How to set margins of buffer when window changes?

[edgar]

Hello dear Emacs users!

I am trying to have some buffers centre the text. I figured that I  
could do it with margins. I want this to adjust depending on the value  
of `fill-column' (could be any other variable) and the width of the  
window (if it is too small, don't centre). I have the code below, but  
I get the error: `Window ... too small for splitting' (replace `...'  
with the name of the buffer's window). I added a hook to the major  
mode list of hooks, but it could be something else.

The format is very similar to what they seek here:  
[https://stackoverflow.com/q/39083118]

How can I resize the window and adjust the margins depending on  
`fill-column'? Thanks.


    (with-eval-after-load 'python
     (defun centre-text-with-margins (&optional window width)
       "Moves the left and right margins to centre the contents of  
the current buffer in the current window"
       ;; https://stackoverflow.com/a/54098261
       ;; https://stackoverflow.com/q/39083118
        ;; (if (or (> left-margin-width 0) (> right-margin-width 0))
        ;;      (progn
              (setq left-margin-width 0)
              (setq right-margin-width 0)
              ;; (set-window-buffer nil (current-buffer))
              (set-window-margins window 0 0)
              ;; ))
          (let* ((txtwidth (cond (width) (fill-column)))
                 (space (max 0 (- (window-total-width) txtwidth)))
                 (leftside (floor (/ space 2)))
                 (rightside (- space leftside)))
            (setq left-margin-width leftside)
            (setq right-margin-width rightside)
            (set-window-buffer window (current-buffer))
            (format "lm:%s rm:%s sp:%s" left-margin-width  
right-margin-width space)))
     (defun py-margins-hook ()
       (add-hook 'window-state-change-hook #'centre-text-with-margins t t))
     (add-hook 'python-mode-hook 'py-margins-hook))


Emacs:
GNU Emacs 27.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.27,  
cairo version 1.17.4) of 2021-03-26


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