From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Richard Wordingham Newsgroups: gmane.emacs.help Subject: Composed Sequences (was: Manually parsing char-tables) Date: Sat, 26 Feb 2022 00:28:37 +0000 Message-ID: <20220226002837.699ae2b1@JRWUBU2> References: <20220220110926.25c675be@JRWUBU2> <835yp9ya4x.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="31466"; mail-complaints-to="usenet@ciao.gmane.io" To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Feb 26 01:29:46 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 1nNky2-00084Q-B1 for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 26 Feb 2022 01:29:46 +0100 Original-Received: from localhost ([::1]:40618 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nNkxz-0004oz-Sx for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 25 Feb 2022 19:29:43 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:42122) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nNkx4-0004oq-2R for help-gnu-emacs@gnu.org; Fri, 25 Feb 2022 19:28:46 -0500 Original-Received: from smtpq1.tb.ukmail.iss.as9143.net ([212.54.57.96]:46450) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nNkx1-0001zo-Fg for help-gnu-emacs@gnu.org; Fri, 25 Feb 2022 19:28:45 -0500 Original-Received: from [212.54.57.106] (helo=csmtp2.tb.ukmail.iss.as9143.net) by smtpq1.tb.ukmail.iss.as9143.net with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nNkww-0002zz-Ra for help-gnu-emacs@gnu.org; Sat, 26 Feb 2022 01:28:38 +0100 Original-Received: from JRWUBU2 ([82.27.122.109]) by cmsmtp with ESMTP id Nkwwnh7DvYDyuNkwwnG9aw; Sat, 26 Feb 2022 01:28:38 +0100 X-SourceIP: 82.27.122.109 X-Spam: 0 X-Authority: v=2.4 cv=eu3Mc6lX c=1 sm=1 tr=0 ts=62197436 cx=a_exe a=lZfnwhydZ+7bl6OdZ0zTBw==:117 a=lZfnwhydZ+7bl6OdZ0zTBw==:17 a=kj9zAlcOel0A:10 a=oGFeUVbbRNcA:10 a=mDV3o1hIAAAA:8 a=NLZqzBF-AAAA:8 a=EMxJQFfyRQ0K1BD6NLcA:9 a=CjuIK1q_8ugA:10 a=_FVE-zBwftR9WsbkzFJk:22 a=wW_WBVUImv98JQXhvVPZ:22 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ntlworld.com; s=meg.feb2017; t=1645835318; bh=L30ThpL3e/XirdDea8coZvk9Ig2k8pgbor83b7hJBJ4=; h=Date:From:To:Subject:In-Reply-To:References; b=qpiDQGQ93IM/T4xDp9at63WlsIakyWsTAtZJHWHHvVaSyxBJwdEmdvyO4oJff3Ri8 G936smqvt3H2ObS2+ctQTcfcm5rgt1yCVaUu1JbQ0Pu3zsleVJoTIdcSg9XUCRvAkq yamYbYsGObWdxrFPb5SZKgQTvLXpnPmGNI8/ZeU6mY3ZXkbQmhAQGE4FoUEjXn9LkR Gf1KIKVWWhVwr1lE6M+ULyLeTCmv8p9ic4DkNeV6fsMH40vzyHAUuO7Mu00E6KcITc HesMlNQ78zwzE/NK87R1jUaIAemKzNcmI6XXhZ4A7AE7NzTNMF4IovsdCvMfOzD7YX u8VJodEw3jp2g== In-Reply-To: <835yp9ya4x.fsf@gnu.org> X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) X-CMAE-Envelope: MS4xfClzhl2sH0kJyxEzsQP0tu43ArxnSinWDmDxLTxlQmhIKZHtR/Jee5BP8TYSSIOjuNccz3uU8cZgsDxI8TgMJnkvjLKGL6HoqzkH5V1qqQd07UVB13w0 6PyFMIkx9P9S6Wk0SEG47QnbfuXtXITzRCaymmymWAfCvWMwFGF7Vur5Iw2vMWEqqDzkmPaB1VNxHm/5j4CkJCMF7IIaneB1nhc= Received-SPF: pass client-ip=212.54.57.96; envelope-from=richard.wordingham@ntlworld.com; helo=smtpq1.tb.ukmail.iss.as9143.net X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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:136189 Archived-At: On Sun, 20 Feb 2022 14:50:54 +0200 Eli Zaretskii wrote: > > Date: Sun, 20 Feb 2022 11:09:26 +0000 > > From: Richard Wordingham > > > > I am trying to understand how Arabic script rendering works in Emacs > > 28.0.90, as it seems to be using a different mechanism to that used > > for Indic or European scripts. (There seems to be more to it than > > just the asymmetries between right-to-left and left-to-right.) To > > that end, I am trying to understand the contents of the variable > > composition-function-table. (The version above should actually read 28.0.91.) > I think it is easier to just look at how the Arabic part of this table > is populated. See lisp/language/misc-lang.el starting from line 105. I still haven't found the code where the difference occurs, but I now have a better idea of what is going on. It seems that runs with the same value of the composition property ('composed sequences') are sequences of clusters for the font that match a regular expression given in composition-function-table. Different renderers give different clusters, and thus, by default, different cursor motion! The insight was given by GNU Emacs 23.4.1 (i386-mingw-nt6.2.9200) running on Windows 10. The reason Arabic seemed different is that when lam+hah appears to ligate, what is happening (at least with Amiri) is that substitutions are made which give the effect of a ligature, while remaining two distinct glyphs. Richard.