Subject: bug#47819: closed (Re: bug#47819: 8.0.50; When :height/:width image attribute is specified, :scale factor is not applied)

From: [email-masked] (GNU bug Tracking System)
Date: Sat, 17 Apr 2021 08:43:02 +0000

Your bug report

#47819: 8.0.50; When :height/:width image attribute is specified, :scale factor is not applied

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
47819: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=47819
GNU Bug Tracking System
Contact [email-masked] with problems

Subject: Re: bug#47819: 8.0.50; When :height/:width image attribute is specified, :scale factor is not applied
From: Alan Third <[email-masked]>
To: David Ponce <[email-masked]>, [email-masked]
Date: Sat, 17 Apr 2021 09:42:18 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

On Sat, Apr 17, 2021 at 09:23:55AM +0100, Alan Third wrote:
> 
> I don't know why you would want to use scale with em dimensions, since
> you can just set the em dimensions directly.
> 
> For example ":scale 2 :height '(1 . em)" is exactly the same as
> ":scale 1 :height '(2 . em)", so why bother?
> 
> Plus if you specify something to be 1em in height, then create-image
> applies its magic scale factor, you end up with something that is not
> 1em in height.
> 
> So yeah, I'm not convinced that this is behaviour we want.

OK, I'm still convinced this isn't really the behaviour we want, but I
did some further investigation and realised this is a bug introduced
by me recently. I thought it had worked this way for a long time.

I'll just push the change up to fix it.
-- 
Alan Third

Subject: 8.0.50; When :height/:width image attribute is specified, :scale factor is not applied
From: David Ponce <[email-masked]>
To: [email-masked]
Date: Fri, 16 Apr 2021 08:16:20 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hello,

For the image :scale attribute the Elisp reference manual say that:

      If both ‘:scale’ and ‘:height’/‘:width’ are
      specified, the height/width will be adjusted by the specified
      scaling factor.

It seems, however, that this is not true, when the :height or :width
or both attributes of an image are specified, the :scale factor is not
applied.  For ex., evaluating the below code in the *scratch* buffer
should produce images with same size, but in the 2nd case the scale
factor is not applied:

(progn
   (insert-image
    (find-image
     '((:file "/usr/share/icons/oxygen/base/22x22/places/folder.png"
              :type png
              :scale 2
              ))))
   (insert-image
    (find-image
     '((:file "/usr/share/icons/oxygen/base/22x22/places/folder.png"
              :type png
              :scale 2
              :height 22
              :width 22
              ))))
   )

So, either the manual is wrong, or (better IMO) the code should be
fixed.

Thanks & Regards,
David Ponce

In GNU Emacs 28.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version 3.24.28, cairo version 1.16.0)
  of 2021-04-15 built on kilauea
Repository revision: c2372096433e6a7ab173e5f1993f0c65b85f353e
Repository branch: master
Windowing system distributor 'Fedora Project', version 11.0.12011000
System Description: Fedora 33 (KDE Plasma)

Configured using:
  'configure --prefix=/home/dponce --with-cairo
  PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/lib/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
X11 XDBE XIM XPM GTK3 ZLIB

Important settings:
   value of $LC_TIME: fr_FR.utf8
   value of $LANG: fr_FR.UTF-8
   locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
   tooltip-mode: t
   global-eldoc-mode: t
   eldoc-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   tool-bar-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   blink-cursor-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t
   line-number-mode: t
   transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg epg-config gnus-util rmail
rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map text-property-search time-date
subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
iso-transl tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page tab-bar menu-bar
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cl-preloaded nadvice button loaddefs faces cus-face macroexp files
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mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 50691 7522)
  (symbols 48 6501 1)
  (strings 32 18168 1362)
  (string-bytes 1 604792)
  (vectors 16 12723)
  (vector-slots 8 171820 12342)
  (floats 8 23 45)
  (intervals 56 197 0)
  (buffers 992 10))