bug#64166: 29.0.92; A :box with negative vertical width does not avoid any increase in the line height

bug#64166: 29.0.92; A :box with negative vertical width does not avoid any increase in the line height

[Sebastian Miele]

In ‘src/emacs -Q’ create a buffer in fundamental mode and add the
following contents:

  text
  text
  text

At the end of the second line, evaluate (‘eval-expression’):

  (insert (propertize "text" 'face '(:box '(:line-width (-1 . -1)))))

The height of the line clearly changes.  But that is contrary to what
the manual says about the ‘:box’ face attribute:

  "A negative horizontal or vertical width −N means to draw a line of
  width N that occupies the space of the underlying text, thus avoiding
  any increase in the character height or width."

Apart from that:

(1) Using ‘:line-width (-1 . -1)’ seems to yield the exact same result
as ‘:line-width (1 . 1)’ does, both in width and in height.

(2) Using even larger negative values has no effect.
‘:line-width (-10 . -10)’ also seems to yield the exact same result as
‘:line-width (1 . 1)’ does.

Apparantly, all negative values are treates as positive 1, contrary to
what the manual states.

In GNU Emacs 29.0.92 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.17.8) of 2023-06-18 built on huette
Repository revision: a24e9e3fee59435422af0473b7ec585de2c13b4e
Repository branch: emacs-29
Windowing system distributor 'The X.Org Foundation', version 11.0.12101008
System Description: Arch Linux

Configured using:
 'configure --with-x-toolkit=gtk --with-native-compilation=yes
 --with-tree-sitter --with-json --with-mailutils --with-imagemagick'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ
IMAGEMAGICK JPEG JSON LCMS2 LIBOTF LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINPUT2
XPM GTK3 ZLIB

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

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-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
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util text-property-search time-date mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils comp comp-cstr
warnings icons subr-x rx cl-seq cl-macs gv cl-extra help-mode
cl-loaddefs cl-lib bytecomp byte-compile rmc iso-transl tooltip cconv
eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type
elisp-mode 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 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 nadvice seq simple cl-generic
indonesian philippine 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 abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit xinput2 x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 65864 6640)
 (symbols 48 7137 0)
 (strings 32 19744 3785)
 (string-bytes 1 595129)
 (vectors 16 15226)
 (vector-slots 8 279775 8789)
 (floats 8 28 24)
 (intervals 56 241 0)
 (buffers 984 13))

bug#64166: 29.0.92; A :box with negative vertical width does not avoid any increase in the line height

[Eli Zaretskii]

> From: Sebastian Miele <iota@whxvd.name>
> Date: Mon, 19 Jun 2023 14:46:17 +0200
> 
> In ‘src/emacs -Q’ create a buffer in fundamental mode and add the
> following contents:
> 
>   text
>   text
>   text
> 
> At the end of the second line, evaluate (‘eval-expression’):
> 
>   (insert (propertize "text" 'face '(:box '(:line-width (-1 . -1)))))
> 
> The height of the line clearly changes.  But that is contrary to what
> the manual says about the ‘:box’ face attribute:
> 
>   "A negative horizontal or vertical width −N means to draw a line of
>   width N that occupies the space of the underlying text, thus avoiding
>   any increase in the character height or width."

The above is incorrect face specification.  Try this instead:

  (insert (propertize "text" 'face '(:box (:line-width (-1 . -1)))))

> Apart from that:
> 
> (1) Using ‘:line-width (-1 . -1)’ seems to yield the exact same result
> as ‘:line-width (1 . 1)’ does, both in width and in height.
> 
> (2) Using even larger negative values has no effect.
> ‘:line-width (-10 . -10)’ also seems to yield the exact same result as
> ‘:line-width (1 . 1)’ does.
> 
> Apparantly, all negative values are treates as positive 1, contrary to
> what the manual states.

What happens if you remove the redundant quote?

bug#64166: 29.0.92; A :box with negative vertical width does not avoid any increase in the line height

[Sebastian Miele]

Eli Zaretskii <eliz@gnu.org> writes:

>> At the end of the second line, evaluate (‘eval-expression’):
>> 
>>   (insert (propertize "text" 'face '(:box '(:line-width (-1 . -1)))))
>> 
>> The height of the line clearly changes.  But that is contrary to what
>> the manual says about the ‘:box’ face attribute:
>> 
>>   "A negative horizontal or vertical width −N means to draw a line of
>>   width N that occupies the space of the underlying text, thus avoiding
>>   any increase in the character height or width."
>
> The above is incorrect face specification.  Try this instead:
>
>   (insert (propertize "text" 'face '(:box (:line-width (-1 . -1)))))
>
>> Apart from that:
>> 
>> (1) Using ‘:line-width (-1 . -1)’ seems to yield the exact same result
>> as ‘:line-width (1 . 1)’ does, both in width and in height.
>> 
>> (2) Using even larger negative values has no effect.
>> ‘:line-width (-10 . -10)’ also seems to yield the exact same result as
>> ‘:line-width (1 . 1)’ does.
>> 
>> Apparantly, all negative values are treates as positive 1, contrary to
>> what the manual states.
>
> What happens if you remove the redundant quote?

Everything works as expected.  Sorry for the noise.

All the best!

bug#64166: 29.0.92; A :box with negative vertical width does not avoid any increase in the line height

[Eli Zaretskii]

tags 64166 notabug
close 64166
thanks

> From: Sebastian Miele <iota@whxvd.name>
> Cc: 64166@debbugs.gnu.org
> Date: Tue, 20 Jun 2023 18:12:25 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> At the end of the second line, evaluate (‘eval-expression’):
> >> 
> >>   (insert (propertize "text" 'face '(:box '(:line-width (-1 . -1)))))
> >> 
> >> The height of the line clearly changes.  But that is contrary to what
> >> the manual says about the ‘:box’ face attribute:
> >> 
> >>   "A negative horizontal or vertical width −N means to draw a line of
> >>   width N that occupies the space of the underlying text, thus avoiding
> >>   any increase in the character height or width."
> >
> > The above is incorrect face specification.  Try this instead:
> >
> >   (insert (propertize "text" 'face '(:box (:line-width (-1 . -1)))))
> >
> >> Apart from that:
> >> 
> >> (1) Using ‘:line-width (-1 . -1)’ seems to yield the exact same result
> >> as ‘:line-width (1 . 1)’ does, both in width and in height.
> >> 
> >> (2) Using even larger negative values has no effect.
> >> ‘:line-width (-10 . -10)’ also seems to yield the exact same result as
> >> ‘:line-width (1 . 1)’ does.
> >> 
> >> Apparantly, all negative values are treates as positive 1, contrary to
> >> what the manual states.
> >
> > What happens if you remove the redundant quote?
> 
> Everything works as expected.  Sorry for the noise.

No sweat, I'm therefore closing the bug.