From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Image transformations Date: Thu, 27 Jun 2019 16:13:42 +0300 Message-ID: <834l4bjhmh.fsf@gnu.org> References: <20190613165804.GB11266@breton.holly.idiocy.org> <83d0jhz9za.fsf@gnu.org> <20190613192724.GA11945@breton.holly.idiocy.org> <83zhmlxo6d.fsf@gnu.org> <20190613222626.GA12971@breton.holly.idiocy.org> <83o930y7cl.fsf@gnu.org> <20190615104242.GA13368@breton.holly.idiocy.org> <838su3w0de.fsf@gnu.org> <20190616152259.GA22789@breton.holly.idiocy.org> <83d0jdv68i.fsf@gnu.org> <20190617211332.GA55597@breton.holly.idiocy.org> <83a7e6na26.fsf@gnu.org> <8336jymm0g.fsf@gnu.org> <95554A73-A5B5-4407-A5B4-4F901FF5E6CF@gnu.org> <83sgrxllt1.fsf@gnu.org> <83r27gjr87.fsf@gnu.org> Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="149356"; mail-complaints-to="usenet@blaine.gmane.org" Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org To: YAMAMOTO Mitsuharu Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Jun 27 15:14:12 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 (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hgUE5-000cdN-EO for ged-emacs-devel@m.gmane.org; Thu, 27 Jun 2019 15:14:09 +0200 Original-Received: from localhost ([::1]:50648 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgUE4-0001cU-Fg for ged-emacs-devel@m.gmane.org; Thu, 27 Jun 2019 09:14:08 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:59863) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgUDt-0001c9-UX for emacs-devel@gnu.org; Thu, 27 Jun 2019 09:13:59 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:49993) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hgUDr-0002Ar-UN; Thu, 27 Jun 2019 09:13:57 -0400 Original-Received: from [176.228.60.248] (port=3463 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1hgUDr-0000hW-Cd; Thu, 27 Jun 2019 09:13:55 -0400 In-reply-to: (message from YAMAMOTO Mitsuharu on Thu, 27 Jun 2019 12:37:15 +0900) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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:238191 Archived-At: > Date: Thu, 27 Jun 2019 12:37:15 +0900 > From: YAMAMOTO Mitsuharu > Cc: monnier@iro.umontreal.ca, > emacs-devel@gnu.org > > > > Guessing from its API design, I think GDI does not internally perform > > > any (real-valued) matrix calculations, but uses some variant of > > > Bresenham's line algorithm for image transformations to prefer integer > > > arithmetics. > > > > I think the fact that SetWorldTransform exists contradicts this > > conclusion. The matrix is defined as an array of floats. > > It seems that SetWorldTransform is only effective on vector drawings, > but not on bitmap image drawings. My conclusion was different, because I saw examples of using SetWorldTransform to rotate bitmap images. But I don't think it's important enough to argue about, as we both are just guessing.