_cell_has_tiled_child(lcchild))
      continue;
    count++;
    if (lc->type == LAYOUT_LEFTRIGHT)
      prev += lcchild->g.sx;
    else if (lc->type == LAYOUT_TOPBOTTOM)
      prev += lcchild->g.sy;
  }
  prev += (count - 1);

  /* And how much is available? */
  available = 0;
  if (lc->type == LAYOUT_LEFTRIGHT)
    available = lc->g.sx;
  else if (lc->type == LAYOUT_TOPBOTTOM)
    available = lc->g.sy;

  /* Resize children into the new size. */
  idx = 0;
  TAILQ_FOREACH(lcchild, &lc->cells, entry) {
    if (!layout_cell_is_tiled(lcchild) &&
        !layout_cell_has_tiled_child(lcchild))
      continue;
    if (lc->type == LAYOUT_TOPBOTTOM) {
      lcchild->g.sx = lc->g.sx;
      lcchild->g.xoff = lc->g.xoff;
    } else {
      lcchild->g.sx = layout_new_pane_size(w, prev, lcchild,
          lc->type, lc->g.sx, count - idx, available);
      available -= (lcchild->g.sx + 1);
    }
    if (lc->type == LAYOUT_LEFTRIGHT) {
      lcchild->g.sy = lc->g.sy;
      lcchild->g.yoff = lc->g.yoff;
    } else {
      lcchild->g.sy = layout_new_pane_size(w, prev, lcchild,
          lc->type, lc->g.sy, count - idx, available);
      available -= (lcchild->g.sy + 1);
    }
    layout_resize_child_cells(w, lcchild);
    idx++;
  }
}

/*
 * Replaces the provided layout cell with a new node of the specified type and
 * inserts the cell into it. Used when creating new cells requires a different
 * layout type, or when the root layout is a window pane.
 */
struct layout_cell *
layout_replace_with_node(struct window *w, struct layout_cell *lc,
    enum layout_type type)
{
  struct layout_cell  *lcparent;

  lcparent = layout_create_cell(lc->parent);
  layout_make_node(lcparent, type);
  layout_set_size(lcparent, lc->g.sx, lc->g.sy, lc->g.xoff, lc->g.yoff);
  if (lc->parent == NULL)
    w->layout_root = lcparent;
  else
    TAILQ_REPLACE(&lc->parent->cells, lc, lcparent, entry);

  /* Insert the old cell. */
  lc->parent = lcparent;
  TAILQ_INSERT_HEAD(&lcparent->cells, lc, entry);

  return (lcparent);
}

/* Checks if there is enough space for two new panes. */
int
layout_split_check_space(struct window_pane *wp, struct layout_cell *lc,
   enum layout_type type)
{
  struct layout_cell  *root = wp->window->layout_root;
  struct style    *sb_style = &wp->scrollbar_style;
  u_int      minimum, sx = lc->g.sx, sy = lc->g.sy;
  int      status;

  if (lc->flags & LAYOUT_CELL_FLOATING)
    fatalx("floating cells cannot be split");

  status = window_get_pane_status(wp->window);

  switch (type) {
  case LAYOUT_LEFTRIGHT:
    if (wp->window->sb == PANE_SCROLLBARS_ALWAYS) {
      minimum = PANE_MINIMUM * 2 + sb_style->width +
          sb_style->pad;
    } else
      minimum = PANE_MINIMUM * 2 + 1;
    if (sx < minimum)
      return (0);
    break;
  case LAYOUT_TOPBOTTOM:
    if (layout_add_horizontal_border(root, lc, status))
      minimum = PANE_MINIMUM * 2 + 2;
    else
      minimum = PANE_MINIMUM * 2 + 1;
    if (sy < minimum)
      return (0);
    break;
  default:
    fatalx("bad layout type");
  }

