bug#38109: 27.0.50; xpm image scaling doesn't work

[Adam Sjøgren]

I *think* scaling of xpm images used to work (maybe back when
ImageMagick did the scaling?) - but it doesn't now, e.g. if you go:

  (insert-image (create-image 
"/usr/src/emacs/etc/images/smilies/medium/wry.xpm" nil nil :scale 20.0))

a tiny 16x16 image is inserted. The expected result was a huge 320x320
image.

If I convert the image to png:

  convert /usr/src/emacs/etc/images/smilies/medium/wry.xpm /tmp/wry.gif

and insert it with:

  (insert-image (create-image "/tmp/wry.gif" nil nil :scale 20.0))

I do get a bug 320x320 pixel image in my buffer.

(Interestingly, if I convert it to PNG and insert it, I get a 320x320
pixel image, with the original small 16x16 graphics inside it, so
scaling seems to not work for PNG either, in a different way.)

This is what it looks like in emacs -Q:

In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.12)
 of 2019-10-31 built on tullinupnew
Repository revision: 058e293fddeaa7821f13055b451951360a135b0c
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux bullseye/sid

Recent messages:
Reading active file via nnml...done
Reading active file from archive via nnml...
Opening nnml server on archive...done
Reading active file from archive via nnml...done
Reading active file via nnir...done
Reading active file via nndraft...done
Opening nnml server...done
Registering 1 specific articles as ham using backend spam-use-move
Opening nntp server on gm...done
Mark set

Configured using:
 'configure --without-pop'

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

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

Major mode: Group

Minor modes in effect:
  gnus-topic-mode: t
  gnus-undo-mode: t
  pixel-scroll-mode: t
  engine-mode: t
  global-magit-file-mode: t
  magit-auto-revert-mode: t
  global-git-commit-mode: t
  dumb-jump-mode: t
  which-function-mode: t
  global-auto-complete-mode: t
  shell-dirtrack-mode: t
  save-place-mode: t
  jabber-activity-mode: t
  winner-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t

Load-path shadows:
/usr/share/emacs/site-lisp/elpa-src/ess-18.10.2/debian-autoloads hides 
/usr/share/emacs/site-lisp/elpa-src/dpkg-dev-el-37.0/debian-autoloads
/usr/share/emacs/site-lisp/elpa-src/boxquote-2.1/boxquote hides 
~/elisp/extra/boxquote
~/elisp/let-alist/let-alist hides ~/elisp/extra/let-alist
~/elisp/with-editor/with-editor hides ~/elisp/extra/with-editor
~/elisp/with-editor/with-editor-autoloads hides 
~/elisp/extra/with-editor-autoloads
~/elisp/let-alist/let-alist hides /usr/src/emacs/lisp/emacs-lisp/let-alist

