From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Fill column indicator functionality Date: Fri, 15 Mar 2019 11:09:25 -0400 Message-ID: References: <20190309132207.w2ho3j6p5on6fyzw@Ergus> <838sxo87gc.fsf@gnu.org> <20190311104814.kp2nv6arv47hcykz@Ergus> <83y35l4ee0.fsf@gnu.org> <20190312152928.73o4b5fk4paz7wm5@Ergus> <834l883w15.fsf@gnu.org> <20190312192017.fkfd4h5gsbdue5q3@Ergus> <83imwm3fxf.fsf@gnu.org> <20190313200225.dpqrw7xthkj47fqw@Ergus> <83bm2e35a1.fsf@gnu.org> <20190314030224.l5zseslncw3xc5ox@Ergus> <835zsm2c2s.fsf@gnu.org> <303612d8-e691-f753-84c9-f462d88262b6@gmail.com> <83d0ms1to4.fsf@gnu.org> <32B82860-3C7D-41CC-BD2F-8114BBA170B8@acm.org> <83va0kz04o.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="240542"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Mar 15 16:13:40 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1h4oWe-0010Md-4F for ged-emacs-devel@m.gmane.org; Fri, 15 Mar 2019 16:13:36 +0100 Original-Received: from localhost ([127.0.0.1]:57085 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h4oWc-0001F5-WA for ged-emacs-devel@m.gmane.org; Fri, 15 Mar 2019 11:13:35 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:56882) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h4oVL-00014Q-H7 for emacs-devel@gnu.org; Fri, 15 Mar 2019 11:12:16 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h4oSk-0005hL-Aq for emacs-devel@gnu.org; Fri, 15 Mar 2019 11:09:35 -0400 Original-Received: from [195.159.176.226] (port=46902 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h4oSj-0005gl-Nf for emacs-devel@gnu.org; Fri, 15 Mar 2019 11:09:34 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.89) (envelope-from ) id 1h4oSi-000vlD-7O for emacs-devel@gnu.org; Fri, 15 Mar 2019 16:09:32 +0100 X-Injected-Via-Gmane: http://gmane.org/ Cancel-Lock: sha1:6rgL0Yl/js8SeUZ14RY9/RWqTik= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:234165 Archived-At: >> Being its own terminal emulator, Emacs could do the same to avoid gaps in >> horizontal and vertical lines that should connect. > > Unfortunately, this is not currently possible, not without significant > changes in how the Emacs display engine works internally. The display > routines are currently called in a way that doesn't allow them to have > a window-global view of the display, not even a way of knowing what's > on the previous and the next screen lines. In fact, the display > routines need to do their job even if the information about the layout > of adjacent screen lines is not available at all, and redisplay > optimizations frequently make use of this property, by starting a new > redisplay cycle on a specific line, doing part of the layout, then > throwing out the results. About the only thing the display routines > can rely on is the window-start point and the window pixel > dimensions. Even the vertical coordinate of a line on which the > display routine was called is frequently unknown. I think what Mattias is referring to is to change the part of the code where we draw the glyph matrix onto the screen (i.e. the part that's window-system specific), to add ad-hoc hacks that try to display box-drawing characters differently to try and fill small gaps between them. I don't know how workable that would be, especially when considering proportional fonts (i.e. the problems with box-drawing characters aren't limited to gaps between them but also include misalignment). Stefan