Quickly switch windows in Emacs
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README.md

ace-window

GNU Emacs package for selecting a window to switch to

What and why

I'm sure you're aware of the other-window command. While it's great for two windows, it quickly loses its value when there are more windows. You need to call it many times, and since it's not easily predictable, you have to check each time if you're in the window that you wanted.

Another approach is to use windmove-left, windmove-up, etc. These are fast and predictable. Their disadvantage is that they need 4 key bindings. The default ones are shift+arrows, which are hard to reach.

This package aims to take the speed and predictability of windmove and pack it into a single key binding, similar to other-window.

Setup

Just assign ace-window to a short key binding, as switching windows is a common task. I suggest M-o, as it's short and not bound to anything important in the default Emacs.

Usage

When there are two windows, ace-window will call other-window (unless aw-dispatch-always is set non-nil). If there are more, each window will have the first character of its window label highlighted at the upper left of the window. Pressing that character will either switch to that window or filter to the next character needed to select a specific window. Note that, unlike ace-jump-mode, the position of point will not be changed, i.e. the same behavior as that of other-window.

A special character defined by aw-make-frame-char (default = z) means create a new frame and use its window as the target. The new frame's location is set relative to the prior selected frame's location and given by aw-frame-offset. The new frame's size is given by aw-frame-size. See their documentation strings for more information.

The windows are ordered top-down, left-to-right. This means that if you remember your window layouts, you can switch windows without even looking at the leading char. For instance, the top left window will always be 1 (or a if you use letters for window characters).

ace-window works across multiple frames, as you can see from the in-action gif.

Swap and delete window

  • You can swap windows by calling ace-window with a prefix argument C-u.

  • You can delete the selected window by calling ace-window with a double prefix argument, i.e. C-u C-u.

Change the action midway

You can also start by calling ace-window and then decide to switch the action to delete or swap etc. By default the bindings are:

  • x - delete window
  • m - swap windows
  • M - move window
  • j - select buffer
  • n - select the previous window
  • u - select buffer in the other window
  • c - split window fairly, either vertically or horizontally
  • v - split window vertically
  • b - split window horizontally
  • o - maximize current window
  • ? - show these command bindings

For proper operation, these keys must not be in aw-keys. Additionally, if you want these keys to work with fewer than three windows, you need to have aw-dispatch-always set to t.

Customization

Aside from binding ace-window:

(global-set-key (kbd "M-o") 'ace-window)

the following customizations are available:

aw-keys

aw-keys - the list of initial characters used in window labels:

(setq aw-keys '(?a ?s ?d ?f ?g ?h ?j ?k ?l))

aw-keys are 0-9 by default, which is reasonable, but in the setup above, the keys are on the home row.

aw-scope

The default one is global, which means that ace-window will work across frames. If you set this to frame, ace-window will offer you only the windows of the current frame.

aw-background

By default, ace-window temporarily sets a gray background and removes color from available windows in order to make the window-switching characters more visible. This is the behavior inherited from ace-jump-mode.

This behavior might not be necessary, as you already know the locations where to look, i.e. the top-left corners of each window. So you can turn off the gray background with:

(setq aw-background nil)

aw-dispatch-always

When non-nil, ace-window will issue a read-char even for one window. This will make ace-window act differently from other-window for one or two windows. This is useful to change the action midway and execute an action other than the default jump action. By default, this is set to nil.

aw-dispatch-alist

This is the list of actions you can trigger from ace-window other than the jump default. By default it is:

(defvar aw-dispatch-alist
  '((?x aw-delete-window "Delete Window")
	(?m aw-swap-window "Swap Windows")
	(?M aw-move-window "Move Window")
	(?j aw-switch-buffer-in-window "Select Buffer")
	(?n aw-flip-window)
	(?u aw-switch-buffer-other-window "Switch Buffer Other Window")
	(?c aw-split-window-fair "Split Fair Window")
	(?v aw-split-window-vert "Split Vert Window")
	(?b aw-split-window-horz "Split Horz Window")
	(?o delete-other-windows "Delete Other Windows")
	(?? aw-show-dispatch-help))
  "List of actions for `aw-dispatch-default'.")

When using ace-window, if the action character is followed by a string, then ace-window will be invoked again to select the target window for the action. Otherwise, the current window is selected.

aw-minibuffer-flag

When non-nil, also display ace-window-mode string in the minibuffer when ace-window is active. This is useful when there are many side-by-side windows and the ace-window-mode string is cutoff in the minor mode area of the modeline.

aw-ignored-buffers

List of buffers and major-modes to ignore when choosing a window from the window list. Active only when aw-ignore-on is non-nil. Windows displaying these buffers can still be chosen by typing their specific labels.

aw-ignore-on

When t, ace-window will ignore buffers and major-modes in aw-ignored-buffers. Use M-0 ace-window to toggle this value. :type 'boolean)

aw-ignore-current

When t, ace-window will ignore `selected-window'.