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.devel Subject: Re: Ligature support Date: Fri, 05 Nov 2021 18:34:47 +0200 Message-ID: <83o86yd0ig.fsf@gnu.org> References: <87cznths5j.fsf@gnus.org> <8ff3b131c531f5254799@heytings.org> <83a6ittp5r.fsf@gnu.org> <8ff3b131c53b9df49236@heytings.org> <834k91th5c.fsf@gnu.org> <8ff3b131c5fe09753ca0@heytings.org> <83mtmtru6l.fsf@gnu.org> <8ff3b131c57f741d04e5@heytings.org> <83lf2drqx6.fsf@gnu.org> <87lf2c3k0z.fsf@gnus.org> <83wnlwqocq.fsf@gnu.org> <87wnlwyox9.fsf@gnus.org> <83lf2cq7n5.fsf@gnu.org> <87wnlnkxbo.fsf@gnus.org> <83cznfdohr.fsf@gnu.org> <87zgqik9bk.fsf@gnus.org> <83v916d64z.fsf@gnu.org> <878ry2k6qz.fsf@gnus.org> <83tugqd488.fsf@gnu.org> <87zgqiiq8c.fsf@gnus.org> <83r1bud3or.fsf@gnu.org> <87r1buipf5.fsf@gnus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="16142"; mail-complaints-to="usenet@ciao.gmane.io" Cc: mattiase@acm.org, raman@google.com, gregory@heytings.org, schwab@linux-m68k.org, stefankangas@gmail.com, emacs-devel@gnu.org To: Lars Ingebrigtsen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Nov 05 17:41:10 2021 Return-path: Envelope-to: ged-emacs-devel@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 1mj2H7-0003yx-D0 for ged-emacs-devel@m.gmane-mx.org; Fri, 05 Nov 2021 17:41:09 +0100 Original-Received: from localhost ([::1]:58470 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mj2H6-0006TB-9Q for ged-emacs-devel@m.gmane-mx.org; Fri, 05 Nov 2021 12:41:08 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:34894) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mj2BJ-00078L-Uk for emacs-devel@gnu.org; Fri, 05 Nov 2021 12:35:10 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:57776) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mj2BH-0002TK-US; Fri, 05 Nov 2021 12:35:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=MIME-version:References:Subject:In-Reply-To:To:From: Date; bh=Ctrz+n/MgfdPia+fvFDyvEqfBIlbsa3kOKePsl73q8k=; b=FLZGiJ8uwjcuo0RG3f5H 1sZpPgdGjlVeyOpDp0XVYna1A4wkYNIeTsyGe9KZvCF9rPO0atiJ/wOgYvwwgO/hDT5ePwebeApLf 38kLMEECX+DrIrTkjLBTM38AbDgtnnNaS1/2Nkcg/Y16q3m5If4eL9dlO6nXKwKQlYsVe7lStw5Zs wGRXuP7a5CqBVznCwFXlE0ExuapYIFTEqh8kpDG/m9iAK0mwo6Nogq5SdLTuyJI32sddO24YCuSXY yjnY6D8kbo9raXzYESbTE15EQq1PCqmj3gaCtu6oLIvMZPjju5fnhPvlAKLPIVr6XZ5Tk6ilJraB/ eqdKhVqk5F5+sw==; Original-Received: from [87.69.77.57] (port=1322 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 1mj2BF-0002pN-OA; Fri, 05 Nov 2021 12:35:07 -0400 In-Reply-To: <87r1buipf5.fsf@gnus.org> (message from Lars Ingebrigtsen on Fri, 05 Nov 2021 16:37:50 +0100) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:278785 Archived-At: > From: Lars Ingebrigtsen > Cc: gregory@heytings.org, mattiase@acm.org, emacs-devel@gnu.org, > schwab@linux-m68k.org, stefankangas@gmail.com, raman@google.com > Date: Fri, 05 Nov 2021 16:37:50 +0100 > > Eli Zaretskii writes: > > > How many ligatures are there in the best of all fonts? If the number > > of the ligatures is not too large, then passing them to the shaper may > > not be such a terrible idea. > > I don't really know -- my test font has 27 ligatures, apparently, but > some of the more fun programming fonts have at least a hundred, I think. > And there's fonts that turn things like :warning: into its own glyph, > using the ligature mechanism, and who knows how many of those there may > be. If the sequences of characters that are converted to ligatures are not too frequent, that is still not a catastrophe. > > So I think we should first consider which ligatures we'd like to > > support, and whether the answer differs depending on the major mode. > > For example, ligatures like ==> etc. are relevant to prog-mode modes, > > but probably not to text modes. By contrast, "ff" and "fi" are > > relevant only to text mode, I think. > > I think we want to support all ligatures the font supports (in general). All the time? really?? For example, the mode line can show stuff like "=-", and the font could have a ligature for that -- do we really want that ligature on the mode line? Or the font could have a ligature for "ffi" -- do we want a variable named "efficient" be displayed with that ligature? I'd be surprised. > But as you say, we may not want to switch all the ligatures on in all > modes -- but I'm not really sure about that, either. If a person is > using the Firabase font (or whatever it was called), they presumably do > so because they want to get all the funny glyphs everywhere (that they > use that font). Most of them use prettify-symbols-mode or similar stuff, and that's different from how character compositions work: you must actually put a special text property to make that happen. So there's is not much for us to learn from that. > But it's certainly possible -- having a switch to tweak which ligatures > should be active on a per-mode/buffer basis is something we'd need to > look at. I think we can look at that after we actually have ligatures > displayed at all, though. 😀 Displaying them is easy, just set up composition-function-table accordingly (I can show you the code if you cannot figure that out). That's the least of our problems.