Pulled code out of layout_split_pane for reuse and added

layout_insert_tile. From Dane Jensen.

layout.c

@@ -31,8 +31,9 @@
  * 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. A cell's 'split' size refers to the side that is shortened when
- * splitting it, determined by the parent's type.
+ * 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
@@ -296,6 +297,27 @@ layout_cell_is_first_tiled(struct layout_cell *lc)
 	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
@@ -609,6 +631,20 @@ layout_resize_adjust(struct window *w, struct layout_cell *lc,
 	}
 }
 
+/* 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->sx;
+	else
+		change = size - lc->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_direction(struct layout_cell *lc, int direction)
@@ -1210,6 +1246,75 @@ layout_replace_with_node(struct window *w, struct layout_cell *lc,
 	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 style	*sb_style = &wp->scrollbar_style;
+	u_int		 minimum, sx = lc->sx, sy = lc->sy;
+	int		 scrollbars, status;
+
+	if (lc->flags & LAYOUT_CELL_FLOATING)
+		fatalx("floating cells cannot be split");
+
+	status = window_get_pane_status(wp->window);
+	scrollbars = options_get_number(wp->window->options, "pane-scrollbars");
+
+	switch (type) {
+	case LAYOUT_LEFTRIGHT:
+		if (scrollbars) {
+			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(wp->window, 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->sx, sy = lc->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 > sx - 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!
@@ -1219,11 +1324,10 @@ layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
     int flags)
 {
 	struct layout_cell	*lc, *lcparent, *lcnew, *lc1, *lc2;
-	struct style		*sb_style = &wp->scrollbar_style;
-	u_int			 sx, sy, xoff, yoff, size1, size2, minimum;
+	u_int			 sx, sy, xoff, yoff, size1, size2;
 	u_int			 new_size, saved_size, resize_first = 0;
-	int			 full_size = (flags & SPAWN_FULLSIZE), status;
-	int			 scrollbars;
+	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
@@ -1233,8 +1337,6 @@ layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
 		lc = wp->window->layout_root;
 	else
 		lc = wp->layout_cell;
-	status = window_get_pane_status(wp->window);
-	scrollbars = options_get_number(wp->window->options, "pane-scrollbars");
 
 	/* Copy the old cell size. */
 	sx = lc->sx;
@@ -1243,47 +1345,14 @@ layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
 	yoff = lc->yoff;
 
 	/* Check there is enough space for the two new panes. */
-	switch (type) {
-	case LAYOUT_LEFTRIGHT:
-		if (scrollbars) {
-			minimum = PANE_MINIMUM * 2 + sb_style->width +
-			    sb_style->pad;
-		} else
-			minimum = PANE_MINIMUM * 2 + 1;
-		if (sx < minimum)
-			return (NULL);
-		break;
-	case LAYOUT_TOPBOTTOM:
-		if (layout_add_horizontal_border(wp->window, lc, status))
-			minimum = PANE_MINIMUM * 2 + 2;
-		else
-			minimum = PANE_MINIMUM * 2 + 1;
-		if (sy < minimum)
-			return (NULL);
-		break;
-	default:
-		fatalx("bad layout type");
-	}
+	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.
 	 */
-	if (type == LAYOUT_LEFTRIGHT)
-		saved_size = sx;
-	else
-		saved_size = sy;
-	if (size < 0)
-		size2 = ((saved_size + 1) / 2) - 1;
-	else if (flags & SPAWN_BEFORE)
-		size2 = saved_size - size - 1;
-	else
-		size2 = size;
-	if (size2 < PANE_MINIMUM)
-		size2 = PANE_MINIMUM;
-	else if (size2 > saved_size - 2)
-		size2 = saved_size - 2;
-	size1 = saved_size - 1 - size2;
+	layout_split_sizes(lc, size, before, type, &size1, &size2, &saved_size);
 
 	/* Which size are we using? */
 	if (flags & SPAWN_BEFORE)
@@ -1729,3 +1798,67 @@ layout_remove_tile(struct window *w, struct layout_cell *lc)
 		layout_set_size(lc, 0, 0, 0, 0);
 	return (1);
 }
+
+/*
+ * 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");
+
+	lcparent = lc->parent;
+	if (lc->flags & LAYOUT_CELL_FLOATING)
+		return (1);
+
+	if (lcparent == NULL) {
+		/* Only pane in the layout. */
+		layout_set_size(lc, w->sx, w->sy, 0, 0);
+		return (1);
+	}
+
+	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->sx;
+		else
+			size1 = lcparent->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 (0);
+		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->sy;
+		type = LAYOUT_TOPBOTTOM;
+	} else {
+		size1 = lcparent->sx;
+		type = LAYOUT_LEFTRIGHT;
+	}
+	layout_resize_set_size(w, lc, type, size1);
+
+	return (1);
+}

tmux.h

@@ -3629,6 +3629,8 @@ void		 layout_fix_offsets(struct window *);
 void		 layout_fix_panes(struct window *, struct window_pane *);
 void		 layout_resize_adjust(struct window *, struct layout_cell *,
 		     enum layout_type, int);
+void		 layout_resize_set_size(struct window *, struct layout_cell *,
+		     enum layout_type, u_int);
 struct layout_cell *layout_cell_get_neighbour(struct layout_cell *);
 void		 layout_init(struct window *, struct window_pane *);
 void		 layout_free(struct window *);
@@ -3643,6 +3645,10 @@ int		 layout_resize_floating_pane_to(struct window_pane *,
 		     enum layout_type, u_int, char **);
 void		 layout_assign_pane(struct layout_cell *, struct window_pane *,
 		     int);
+int		 layout_split_check_space(struct window_pane *,
+		     struct layout_cell *, enum layout_type);
+void		 layout_split_sizes(struct layout_cell *, int, int,
+		     enum layout_type, u_int *, u_int *, u_int *);
 struct layout_cell *layout_replace_with_node(struct window *,
 		     struct layout_cell *, enum layout_type);
 struct layout_cell *layout_split_pane(struct window_pane *, enum layout_type,
@@ -3661,6 +3667,7 @@ int		 layout_floating_args_parse(struct cmdq_item *, struct args *,
 		     enum pane_lines, struct window *, u_int *, u_int *, int *,
 		     int *, char **);
 int		 layout_remove_tile(struct window *, struct layout_cell *);
+int		 layout_insert_tile(struct window *, struct layout_cell *);
 
 /* layout-custom.c */
 char		*layout_dump(struct window *, struct layout_cell *);