Re: find-file-hook, recenter, scroll-conservatively and save-place

[Juri Linkov <juri@jurta.org>]

>> My question: is there a better hook that we could use for save-place
>> restoration purposes?
>>
>> I also looked into xref, and there the behavior is much better: the
>> (recenter) is included in the default configuration of
>> xref-after-jump-hook and it works in all the scenarios that I have
>> tried.
>
> Juri, should we handle this somehow?

I don't like the default recentering too.  I had to fix it with
a lot of customization, e.g.

(add-hook 'xref-after-jump-hook 'reposition-window)
(add-hook 'xref-after-return-hook 'reposition-window)
(add-hook 'find-function-after-hook 'reposition-window)

;; Let `C-M-a' (beginning-of-defun) not scroll the window
;; when after jumping point stays within current window bounds
(advice-add 'beginning-of-defun :around
	    (lambda (orig-fun &rest args)
	      (let ((w-s (window-start))
		    (w-e (window-end)))
		(apply orig-fun args)
		(when (and
		       ;; Only when used interactively
		       (eq this-command 'beginning-of-defun)
		       ;; And only when jumping outside of window
		       ;; to the center of the window
		       (or (< (point) w-s) (> (point) w-e)))
		  (recenter 11))))
	    '((name . recenter)))

;; Save and restore window start positions on returning to previous search
(setq isearch-push-state-function
      (lambda ()
	;; Recenter new search hits outside of window boundaries
        (when (and isearch-success (not (pos-visible-in-window-p)))
	  ;; reposition-window takes too much time in large buffers
          (if (or (eq major-mode 'fundamental-mode)
                  (> (buffer-size) 1000000))
	      (recenter 11)
	    (condition-case nil
		;; Prevent errors from reposition-window
		(reposition-window)
	      (error nil))))
        `(lambda (cmd)
           (when isearch-success
             (set-window-start nil ,(window-start))))))

> That is, provide 'window-point' and 'window-start' action alist entries
> with the former allowing the 'switch-to-buffer-preserve-window-point'
> logic (among others) and the latter optionally allowing to recenter.

Like switch-to-buffer-preserve-window-point used in dired-find-file?

> I don't know how 'save-place' could pass these on to the
> 'pop-to-buffer' call in 'find-file' though.  Can you think
> of any other use cases where these would be helpful?

Interesting question.  Maybe introduce two new buffer-local variables
'window-point' and 'window-start' that a hook could set and then
display-buffer could read and call functions window-point and window-start?
These buffer-local values should be used only once and should be reverted
to nil after the first use.

BTW, a related question: should save-place save window-start as well?
It should be easy to implement after this problem is solved.