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bug#22404: 25.1.50; Forcing `window-scroll-functions` to run.
From: |
Eli Zaretskii |
Subject: |
bug#22404: 25.1.50; Forcing `window-scroll-functions` to run. |
Date: |
Thu, 21 Jan 2016 22:28:05 +0200 |
> Date: Thu, 21 Jan 2016 11:54:30 -0800
> From: Keith David Bershatsky <esq@lawlist.com>
> Cc: 22404@debbugs.gnu.org
>
> The calculations (primarily because of `vertical-motion`) are too costly
> time-wise to perform more than once during each command loop because it slows
> down performance.
>
> If I run the calculations from the `post-command-hook`, I will have wasted
> precious time IF the `window-scroll-functions` hook will be running. IF the
> `window-scroll-functions` hook will be running, then the `window-start` and
> `window-end` obtained from the `post-command-hook` will be wrong -- so there
> is no point using those PCH wrong numbers.
>
> If I run the calculations from the INITIAL run of the
> `window-scroll-functions` hook, I will have wasted precious time IF the WSF
> hook will be running a SECOND time. [WSF runs a SECOND time if point was
> PARTIALLY visible.] IF the WSF will be running more than one time, then the
> INITIAL values for `window-start` and `window-end` will be wrong -- so there
> is no point using those WSF wrong numbers. Instead, I have to wait until the
> LAST call on the WSF when the final correct values for `window-start` and
> `window-end` can be truly ascertained.
>
> Without the benefit of feature request 22404, there are a couple of options
> that are not ideal.
What do you need from window-scroll-functions? Only the correct
values of window-start and window-end? Or something else?
The other thing I still don't understand is how forcing
window-scroll-functions to run could fix your problem or _avoiding_
extra calculations. Where and under what conditions would you call
the function that forces Emacs to run window-scroll-functions?
Doesn't that waste processing in those cases where normally
window-scroll-functions didn't need to be run (because window-start
and window-end don't change)? IOW, aren't you running those costly
calculations from window-scroll-functions?
Finally, wouldn't running from pre-command-hook solve the problem?
The values of window-start and window-end are known by then, and you
can record the old values to compare them against new, to know when
they change. No?
- bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., (continued)
- 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, 2016/01/20
- 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.,
Eli Zaretskii <=
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
bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/29
bug#22404: 25.1.50; Forcing `window-scroll-functions` to run., Keith David Bershatsky, 2016/01/31