  return (1);
}

/* Calculates the new cell sizes when splitting a pane. */
void
layout_split_sizes(struct layout_cell *lc, int size, int before,
    enum layout_type type, u_int *size1, u_int *size2, u_int *saved_size)
{
  u_int s1, s2, ss;
  u_int sx = lc->g.sx, sy = lc->g.sy;

  if (type == LAYOUT_LEFTRIGHT)
    ss = sx;
  else
    ss = sy;
  if (size < 0)
    s2 = ((ss + 1) / 2) - 1;
  else if (before)
    s2 = ss - size - 1;
  else
    s2 = size;
  if (s2 < PANE_MINIMUM)
    s2 = PANE_MINIMUM;
  else if (s2 > ss - 2)
    s2 = ss - 2;
  s1 = ss - 1 - s2;

  *size1 = s1;
  *size2 = s2;
  *saved_size = ss;
}

/*
 * Split a pane into two. size is a hint, or -1 for default half/half
 * split. This must be followed by layout_assign_pane before much else happens!
 */
struct layout_cell *
layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
    int flags)
{
  struct layout_cell  *lc, *lcparent, *lcnew, *lc1, *lc2;
  u_int      sx, sy, xoff, yoff, size1, size2;
  u_int      new_size, saved_size, resize_first = 0;
  int      full_size = (flags & SPAWN_FULLSIZE);
  int      before = (flags & SPAWN_BEFORE);

  /*
   * If full_size is specified, add a new cell at the top of the window
   * layout. Otherwise, split the cell for the current pane.
   */
  if (full_size)
    lc = wp->window->layout_root;
  else
    lc = wp->layout_cell;

  /* Copy the old cell size. */
  sx = lc->g.sx;
  sy = lc->g.sy;
  xoff = lc->g.xoff;
  yoff = lc->g.yoff;

  /* Check there is enough space for the two new panes. */
  if (!layout_split_check_space(wp, lc, type))
    return (NULL);

  /*
   * Calculate new cell sizes. size is the target size or -1 for middle
   * split, size1 is the size of the top/left and size2 the bottom/right.
   */
  layout_split_sizes(lc, size, before, type, &size1, &size2, &saved_size);

  /* Which size are we using? */
  if (flags & SPAWN_BEFORE)
    new_size = size2;
  else
    new_size = size1;

  /* Confirm there is enough space for full size pane. */
  if (full_size && !layout_set_size_check(wp->window, lc, type, new_size))
    return (NULL);

  if (lc->parent != NULL && lc->parent->type == type) {
    /*
     * If the parent exists and is of the same type as the split,
     * create a new cell and insert it after this one.
     */
    lcparent = lc->parent;
    lcnew = layout_create_cell(lcparent);
    if (flags & SPAWN_BEFORE)
      TAILQ_INSERT_BEFORE(lc, lcnew, entry);
    else
      TAILQ_INSERT_AFTER(&lcparent->cells, lc, lcnew, entry);
  } else if (full_size && lc->parent == NULL && lc->type == type) {
    /*
     * If the new full size pane is the same type as the root
     * split, insert the new pane under the existing root cell
     * instead of creating a new root cell. The existing layout
     * must be resized before inserting the new cell.
     */
    if (lc->type == LAYOUT_LEFTRIGHT) {
      lc->g.sx = new_size;
      layout_resize_child_cells(wp->window, lc);
      lc->g.sx = saved_size;
    } else if (lc->type == LAYOUT_TOPBOTTOM) {
      lc->g.sy = new_size;
      layout_resize_child_cells(wp->window, lc);
      lc->g.sy = saved_size;
    }
    resize_first = 1;

