From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.bugs Subject: bug#50177: Support U+20DD COMBINING ENCLOSING CIRCLE Date: Sat, 28 Aug 2021 10:32:26 +0300 Message-ID: <83y28mnhx1.fsf@gnu.org> References: <87tuja2ido.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="11987"; mail-complaints-to="usenet@ciao.gmane.io" Cc: 50177@debbugs.gnu.org, larsi@gnus.org, jidanni@jidanni.org To: handa Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sat Aug 28 09:33:10 2021 Return-path: Envelope-to: geb-bug-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 1mJspy-00030O-2b for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 28 Aug 2021 09:33:10 +0200 Original-Received: from localhost ([::1]:39870 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJspw-0001jF-UM for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 28 Aug 2021 03:33:08 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:59788) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJspq-0001ip-Qj for bug-gnu-emacs@gnu.org; Sat, 28 Aug 2021 03:33:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:41779) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mJspq-0004u9-JE for bug-gnu-emacs@gnu.org; Sat, 28 Aug 2021 03:33:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1mJspq-00029Z-De for bug-gnu-emacs@gnu.org; Sat, 28 Aug 2021 03:33:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Eli Zaretskii Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sat, 28 Aug 2021 07:33:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 50177 X-GNU-PR-Package: emacs Original-Received: via spool by 50177-submit@debbugs.gnu.org id=B50177.16301359708260 (code B ref 50177); Sat, 28 Aug 2021 07:33:02 +0000 Original-Received: (at 50177) by debbugs.gnu.org; 28 Aug 2021 07:32:50 +0000 Original-Received: from localhost ([127.0.0.1]:53325 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mJspe-000299-G4 for submit@debbugs.gnu.org; Sat, 28 Aug 2021 03:32:50 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:43680) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mJspd-00028x-6h for 50177@debbugs.gnu.org; Sat, 28 Aug 2021 03:32:49 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:55834) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJspX-0004f6-RU; Sat, 28 Aug 2021 03:32:43 -0400 Original-Received: from 84.94.185.95.cable.012.net.il ([84.94.185.95]:1762 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJspV-00057M-5E; Sat, 28 Aug 2021 03:32:43 -0400 In-Reply-To: <87tuja2ido.fsf@gnu.org> (message from handa on Sat, 28 Aug 2021 15:28:03 +0900) X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list 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-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:212856 Archived-At: > From: handa > Cc: larsi@gnus.org, jidanni@jidanni.org, 50177@debbugs.gnu.org, handa@gnu.org > Date: Sat, 28 Aug 2021 15:28:03 +0900 > > In article <8335qyx0f3.fsf@gnu.org>, Eli Zaretskii writes: > > > I haven't looked at the machinery here at all -- is there a fundamental > > > reason why Emacs can't combine glyphs from different fonts? > > > The basic reason is that glyphs from different fonts cannot combine > > well because they were designed to look differently, and so offsets > > don't match. That is almost certainly the reason when we use our > > fallback composition code in composite.el. I'm less sure about modern > > shaping engines like HarfBuzz -- we should ask their developers to be > > sure; feel free to open an issue/question on their GitHub. > > > CC'ing Handa-san, in the hope that he could explain better why we > > disallow character composition from different fonts. > > The main reason is what Eli wrote. An opentype font contains rules to > tell how to compose two glyphs in that font. But such rules are > specific to that font, and there's no way to combine rules of different > fonts. So, an opentype rendering engine does not work for different > fonts. > > And, when we artificially compose characters from different fonts, there > is a possibility that the resulting image looks like a different > character which I think is worse than not composing. OK, thanks.