how to get ace-window to do row-major numbering of windows?

Question

I use ace-window, and when I have at least two rows and columns of windows. When I invoke ace-window, it does column-major ordering of the windows:

|----------+----------|
|          |          |
| window 1 | window 3 |
|          |          |
|----------+----------|
|          |          |
| window 2 | window 4 |
|          |          |
|----------+----------|

That just never seems right to me; windows 2 and 3 just seem wrong. I want row-major ordering for the window numbers:

|----------+----------|
|          |          |
| window 1 | window 2 |
|          |          |
|----------+----------|
|          |          |
| window 3 | window 4 |
|          |          |
|----------+----------|

How can I get this behavior?

Answer 1

ace-window calls window-list when it builds its list of windows using aw-window-list and sorts the windows using aw-window<.

I tried just bypassing the sorting entirely by redefining ace-window's sorting:

(defun aw-window< (wnd1 wnd2) t)

...but ace-window has its own window ring, and uses that somehow when numbering the windows. So after switching, the order is different!

That said, it's easy enough to swap the row/column logic in aw-window<:

(defun aw-window< (wnd1 wnd2)
  "Return true if WND1 is less than WND2.
This is determined by their respective window coordinates.

This modification of what's in ace-window.el numbers the
windows in a row-major way: left to right, top down."
  (let* ((f1 (window-frame wnd1))
         (f2 (window-frame wnd2))
         (e1 (window-edges wnd1))
         (e2 (window-edges wnd2))
         (p1 (frame-position f1))
         (p2 (frame-position f2))
         (nl (or (null (car p1)) (null (car p2)))))
    (cond ((and (not nl) (< (car p1) (car p2)))
           (not aw-reverse-frame-list))
          ((and (not nl) (> (car p1) (car p2)))
           aw-reverse-frame-list)
          ;; You can read "car" below as "the upper left x-coordinate"
          ;; and "cadr" as "the upper left y-coordinate". The usage here
          ;; is swapped from ace-window.el to change column-major
          ;; ordering to row-major.
          ((< (cadr e1) (cadr e2))
           t)
          ((> (cadr e1) (cadr e2))
           nil)
          ((< (car e1) (car e2))
           t))))

...which is identical to the source code, except for exchanging the car and cadr usage.

I haven't fully figured out why the first approach -- using an always-true or always-nil predicate -- doesn't work, but it's easy enough to just evaluate the above. I'm sure there's a more elegant way to handle this override but this works. shrug