    /* Create the new cell. */
    lcnew = layout_create_cell(lc);
    size = saved_size - 1 - new_size;
    if (lc->type == LAYOUT_LEFTRIGHT)
      layout_set_size(lcnew, size, sy, 0, 0);
    else if (lc->type == LAYOUT_TOPBOTTOM)
      layout_set_size(lcnew, sx, size, 0, 0);
    if (flags & SPAWN_BEFORE)
      TAILQ_INSERT_HEAD(&lc->cells, lcnew, entry);
    else
      TAILQ_INSERT_TAIL(&lc->cells, lcnew, entry);
  } else {
    /*
     * Otherwise create a new parent and insert it.
     */

    /* Create and insert the replacement parent. */
    lcparent = layout_replace_with_node(wp->window, lc, type);

    /* Create the new child cell. */
    lcnew = layout_create_cell(lcparent);
    if (flags & SPAWN_BEFORE)
      TAILQ_INSERT_HEAD(&lcparent->cells, lcnew, entry);
    else
      TAILQ_INSERT_TAIL(&lcparent->cells, lcnew, entry);
  }
  if (flags & SPAWN_BEFORE) {
    lc1 = lcnew;
    lc2 = lc;
  } else {
    lc1 = lc;
    lc2 = lcnew;
  }

  /*
   * Set new cell sizes. size1 is the size of the top/left and size2 the
   * bottom/right.
   */
  if (!resize_first && type == LAYOUT_LEFTRIGHT) {
    layout_set_size(lc1, size1, sy, xoff, yoff);
    layout_set_size(lc2, size2, sy, xoff + lc1->g.sx + 1, yoff);
  } else if (!resize_first && type == LAYOUT_TOPBOTTOM) {
    layout_set_size(lc1, sx, size1, xoff, yoff);
    layout_set_size(lc2, sx, size2, xoff, yoff + lc1->g.sy + 1);
  }
  if (full_size) {
    if (!resize_first)
      layout_resize_child_cells(wp->window, lc);
    layout_fix_offsets(wp->window);
  } else
    layout_make_leaf(lc, wp);

  return (lcnew);
}

/*
 * Creates a cell for a new floating pane. This must be followed by
 * layout_assign_pane before much else happens!
 */
struct layout_cell *
layout_floating_pane(struct window *w, struct window_pane *wp,
    struct layout_geometry *lg)
{
  struct layout_cell  *lc, *lcnew, *lcparent;

  if (wp == NULL)
    lc = w->layout_root;
  else
    lc = wp->layout_cell;
  lcparent = lc->parent;

  if (lcparent == NULL) {
    /*
     * Adding a pane to a root that isn't a node. Must create and
     * insert a new root.
     */
    lcparent = layout_replace_with_node(w, lc, LAYOUT_TOPBOTTOM);
  }

  lcnew = layout_create_cell(lcparent);
  TAILQ_INSERT_AFTER(&lcparent->cells, lc, lcnew, entry);
  lcnew->flags |= LAYOUT_CELL_FLOATING;
  layout_set_size(lcnew, lg->sx, lg->sy, lg->xoff, lg->yoff);

  return (lcnew);
}

/* Destroy the cell associated with a pane. */
void
layout_close_pane(struct window_pane *wp)
{
  struct window *w = wp->window;

  if (wp->layout_cell == NULL)
    return;

  /* Remove the cell. */
  layout_destroy_cell(w, wp->layout_cell, &w->layout_root);
  wp->layout_cell = NULL;

  /* Fix pane offsets and sizes. */
  if (w->layout_root != NULL) {
    layout_fix_offsets(w);
    layout_fix_panes(w, NULL);
  }
  events_fire_window("window-layout-changed", w);
}

/* Spread out cells inside a parent cell. */
int
layout_spread_cell(struct window *w, struct layout_cell *parent)
{
  struct layout_cell  *lc, *root = w->layout_root;
  u_int      number, each, size, this, remainder;
  int      change, changed, status;

  number = 0;
  TAILQ_FOREACH (lc, &parent->cells, entry)
    if (layout_cell_is_tiled(lc))
      number++;
  if (number <= 1)
    return (0);
  status = window_get_pane_status(w);

  if (parent->type == LAYOUT_LEFTRIGHT)
    size = parent->g.sx;
  else if (parent->type == LAYOUT_TOPBOTTOM) {
    if (layout_add_horizontal_border(root, parent, status))
      size = parent->g.sy - 1;
    else
      size = parent->g.sy;
  } else
    return (0);
  if (size < number - 1)
    return (0);
  each = (size - (number - 1)) / number;
  if (each == 0)
    return (0);

