From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Michael Heerdegen Newsgroups: gmane.emacs.help Subject: Re: are there hooks for text becoming visible or hidden in a given window? Date: Fri, 25 Feb 2022 03:42:12 +0100 Message-ID: <87a6efr7jv.fsf@web.de> References: <06e7c939da37479902e9a935fbaf487a@basiscraft.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="16611"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:eTXOt95Bb2XWF65wxnZvx3WJbEM= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Feb 25 03:43:12 2022 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nNQZb-00046I-Vf for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 25 Feb 2022 03:43:11 +0100 Original-Received: from localhost ([::1]:39502 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nNQZa-0003Dd-Dz for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 24 Feb 2022 21:43:10 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:42174) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nNQYr-0003D8-GQ for help-gnu-emacs@gnu.org; Thu, 24 Feb 2022 21:42:28 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:54558) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nNQYp-00017H-NO for help-gnu-emacs@gnu.org; Thu, 24 Feb 2022 21:42:25 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1nNQYl-0002zL-9U for help-gnu-emacs@gnu.org; Fri, 25 Feb 2022 03:42:19 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -13 X-Spam_score: -1.4 X-Spam_bar: - X-Spam_report: (-1.4 / 5.0 requ) BAYES_00=-1.9, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:136184 Archived-At: Thomas Lord writes: > I couldn't find anything like this and I don't see a clean > alternative. Reminds me of the task I had to solve when implementing "on-screen.el" - a package that indicates the formerly visible region after scrolling a window. What you want is nearly the same: observe the visible region of a window, do something (involving redisplay) when it changes. It was surprisingly tricky to do. I didn't use jit-lock, I used hooks. Dunno if the solution I implemented is a good one, aesthetically, but it worked reliably over the years, so that approach is somewhat tested. Michael.