bug#63232: 28.1; image-converter may fail to display archived images

bug#63232: 28.1; image-converter may fail to display archived images

[awrhygty]

If a WEBP image is archived in a ZIP archive,
when opening the image with archive-mode,
the subfile buffer of the WEBP image is opened as a multibyte buffer.
So image-converter fails to display the image.
Sometimes a wrong image is displayed, otherwise the buffer is not
recognized as an image.

Typing 'M-x toggle-enable-multibyte-characters RET' in the subfile
buffer, image-converter works correctly.


In GNU Emacs 28.1 (build 2, x86_64-w64-mingw32)
 of 2022-04-22 built on AVALON
Windowing system distributor 'Microsoft Corp.', version 10.0.19045
System Description: Microsoft Windows 10 Pro (v10.0.2009.19045.2846)

Configured using:
 'configure --with-modules --without-dbus --with-native-compilation
 --without-compress-install CFLAGS=-O2'

Configured features:
ACL GIF GMP GNUTLS HARFBUZZ JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP
NOTIFY W32NOTIFY PDUMPER PNG RSVG SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
XPM ZLIB

(NATIVE_COMP present but libgccjit not available)

Important settings:
  value of $LANG: JPN
  locale-coding-system: cp932

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-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
  indent-tabs-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 rfc6068 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
term/bobcat japan-util iso-transl tooltip eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode mwheel dos-w32 ls-lisp
disp-table term/w32-win w32-win w32-vars term/common-win tool-bar dnd
fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow
isearch easymenu timer select scroll-bar mouse jit-lock font-lock syntax
font-core term/tty-colors frame minibuffer 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 emoji-zwj charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads w32notify
w32 lcms2 multi-tty make-network-process native-compile emacs)

Memory information:
((conses 16 58912 9066)
 (symbols 48 6717 1)
 (strings 32 20475 1504)
 (string-bytes 1 667341)
 (vectors 16 14755)
 (vector-slots 8 327403 14920)
 (floats 8 23 313)
 (intervals 56 218 0)
 (buffers 992 10))

bug#63232: 28.1; image-converter may fail to display archived images

[Eli Zaretskii]

> From: awrhygty@outlook.com
> Date: Tue, 02 May 2023 17:10:20 +0900
> 
> 
> If a WEBP image is archived in a ZIP archive,
> when opening the image with archive-mode,
> the subfile buffer of the WEBP image is opened as a multibyte buffer.
> So image-converter fails to display the image.
> Sometimes a wrong image is displayed, otherwise the buffer is not
> recognized as an image.

Emacs 29 support WebP images natively, so there's no need for
image-converter and the problem doesn't happen.

Patches to have this solved with image-converter when WebP is not
supported natively are welcome.

bug#63232: 28.1; image-converter may fail to display archived images

[awrhygty]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: awrhygty@outlook.com
>> Date: Tue, 02 May 2023 17:10:20 +0900
>> 
>> 
>> If a WEBP image is archived in a ZIP archive,
>> when opening the image with archive-mode,
>> the subfile buffer of the WEBP image is opened as a multibyte buffer.
>> So image-converter fails to display the image.
>> Sometimes a wrong image is displayed, otherwise the buffer is not
>> recognized as an image.
>
> Emacs 29 support WebP images natively, so there's no need for
> image-converter and the problem doesn't happen.
>
> Patches to have this solved with image-converter when WebP is not
> supported natively are welcome.

This bug applys not only to WEBP format, but also other binary image
formats which are supported by image-converter, such as ICO.