  /*
   * Remaining space after assigning that which can be evenly
   * distributed.
   */
  remainder = size - (number * (each + 1)) + 1;

  changed = 0;
  TAILQ_FOREACH (lc, &parent->cells, entry) {
    if (!layout_cell_is_tiled(lc))
      continue;
    change = 0;
    if (parent->type == LAYOUT_LEFTRIGHT) {
      change = each - (int)lc->g.sx;
      if (remainder > 0) {
        change++;
        remainder--;
      }
      layout_resize_adjust(w, lc, LAYOUT_LEFTRIGHT, change);
    } else if (parent->type == LAYOUT_TOPBOTTOM) {
      if (layout_add_horizontal_border(root, lc, status))
        this = each + 1;
      else
        this = each;
      if (remainder > 0) {
        this++;
        remainder--;
      }
      change = this - (int)lc->g.sy;
      layout_resize_adjust(w, lc, LAYOUT_TOPBOTTOM, change);
    }
    if (change != 0)
      changed = 1;
  }
  return (changed);
}

/* Spread out cells evenly. */
void
layout_spread_out(struct window_pane *wp)
{
  struct layout_cell  *parent;
  struct window   *w = wp->window;

  parent = wp->layout_cell->parent;
  if (parent == NULL)
    return;

  do {
    if (layout_spread_cell(w, parent)) {
      layout_fix_offsets(w);
      layout_fix_panes(w, NULL);
      break;
    }
  } while ((parent = parent->parent) != NULL);
}

/* Get a new tiled cell. */
struct layout_cell *
layout_get_tiled_cell(struct cmdq_item *item, struct args *args,
    struct window *w, struct window_pane *wp, int flags, char **cause)
{
  struct layout_cell  *lc;
  enum layout_type   type = LAYOUT_TOPBOTTOM;
  u_int      curval;
  int      size = -1;
  char      *error = NULL;

  if (window_pane_is_floating(wp)) {
    *cause = xstrdup("can't split a floating pane");
    return (NULL);
  }

  if (flags & SPAWN_HORIZONTAL)
    type = LAYOUT_LEFTRIGHT;

  if (args_has(args, 'l') || args_has(args, 'p')) {
    if (flags & SPAWN_FULLSIZE) {
      if (type == LAYOUT_TOPBOTTOM)
        curval = w->sy;
      else
        curval = w->sx;
    } else {
      if (type == LAYOUT_TOPBOTTOM)
        curval = wp->sy;
      else
        curval = wp->sx;
    }
  }

  if (args_has(args, 'l')) {
    size = args_percentage_and_expand(args, 'l', 0, INT_MAX, curval,
        item, &error);
  } else if (args_has(args, 'p')) {
    size = args_strtonum_and_expand(args, 'p', 0, 100, item,
        &error);
    if (error == NULL)
      size = curval * size / 100;
  }
  if (error != NULL) {
    xasprintf(cause, "invalid tiled geometry %s", error);
    free(error);
    return (NULL);
  }

  if (window_active_pane_is_over_zoom(w))
    window_push_zoom(w, 0, 1);
  else
    window_push_zoom(w, 1, (flags & SPAWN_ZOOM));
  lc = layout_split_pane(wp, type, size, flags);
  if (lc == NULL)
    *cause = xstrdup("no space for a new pane");

  return (lc);
}

struct layout_cell *
layout_get_floating_cell(struct cmdq_item *item, struct args *args,
    enum pane_lines lines, struct window *w, struct window_pane *wp, int flags,
    char **cause)
{
  struct layout_cell  *lcnew, *lc = wp->layout_cell;
  struct layout_geometry   fg;

