GNU bug report logs - #75928
31.0.50; `dom-print' often fails to print an SVG DOM

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From: David Ponce <da_vid <at> orange.fr>
To: 75928 <at> debbugs.gnu.org
Subject: bug#75928: 31.0.50; `dom-print' often fails to print an SVG DOM
Date: Wed, 29 Jan 2025 16:52:28 +0100

[Message part 1 (text/plain, inline)]

Hello,

Currently `dom-print' is mostly unusable to print an SVG DOM because it
fails as soon as it encounters an attribute value which is not a string.
This is unfortunate, because `dom-print' can be very useful for
examining a DOM by pretty-printing it.

Here is a simple example that illustrates the problem:

(require 'svg)
(let ((svg (svg-create 100 100)))
  (svg-rectangle svg 0 0 "100%" "100%" :fill "blue")
  (svg-text svg "A text" :x 0 :y 55 :stroke "yellow" :fill "yellow")
  (dom-print svg t t))

Which produce this backtrace when evaluated in the *scratch* buffer:

Debugger entered--Lisp error: (wrong-type-argument sequencep 100)
  replace-regexp-in-string("[&<>\"]" #f(compiled-function (c) #<bytecode 0x1119c0c6891a2a03>) 100)
  url-insert-entities-in-string(100)
  dom-print((svg ((width . 100) (height . 100) (version . "1.1") (xmlns . "http://www.w3.org/2000/svg") (xmlns:xlink . "http://www.w3.org/1999/xlink")) (rect ((width . "100%") (height . "100%") (x . 0) (y . 0) (fill . "blue"))) (text ((fill . "yellow") (stroke . "yellow") (y . 55) (x . 0)) "A text")) t t)
  (let ((svg (svg-create 100 100))) (svg-rectangle svg 0 0 "100%" "100%" :fill "blue") (svg-text svg "A text" :x 0 :y 55 :stroke "yellow" :fill "yellow") (dom-print svg t t))
  (progn (let ((svg (svg-create 100 100))) (svg-rectangle svg 0 0 "100%" "100%" :fill "blue") (svg-text svg "A text" :x 0 :y 55 :stroke "yellow" :fill "yellow") (dom-print svg t t)))
  eval((progn (let ((svg (svg-create 100 100))) (svg-rectangle svg 0 0 "100%" "100%" :fill "blue") (svg-text svg "A text" :x 0 :y 55 :stroke "yellow" :fill "yellow") (dom-print svg t t))) t)
  elisp--eval-last-sexp(t)
  #f(compiled-function () #<bytecode 0x299b97085c5ba>)()
  handler-bind-1(#f(compiled-function () #<bytecode 0x299b97085c5ba>) (error) eval-expression--debug)
  eval-last-sexp(t)
  eval-print-last-sexp(nil)
  funcall-interactively(eval-print-last-sexp nil)
  call-interactively(eval-print-last-sexp nil nil)
  command-execute(eval-print-last-sexp)
 
The cause is that `dom-print' calls the function
`url-insert-entities-in-string' to convert special characters in
attribute value assuming this value is a string, which is not always
true in an SVG DOM.

I propose the attached very simple patch that solves the issue.
Here is a possible changelog:

2025-01-29  David Ponce  <da_vid <at> orange.fr>

	* dom.el (dom-print): Ensure to pass a string to
	`url-insert-entities-in-string'.

With this patch applied the above example prints the expected result:

<svg width="100" height="100" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
  <rect width="100%" height="100%" x="0" y="0" fill="blue" />
  <text fill="yellow" stroke="yellow" y="55" x="0">A text</text>
</svg>nil



In GNU Emacs 31.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.43, cairo version 1.18.0) of 2025-01-28
Repository revision: 8c4a4b4eab8ac4dc26e65d552821f3f0b49c79c4
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
System Description: Fedora Linux 40 (KDE Plasma)

Configured using:
 'configure --with-native-compilation=no'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES 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_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
  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
  minibuffer-regexp-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.

[dom-patch-V0.patch (text/x-patch, attachment)]

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