From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stephan Mueller Newsgroups: gmane.emacs.devel Subject: RE: Slow redisplay with long lines Date: Fri, 16 May 2014 18:08:18 +0000 Message-ID: <9711a21a06fb4257889f7541110f6017@BL2PR03MB145.namprd03.prod.outlook.com> References: <83mwein6w1.fsf@gnu.org> <83ha4qmgbs.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1400263734 19048 80.91.229.3 (16 May 2014 18:08:54 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 16 May 2014 18:08:54 +0000 (UTC) Cc: "monnier@iro.umontreal.ca" , "emacs-devel@gnu.org" To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri May 16 20:08:47 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WlMYp-00036b-Ba for ged-emacs-devel@m.gmane.org; Fri, 16 May 2014 20:08:47 +0200 Original-Received: from localhost ([::1]:37167 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlMYo-0008UC-QB for ged-emacs-devel@m.gmane.org; Fri, 16 May 2014 14:08:46 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:40709) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlMYg-0008U7-43 for emacs-devel@gnu.org; Fri, 16 May 2014 14:08:44 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WlMYZ-0005pf-Rr for emacs-devel@gnu.org; Fri, 16 May 2014 14:08:37 -0400 Original-Received: from mail-bn1lp0142.outbound.protection.outlook.com ([207.46.163.142]:45203 helo=na01-bn1-obe.outbound.protection.outlook.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WlMYZ-0005pX-NR for emacs-devel@gnu.org; Fri, 16 May 2014 14:08:31 -0400 Original-Received: from BL2PR03MB145.namprd03.prod.outlook.com (10.255.230.13) by BL2PR03MB148.namprd03.prod.outlook.com (10.255.230.27) with Microsoft SMTP Server (TLS) id 15.0.944.11; Fri, 16 May 2014 18:08:29 +0000 Original-Received: from BL2PR03MB145.namprd03.prod.outlook.com ([169.254.10.185]) by BL2PR03MB145.namprd03.prod.outlook.com ([169.254.10.185]) with mapi id 15.00.0944.000; Fri, 16 May 2014 18:08:29 +0000 Thread-Topic: Slow redisplay with long lines Thread-Index: AQHPcH3aPPu34tg1YkSZcmgMQA+zZ5tCHvBAgACS0ICAAM4tcA== Importance: low X-Priority: 5 Deferred-Delivery: Fri, 16 May 2014 18:08:00 +0000 In-Reply-To: <83ha4qmgbs.fsf@gnu.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [2001:4898:80e0:ee43::3] x-forefront-prvs: 02135EB356 x-forefront-antispam-report: SFV:NSPM; SFS:(6009001)(428001)(199002)(189002)(74316001)(76576001)(76482001)(2656002)(77982001)(99286001)(86612001)(50986999)(99396002)(76176999)(81686999)(54356999)(101416001)(86362001)(21056001)(74502001)(46102001)(87936001)(85852003)(81342001)(81542001)(80022001)(79102001)(4396001)(64706001)(20776003)(83322001)(19580395003)(19580405001)(33646001)(24736002); DIR:OUT; SFP:; SCL:1; SRVR:BL2PR03MB148; H:BL2PR03MB145.namprd03.prod.outlook.com; FPR:; MLV:sfv; PTR:InfoNoRecords; A:1; MX:1; LANG:en; received-spf: None (: microsoft.com does not designate permitted sender hosts) authentication-results: spf=none (sender IP is ) smtp.mailfrom=Stephan.Mueller@microsoft.com; X-OriginatorOrg: microsoft.onmicrosoft.com X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 X-Received-From: 207.46.163.142 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:171892 Archived-At: From: Eli Zaretskii [mailto:eliz@gnu.org]=20 " > From: Stephan Mueller " > " > Long lines slow down redisplay because it needs to scan the entire " > " > line to see how tall it will be on display. " > " " > " Why should it care about the whole line rather than only the part " > " of it that's displayed? " >=20 " > So that the line height doesn't change when scrolling horizontally " > and a taller character comes into view? " " No, horizontal scrolling causes another redisplay, which examines the " characters that came into view at that time. So, IIUC, that means that scrolling horizontally _can_ cause the user's experience to be that the height of a line was changed by looking at a different portion of it. Understood it is redisplayed (and so no doubt draws correctly), but I'd still consider the height change to be an odd behaviour. I'm curious if it was an intentional choice (perhaps in the name of perf, removing one of the reasons to scan the whole line)? =20 stephan($0.02);