From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#18739: 24.3; Request for a hook to be provided when scrolling will move the cursor Date: Thu, 16 Oct 2014 17:13:41 +0300 Message-ID: <831tq83xwq.fsf@gnu.org> References: <83wq813vyx.fsf@gnu.org> <83r3y84iuv.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1413468864 25474 80.91.229.3 (16 Oct 2014 14:14:24 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 16 Oct 2014 14:14:24 +0000 (UTC) Cc: josh+gnu@nispio.net, 18739@debbugs.gnu.org To: Stefan Monnier Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Thu Oct 16 16:14:17 2014 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Xelol-0002gk-LY for geb-bug-gnu-emacs@m.gmane.org; Thu, 16 Oct 2014 16:14:15 +0200 Original-Received: from localhost ([::1]:50633 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xelol-0001KY-8J for geb-bug-gnu-emacs@m.gmane.org; Thu, 16 Oct 2014 10:14:15 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:33857) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xelod-0001Js-El for bug-gnu-emacs@gnu.org; Thu, 16 Oct 2014 10:14:12 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XeloY-0001QH-J5 for bug-gnu-emacs@gnu.org; Thu, 16 Oct 2014 10:14:07 -0400 Original-Received: from debbugs.gnu.org ([140.186.70.43]:54473) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XeloY-0001QB-GD for bug-gnu-emacs@gnu.org; Thu, 16 Oct 2014 10:14:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.80) (envelope-from ) id 1XeloY-0006YM-34 for bug-gnu-emacs@gnu.org; Thu, 16 Oct 2014 10:14:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Thu, 16 Oct 2014 14:14:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 18739 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 18739-submit@debbugs.gnu.org id=B18739.141346882525158 (code B ref 18739); Thu, 16 Oct 2014 14:14:02 +0000 Original-Received: (at 18739) by debbugs.gnu.org; 16 Oct 2014 14:13:45 +0000 Original-Received: from localhost ([127.0.0.1]:46037 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XeloG-0006Xh-F1 for submit@debbugs.gnu.org; Thu, 16 Oct 2014 10:13:45 -0400 Original-Received: from mtaout22.012.net.il ([80.179.55.172]:64042) by debbugs.gnu.org with esmtp (Exim 4.80) (envelope-from ) id 1XeloC-0006XX-V0 for 18739@debbugs.gnu.org; Thu, 16 Oct 2014 10:13:42 -0400 Original-Received: from conversion-daemon.a-mtaout22.012.net.il by a-mtaout22.012.net.il (HyperSendmail v2007.08) id <0NDJ00400JDYRW00@a-mtaout22.012.net.il> for 18739@debbugs.gnu.org; Thu, 16 Oct 2014 17:13:39 +0300 (IDT) Original-Received: from HOME-C4E4A596F7 ([87.69.4.28]) by a-mtaout22.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0NDJ004HBJIRS000@a-mtaout22.012.net.il>; Thu, 16 Oct 2014 17:13:39 +0300 (IDT) In-reply-to: X-012-Sender: halo1@inter.net.il X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.15 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 140.186.70.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:94614 > From: Stefan Monnier > Cc: josh+gnu@nispio.net, 18739@debbugs.gnu.org > Date: Thu, 16 Oct 2014 09:44:34 -0400 > > >> >> It would be helpful to have a hook that would be called before any > >> >> scrolling command moves the cursor. In other words, I want to be > >> >> notified when an update to the display will force the location of > >> >> `point' to change in the current buffer. > >> > What's wrong with window-scroll-functions? > >> But these are also called when point is not affected, right? > > Yes. But it's easy to detect that situation, I think. > > Is it? I think. > I think the main reason why I ask is because I truly have no idea when > window-scroll-functions is called. You seem to be somewhat familiar > with it, so could you try and clarify it in the docstring? When it's clear what to clarify, I will ;-) > Currently I see "List of functions to call before redisplaying a window > with scrolling" and "Note that these functions are also called by > `set-window-buffer'". That's correct. > Here are some of the questions this brings up for me: > - is it called during set-window-buffer itself, or is it called in the > first redisplay after set-window-buffer? The former, see window.c:set_window_buffer. > - what means "redisplaying a window with scrolling" exactly? Does it > mean "redisplay with a different window-start then during the last > redisplay"? Yes, that's one of the causes. For example, if point moved outside the window. > Does that include the case where window-start is changed > so as to follow point or is it only the cases where window-start was > changed explicitly by a scrolling command? Both. > - how could a window-scroll-function distinguish the 3 cases: > "set-window-buffer", "used a scroll command", "moved point out of viewport". I have no idea (but this is not exactly a question about the doc string). > I tried already a few times to understand window-scroll-functions, but > so far it has eluded me. FWIW, I found 3 kinds of uses: > - A crutch from when jit-lock didn't exist (in linum and lazy-lock). > - A way to try and keep a window fully empty showing only point-max by > calling set-window-start with the same window-start (in follow-mode). > Not clear exactly why this should work, and arguably goes against the > warning in window-scroll-functions's docstring. > - Do fancy auto-scrolling in eshell/em-smart (which does exactly what > window-scroll-functions's docstring warns not to do, AFAICT), calling > redisplay internally. Did the above clarifications help you?