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.help Subject: Re: Confusing issue with redisplay Date: Thu, 19 Aug 2021 17:06:07 +0300 Message-ID: <83pmu91qcw.fsf@gnu.org> References: <875yw1lwd9.fsf.ref@yahoo.com> <875yw1lwd9.fsf@yahoo.com> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="33965"; 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 Thu Aug 19 16:06:57 2021 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 1mGih6-0008bq-RZ for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 19 Aug 2021 16:06:56 +0200 Original-Received: from localhost ([::1]:57660 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mGih5-0004tN-46 for geh-help-gnu-emacs@m.gmane-mx.org; Thu, 19 Aug 2021 10:06:55 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:50710) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mGige-0004sa-3i for help-gnu-emacs@gnu.org; Thu, 19 Aug 2021 10:06:28 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:46350) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mGigd-00024e-S9 for help-gnu-emacs@gnu.org; Thu, 19 Aug 2021 10:06:27 -0400 Original-Received: from 84.94.185.95.cable.012.net.il ([84.94.185.95]:4875 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 1mGigd-0001D0-Ev for help-gnu-emacs@gnu.org; Thu, 19 Aug 2021 10:06:27 -0400 In-Reply-To: <875yw1lwd9.fsf@yahoo.com> (message from Po Lu on Thu, 19 Aug 2021 15:36:02 +0800) X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 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:132613 Archived-At: > From: Po Lu > Date: Thu, 19 Aug 2021 15:36:02 +0800 > > > I've run across an odd issue whilst bringing up a new window system: it > seems that each glyph overlaps its surroundings by exactly one pixel, > which leads to visible artifacting. For instance, while I would have > expected the output from redisplay to be as follows: > > ["f" CHAR_GLYPH x=0 width=15 y=0 height=15] ["o" x=16 width=15 y=0 > height = 15] > > In this case "o" would actually start at 15 on the X axis, causing the > glyph "f" to be partially overdrawn. What is even more confusing is > that the output of redisplay seems to exhibit the same overlap under > other window systems, whilst no artifacting is visible. If "f" starts at 0 and its width is 15, then its last pixel is at x=14, and the following glyph can start at x=15 without any overlap. Or maybe you didn't tell enough details to understand what goes on there.