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bug#22404: 25.1.50; Forcing `window-scroll-functions` to run.
From: |
Keith David Bershatsky |
Subject: |
bug#22404: 25.1.50; Forcing `window-scroll-functions` to run. |
Date: |
Wed, 20 Jan 2016 18:32:40 -0800 |
`set-window-start` (without the third option) would indeed trigger the WSF
because it contains a key ingredient: `w->force_start = true`.
Because the second argument (i.e., POS) cannot be known from the PCH when point
has moved beyond the visible window, `set-window-start` is not a viable
substitute for this feature request.
The attached patch is an example of an implementation of this feature request.
I created a new function called `force-wsf`, whose sole purpose is to trigger
the WSF to run during redisplay -- after the PCH has already finished. As
noted in a previous e-mail, `run-window-scroll-functions` doesn't accomplish
what `force-wsf` can achieve because the former runs the function attached to
the WSF immediately -- instead of waiting until later on during redisplay when
the correct values of `window-start` and `window-end` are ascertainable.
This is my first attempt at writing something like this, and I'm not sure
exactly if everything is correct. It does, however, appear to achieve the
desired affect -- i.e., run the WSF at least once every command loop (even if
no scrolling occurs) so we can always know the correct values for
`window-start` and `window-end`. It is no longer necessary to guess with
`elisp` from the PCH regarding whether WSF will run.
I would, however, still like to come up with a test at the C-source code level
that tells me whether the WSF will run more than one time -- because I only
care about the last call on the WSF when the final values for `window-start`
and `window-end` become available.
The usage for the new function `force-wsf` is as follows:
(defun pch-fn ()
(force-wsf (selected-window)))
(add-hook 'post-command-hook 'pch-fn nil 'local)
(defun wsf-fn (win start)
(message "point: %s | win: %s | start: %s | end: %s"
;; A better test at the C-source code level appears to be needed to
ascertain whether
;; the WSF will run more than one time -- because we want the value for
`window-start`
;; and `window-end win t` based on the LAST time WSF runs during the
command loop.
(if (pos-visible-in-window-p nil nil nil)
"visible"
"NOT visible")
win start (window-end win t)))
(add-hook 'window-scroll-functions 'wsf-fn nil 'local)
The new function in window.c looks like this:
DEFUN ("force-wsf", Fforce_wsf, Sforce_wsf, 0, 1, 0,
doc: /* Set force_start so that redisplay_window will run the
window-scroll-functions. */)
(Lisp_Object window)
{
register struct window *w = decode_live_window (window);
w->optional_new_start = true;
return;
}
And, the there is one additional line that may also be required further on down
in window.d:
defsubr (&Sforce_wsf);
Thanks,
Keith
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
At Wed, 20 Jan 2016 15:34:41 +0200,
Eli Zaretskii wrote:
>
> > . . . you need to call set-window-start with its 3rd
> argument omitted or nil. Does that solve your problem?
patch.diff
Description: application/diff
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Eli Zaretskii, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., John Wiegley, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/19
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run.,
Keith David Bershatsky <=
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/21
bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/21
bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/28