  layout_geometry_init(&fg);
  if (flags & SPAWN_SPLIT) {
    if (layout_split_floating_cell(lc, w, &fg, lines, flags, cause)
        != 0)
      return (NULL);
  } else {
    if (layout_floating_args_parse(item, args, lines, w, &fg, cause)
        != 0)
      return (NULL);
  }

  if (flags & SPAWN_FLOATOVERZOOM)
    window_push_zoom(wp->window, 0, 1);
  else if (window_active_pane_is_over_zoom(w))
    window_push_zoom(wp->window, 0, 1);
  else
    window_push_zoom(wp->window, 1, (flags & SPAWN_ZOOM));
  lcnew = layout_floating_pane(w, wp, &fg);
  return (lcnew);
}

int
layout_floating_args_parse(struct cmdq_item *item, struct args *args,
    enum pane_lines lines, struct window *w, struct layout_geometry *lg,
    char **cause)
{
  int  sx, sy, ox, oy;
  char  *error = NULL;

  sx = lg->sx == UINT_MAX ? w->sx / 2 : lg->sx;
  sy = lg->sy == UINT_MAX ? w->sy / 4 : lg->sy;
  ox = lg->xoff;
  oy = lg->yoff;

  if (args_has(args, 'x')) {
    sx = args_percentage_and_expand(args, 'x', 0, PANE_MAXIMUM,
        w->sx, item, &error);
    if (error != NULL) {
      xasprintf(cause, "position %s", error);
      free(error);
      return (-1);
    }
    if (lines != PANE_LINES_NONE)
      sx -= 2;
  }
  if (args_has(args, 'y')) {
    sy = args_percentage_and_expand(args, 'y', 0, PANE_MAXIMUM,
        w->sy, item, &error);
    if (error != NULL) {
      xasprintf(cause, "position %s", error);
      free(error);
      return (-1);
    }
    if (lines != PANE_LINES_NONE)
      sy -= 2;
  }
  if (args_has(args, 'X')) {
    ox = args_percentage_and_expand(args, 'X', -sx, w->sx,
        w->sx, item, &error);
    if (error != NULL) {
      xasprintf(cause, "position %s", error);
      free(error);
      return (-1);
    }
  }
  if (args_has(args, 'Y')) {
    oy = args_percentage_and_expand(args, 'Y', -sy, w->sy,
        w->sy, item, &error);
    if (error != NULL) {
      xasprintf(cause, "position %s", error);
      free(error);
      return (-1);
    }
  }

  if (ox == INT_MAX) {
    if (w->last_new_pane_x == 0)
      ox = 4;
    else {
      ox = w->last_new_pane_x + 4;
      if (w->last_new_pane_x > w->sx)
        ox = 4;
    }
    w->last_new_pane_x = ox;
  } else if (args_has(args, 'X'))
    if (lines != PANE_LINES_NONE)
      ox += 1;
  if (oy == INT_MAX) {
    if (w->last_new_pane_y == 0)
      oy = 2;
    else {
      oy = w->last_new_pane_y + 2;
      if (w->last_new_pane_y > w->sy)
        oy = 2;
    }
    w->last_new_pane_y = oy;
  } else if (args_has(args, 'Y'))
    if (lines != PANE_LINES_NONE)
      oy += 1;

  if (sx < PANE_MINIMUM || sx > PANE_MAXIMUM) {
    *cause = xstrdup("invalid width");
    return (-1);
  }
  if (sy < PANE_MINIMUM || sy > PANE_MAXIMUM) {
    *cause = xstrdup("invalid height");
    return (-1);
  }

  lg->sx = sx;
  lg->sy = sy;
  lg->xoff = ox;
  lg->yoff = oy;
  return (0);
}

int
layout_split_floating_cell(struct layout_cell *lc, struct window *w,
    struct layout_geometry *out, enum pane_lines lines, int flags,
    char **cause)
{
  struct layout_geometry   old, new;
  int      tborder = 1, bborder = w->sy - 1;
  int      lborder = 3, rborder = w->sx - 3;
  int      border = lines != PANE_LINES_NONE ? 1 : 0;
  int      size, space;

