From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: handa Newsgroups: gmane.emacs.bugs Subject: bug#50177: Support U+20DD COMBINING ENCLOSING CIRCLE Date: Sat, 28 Aug 2021 15:28:03 +0900 Message-ID: <87tuja2ido.fsf@gnu.org> References: <87eeaj21py.8.fsf@jidanni.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="8927"; mail-complaints-to="usenet@ciao.gmane.io" Cc: handa@gnu.org, larsi@gnus.org, jidanni@jidanni.org, 50177@debbugs.gnu.org To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sat Aug 28 08:29:13 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 1mJrq2-000262-Ls for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 28 Aug 2021 08:29:10 +0200 Original-Received: from localhost ([::1]:36378 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJrq1-0002mI-GQ for geb-bug-gnu-emacs@m.gmane-mx.org; Sat, 28 Aug 2021 02:29:09 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:53534) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJrpu-0002m6-N5 for bug-gnu-emacs@gnu.org; Sat, 28 Aug 2021 02:29:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:41751) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1mJrpu-0001JL-D7 for bug-gnu-emacs@gnu.org; Sat, 28 Aug 2021 02:29:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1mJrpu-0000aG-2B for bug-gnu-emacs@gnu.org; Sat, 28 Aug 2021 02:29:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: handa Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sat, 28 Aug 2021 06:29:02 +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=B50177.16301321002193 (code B ref 50177); Sat, 28 Aug 2021 06:29:02 +0000 Original-Received: (at 50177) by debbugs.gnu.org; 28 Aug 2021 06:28:20 +0000 Original-Received: from localhost ([127.0.0.1]:53297 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mJrpD-0000ZJ-OU for submit@debbugs.gnu.org; Sat, 28 Aug 2021 02:28:19 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:37270) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1mJrp8-0000Yz-Ng for 50177@debbugs.gnu.org; Sat, 28 Aug 2021 02:28:18 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:54608) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJrp2-0000VD-W0; Sat, 28 Aug 2021 02:28:09 -0400 Original-Received: from fl1-119-240-89-42.iba.mesh.ad.jp ([119.240.89.42]:57090 helo=shatin) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJrp2-0007bE-QZ; Sat, 28 Aug 2021 02:28:08 -0400 Original-Received: from handa by shatin with local (Exim 4.93) (envelope-from ) id 1mJrox-000cdT-QG; Sat, 28 Aug 2021 15:28:03 +0900 In-Reply-To: <8335qyx0f3.fsf@gnu.org> (message from Eli Zaretskii on Tue, 24 Aug 2021 19:38:56 +0300) 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:212854 Archived-At: 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. --- K. Handa handa@gnu.org