Is it possible to calculate a new window-start/end without a redisplay occurring? If so, then an example would be greatly appreciated. If not, then what is the best way to approximate it?
Example: We want to move to a new area of the buffer somewhere off screen, and place overlays when we get there. We might be using page-down or scroll-down or paragraph-down or end-of-buffer. When we get to that new point, we want to calculate the new window-start and the new window-end. However, we want to avoid a momentary naked looking buffer without any overlays. Ideally, the redisplay would occur once those overlays are added. I want to restrict new overlays to the new region based upon the new window-start/end.
Point-Min: point = 1
Old Window Start: point = 1000
Old Window End: point = 1500
New Window Start: point = 3500
New Window End: point = 4000
Point-Max: point = 6000
Problem: When using the post-command-hook to try and calculate the new window-start and new window-end, the previous display positions are being used instead -- i.e., the old window-start and the old window-end.
Here is a sample of the project I am working on. Absent fixing the window-start \ window-end problem, I get the following error:
Error in post-command-hook (my-eol-ruler-function):
(error "Invalid search bound (wrong side of point)")`.
The error happens when going from (point-min) to the end of the buffer with the interactive function end-of-buffer. In the context of this error, (point-max) is beyond the old window-end.
EDIT: Updated code to include a message: (message "point: %s | window-start: %s | window-end: %s | point-max: %s" (point) (window-start) (window-end) (point-max) ). The message is used to demonstrate that the new window-start and new window-end are not calculated within the post-command-hook because a redisplay has not yet occurred. However, I am trying to avoid a redisplay until after the new overlays have been placed -- otherwise, a naked buffer without overlays is visible for a split second.
(defvar my-eol-ruler nil
"A horizontal ruler stretching from eol (end of line) to the window edge.")
(make-variable-buffer-local 'my-eol-ruler)
(defvar my-eol-pilcrow nil
"A pilcrow symbol placed at the end of every line except the current line.")
(make-variable-buffer-local 'my-eol-pilcrow)
(defun my-eol-ruler-function ()
(let* (
(opoint (point))
(window-width (window-width))
(window-start (window-start))
(window-end (window-end))
(col-eovl
(save-excursion
(vertical-motion 1)
(skip-chars-backward " \r\n" (- (point) 1))
(- (current-column) (progn (vertical-motion 0) (current-column)))))
(my-current-line-length (- (- window-width col-eovl) 3))
(pilcrow
(propertize (char-to-string ?\u00B6)
'face '(:foreground "white")
'cursor t))
(pilcrow-underlined
(propertize (char-to-string ?\u00B6)
'face '(:foreground "white" :underline "yellow")
'cursor t))
(underline (propertize (char-to-string ?\u2009)
'display `(space :width ,my-current-line-length)
'face '(:underline "yellow")
'cursor t)))
(when (or my-eol-ruler my-eol-pilcrow)
(dolist (description `(
,my-eol-ruler
,my-eol-pilcrow ))
(remove-overlays (point-min) (point-max)
'after-string description)) )
(setq my-eol-ruler (concat pilcrow-underlined underline))
(setq my-eol-pilcrow pilcrow)
(save-excursion
(end-of-line)
(overlay-put (make-overlay (point) (point))
'after-string my-eol-ruler ) )
(message "point: %s | window-start: %s | window-end: %s | point-max: %s"
(point)
(window-start)
(window-end)
(point-max) )
(save-excursion
(goto-char window-end)
(while (re-search-backward "\n" window-start t)
(let* (
(pbol (point-at-bol))
(pbovl (save-excursion (vertical-motion 0) (point)))
(peol (point))
(peol-pbol-region-p
(if (region-active-p)
(= peol pbol)))
(eol-inside-region-p
(if (region-active-p)
(and
(<= reg-beg peol)
(> reg-end peol))))
(col-eovl
(save-excursion
(vertical-motion 1)
(skip-chars-backward " \r\n" (- (point) 1))
(- (current-column) (progn (vertical-motion 0) (current-column)))))
(my-last-column (current-column))
(window-width-bug-p (= my-last-column (- window-width 1)))
(shazbot-pbol
(save-excursion
(end-of-line)
(re-search-backward "\s\\|\t" pbol t) (+ (point) 1)))
(wrapped-window-width-bug-p (= col-eovl (- window-width 1))) )
(when
(or
(< opoint pbol)
(> opoint peol))
(overlay-put (make-overlay peol peol) 'after-string my-eol-pilcrow))))) ))
(add-hook 'post-command-hook 'my-eol-ruler-function)
Beginning of the buffer, before the error occurs.
End of the buffer -- the error occurs when executing the interactive function end-of-buffer from a point at the beginning of the buffer.
Error in post-command-hook (my-eol-ruler-function):
(error "Invalid search bound (wrong side of point)")