  /* First, move the target cell in-bounds. */
  memcpy(&old, &lc->g, sizeof old);
  if (lborder > old.xoff - border)
    old.xoff = lborder + border;
  if (rborder < old.xoff + (int)old.sx + border)
    old.xoff = rborder - (int)old.sx - border;
  if (tborder > old.yoff - border)
    old.yoff = tborder + border;
  if (bborder < old.yoff + (int)old.sy + border)
    old.yoff = bborder - (int)old.sy - border;

  /* Move the new cell to its ideal position. */
  memcpy(&new, &old, sizeof new);
  if (flags & SPAWN_HORIZONTAL) {
    if (flags & SPAWN_BEFORE)
      new.xoff -= old.sx + 2 * border;
    else
      new.xoff += old.sx + 2 * border;
  } else {
    if (flags & SPAWN_BEFORE)
      new.yoff -= old.sy + 2 * border;
    else
      new.yoff += old.sy + 2 * border;
  }

  /*
   * The position of the new cell is checked to see if it is in bounds.
   * If it isn't, the availible space is split and equally given to both
   * cells. Only one border is check because the target cell is in bounds
   * already.
   */
  if (lborder > new.xoff - border) {
    /*
     * The space for both panes is calculated. Since the offsets are
     * associated to where pane contents start, we remove pane
     * borders from the space. '1' is added in case the space is
     * odd.
     */
    space = old.xoff + old.sx - lborder - 3 * border + 1;
    size = space / 2;
    new.sx = size;
    old.sx = size;
    new.xoff = lborder + border;
    old.xoff = new.xoff + new.sx + 2 * border;
    /*
     * If the original space was to be odd (now even), subtract 1
     * from the rightmost cell
     */
    if (space % 2 == 0)
      old.sx -= 1;
  } else if (rborder < new.xoff + (int)new.sx + border) {
    space = rborder - old.xoff - 3 * border + 1;
    size = space / 2;
    new.sx = size;
    old.sx = size;
    new.xoff = old.xoff + old.sx + 2 * border;
    if (space % 2 == 0)
      new.sx -= 1;
  } else if (tborder > new.yoff - border) {
    space = old.sy + old.yoff - tborder - 3 * border + 1;
    size = space / 2;
    new.sy = size;
    old.sy = size;
    new.yoff = tborder + border;
    old.yoff = new.yoff + new.sy + 2 * border;
    if (space % 2 == 0)
      old.sy -= 1;
  } else if (bborder < new.yoff + (int)new.sy + border) {
    space = bborder - old.yoff - 3 * border + 1;
    size = space / 2;
    new.sy = size;
    old.sy = size;
    new.yoff = old.yoff + old.sy + 2 * border;
    if (space % 2 == 0)
      new.sy -= 1;
  }

  /*
   * Expand the cell to occupy the whole availible space where it was
   * spawned.
   */
  if (flags & SPAWN_FULLSIZE) {
    if (flags & SPAWN_HORIZONTAL) {
      new.yoff = tborder + border;
      new.sy = bborder - tborder - 2 * border;
      if (flags & SPAWN_BEFORE) {
        new.xoff = lborder + border;
        new.sx = old.xoff - new.xoff - 2 * border;
      } else {
        new.sx = rborder - new.xoff - border;
      }
    } else {
      new.xoff = lborder + border;
      new.sx = rborder - lborder - 2 * border;
      if (flags & SPAWN_BEFORE) {
        new.yoff = tborder + border;
        new.sy = old.yoff - new.yoff - 2 * border;
      } else {
        new.sy = bborder - new.yoff - border;
      }
    }
  }

  if (new.sx < PANE_MINIMUM || new.sy < PANE_MINIMUM ||
      old.sx < PANE_MINIMUM || old.sy < PANE_MINIMUM) {
    *cause = xstrdup("no space for a new pane");
    return (-1);
  }

  layout_set_size(lc, old.sx, old.sy, old.xoff, old.yoff);
  memcpy(out, &new, sizeof *out);
  return (0);
}

