windu

Convenient window resizing for Emacs

What is it?

Windu provides a transient minor-mode for quick fine-tuning of window sizes in Emacs, which can be activated using the default keybinding C-x C-m. Once active, windu-transient-mode makes the following keybindings available:

Nudges (incremental window resizing)

sequence	function	effect
<C-left>	'windu-nudge-in-right	move window's right edge to decrease its width by 1
<C-right>	'windu-nudge-out-right	move window's right edge to increase its width by 1
<C-up>	'windu-nudge-in-bottom	move window's bottom edge to decrease its height by 1
<C-down>	'windu-nudge-out-bottom	move window's bottom edge to increase its height by 1
<C-S-left>	'windu-nudge-out-left	move window's left edge to increase its width by 1
<C-S-right>	'windu-nudge-in-left	move window's left edge to decrease its width by 1
<C-S-up>	'windu-nudge-out-top	move window's top edge to increase its height by 1
<C-S-down>	'windu-nudge-in-top	move window's top edge to decrease its height by 1

Once activated, windu-transient-mode remains active until a non-nudge or non-bring command is encountered. This permits easy fine-tuning via repeated invocations of a nudge command without requiring the lengthy C-x C-m sequence to be entered before each nudge:

• C-x C-m <C-right> <C-right> <C-right> will increase the width of the current window by 3 columns.
• C-x C-m <C-right> <C-right> <C-left> will increase the width of the current window by 1 column (first it increases the width by 2, then reduces it by 1).

Orders (specific window resizing)

sequence	function	effect
f	'windu-order-fill-best-effort	set width to the local fill-column by first moving window's right, then left edge
w	'windu-order-width-best-effort	prompt for width and set by first moving window's right, then left edge
h	'windu-order-height-best-effort	prompt for height and set by first moving window's bottom, then top edge
(	'windu-order-fill-right	set width to the local fill-column by moving window's right edge
)	'windu-order-fill-left	set width to the local fill-column by moving window's left edge
[	'windu-order-width-right	prompt for width and set by moving window's right edge
]	'windu-order-width-left	prompt for width and set by moving window's left edge
{	'windu-order-height-bottom	prompt for height and set by moving window's bottom edge
}	'windu-order-height-top	prompt for height and set by moving window's top edge

fill-column is a standard Emacs variable related to maximum line width. Its value is buffer-local and can be set on a per-buffer basis, and can furthermore be customized for each major-mode though hooks. This would allow the same windu-order-fill- keybindings to set a python-mode buffer to 80 columns and a java-mode buffer to 120:

(add-hook 'python-mode-hook (lambda () (set-fill-column 80)))
(add-hook 'java-mode-hook (lambda () (set-fill-column 120)))

windu-fill-column acts as a global override for fill-column for all windu orders and splits. Its value can be set using the Emacs built-in customization system, accessed via M-x customize-variable.

Splits

sequence	function	effect
3	'windu-split-window-best-effort	split side-by-side and order each window to width fill-column by first moving its right, then left edge
r	'windu-split-window-right	split side-by-side and order each window to width fill-column by moving its right edge; fail if too small
l	'windu-split-window-left	split side-by-side and order each window to width fill-column by moving its left edge; fail if too small
+	'windu-order-fill-many-windows	order as many window widths to fill-column as possible, starting from the left and moving along the top

The windu-split- commands mimic the Emacs built-in C-x 3 keybinding, but order the split windows to have width fill-column (or the global override windu-fill-column, if set) after splitting. If there is insufficient width available on the requested left or right side, windu-split-window-right and windu-split-window-left fail with an error message; windu-split-window-best-effort will try its best.

The windu-order-fill-many-windows command mimics the Emacs built-in C-x + keybinding, but orders windows to their local fill-column width. It is currently fairly primitive, and simply orders each window along the top row to set its width via windu-order-width-right.

You can remap the built-in C-x 3 and C-x + keybindings to their windu equivalents globally in your .emacs config file:

(global-set-key (kbd "C-x 3") 'windu-split-window-best-effort)
(global-set-key (kbd "C-x +") 'windu-order-fill-many-windows)

Swaps

sequence	function	effect
,	'windu-swap-left	move the current window's buffer to the window on the left, and move that window's buffer to the current window
.	'windu-swap-right	move the current window's buffer to the window on the right, and move that window's buffer to the current window
<	'windu-swap-top	move the current window's buffer to the window on the top, and move that window's buffer to the current window
>	'windu-swap-bottom	move the current window's buffer to the window on the bottom, and move that window's buffer to the current window
C-,	'windu-bring-left	select the window on the left, and bring the current buffer with you
C-.	'windu-bring-right	select the window on the right, and bring the current buffer with you
C-<	'windu-bring-top	select the window on the top, and bring the current buffer with you
C->	'windu-bring-bottom	select the window on the bottom, and bring the current buffer with you

The 'windu-swap- commands switch the buffer in the active window with the buffer in a window left, right, above, or below the current window. Focus remains in the current window.