Features:
(shadow emacsbug bbdb-gnus-aux misearch multi-isearch shr-color color
canlock ispell bbdb-message sendmail nnir compface gnus-gravatar
gravatar sort smiley gnus-cite mm-archive gnus-async gnus-bcklg gnus-dup
qp gnus-ml gmane gnus-topic paren utf-7 imap rfc2104 epa-file
network-stream nnml bbdb-gnus bbdb-mua nnnil gnus-demon gnus-delay
gnus-draft gnus-agent gnus-srvr gnus-score score-mode nnvirtual nntp
gnus-cache nndraft nnmh mail-extr spam spam-stat bbdb-com gnus-uu yenc
gnus-msg gnus-html url-queue help-fns radix-tree url-cache bbdb-picture
gnus-art mm-uu mml2015 mm-view mml-smime smime dig gnus-sum gnus-group
gnus-undo gnus-fun hashcash gnus-start gnus-cloud nnimap nnmail
mail-source utf7 netrc nnoo gnus-spec gnus-int gnus-range gnus-win
gopher shr with-url mm-url gnus nnheader svg pixel-scroll litable
engine-mode gitpatch magithub magithub-ci magithub-issue magithub-cache
magithub-core magit-submodule magit-obsolete magit-blame magit-stash
magit-bisect magit-push magit-pull magit-fetch magit-clone magit-remote
magit-commit magit-sequence magit-notes magit-worktree magit-tag
magit-merge magit-branch magit-reset magit-collab ghub-graphql treepy
graphql ghub url-http url-gw nsm url-auth let-alist magit-files
magit-refs magit-status magit magit-repos magit-apply magit-wip
magit-log magit-diff smerge-mode diff magit-core magit-autorevert
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mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045 mm-util
ietf-drums mail-prsvr mailabbrev mail-utils gmm-utils mailheader
pcvs-util with-editor term disp-table ehelp eshell esh-cmd esh-ext
esh-opt esh-proc esh-io esh-arg esh-module esh-groups esh-util wgrep-ag
wgrep grep ag vc-svn find-dired dumb-jump f dash s ucs-normalize etags
fileloop generator tex-site auto-loads expand-region
cperl-mode-expansions text-mode-expansions html-mode-expansions
er-basic-expansions expand-region-core expand-region-custom which-func
cperl-mode auto-complete-config auto-complete popup cl-extra help-mode
ess-site ess-toolbar ess-mouse mouseme ess-swv ess-noweb
ess-noweb-font-lock-mode ess-jags-d ess-bugs-l essd-els ess-xls-d
ess-vst-d ess-stata-mode ess-stata-lang cc-vars cc-defs make-regexp
ess-sp6w-d ess-sp5-d ess-sp4-d ess-sas-d ess-sas-l ess-sas-a ess-s4-d
ess-s3-d ess-omg-d ess-omg-l ess-arc-d ess-lsp-l ess-sp6-d ess-dde
ess-sp3-d ess-julia julia-mode ess-r-mode ess-r-flymake rx flymake-proc
flymake warnings thingatpt ess-r-xref xref project ess-trns
ess-r-package ess-r-syntax pcase ess-r-completion ess-roxy ess-rd essddr
noutline outline hideshow ess-s-lang speedbar sb-image ezimage dframe
ess-help info reporter ess-mode ess ess-noweb-mode ess-inf ess-tracebug
easy-mmode ess-generics compile ess-utils ido ess-custom executable
tramp tramp-loaddefs trampver tramp-integration files-x tramp-compat
shell pcomplete parse-time iso8601 ls-lisp debian-changelog-mode imenu
add-log dpkg-dev-el saveplace vc vc-dispatcher bbdb derived bbdb-site
timezone bbdb-loaddefs boxquote rect jabber-http-file-upload url
url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util jabber-print-html jabber-otr jabber
jabber-notifications notifications jabber-libnotify dbus jabber-awesome
jabber-osd jabber-wmii jabber-xmessage jabber-festival jabber-sawfish
jabber-ratpoison jabber-tmux jabber-screen jabber-socks5
jabber-ft-server jabber-si-server jabber-ft-client jabber-ft-common
jabber-si-client jabber-si-common jabber-feature-neg jabber-truncate
jabber-time jabber-autoaway time-date jabber-vcard-avatars
jabber-chatstates jabber-events jabber-vcard jabber-avatar mailcap
jabber-activity jabber-watch jabber-modeline advice jabber-ahc-presence
jabber-ahc jabber-version jabber-ourversion jabber-muc-nick-completion
hippie-exp comint ansi-color jabber-browse jabber-search jabber-register
jabber-roster format-spec jabber-presence jabber-muc jabber-bookmarks
jabber-private jabber-muc-nick-coloring hexrgb jabber-widget
jabber-disco wid-edit jabber-chat jabber-history jabber-chatbuffer
jabber-alert jabber-iq jabber-core jabber-console sgml-mode dom ewoc
jabber-keymap jabber-sasl sasl sasl-anonymous sasl-login sasl-plain fsm
jabber-logon jabber-conn srv dns starttls tls jabber-xml xml jabber-menu
jabber-util cl winner ring gnutls puny find-file-from-selection
find-lisp dired dired-loaddefs cap-words superword subword edmacro
kmacro server finder-inf package easymenu browse-url url-handlers
url-parse auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache json subr-x map url-vars seq byte-opt gv bytecomp
byte-compile cconv cl-loaddefs cl-lib 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 rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads dbusbind inotify lcms2 dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 903266 194934)
 (symbols 48 41175 5)
 (strings 32 264148 17332)
 (string-bytes 1 11187328)
 (vectors 16 82347)
 (vector-slots 8 2589302 201528)
 (floats 8 706 677)
 (intervals 56 1323 779)
 (buffers 1000 93))

-- 
 "Please don't "meh" the panopticon. You are                   Adam Sjøgren
  not making things better by doing that."                asjo@koldfront.dk