/*
 * Removes a cell from the tiled layout by giving the cell's space to the
 * nearest neighbour.
 */
int
layout_remove_tile(struct window *w, struct layout_cell *lc)
{
  struct layout_cell  *lcneighbour, *lcparent;
  enum layout_type   type;
  int      change;

  if (lc->flags & LAYOUT_CELL_FLOATING)
    return (-1);

  lcneighbour = layout_cell_get_neighbour(lc);
  if (lcneighbour == NULL) {
    if (lc->parent != NULL)
      layout_remove_tile(w, lc->parent);
  } else if ((lcparent = lcneighbour->parent) != NULL) {
    type = lcparent->type;
    /*
     * Adding the size of the layout cell plus its border to the
     * neighbour.
     */
    if (type == LAYOUT_TOPBOTTOM)
      change = lc->g.sy + 1;
    else
      change = lc->g.sx + 1;
    layout_resize_adjust(w, lcneighbour, type, change);
  }

  /*
   * Zeroing out the cell geometry until the cell is retiled unless this
   * is the top level node.
   */
  if (lc->parent != NULL)
    layout_set_size(lc, 0, 0, 0, 0);
  return (0);
}

/*
 * Inserts a cell back into the tiled layout by taking half the space from its
 * nearest neighbour.
 */
int
layout_insert_tile(struct window *w, struct layout_cell *lc)
{
  struct layout_cell  *lcneighbour, *lctiled, *lcparent;
  enum layout_type   type;
  u_int      size1, size2, saved_size;

  if (lc == NULL)
    fatalx("layout cell cannot be null when tiling");

  if (layout_cell_is_tiled(lc))
    return (-1);

  lcparent = lc->parent;
  if (lcparent == NULL) {
    /* Only pane in the layout. */
    layout_set_size(lc, w->sx, w->sy, 0, 0);
    return (0);
  }

  type = lcparent->type;
  lcneighbour = layout_cell_get_neighbour(lc);
  if (lcneighbour == NULL) {
    /*
     * This will become the only visible cell in the parent.
     * Tile the parent, then set the child's 'split' size.
     */
    layout_insert_tile(w, lcparent);
    if (type == LAYOUT_LEFTRIGHT)
      size1 = lcparent->g.sx;
    else
      size1 = lcparent->g.sy;
    layout_resize_set_size(w, lc, type, size1);
  } else {
    /*
     * If the neighbour is a node, a tiled child in the subtree of
     * the neighbour is needed to check for space.
     */
    lctiled = layout_cell_get_first_tiled(lcneighbour);
    if (!layout_split_check_space(lctiled->wp, lcneighbour, type))
      return (-1);
    layout_split_sizes(lcneighbour, -1, 0, type, &size1, &size2,
        &saved_size);
    layout_resize_set_size(w, lc, type, size1);
    layout_resize_set_size(w, lcneighbour, type, size2);
  }

  /* Setting opposite of the 'split' size to that of the parent. */
  if (lcparent->type == LAYOUT_LEFTRIGHT) {
    size1 = lcparent->g.sy;
    type = LAYOUT_TOPBOTTOM;
  } else {
    size1 = lcparent->g.sx;
    type = LAYOUT_LEFTRIGHT;
  }
  layout_resize_set_size(w, lc, type, size1);

  return (0);
}

Coverage Report

Created: 2026-08-31 06:23