The 'windu-bring- commands, on the other hand, switch buffers like 'windu-swap- but move focus to the other window as well. Multiple bring commands can be chained together without requiring the lengthy C-x C-m sequence to be entered before each bring:

• C-x C-m C-> will result in the simultaneous evaluation of:

    window0.buffer = window1.buffer
    window1.buffer = window0.buffer
  

  Additionally, window1 will become the current window.

• C-x C-m C-> C-> will result in the simultaneous evaluation of:

    window0.buffer = window1.buffer
    window1.buffer = window2.buffer
    window2.buffer = window0.buffer
  

  Additionally, window2 will become the current window.

You can make the 'windu-bring- commands available globally through convenient keybindings in your .emacs config file:

(global-set-key (kbd "<C-S-left>") 'windu-bring-left)
(global-set-key (kbd "<C-S-right>") 'windu-bring-right)
(global-set-key (kbd "<C-S-up>") 'windu-bring-top)
(global-set-key (kbd "<C-S-down>") 'windu-bring-bottom)

Informational

sequence	function	effect
i	'windu-echo-size	display window's current size in the minibuffer

Auto-saving layouts

Windu also overrides the default C-x 0 (delete-window) and C-x 1 (delete-other-windows) bindings to save the current layout of windows (size, position, and buffer) before deleting. This allows restoring windows to their previous layout to, for example, toggle a focused view of one buffer. The layouts can be restored using the delete window commands with Shift, i.e. C-x ) to restore layout to what it was before delete-window and C-x ! to restore to before delete-other-windows. Here are the keybindings affected:

key	old function	new function	effect
C-x 0	delete-window	windu-auto-save-set-window-configuration-0	save window layout before deleting the current window
C-x 1	delete-other-windows	windu-auto-save-set-window-configuration-1	save window layout before deleting other windows
C-x )		windu-auto-save-load-window-configuration-0	restore window layout the one saved in configuration-0, if exists
C-x !		windu-auto-save-load-window-configuration-1	restore window layout the one saved in configuration-1, if exists

Installation

Place windu.el in your emacs load path (often somewhere under ~/.emacs.d/) and then enable it in your .emacs config:

;; Use default keybinding "C-x C-m"
(require 'windu)
(windu-setup-keybindings)

Alternately, you can customize the windu prefix key:

;; Use custom keybinding "M-w"
(require 'windu)
(windu-setup-keybindings (kbd "M-w"))

Then reload your config via M-x eval-buffer or simply restart Emacs :)

One suggested configuration

In this suggested config:

sequence	old effect	new effect
C-x C-m		temporarily enable the windu keymap
C-x 3	split-window-right	split side-by-side, and order both windows to width fill-column
C-x +	balance-windows	order as many windows to width fill-column as possible
C-S-<left>	select left-word	select the left window, and bring the current buffer along
C-S-<right>	select right-word	select the right window, and bring the current buffer along
C-S-<up>	select backward-paragraph	select the top window, and bring the current buffer along
C-S-<down>	select forward-paragraph	select the bottom window, and bring the current buffer along

Place the following in your .emacs config file:

;; Use default keybinding "C-x C-m" to activate windu-transient-mode
(require 'windu)
(windu-setup-keybindings)
;; Shadow existing emacs keybindings with their windu equivalents
;; Replaces default 'split-window-right
(global-set-key (kbd "C-x 3") 'windu-split-window-best-effort)
;; Replaces default 'balance-windows
(global-set-key (kbd "C-x +") 'windu-order-fill-many-windows)
;; Replaces default text movement/selection 'right-word etc.
(global-set-key (kbd "<C-S-left>") 'windu-bring-left)
(global-set-key (kbd "<C-S-right>") 'windu-bring-right)
(global-set-key (kbd "<C-S-up>") 'windu-bring-top)
(global-set-key (kbd "<C-S-down>") 'windu-bring-bottom)